Design of Super-Paramagnetic Core-Shell Nanoparticles for Enhanced Performance of Inverted Polymer Solar Cells.

PubMed

Jaramillo, Johny; Boudouris, Bryan W; Barrero, César A; Jaramillo, Franklin

2015-11-18

Controlling the nature and transfer of excited states in organic photovoltaic (OPV) devices is of critical concern due to the fact that exciton transport and separation can dictate the final performance of the system. One effective method to accomplish improved charge separation in organic electronic materials is to control the spin state of the photogenerated charge-carrying species. To this end, nanoparticles with unique iron oxide (Fe3O4) cores and zinc oxide (ZnO) shells were synthesized in a controlled manner. Then, the structural and magnetic properties of these core-shell nanoparticles (Fe3O4@ZnO) were tuned to ensure superior performance when they were incorporated into the active layers of OPV devices. Specifically, small loadings of the core-shell nanoparticles were blended with the previously well-characterized OPV active layer of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Upon addition of the core-shell nanoparticles, the performance of the OPV devices was increased up to 25% relative to P3HT-PCBM active layer devices that contained no nanoparticles; this increase was a direct result of an increase in the short-circuit current densities of the devices. Furthermore, it was demonstrated that the increase in photocurrent was not due to enhanced absorption of the active layer due to the presence of the Fe3O4@ZnO core-shell nanoparticles. In fact, this increase in device performance occurred because of the presence of the superparamagnetic Fe3O4 in the core of the nanoparticles as incorporation of ZnO only nanoparticles did not alter the device performance. Importantly, however, the ZnO shell of the nanoparticles mitigated the negative optical effect of Fe3O4, which have been observed previously. This allowed the core-shell nanoparticles to outperform bare Fe3O4 nanoparticles when the single-layer nanoparticles were incorporated into the active layer of OPV devices. As such, the new materials described here present a tangible pathway toward the development of enhanced design schemes for inorganic nanoparticles such that magnetic and energy control pathways can be tailored for flexible electronic applications.

Effect of ZnO:Cs2CO3 on the performance of organic photovoltaics

PubMed Central

2014-01-01

We demonstrate a new solution-processed electron transport layer (ETL), zinc oxide doped with cesium carbonate (ZnO:Cs2CO3), for achieving organic photovoltaics (OPVs) with good operational stability at ambient air. An OPV employing the ZnO:Cs2CO3 ETL exhibits a fill factor of 62%, an open circuit voltage of 0.90 V, and a short circuit current density of −6.14 mA/cm2 along with 3.43% power conversion efficiency. The device demonstrated air stability for a period over 4 weeks. In addition, we also studied the device structure dependence on the performance of organic photovoltaics. Thus, we conclude that ZnO:Cs2CO3 ETL could be employed in a suitable architecture to achieve high-performance OPV. PMID:25045340

SU-E-T-163: Thin-Film Organic Photocell (OPV) Properties in MV and KV Beams for Dosimetry Applications.

PubMed

Ng, S K; Hesser, J; Zhang, H; Gowrisanker, S; Yakushevich, S; Shulhevich, Y; Abkai, C; Wack, L; Zygmanski, P

2012-06-01

To characterize dosimetric properties of low-cost thin film organic-based photovoltaic (OPV) cells to kV and MV x-ray beams for their usage as large area dosimeter for QA and patient safety monitoring device. A series of thin film OPV cells of various areas and thicknesses were irradiated with MV beams to evaluate the stability and reproducibility of their response, linearity and sensitivity to absorbed dose. The OPV response to x-rays of various linac energies were also characterized. Furthermore the practical (clinical) sensitivity of the cells was determined using IMRT sweeping gap test generated with various gap sizes. To evaluate their potential usage in the development of low cost kV imaging device, the OPV cells were irradiated with kV beam (60-120 kVp) from a fluoroscopy unit. Photocell response to the absorbed dose was characterized as a function of the organic thin film thickness and size, beam energy and exposure for kV beams as well. In addition, photocell response was determined with and without thin plastic scintillator. Response of the OPV cells to the absorbed dose from kV and MV beams are stable and reproducible. The photocell response was linearly proportional to the size and about slightly decreasing with the thickness of the organic thin film, which agrees with the general performance of the photocells in visible light. The photocell response increases as a linear function of absorbed dose and x-ray energy. The sweeping gap tests performed showed that OPV cells have sufficient practical sensitivity to measured MV x-ray delivery with gap size as small as 1 mm. With proper calibration, the OPV cells could be used for online radiation dose measurement for quality assurance and patient safety purposes. Their response to kV beam show promising potential in development of low cost kV radiation detection devices. © 2012 American Association of Physicists in Medicine.

Organic Photovoltaic Devices Based on Oriented n-Type Molecular Films Deposited on Oriented Polythiophene Films.

PubMed

Mizokuro, Toshiko; Tanigaki, Nobutaka; Miyadera, Tetsuhiko; Shibata, Yousei; Koganezawa, Tomoyuki

2018-04-01

The molecular orientation of π-conjugated molecules has been reported to significantly affect the performance of organic photovoltaic devices (OPVs) based on molecular films. Hence, the control of molecular orientation is a key issue toward the improvement of OPV performance. In this research, oriented thin films of an n-type molecule, 3,4,9,10-Perylenetetracarboxylic Bisbenzimida-zole (PTCBI), were formed by deposition on in-plane oriented polythiophene (PT) films. Orientation of the PTCBI films was evaluated by polarized UV-vis spectroscopy and 2D-Grazing incidence X-ray diffraction. Results indicated that PTCBI molecules on PT film exhibit nearly edge-on and in-plane orientation (with molecular long axis along the substrate), whereas PTCBI molecules without PT film exhibit neither. OPVs composed of PTCBI molecular film with and without PT were fabricated and evaluated for correlation of orientation with performance. The OPVs composed of PTCBI film with PT showed higher power conversion efficiency (PCE) than that of film without PT. The experiment indicated that in-plane orientation of PTCBI molecules absorbs incident light more efficiently, leading to increase in PCE.

Systematic Investigation of Organic Photovoltaic Cell Charge Injection/Performance Modulation by Dipolar Organosilane Interfacial Layers

DTIC Science & Technology

2013-08-13

performance in bulk- heterojunction (BHJ) organic photovoltaic (OPV) cells, the glass/tin-doped indium oxide (ITO) anodes are modified with a series of...anode in bulk- heterojunction (BHJ) organic photovoltaic cells (OPVs) plays a vital role in enhancing device performance. Appropriately tailored IFLs...unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT With the goal of investigating and enhancing anode performance in bulk- heterojunction (BHJ) organic

Hierarchical Nanomorphologies Promote Exciton Dissociation in Polymer: Fullerene Bulk Heterojunction Solar Cells

NASA Astrophysics Data System (ADS)

Chen, Wei; Darling, Seth

2012-02-01

In the last fifteen years, research efforts have led to organic photovoltaic (OPV) devices with power conversion efficiencies (PCEs) up to ˜8%, but these values are still insufficient for the devices to become widely marketable. To further improve solar cell performance a thorough understanding of the complex structure-property relationships in the OPV devices is required. In this work, we demonstrated that the OPV active layer of PTB7:fullerene bulk heterojunction (BHJ) solar cells, which set a historic record of PCE (7.4%), involves hierarchical nanomorphologies ranging from several nanometers of crystallites to tens of nanometers of nanocrystallite aggregates in PTB7-rich and fullerene-rich domains, themselves hundreds of nanometers in size. These hierarchical nanomorphologies with optimum crystallinity and intermixing of PTB7 with fullerenes are coupled to significantly enhanced exciton dissociation, which consequently contribute to photocurrent, leading to the superior performance of PTB7:fullerene BHJ solar cells. New insights of performance-related structures afforded by the current study should aid in the rational design of even higher performance polymeric solar cells.

Interfacial thermal degradation in inverted organic solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greenbank, William; Hirsch, Lionel; Wantz, Guillaume

2015-12-28

The efficiency of organic photovoltaic (OPV) solar cells is constantly improving; however, the lifetime of the devices still requires significant improvement if the potential of OPV is to be realised. In this study, several series of inverted OPV were fabricated and thermally aged in the dark in an inert atmosphere. It was demonstrated that all of the devices undergo short circuit current-driven degradation, which is assigned to morphology changes in the active layer. In addition, a previously unreported, open circuit voltage-driven degradation mechanism was observed that is highly material specific and interfacial in origin. This mechanism was specifically observed inmore » devices containing MoO{sub 3} and silver as hole transporting layers and electrode materials, respectively. Devices with this combination were among the worst performing devices with respect to thermal ageing. The physical origins of this mechanism were explored by Rutherford backscattering spectrometry and atomic force microscopy and an increase in roughness with thermal ageing was observed that may be partially responsible for the ageing mechanism.« less

Homogeneous PCBM layers fabricated by horizontal-dip coating for efficient bilayer heterojunction organic photovoltaic cells.

PubMed

Huh, Yoon Ho; Bae, In-Gon; Jeon, Hong Goo; Park, Byoungchoo

2016-10-31

We herein report a homogeneous [6,6]-phenyl C₆₁ butyric acid methyl ester (PCBM) layer, produced by a solution process of horizontal-dipping (H-dipping) to improve the photovoltaic (PV) effects of bilayer heterojunction organic photovoltaic cells (OPVs) based on a bi-stacked poly(3-hexylthiophene) (P3HT) electron donor layer and a PCBM electron acceptor layer (P3HT/PCBM). It was shown that a homogeneous and uniform coating of PCBM layers in the P3HT/PCBM bilayer OPVs resulted in reliable and reproducible device performance. We recorded a power conversion efficiency (PCE) of 2.89%, which is higher than that (2.00%) of bilayer OPVs with a spin-coated PCBM layer. Moreover, introducing surfactant additives of poly(oxyethylene tridecyl ether) (PTE) into the homogeneous P3HT/PCBM PV layers resulted in the bilayer OPVs showing a PCE value of 3.95%, which is comparable to those of conventional bulk-heterojunction (BHJ) OPVs (3.57-4.13%) fabricated by conventional spin-coating. This improved device performance may be attributed to the selective collection of charge carriers at the interfaces among the active layers and electrodes due to the PTE additives as well as the homogeneous formation of the functional PCBM layer on the P3HT layer. Furthermore, H-dip-coated PCBM layers were deposited onto aligned P3HT layers by a rubbing technique, and the rubbed bilayer OPV exhibited improved in-plane anisotropic PV effects with PCE anisotropy as high as 1.81, which is also higher than that (1.54) of conventional rubbed BHJ OPVs. Our results suggest that the use of the H-dip-coating process in the fabrication of PCBM layers with the PTE interface-engineering additive could be of considerable interest to those seeking to improve PCBM-based opto-electrical organic thin-film devices.

Mixing Behavior in Small Molecule: Fullerene Organic Photovoltaics [On the Mixing Behavior in Small Molecule: Fullerene Organic Photovoltaics

DOE PAGES

Oosterhout, Stefan D.; Savikhin, Victoria; Zhang, Junxiang; ...

2017-02-22

Here, we report a novel method to determine the amount of pure, aggregated phase of donor and acceptor in organic photovoltaic (OPV) bulk heterojunctions. By determination of the diffraction intensity per unit volume for both donor and acceptor, the volume content of pure, aggregated donor and acceptor in the blend can be determined. We find that for the small molecule X2:[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) system, in contrast to most polymer systems, all the PCBM is aggregated, indicating there is negligible miscibility of PCBM with X2. This provides an explanation why the performance of OPV devices of X2:PCBM are highmore » over a large range of PCBM concentrations. This is in contrast to many other OPV blends, where PCBM forms a mixed phase with the donor and does not provide sufficient transport for electrons when the PCBM concentration is low. This study demonstrates that a mixed phase is not necessarily a requirement for good OPV device performance.« less

Using resonant x-ray scattering to determine how structure controls the charge generation process in PCPDTBT:PC70BM solar cells

NASA Astrophysics Data System (ADS)

Pope, Michael; Waldrip, Matthew; Ferron, Thomas; Collins, Brian

Increased solar power conversion efficiencies to 12% in bulk heterojunction organic photovoltaics (OPVs) continue to brighten their prospects as an economically viable source of solar energy. It is known that OPV performance can be enhanced through processing additives that change the nanostructure. We track these critical structure-property relationships in the OPV system PCPDTBT:PC70BM while varying the amount of DIO additive. Resonant Soft X-ray Scattering reveals domain purity, domain size, and molecular orientation to highlight the system's complex dependence on DIO concentration. We will show the effect the resulting structure has on charge generation and recombination via in-situ transient and steady state optoelectronic measurements. By measuring structure, excited state dynamics and device performance all on the same sample enables direct relationships to be measured. We show that the appropriate balance of crystallinity, domain size and domain purity are important for optimized excited state dynamics and device performance.

Molecular materials for high performance OPV devices (Conference Presentation)

NASA Astrophysics Data System (ADS)

Jones, David J.

2016-09-01

We recently reported the high performing molecular donor for OPV devices based on a benzodithiophene core, a terthiophene bridge and a rhodamine acceptor (BTR) [1]. In this work we optimized side-chain placement of a known chromophore by ensuring the thiophene hexyl side-chains are regioregular, which should allow the chromophore to lie flat. The unexpected outcome was a nematic liquid crystalline material with significantly improved performance (now 9.6% PCE), excellent charge transport properties, reduced geminate recombination rates and excellent performance with active layers up to 400nm. Three phase changes were indicated by DSC analysis with a melt to a crystalline domain at 175 oC, transition to a nematic liquid crystalline domain at 186 oC and an isotropic melt at 196 oC. In our desire to better understand the structure property relationships of this class of p-type organic semiconductor we have synthesized a series of analogues where the length of the chromophore has been altered through modification of the oligothiophene bridge to generate, the monothiophene (BMR), the bisthiophene (BBR), the known terthiophene (BTR), the quaterthiophene (BQR) and the pentathiophene (BPR). BMR, BBR and BPR have clean melting points while BQR, like BTR shows a complicated series of phase transitions. Device efficiencies after solvent vapour annealing are BMR (3.5%), BBR (6.0%), BTR (9.3%), BQR (9.4%), and BPR (8.7%) unoptimised. OPV devices with BTR in the active layer are not stable under thermal annealing, however the bridge extended BQR and BPR form thermally stable devices. We are currently optimising these devices, but initial results indicate PCEs >9% for thermally annealed devices containing BQR, while BPR devices have not yet been optimised and have PCEs > 8%. In order to develop the device performance we have included BQR in ternary devices with the commercially available PTB7-Th and we report device efficiencies of over 10.5%. We are currently optimising device assembly and annealing conditions and relating these back to key materials properties. I will discuss the development of these new materials, their materials properties, structural data, and optimised device performance. I will examination of chromophore length on the Nematic Liquid Crystalline properties and on materials development and performance resulting in materials with > 9% PCE in OPV. [1] Sun, K.; Xiao, Z.; Lu, S.; Zajaczkowski, W.; Pisula, W.; Hanssen, E.; White, J. M.; Williamson, R. M.; Subbiah, J.; Ouyang, J.; Holmes, A. B.; Wong, W. W.; Jones, D. J., Nat. Commun. 2015, 6, 6013. DOI: 10.1038/ncomms7013

Strategies toward High Performance Organic Photovoltaic Cell: Material and Process

NASA Astrophysics Data System (ADS)

Kim, Bong Gi

The power conversion efficiency of organic photovoltaic (OPV) cells has been rapidly improved during the last few years and currently reaches around 10 %. The performance is evenly governed by absorption, exciton diffusion, exciton dissociation, carrier transfer, and collection efficiencies. Establishing a better understanding of OPV device physics combined with the development of new materials for each executive step contributes to this dramatic improvement. This dissertation focuses mainly on material design and development to correlate the intrinsic properties of organic semiconductors and the OPV performance. The introductory Chapter 1 briefly reviews the motivation of OPV research, its working mechanism, and representative organic materials for OPV application. Chapter 2 discusses the modulation of conjugated polymer's (CP's) absorption behavior and an efficient semi-empirical approach to predict CP's energy levels from its constituent monomers' HOMO/LUMO values. A strong acceptor lowered both the HOMO and LUMO levels of the CP, but the LUMO dropped more rapidly which ultimately produced a narrowed band-gap in the electron donating/accepting alternating copolymer system. In addition, the energy level difference between the CP and the constituent monomers converged to a constant value, providing an energy level prediction tool. Chapter 3 illustrates the systematic investigation on the relationship between the molecular structure of an energy harvesting organic dye and the exciton dissociation efficiency. The study showed that the quantum yield decreased as the exciton binding energy increases, and dipole moment direction should be properly oriented in the dye framework in order to improve photo-current generation when used in a dye sensitized photovoltaic device. Chapter 4 demonstrates the ultrasonic-assisted self-assembly of CPs in solution, rapidly and efficiently. Ultrasonication combined with dipolar media accelerated CP's aggregation, and the effect of CP's aggregation on the enhancement of OPV performance by promoting photo-current generation and increasing carrier mobility was systematically investigated. The correlation between the chemical structure of a CP and it aggregation behavior is further described in Chapter 5. To promote CP aggregate, a planar chain conformation was advantageous and CP aggregation improved hole mobility in the OPV device. However, thermally induced CP aggregates caused strong charge recombination, resulting in open circuit voltage drop. In Chapter 6, a novel polymer design principle to enable directed CP alignment is discussed. Regulating chain planarity and preventing massive crystallization of CP achieved by the developed molecular design principle allowed directed CP alignment under small shear flow.

Photoprecursor approach as an effective means for preparing multilayer organic semiconducting thin films by solution processes

PubMed Central

Yamaguchi, Yuji; Suzuki, Mitsuharu; Motoyama, Takao; Sugii, Shuhei; Katagiri, Chiho; Takahira, Katsuya; Ikeda, Shinya; Yamada, Hiroko; Nakayama, Ken-ichi

2014-01-01

The vertical composition profile of active layer has a major effect on the performance of organic photovoltaic devices (OPVs). While stepwise deposition of different materials is a conceptually straightforward method for controlled preparation of multi-component active layers, it is practically challenging for solution processes because of dissolution of the lower layer. Herein, we overcome this difficulty by employing the photoprecursor approach, in which a soluble photoprecursor is solution-deposited then photoconverted in situ to a poorly soluble organic semiconductor. This approach enables solution-processing of the p-i-n triple-layer architecture that has been suggested to be effective in obtaining efficient OPVs. We show that, when 2,6-dithienylanthracene and a fullerene derivative PC71BM are used as donor and acceptor, respectively, the best p-i-n OPV affords a higher photovoltaic efficiency than the corresponding p-n device by 24% and bulk-heterojunction device by 67%. The photoprecursor approach is also applied to preparation of three-component p-i-n films containing another donor 2,6-bis(5′-(2-ethylhexyl)-(2,2′-bithiophen)-5-yl)anthracene in the i-layer to provide a nearly doubled efficiency as compared to the original two-component p-i-n system. These results indicate that the present approach can serve as an effective means for controlled preparation of well-performing multi-component active layers in OPVs and related organic electronic devices. PMID:25413952

Targeting ideal acceptor-donor materials based on hexabenzocoronene

NASA Astrophysics Data System (ADS)

Santos Silva, H.; Metz, Sebastian; Hiorns, Roger C.; Bégué, D.

2018-06-01

A series of new hybrid donor-acceptor materials based on hexabenzocoronenes (HBC) functionalized with electron donors is investigated by combining a variety of quantum mechanical and molecular dynamic methodologies for use in organic photovoltaic (OPV) devices. Segments of a low band gap alternating copolymer constructed of benzo[1,2-b;3,4-b]dithiophene and thieno[3,4-c]pyrrole-4,6-dione were attached to the conjugated HBC core. The copolymer was chosen for its known high performance in OPVs, and both moieties were singled out due to their exceptional resistance to photo-oxidation, an important requirement for such applications. The macromolecular topology of these systems are expected to induce supra-molecular columns, such as those common to discotic liquid crystals, conducive to the effective percolation of electrons in OPV devices. A challenge with these systems, that of the mixing of the electronic structures of the donor and acceptor moieties that result in excitonic losses and charge recombination, was diminished by trialling a range of linking units. It was found possible to propose ideal donor-acceptor structures with enhanced charge dissociations and transfers in the π-stacking direction for use in OPV and other organic electronic devices.

High Photoelectric Conversion Efficiency of Metal Phthalocyanine/Fullerene Heterojunction Photovoltaic Device

PubMed Central

Lin, Chi-Feng; Zhang, Mi; Liu, Shun-Wei; Chiu, Tien-Lung; Lee, Jiun-Haw

2011-01-01

This paper introduces the fundamental physical characteristics of organic photovoltaic (OPV) devices. Photoelectric conversion efficiency is crucial to the evaluation of quality in OPV devices, and enhancing efficiency has been spurring on researchers to seek alternatives to this problem. In this paper, we focus on organic photovoltaic (OPV) devices and review several approaches to enhance the energy conversion efficiency of small molecular heterojunction OPV devices based on an optimal metal-phthalocyanine/fullerene (C60) planar heterojunction thin film structure. For the sake of discussion, these mechanisms have been divided into electrical and optical sections: (1) Electrical: Modification on electrodes or active regions to benefit carrier injection, charge transport and exciton dissociation; (2) Optical: Optional architectures or infilling to promote photon confinement and enhance absorption. PMID:21339999

Interplay between Interfacial Structures and Device Performance in Organic Solar Cells: A Case Study with the Low Work Function Metal, Calcium.

PubMed

Ju, Huanxin; Knesting, Kristina M; Zhang, Wei; Pan, Xiao; Wang, Chia-Hsin; Yang, Yaw-Wen; Ginger, David S; Zhu, Junfa

2016-01-27

A better understanding of how interfacial structure affects charge carrier recombination would benefit the development of highly efficient organic photovoltaic (OPV) devices. In this paper, transient photovoltage (TPV) and charge extraction (CE) measurements are used in combination with synchrotron radiation photoemission spectroscopy (SRPES) to gain insight into the correlation between interfacial properties and device performance. OPV devices based on PCDTBT/PC71BM with a Ca interlayer were studied as a reference system to investigate the interfacial effects on device performance. Devices with a Ca interlayer exhibit a lower recombination than devices with only an Al cathode at a given charge carrier density (n). In addition, the interfacial band structures indicate that the strong dipole moment produced by the Ca interlayer can facilitate the extraction of electrons and drive holes away from the cathode/polymer interface, resulting in beneficial reduction in interfacial recombination losses. These results help explain the higher efficiencies of devices made with Ca interlayers compared to that without the Ca interlayer.

Screening of inorganic wide-bandgap p-type semiconductors for high performance hole transport layers in organic photovoltaic devices

NASA Astrophysics Data System (ADS)

Ginley, David; Zakutayev, Andriy; Garcia, Andreas; Widjonarko, Nicodemus; Ndione, Paul; Sigdel, Ajaya; Parilla, Phillip; Olson, Dana; Perkins, John; Berry, Joseph

2011-03-01

We will report on the development of novel inorganic hole transport layers (HTL) for organic photovoltaics (OPV). All the studied materials belong to the general class of wide-bandgap p-type oxide semiconductors. Potential candidates suitable for HTL applications include SnO, NiO, Cu2O (and related CuAlO2, CuCrO2, SrCu2O4 etc) and Co3O4 (and related ZnCo2O4, NiCo2O4, MgCo2O4 etc.). Materials have been optimized by high-throughput combinatorial approaches. The thin films were deposited by RF sputtering and pulsed laser deposition at ambient and elevated temperatures. Performance of the inorganic HTLs and that of the reference organic PEDOT:PSS HTL were compared by measuring the power conversion efficiencies and spectral responses of the P3HT/PCBM- and PCDTBT/PCBM-based OPV devices. Preliminary results indicate that Co3O4-based HTLs have performance comparable to that of our previously reported NiOs and PEDOT:PSS HTLs, leading to a power conversion efficiency of about 4 percent. The effect of composition and work function of the ternary materials on their performance in OPV devices is under investigation.

Peculiarity of two thermodynamically-stable morphologies and their impact on the efficiency of small molecule bulk heterojunction solar cells

DOE PAGES

Herath, Nuradhika; Das, Sanjib; Keum, Jong K.; ...

2015-08-28

Structural characteristics of the active layers in organic photovoltaic (OPV) devices play a critical role in charge generation, separation and transport. Here we report on morphology and structural control of p-DTS(FBTTh 2) 2:PC 71BM films by means of thermal annealing and 1,8-diiodooctane (DIO) solvent additive processing, and correlate it to the device performance. By combining surface imaging with nanoscale depth-sensitive neutron reflectometry (NR) and X-ray diffraction, three-dimensional morphologies of the films are reconstituted with information extending length scales from nanometers to microns. DIO promotes the formation of a well-mixed donor-acceptor vertical phase morphology with a large population of small p-DTS(FBTTh2)2more » nanocrystals arranged in an elongated domain network of the film, thereby enhancing the device performance. In contrast, films without DIO exhibit three-sublayer vertical phase morphology with phase separation in agglomerated domains. Our findings are supported by thermodynamic description based on the Flory-Huggins theory with quantitative evaluation of pairwise interaction parameters that explain the morphological changes resulting from thermal and solvent treatments. Our study reveals that vertical phase morphology of small-molecule based OPVs is significantly different from polymer-based systems. Lastly, the significant enhancement of morphology and information obtained from theoretical modeling may aid in developing an optimized morphology to enhance device performance for OPVs.« less

Interfacial Surface Modification via Nanoimprinting to Increase Open-Circuit Voltage of Organic Solar Cells

NASA Astrophysics Data System (ADS)

Emah, Joseph B.; George, Nyakno J.; Akpan, Usenobong B.

2017-08-01

The low-cost patterning of poly(3,4-ethylenedioxythiophene) poly(4-styrenesulfonate) (PEDOT:PSS) interfacial layers inserted between indium tin oxide and poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl-C61-butyric acid ester blends leads to an improvement in organic photovoltaics (OPV) device performance. Significantly, improvements in all device parameters, including the open-circuit voltage, are achieved. The nanoimprinted devices improved further as the pattern period and imprinting depth was reduced from 727 nm and 42 nm to 340 nm and 10 nm, respectively. A residue of poly(dimethylsiloxane) (PDMS) is found on the interfacial PEDOT:PSS film following patterning and can be used to explain the increase in OPV performance. Ultraviolet photoelectron spectroscopy measurements of the PEDOT:PSS interfacial layer demonstrated a reduction of the work function of 0.4 eV following nanoimprinting which may originate from chemical modification of the PDMS residue or interfacial dipole formation supported by x-ray photoelectron spectroscopy analysis. Ultimately, we have demonstrated a 39% improvement in OPV device performance via a simple low-cost modification of the anode interfacial layer. This improvement can be assigned to two effects resulting from a PDMS residue on the PEDOT:PSS surface: (1) the reduction of the anode work function which in turn decreases the hole extraction barrier, and (2) the reduction of electron transfer from the highest occupied molecular orbital of PCBM to the anode.

Indium tin oxide nanopillar electrodes in polymer/fullerene solar cells.

PubMed

Rider, David A; Tucker, Ryan T; Worfolk, Brian J; Krause, Kathleen M; Lalany, Abeed; Brett, Michael J; Buriak, Jillian M; Harris, Kenneth D

2011-02-25

Using high surface area nanostructured electrodes in organic photovoltaic (OPV) devices is a route to enhanced power conversion efficiency. In this paper, indium tin oxide (ITO) and hybrid ITO/SiO(2) nanopillars are employed as three-dimensional high surface area transparent electrodes in OPVs. The nanopillar arrays are fabricated via glancing angle deposition (GLAD) and electrochemically modified with nanofibrous PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(p-styrenesulfonate)). The structures are found to have increased surface area as characterized by porosimetry. When applied as anodes in polymer/fullerene OPVs (architecture: commercial ITO/GLAD ITO/PEDOT:PSS/P3HT:PCBM/Al, where P3HT is 2,5-diyl-poly(3-hexylthiophene) and PCBM is [6,6]-phenyl-C(61)-butyric acid methyl ester), the air-processed solar cells incorporating high surface area, PEDOT:PSS-modified ITO nanoelectrode arrays operate with improved performance relative to devices processed identically on unstructured, commercial ITO substrates. The resulting power conversion efficiency is 2.2% which is a third greater than for devices prepared on commercial ITO. To further refine the structure, insulating SiO(2) caps are added above the GLAD ITO nanopillars to produce a hybrid ITO/SiO(2) nanoelectrode. OPV devices based on this system show reduced electrical shorting and series resistance, and as a consequence, a further improved power conversion efficiency of 2.5% is recorded.

Empirically based device modeling of bulk heterojunction organic photovoltaics

NASA Astrophysics Data System (ADS)

Pierre, Adrien; Lu, Shaofeng; Howard, Ian A.; Facchetti, Antonio; Arias, Ana Claudia

2013-10-01

An empirically based, open source, optoelectronic model is constructed to accurately simulate organic photovoltaic (OPV) devices. Bulk heterojunction OPV devices based on a new low band gap dithienothiophene- diketopyrrolopyrrole donor polymer (P(TBT-DPP)) are blended with PC70BM and processed under various conditions, with efficiencies up to 4.7%. The mobilities of electrons and holes, bimolecular recombination coefficients, exciton quenching efficiencies in donor and acceptor domains and optical constants of these devices are measured and input into the simulator to yield photocurrent with less than 7% error. The results from this model not only show carrier activity in the active layer but also elucidate new routes of device optimization by varying donor-acceptor composition as a function of position. Sets of high and low performance devices are investigated and compared side-by-side.

Advances in Plexcore active layer technology systems for organic photovoltaics: roof-top and accelerated lifetime analysis of high performance organic photovoltaic cells

NASA Astrophysics Data System (ADS)

Laird, Darin W.; Vaidya, Swanand; Li, Sergey; Mathai, Mathew; Woodworth, Brian; Sheina, Elena; Williams, Shawn; Hammond, Troy

2007-09-01

We report NREL-certified efficiencies and initial lifetime data for organic photovoltaic (OPV) cells based on Plexcore PV photoactive layer and Plexcore HTL-OPV hole transport layer technology. Plexcore PV-F3, a photoactive layer OPV ink, was certified in a single-layer OPV cell at the National Renewable Energy Laboratory (NREL) at 5.4%, which represents the highest official mark for a single-layer organic solar cell. We have fabricated and measured P3HT:PCBM solar cells with a peak efficiency of 4.4% and typical efficiencies of 3 - 4% (internal, NREL-calibrated measurement) with P3HT manufactured at Plextronics by the Grignard Metathesis (GRIM) method. Outdoor and accelerated lifetime testing of these devices is reported. Both Plexcore PV-F3 and P3HT:PCBM-based OPV cells exhibit >750 hours of outdoor roof-top, non-accelerated lifetime with less than 8% loss in initial efficiency for both active layer systems when exposed continuously to the climate of Western Pennsylvania. These devices are continuously being tested to date. Accelerated testing using a high-intensity (1000W) metal-halide lamp affords shorter lifetimes; however, the true acceleration factor is still to be determined.

Molecular engineering to improve carrier lifetimes for organic photovoltaic devices with thick active layers

DOE PAGES

Oosterhout, Stefan D.; Braunecker, Wade A.; Owczarczyk, Zbyslaw R.; ...

2017-04-27

The morphology of the bulk heterojunction absorber layer in an organic photovoltaic (OPV) device has a profound effect on the electrical properties and efficiency of the device. Previous work has consistently demonstrated that the solubilizing side-chains of the donor material affect these properties and device performance in a non-trivial way. Here, using Time-Resolved Microwave Conductivity (TRMC), we show by direct measurements of carrier lifetimes that the choice of side chains can also make a substantial difference in photocarrier dynamics. We have previously demonstrated a correlation between peak photoconductance measured by TRMC and device efficiencies; here, we demonstrate that TRMC photocarriermore » dynamics have an important bearing on device performance in a case study of devices made from donor materials with linear vs. branched side-chains and with variable active layer thicknesses. We use Grazing-Incidence Wide Angle X-ray Scattering to elucidate the cause of the different carrier lifetimes as a function of different aggregation behavior in the polymers. Consequently, the results help establish TRMC as a technique for screening OPV donor materials whose devices maintain performance in thick active layers (>250 nm) designed to improve light harvesting, film reproducibility, and ease of processing.« less

Plasmonic-enhanced organic photovoltaics: breaking the 10% efficiency barrier.

PubMed

Gan, Qiaoqiang; Bartoli, Filbert J; Kafafi, Zakya H

2013-05-07

Recent advances in molecular organic photovoltaics (OPVs) have shown 10% power conversion efficiency (PCE) for single-junction cells, which put them in direct competition with PVs based on amorphous silicon. Incorporation of plasmonic nanostructures for light trapping in these thin-film devices offers an attractive solution to realize higher-efficiency OPVs with PCE>10%. This article reviews recent progress on plasmonic-enhanced OPV devices using metallic nanoparticles, and one-dimensional (1D) and two-dimensional (2D) patterned periodic nanostructures. We discuss the benefits of using various plasmonic nanostructures for broad-band, polarization-insensitive and angle-independent absorption enhancement, and their integration with one or two electrode(s) of an OPV device. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Robot-Based High-Throughput Engineering of Alcoholic Polymer: Fullerene Nanoparticle Inks for an Eco-Friendly Processing of Organic Solar Cells.

PubMed

Xie, Chen; Tang, Xiaofeng; Berlinghof, Marvin; Langner, Stefan; Chen, Shi; Späth, Andreas; Li, Ning; Fink, Rainer H; Unruh, Tobias; Brabec, Christoph J

2018-06-27

Development of high-quality organic nanoparticle inks is a significant scientific challenge for the industrial production of solution-processed organic photovoltaics (OPVs) with eco-friendly processing methods. In this work, we demonstrate a novel, robot-based, high-throughput procedure performing automatic poly(3-hexylthio-phene-2,5-diyl) and indene-C 60 bisadduct nanoparticle ink synthesis in nontoxic alcohols. A novel methodology to prepare particle dispersions for fully functional OPVs by manipulating the particle size and solvent system was studied in detail. The ethanol dispersion with a particle diameter of around 80-100 nm exhibits reduced degradation, yielding a power conversion efficiency of 4.52%, which is the highest performance reported so far for water/alcohol-processed OPV devices. By successfully deploying the high-throughput robot-based approach for an organic nanoparticle ink preparation, we believe that the findings demonstrated in this work will trigger more research interest and effort on eco-friendly industrial production of OPVs.

Computational fluid dynamics (CFD) simulations of molten steel flow patterns and particle-wall adhesion in continuous casting of steels

NASA Astrophysics Data System (ADS)

Mohammadi-Ghaleni, Mahdi

The Sun has long been the most important energy source for planet Earth. Sunlight offers the potential to function as a source of clean, renewable energy; photovoltaic (PV) cells have been designed to tap into this abundant solar energy to generate electricity. Organic photovoltaic (OPV) devices show promise as technologies capable of lightweight, low cost and flexible alternatives to traditional silicon PV but the nature of conjugated organic and polymeric semiconductors have limited performance and, therefore, application. However, recent advances have shown that the addition of pristine graphene (PG) to the active layer of OPV devices can yield three-fold performance improvements in blends of P3HT (poly(3-hexylthiophene-2,5-diyl) & PCBM (phenyl C 61 butyric acid methyl ester) and, later, in all-polymer blends of P3HT & F8BT (poly(9,9-dioctylfluorene-alt-benzothiadiazole). In both OPV systems, increased performance is believed to be due to high charge carrier mobility imparted by the PG additive to the composite active layer blend. In this work, the effect of addition of PG to the active layer blend of P3HT & PCPDTBT (poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta [2,1-b;3,4-b']dithiophene)-alt-4,7(2,1,3-benzothiadiazole)]) systems was investigated. PV devices were designed, fabricated and tested using standard processing methods and testing procedures. Although PG increased OPV device performance relative to samples without PG, power conversion efficiency (eta) on an absolute scale was lower than expected despite the otherwise complementary properties of these materials. Based on the literature, the low performance of these devices was hypothesized to result from non-ideal active layer morphology, lacking charge carried percolation pathways to the electrodes. Small angle neutron scattering (SANS) was employed to probe the active layer morphology in polymer blend films similar to the active layers of the cells. Deuterated P3HT (d-P3HT) was used to exploit the large scattering length density (SLD) contrast between hydrogen and deuterium. Rigorous analysis of the SANS data allowed the nanostructure to be determined and a model of disk-like d-P3HT crystallites dispersed in a matrix of the amorphous polymers was constructed. This structure shows limited interfacial area for exciton dissociation and exhibits a lack of charge percolation pathways to the electrodes. Morphological insight offered by SANS analysis along with literature review allowed higher performance all-polymer photovoltaic cells to be designed and tested using the same semiconducting polymers. By introducing a co-solvent and modifying the thermal annealing procedure, significant performance gains were realized for subsequent devices. The increased performance observed following the change in procedure is believed to be due to enhanced active layer morphology and formation of a bulk heterojunction (BHJ) structure, to be studied in future work. Although there is room for further performance gains in P3HT-PCPDTBT devices as well as application to other OPV systems in future work, the methods, results and discussion presented here highlight the importance of structure-property relationships in all-polymer photovoltaic cells.

Polystyrene-block-Poly(ionic liquid) Copolymers as Work Function Modifiers in Inverted Organic Photovoltaic Cells.

PubMed

Park, Jong Baek; Isik, Mehmet; Park, Hea Jung; Jung, In Hwan; Mecerreyes, David; Hwang, Do-Hoon

2018-02-07

Interfacial layers play a critical role in building up the Ohmic contact between electrodes and functional layers in organic photovoltaic (OPV) solar cells. These layers are based on either inorganic oxides (ZnO and TiO 2 ) or water-soluble organic polymers such as poly[(9,9-dioctyl-2,7-fluorene)-alt-(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)] and polyethylenimine ethoxylated (PEIE). In this work, we have developed a series of novel poly(ionic liquid) nonconjugated block copolymers for improving the performance of inverted OPV cells by using them as work function modifiers of the indium tin oxide (ITO) cathode. Four nonconjugated polyelectrolytes (n-CPEs) based on polystyrene and imidazolium poly(ionic liquid) (PSImCl) were synthesized by reversible addition-fragmentation chain transfer polymerization. The ratio of hydrophobic/hydrophilic block copolymers was varied depending on the ratio of polystyrene to the PSImCl block. The ionic density, which controls the work function of the electrode by forming an interfacial dipole between the electrode and the block copolymers, was easily tuned by simply changing the PSImCl molar ratio. The inverted OPV device with the ITO/PS 29 -b-PSImCl 60 cathode achieved the best power conversion efficiency (PCE) of 7.55% among the synthesized block copolymers, exhibiting an even higher PCE than that of the reference OPV device with PEIE (7.30%). Furthermore, the surface properties of the block copolymers films were investigated by contact angle measurements to explore the influence of the controlled hydrophobic/hydrophilic characters on the device performances.

A versatile approach to organic photovoltaics evaluation using white light pulse and microwave conductivity.

PubMed

Saeki, Akinori; Yoshikawa, Saya; Tsuji, Masashi; Koizumi, Yoshiko; Ide, Marina; Vijayakumar, Chakkooth; Seki, Shu

2012-11-21

State-of-the-art low band gap conjugated polymers have been investigated for application in organic photovoltaic cells (OPVs) to achieve efficient conversion of the wide spectrum of sunlight into electricity. A remarkable improvement in power conversion efficiency (PCE) has been achieved through the use of innovative materials and device structures. However, a reliable technique for the rapid screening of the materials and processes is a prerequisite toward faster development in this area. Here we report the realization of such a versatile evaluation technique for bulk heterojunction OPVs by the combination of time-resolved microwave conductivity (TRMC) and submicrosecond white light pulse from a Xe-flash lamp. Xe-flash TRMC allows examination of the OPV active layer without requiring fabrication of the actual device. The transient photoconductivity maxima, involving information on generation efficiency, mobility, and lifetime of charge carriers in four well-known low band gap polymers blended with phenyl-C(61)-butyric acid methyl ester (PCBM), were confirmed to universally correlate with the PCE divided by the open circuit voltage (PCE/V(oc)), offering a facile way to predict photovoltaic performance without device fabrication.

High-efficiency, broad-band and wide-angle optical absorption in ultra-thin organic photovoltaic devices.

PubMed

Wang, Wenyan; Hao, Yuying; Cui, Yanxia; Tian, Ximin; Zhang, Ye; Wang, Hua; Shi, Fang; Wei, Bin; Huang, Wei

2014-03-10

Metal nanogratings as one of the promising architectures for effective light trapping in organic photovoltaics (OPVs) have been actively studied over the past decade. Here we designed a novel metal nanowall grating with ultra-small period and ultra-high aspect-ratio as the back electrode of the OPV device. Such grating results in the strong hot spot effect in-between the neighboring nanowalls and the localized surface plasmon effect at the corners of nanowalls. These combined effects make the integrated absorption efficiency of light over the wavelength range from 400 to 650 nm in the active layer for the proposed structure, with respect to the equivalent planar structure, increases by 102% at TM polarization and by 36.5% at the TM/TE hybrid polarization, respectively. Moreover, it is noted that the hot spot effect in the proposed structure is more effective for ultra-thin active layers, which is very favorable for the exciton dissociation and charge collection. Therefore such a nanowall grating is expected to improve the overall performance of OPV devices.

Increasing the efficiency of organic solar cells by photonic and electrostatic-field enhancements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nalwa, Kanwar

2011-01-01

Organic photovoltaic (OPV) technology is an attractive solar-electric conversion paradigm due to the promise of low cost roll-to-roll production and amenability to flexible substrates. Power conversion efficiency (PCE) exceeding 7% has recently been achieved. OPV cells suffer from low charge carrier mobilities of polymers, leading to recombination losses, higher series resistances and lower fill-factors. Thus, it is imperative to develop fabrication methodologies that can enable efficient optical absorption in films thinner than optical absorption length. Active layers conformally deposited on light-trapping, microscale textured, grating-type surfaces is one possible approach to achieve this objective. In this study, 40% theoretical increase inmore » photonic absorption over flat OPVs is shown for devices with textured geometry by the simulation results. For verifying this theoretical result and improving the efficiency of OPVs by light trapping, OPVs were fabricated on grating-type textured substrates possessing t pitch and -coat PV active-layer on these textured substrates led to over filling of the valleys and shunts at the crest, which severely affected the performance of the resultant PV devices. Thus, it is established that although the optical design is important for OPV performance but the potential of light trapping can only be effectively tapped if the textures are amenable for realizing a conformal active layer. It is discovered that if the height of the underlying topographical features is reduced to sub-micron regime (e.g. 300 nm) and the pitch is increased to more than a micron (e.g. 2 μm), the textured surface becomes amenable to coating a conformal PV active-layer. The resultant PV cells showed 100% increase in average light absorption near the band edge due to trapping of higher wavelength photons, and 20% improvement in power conversion efficiency as compared with the flat PV cell. Another factor that severely limits the performance of OPVs is recombination of charge carriers. Thus it becomes imperative to understand the effect of processing conditions such as spin coating speed and drying rate on defect density and hence induced carrier recombination mechanism. In this study, It is shown that slow growth (longer drying time) of the active-layer leads to reduction of sub-bandgap traps by an order of magnitude as compared to fast grown active-layer. By coupling the experimental results with simulations, it is demonstrated that at one sun condition, slow grown device has bimolecular recombination as the major loss mechanism while in the fast grown device with high trap density, the trap assisted recombination dominates. It has been estimated that non-radiative recombination accounts nearly 50% of efficiency loss in modern OPVs. Generally, an external bias (electric field) is required to collect all the photogenerated charges and thus prevent their recombination. The motivation is to induce additional electric field in otherwise low mobility conjugated polymer based active layer by incorporating ferroelectric dipoles. This is expected to facilitate singlet exciton dissociation in polymer matrix and impede charge transfer exciton (CTE) recombination at polymer:fullerene interface. For the first time, it is shown that the addition of ferroelectric dipoles to modern bulk heterojunction (BHJ) can significantly improve exciton dissociation, resulting in a ~50% enhancement of overall solar cell efficiency. The devices also exhibit the unique ferroelectric-photovoltaic effect with polarization-controlled power conversion efficiency.« less

25th anniversary article: a decade of organic/polymeric photovoltaic research.

PubMed

Dou, Letian; You, Jingbi; Hong, Ziruo; Xu, Zheng; Li, Gang; Street, Robert A; Yang, Yang

2013-12-10

Organic photovoltaic (OPV) technology has been developed and improved from a fancy concept with less than 1% power conversion efficiency (PCE) to over 10% PCE, particularly through the efforts in the last decade. The significant progress is the result of multidisciplinary research ranging from chemistry, material science, physics, and engineering. These efforts include the design and synthesis of novel compounds, understanding and controlling the film morphology, elucidating the device mechanisms, developing new device architectures, and improving large-scale manufacture. All of these achievements catalyzed the rapid growth of the OPV technology. This review article takes a retrospective look at the research and development of OPV, and focuses on recent advances of solution-processed materials and devices during the last decade, particular the polymer version of the materials and devices. The work in this field is exciting and OPV technology is a promising candidate for future thin film solar cells. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Small-Molecule Solar Cells with Simultaneously Enhanced Short-Circuit Current and Fill Factor to Achieve 11% Efficiency.

PubMed

Nian, Li; Gao, Ke; Jiang, Yufeng; Rong, Qikun; Hu, Xiaowen; Yuan, Dong; Liu, Feng; Peng, Xiaobin; Russell, Thomas P; Zhou, Guofu

2017-08-01

High-efficiency small-molecule-based organic photovoltaics (SM-OPVs) using two electron donors (p-DTS(FBTTh 2 ) 2 and ZnP) with distinctively different absorption and structural features are reported. Such a combination works well and synergically improves device short-circuit current density (J sc ) to 17.99 mA cm -2 and fill factor (FF) to 77.19%, yielding a milestone efficiency of 11%. To the best of our knowledge, this is the highest power conversion efficiency reported for SM-OPVs to date and the first time to combine high J sc over 17 mA cm -2 and high FF over 77% into one SM-OPV. The strategy of using multicomponent materials, with a selecting role of balancing varied electronic and structural necessities can be an important route to further developing higher performance devices. This development is important, which broadens the dimension and versatility of existing materials without much chemistry input. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Radiative efficiency of lead iodide based perovskite solar cells

PubMed Central

Tvingstedt, Kristofer; Malinkiewicz, Olga; Baumann, Andreas; Deibel, Carsten; Snaith, Henry J.; Dyakonov, Vladimir; Bolink, Henk J.

2014-01-01

The maximum efficiency of any solar cell can be evaluated in terms of its corresponding ability to emit light. We herein determine the important figure of merit of radiative efficiency for Methylammonium Lead Iodide perovskite solar cells and, to put in context, relate it to an organic photovoltaic (OPV) model device. We evaluate the reciprocity relation between electroluminescence and photovoltaic quantum efficiency and conclude that the emission from the perovskite devices is dominated by a sharp band-to-band transition that has a radiative efficiency much higher than that of an average OPV device. As a consequence, the perovskite have the benefit of retaining an open circuit voltage ~0.14 V closer to its radiative limit than the OPV cell. Additionally, and in contrast to OPVs, we show that the photoluminescence of the perovskite solar cell is substantially quenched under short circuit conditions in accordance with how an ideal photovoltaic cell should operate. PMID:25317958

Assessing the potential roles of silicon and germanium phthalocyanines in planar heterojunction organic photovoltaic devices and how pentafluoro phenoxylation can enhance π-π interactions and device performance.

PubMed

Lessard, Benoît H; White, Robin T; Al-Amar, Mohammad; Plint, Trevor; Castrucci, Jeffrey S; Josey, David S; Lu, Zheng-Hong; Bender, Timothy P

2015-03-11

In this study, we have assessed the potential application of dichloro silicon phthalocyanine (Cl2-SiPc) and dichloro germanium phthalocyanine (Cl2-GePc) in modern planar heterojunction organic photovoltaic (PHJ OPV) devices. We have determined that Cl2-SiPc can act as an electron donating material when paired with C60 and that Cl2-SiPc or Cl2-GePc can also act as an electron acceptor material when paired with pentacene. These two materials enabled the harvesting of triplet energy resulting from the singlet fission process in pentacene. However, contributions to the generation of photocurrent were observed for Cl2-SiPc with no evidence of photocurrent contribution from Cl2-GePc. The result of our initial assessment established the potential for the application of SiPc and GePc in PHJ OPV devices. Thereafter, bis(pentafluoro phenoxy) silicon phthalocyanine (F10-SiPc) and bis(pentafluoro phenoxy) germanium phthalocyanine (F10-GePc) were synthesized and characterized. During thermal processing, it was discovered that F10-SiPc and F10-GePc underwent a reaction forming small amounts of difluoro SiPc (F2-SiPc) and difluoro GePc (F2-GePc). This undesirable reaction could be circumvented for F10-SiPc but not for F10-GePc. Using single crystal X-ray diffraction, it was determined that F10-SiPc has significantly enhanced π-π interactions compared with that of Cl2-SiPc, which had little to none. Unoptimized PHJ OPV devices based on F10-SiPc were fabricated and directly compared to those constructed from Cl2-SiPc, and in all cases, PHJ OPV devices based on F10-SiPc had significantly improved device characteristics compared to Cl2-SiPc.

Control of indium tin oxide anode work function modified using Langmuir-Blodgett monolayer for high-efficiency organic photovoltaics

NASA Astrophysics Data System (ADS)

Yokokura, Yuya; Dogase, Tomomichi; Shinbo, Tatsuki; Nakayashiki, Yuya; Takagi, Yusuke; Ueda, Kazuyoshi; Sarangerel, Khayankhyarvaa; Delgertsetseg, Byambasuren; Ganzorig, Chimed; Sakomura, Masaru

2017-08-01

The use of Langmuir-Blodgett (LB) monolayers to modify the indium tin oxide (ITO) work function and thus improve the performance of zinc phthalocyanine (ZnPc)/fullerene (C60)-based and boron subphthalocyanine chloride (SubPc)/C60-based small molecule organic photovoltaic devices (OPVs) was examined. In general, LB precursor compounds contain one or more long alkyl chain substituents that can act as spacers to prevent electrical contact with adjoining electrode surfaces. As one example of such a compound, arachidic acid (CH3(CH2)18COOH) was inserted in the forms of one-layer, three-layer or five-layer LB films between the anode ITO layer and the p-type layer in ZnPc-C60-based OPVs to investigate the effects of the long alkyl chain group when it acts as an electrically insulating spacer. The short-circuit current density (Jsc) values of the OPVs with the three- and five-layer inserts (1.78 mA.cm-2 and 0.61 mA.cm-2, respectively) were reduced dramatically, whereas the Jsc value for the OPV with the single-layer insertion (2.88 mA.cm-2) was comparable to that of the OPV without any insert (3.14 mA.cm-2). The ITO work function was shifted positively by LB deposition of a surfactant compound, C9F19C2H4-O-C2H4-COOH (PFECA), which contained a fluorinated head group. This positive effect was maintained even after formation of an upper p-type organic layer. The Jsc and open-circuit voltage (Voc) of the SubPc-C60-based OPV with the LB-modified ITO layers were effectively enhanced. As a result, a 42% increase in device efficiency was achieved.

Naphthobischalcogenadiazole Conjugated Polymers: Emerging Materials for Organic Electronics.

PubMed

Osaka, Itaru; Takimiya, Kazuo

2017-07-01

π-Conjugated polymers are an important class of materials for organic electronics. In the past decade, numerous polymers with donor-acceptor molecular structures have been developed and used as the active materials for organic devices, such as organic field-effect transistors (OFETs) and organic photovoltaics (OPVs). The choice of the building unit is the primary step for designing the polymers. Benzochalcogenadiazoles (BXzs) are one of the most familiar acceptor building units studied in this area. As their doubly fused system, naphthobischalcogenadiazoles (NXzs), i.e., naphthobisthiadiazole (NTz), naphthobisoxadiazole (NOz), and naphthobisselenadiazole (NSz) are emerging building units that provide interesting electronic properties and highly self-assembling nature for π-conjugated polymers. With these fruitful features, π-conjugated polymers based on these building units demonstrate great performances in OFETs and OPVs. In particular, in OPVs, NTz-based polymers have exhibited more than 10% efficiency, which is among the highest values reported so far. In this Progress Report, the synthesis, properties, and structures of NXzs and their polymers is summarized. The device performance is also highlighted and the structure-property relationships of the polymers are discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Charge transport studies in donor-acceptor block copolymer PDPP-TNT and PC71BM based inverted organic photovoltaic devices processed in room conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Srivastava, Shashi B.; Singh, Samarendra P., E-mail: samarendra.singh@snu.edu.in; Sonar, Prashant

2015-07-15

Diketopyrrolopyrole-naphthalene polymer (PDPP-TNT), a donor-acceptor co-polymer, has shown versatile behavior demonstrating high performances in organic field-effect transistors (OFETs) and organic photovoltaic (OPV) devices. In this paper we report investigation of charge carrier dynamics in PDPP-TNT, and [6,6]-phenyl C{sub 71} butyric acid methyl ester (PC71BM) bulk-heterojunction based inverted OPV devices using current density-voltage (J-V) characteristics, space charge limited current (SCLC) measurements, capacitance-voltage (C-V) characteristics, and impedance spectroscopy (IS). OPV devices in inverted architecture, ITO/ZnO/PDPP-TNT:PC71BM/MoO{sub 3}/Ag, are processed and characterized at room conditions. The power conversion efficiency (PCE) of these devices are measured ∼3.8%, with reasonably good fill-factor 54.6%. The analysis ofmore » impedance spectra exhibits electron’s mobility ∼2 × 10{sup −3} cm{sup 2}V{sup −1}s{sup −1}, and lifetime in the range of 0.03-0.23 ms. SCLC measurements give hole mobility of 1.12 × 10{sup −5} cm{sup 2}V{sup −1}s{sup −1}, and electron mobility of 8.7 × 10{sup −4} cm{sup 2}V{sup −1}s{sup −1}.« less

Nano-pathways: Bridging the divide between water-processable nanoparticulate and bulk heterojunction organic photovoltaics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holmes, Natalie P.; Marks, Melissa; Kumar, Pankaj

2015-11-26

In this paper, we report the application of a conjugated copolymer based on thiophene and quinoxaline units, namely poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1), to nanoparticle organic photovoltaics (NP-OPVs). TQ1 exhibits more desirable material properties for NP-OPV fabrication and operation, particularly a high glass transition temperature (T g) and amorphous nature, compared to the commonly applied semicrystalline polymer poly(3-hexylthiophene) (P3HT). This study reports the optimisation of TQ1:PC 71BM (phenyl C 71 butyric acid methyl ester) NP-OPV device performance by the application of mild thermal annealing treatments in the range of the T g (sub-T g and post-T g), both in the active layer dryingmore » stage and post-cathode deposition annealing stage of device fabrication, and an in-depth study of the effect of these treatments on nanoparticle film morphology. Finally and in addition, we report a type of morphological evolution in nanoparticle films for OPV active layers that has not previously been observed, that of PC 71BM nano-pathway formation between dispersed PC 71BM-rich nanoparticle cores, which have the benefit of making the bulk film more conducive to charge percolation and extraction.« less

Integrating nanostructured electrodes in organic photovoltaic devices for enhancing near-infrared photoresponse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nardes, Alexandre M.; Ahn, Sungmo; Rourke, Devin

2016-12-01

We introduce a simple methodology to integrate prefabricated nanostructured-electrodes in solution-processed organic photovoltaic (OPV) devices. The tailored 'photonic electrode' nanostructure is used for light management in the device and for hole collection. This approach opens up new possibilities for designing photonically active structures that can enhance the absorption of sub-bandgap photons in the active layer. We discuss the design, fabrication and characterization of photonic electrodes, and the methodology for integrating them to OPV devices using a simple lamination technique. We demonstrate theoretically and experimentally that OPV devices using photonic electrodes show a factor of ca. 5 enhancement in external quantummore » efficiency (EQE) in the near infrared region. We use simulations to trace this observed efficiency enhancement to surface plasmon polariton modes in the nanostructure.« less

Bis(tri-n-hexylsilyl oxide) silicon phthalocyanine: a unique additive in ternary bulk heterojunction organic photovoltaic devices.

PubMed

Lessard, Benoît H; Dang, Jeremy D; Grant, Trevor M; Gao, Dong; Seferos, Dwight S; Bender, Timothy P

2014-09-10

Previous studies have shown that the use of bis(tri-n-hexylsilyl oxide) silicon phthalocyanine ((3HS)2-SiPc) as an additive in a P3HT:PC61BM cascade ternary bulk heterojunction organic photovoltaic (BHJ OPV) device results in an increase in the short circuit current (J(SC)) and efficiency (η(eff)) of up to 25% and 20%, respectively. The previous studies have attributed the increase in performance to the presence of (3HS)2-SiPc at the BHJ interface. In this study, we explored the molecular characteristics of (3HS)2-SiPc which makes it so effective in increasing the OPV device J(SC) and η(eff. Initially, we synthesized phthalocyanine-based additives using different core elements such as germanium and boron instead of silicon, each having similar frontier orbital energies compared to (3HS)2-SiPc and tested their effect on BHJ OPV device performance. We observed that addition of bis(tri-n-hexylsilyl oxide) germanium phthalocyanine ((3HS)2-GePc) or tri-n-hexylsilyl oxide boron subphthalocyanine (3HS-BsubPc) resulted in a nonstatistically significant increase in JSC and η(eff). Secondly, we kept the silicon phthalocyanine core and substituted the tri-n-hexylsilyl solubilizing groups with pentadecyl phenoxy groups and tested the resulting dye in a BHJ OPV. While an increase in JSC and η(eff) was observed at low (PDP)2-SiPc loadings, the increase was not as significant as (3HS)2-SiPc; therefore, (3HS)2-SiPc is a unique additive. During our study, we observed that (3HS)2-SiPc had an extraordinary tendency to crystallize compared to the other compounds in this study and our general experience. On the basis of this observation, we have offered a hypothesis that when (3HS)2-SiPc migrates to the P3HT:PC61BM interface the reason for its unique performance is not solely due to its frontier orbital energies but also might be due to a high driving force for crystallization.

High-efficiency and air-stable P3HT-based polymer solar cells with a new non-fullerene acceptor

PubMed Central

Holliday, Sarah; Ashraf, Raja Shahid; Wadsworth, Andrew; Baran, Derya; Yousaf, Syeda Amber; Nielsen, Christian B.; Tan, Ching-Hong; Dimitrov, Stoichko D.; Shang, Zhengrong; Gasparini, Nicola; Alamoudi, Maha; Laquai, Frédéric; Brabec, Christoph J.; Salleo, Alberto; Durrant, James R.; McCulloch, Iain

2016-01-01

Solution-processed organic photovoltaics (OPV) offer the attractive prospect of low-cost, light-weight and environmentally benign solar energy production. The highest efficiency OPV at present use low-bandgap donor polymers, many of which suffer from problems with stability and synthetic scalability. They also rely on fullerene-based acceptors, which themselves have issues with cost, stability and limited spectral absorption. Here we present a new non-fullerene acceptor that has been specifically designed to give improved performance alongside the wide bandgap donor poly(3-hexylthiophene), a polymer with significantly better prospects for commercial OPV due to its relative scalability and stability. Thanks to the well-matched optoelectronic and morphological properties of these materials, efficiencies of 6.4% are achieved which is the highest reported for fullerene-free P3HT devices. In addition, dramatically improved air stability is demonstrated relative to other high-efficiency OPV, showing the excellent potential of this new material combination for future technological applications. PMID:27279376

Fixed Junction Light Emitting Electrochemical Cells based on Polymerizable Ionic Liquids

NASA Astrophysics Data System (ADS)

Brown, Erin; Limanek, Austin; Bauman, James; Leger, Janelle

Organic photovoltaic (OPV) devices are of interest due to ease of fabrication, which increases their cost-effectiveness. OPV devices based on fixed-junction light emitting electrochemical cells (LECs) in particular have shown promising results. LECs are composed of a layer of polymer semiconductor blended with a salt sandwiched between two electrodes. As a forward bias is applied, the ions within the polymer separate, migrate to the electrodes, and enable electrochemical doping, thereby creating a p-n junction analog. In a fixed junction device, the ions are immobilized after the desired distribution has been established, allowing for operation under reverse bias conditions. Fixed junctions can be established using various techniques, including chemically by mixing polymerizable salts that will bond to the polymer under a forward bias. Previously we have demonstrated the use of the polymerizable ionic liquid allyltrioctylammonium allysulfonate (ATOAAS) as an effective means of creating a chemically fixed junction in an LEC. Here we present the application of this approach to the creation of photovoltaic devices. Devices demonstrate higher open circuit voltages, faster charging, and an overall improved device performance over previous chemically-fixed junction PV devices.

Graphene nanoplatelet doping of P3HT:PCBM photoactive layer of bulk heterojunction organic solar cells for enhancing performance

NASA Astrophysics Data System (ADS)

Aïssa, Brahim; Nedil, Mourad; Kroeger, Jens; Ali, Adnan; Isaifan, Rima J.; Essehli, Rachid; Mahmoud, Khaled A.

2018-03-01

Hybrid organic photovoltaic (OPV) cells based on conjugated polymer photoactive materials are promising candidates for flexible, high-performance and low-cost energy sources owing to their inexpensive materials, cost-effective processing and ease of fabrication by simple solution processes. However, the modest PV performance obtained to date—in particular the low power conversion efficiency (PCE)—has impeded the large scale deployment of OPV cells. The low PCE in OPV solar cells is mainly attributed to the low carrier mobility, which is closely correlated to the transport diffusion length of the charge carriers within the photoactive layers. The 2D graphene material could be an excellent candidate for assisting charge transport improvement in the active layer of OPV cells, due to its huge carrier mobility, thermal and chemical stability, and its compatibility with the solution process. In this work, we report on the improvement of the optoelectronic properties and photovoltaic performance of graphene nanoplatelet (GNP)-doped P3HT:PCBM photoactive blended layers, integrated into a bulk heterojunction (BHJ) organic-photovoltaic-based device, using PEDOT:PSS on an ITO/glass substrate. First, the light absorption capacity was observed to increase with respect to the GNP content, while the photoluminescence showed clear quenching, indicating electron transfer between the graphene sheets and the polymeric matrix. Then, the incorporation of GNP into the BHJ active layer resulted in enhanced PV performance with respect to the reference cell, and the best PV performance was obtained with 3 wt.% of GNP loading, with an open-circuit voltage of 1.24 V, a short-circuit current density value of 6.18 mA cm-2, a fill factor of 47.12%, and a power conversion efficiency of about 3.61%. We believe that the obtained results contribute to the development of organic photovoltaic devices and to the understanding of the impact of sp2-bonded carbon therein.

Graphene nanoplatelet doping of P3HT:PCBM photoactive layer of bulk heterojunction organic solar cells for enhancing performance.

PubMed

Aïssa, Brahim; Nedil, Mourad; Kroeger, Jens; Ali, Adnan; Isaifan, Rima J; Essehli, Rachid; Mahmoud, Khaled A

2018-01-31

Hybrid organic photovoltaic (OPV) cells based on conjugated polymer photoactive materials are promising candidates for flexible, high-performance and low-cost energy sources owing to their inexpensive materials, cost-effective processing and ease of fabrication by simple solution processes. However, the modest PV performance obtained to date-in particular the low power conversion efficiency (PCE)-has impeded the large scale deployment of OPV cells. The low PCE in OPV solar cells is mainly attributed to the low carrier mobility, which is closely correlated to the transport diffusion length of the charge carriers within the photoactive layers. The 2D graphene material could be an excellent candidate for assisting charge transport improvement in the active layer of OPV cells, due to its huge carrier mobility, thermal and chemical stability, and its compatibility with the solution process. In this work, we report on the improvement of the optoelectronic properties and photovoltaic performance of graphene nanoplatelet (GNP)-doped P3HT:PCBM photoactive blended layers, integrated into a bulk heterojunction (BHJ) organic-photovoltaic-based device, using PEDOT:PSS on an ITO/glass substrate. First, the light absorption capacity was observed to increase with respect to the GNP content, while the photoluminescence showed clear quenching, indicating electron transfer between the graphene sheets and the polymeric matrix. Then, the incorporation of GNP into the BHJ active layer resulted in enhanced PV performance with respect to the reference cell, and the best PV performance was obtained with 3 wt.% of GNP loading, with an open-circuit voltage of 1.24 V, a short-circuit current density value of 6.18 mA cm -2 , a fill factor of 47.12%, and a power conversion efficiency of about 3.61%. We believe that the obtained results contribute to the development of organic photovoltaic devices and to the understanding of the impact of sp 2 -bonded carbon therein.

Graphene nanoplatelets doping of P3HT:PCBM photoactive layer of bulk heterojunction organic solar cells for enhancing performance.

PubMed

Aissa, Brahim; Nedil, Mourad; Kroeger, Jens; Ali, Adnan; Isaifan, Rima J; Essehli, Rachid; Mahmoud, Khaled

2018-01-09

Hybrid organic photovoltaic (OPV) cells based on conjugated polymers photoactive materials are promising candidates for flexible, high-performance and low-cost energy sources owing to their inexpensive materials, cost-effective processing, and ease of fabrication by simple solution processes. However, the modest PV performance obtained to date -in particular the low power conversion efficiency (PCE)- has impeded the large scale deployment of OPV cells. The low PCE in OPV solar cells has been mainly attributed to low carrier mobility, which is closely correlated to the transport diffusion length of the charge carriers within the photoactive layers. The 2D graphene material can be an excellent candidate for assisting the charge transport improvement in the active layer of OPV cells due to its huge carrier mobility, thermal and chemical stability, and its compatibility with the solution process. In this work, we report on the improvement of optoelectronic properties and photovoltaic performance of graphene nanoplatelets (GNP) doped P3HT:PCBM photoactive blended layers, integrated into a bulk heterojunction (BHJ) organic photovoltaic based device, using PEDOT:PSS on ITO/glass substrate. First, the light absorption capacity was observed to increase with respect to the GNP contents while the photoluminescence showed a clear quenching, indicating electrons transfer between the graphene sheets and the polymeric matrix. Then, the incorporation of GNP into the BHJ active layer has resulted in enhanced PV performance with respect to a reference cell, and the best PV performances were obtained with 3 wt. % of GNP loading, with an open-circuit voltage of 1.24 V, a short-circuit current density value of 6.18 mA/cm2, a fill factor of 47.12 %, and a power conversion efficiency of about 3.61 %. We believe that the obtained results contribute to the development of organic photovoltaic devices and to the understanding of the impact of sp2-bonded carbon therein. © 2018 IOP Publishing Ltd.

Patterning of OPV modules by ultra-fast laser

NASA Astrophysics Data System (ADS)

Kubiš, Peter; Lucera, Luca; Guo, Fei; Spyropolous, George; Voigt, Monika M.; Brabec, Christoph J.

2014-10-01

A novel production process combining slot-die coating, transparent flexible IMI (ITO-Metal-ITO) electrodes and ultra-fast laser ablation can be used for the realization of P3HT:PCBM based thin film flexible OPV modules. The fast and precise laser ablation allows an overall efficiency over 3 % and a device geometric fill factor (GFF) over 95 %. Three functional layers can be ablated using the same wavelength only with varying the laser fluence and overlap. Different OPV device architectures with multilayers utilizing various materials are challenging for ablation but can be structured by using a systematical approach.

Empirically based device modeling of bulk heterojunction organic photovoltaics

NASA Astrophysics Data System (ADS)

Pierre, Adrien; Lu, Shaofeng; Howard, Ian A.; Facchetti, Antonio; Arias, Ana Claudia

2013-04-01

We develop an empirically based optoelectronic model to accurately simulate the photocurrent in organic photovoltaic (OPV) devices with novel materials including bulk heterojunction OPV devices based on a new low band gap dithienothiophene-DPP donor polymer, P(TBT-DPP), blended with PC70BM at various donor-acceptor weight ratios and solvent compositions. Our devices exhibit power conversion efficiencies ranging from 1.8% to 4.7% at AM 1.5G. Electron and hole mobilities are determined using space-charge limited current measurements. Bimolecular recombination coefficients are both analytically calculated using slowest-carrier limited Langevin recombination and measured using an electro-optical pump-probe technique. Exciton quenching efficiencies in the donor and acceptor domains are determined from photoluminescence spectroscopy. In addition, dielectric and optical constants are experimentally determined. The photocurrent and its bias-dependence that we simulate using the optoelectronic model we develop, which takes into account these physically measured parameters, shows less than 7% error with respect to the experimental photocurrent (when both experimentally and semi-analytically determined recombination coefficient is used). Free carrier generation and recombination rates of the photocurrent are modeled as a function of the position in the active layer at various applied biases. These results show that while free carrier generation is maximized in the center of the device, free carrier recombination is most dominant near the electrodes even in high performance devices. Such knowledge of carrier activity is essential for the optimization of the active layer by enhancing light trapping and minimizing recombination. Our simulation program is intended to be freely distributed for use in laboratories fabricating OPV devices.

Integrating theory, synthesis, spectroscopy and device efficiency to design and characterize donor materials for organic photovoltaics: a case study including 12 donors

DOE PAGES

Oosterhout, S. D.; Kopidakis, N.; Owczarczyk, Z. R.; ...

2015-04-07

There have been remarkable improvements in the power conversion efficiency of solution-processable Organic Photovoltaics (OPV) have largely been driven by the development of novel narrow bandgap copolymer donors comprising an electron-donating (D) and an electron-withdrawing (A) group within the repeat unit. The large pool of potential D and A units and the laborious processes of chemical synthesis and device optimization, has made progress on new high efficiency materials slow with a few new efficient copolymers reported every year despite the large number of groups pursuing these materials. In our paper we present an integrated approach toward new narrow bandgap copolymersmore » that uses theory to guide the selection of materials to be synthesized based on their predicted energy levels, and time-resolved microwave conductivity (TRMC) to select the best-performing copolymer–fullerene bulk heterojunction to be incorporated into complete OPV devices. We validate our methodology by using a diverse group of 12 copolymers, including new and literature materials, to demonstrate good correlation between (a) theoretically determined energy levels of polymers and experimentally determined ionization energies and electron affinities and (b) photoconductance, measured by TRMC, and OPV device performance. The materials used here also allow us to explore whether further copolymer design rules need to be incorporated into our methodology for materials selection. For example, we explore the effect of the enthalpy change (ΔH) during exciton dissociation on the efficiency of free charge carrier generation and device efficiency and find that ΔH of -0.4 eV is sufficient for efficient charge generation.« less

A series of simple oligomer-like small molecules based on oligothiophenes for solution-processed solar cells with high efficiency.

PubMed

Kan, Bin; Li, Miaomiao; Zhang, Qian; Liu, Feng; Wan, Xiangjian; Wang, Yunchuang; Ni, Wang; Long, Guankui; Yang, Xuan; Feng, Huanran; Zuo, Yi; Zhang, Mingtao; Huang, Fei; Cao, Yong; Russell, Thomas P; Chen, Yongsheng

2015-03-25

A series of acceptor-donor-acceptor simple oligomer-like small molecules based on oligothiophenes, namely, DRCN4T-DRCN9T, were designed and synthesized. Their optical, electrical, and thermal properties and photovoltaic performances were systematically investigated. Except for DRCN4T, excellent performances were obtained for DRCN5T-DRCN9T. The devices based on DRCN5T, DRCN7T, and DRCN9T with axisymmetric chemical structures exhibit much higher short-circuit current densities than those based on DRCN6T and DRCN8T with centrosymmetric chemical structures, which is attributed to their well-developed fibrillar network with a feature size less than 20 nm. The devices based on DRCN5T/PC71BM showed a notable certified power conversion efficiency (PCE) of 10.10% under AM 1.5G irradiation (100 mW cm(-2)) using a simple solution spin-coating fabrication process. This is the highest PCE for single-junction small-molecule-based organic photovoltaics (OPVs) reported to date. DRCN5T is a rather simpler molecule compared with all of the other high-performance molecules in OPVs to date, and this might highlight its advantage in the future possible commercialization of OPVs. These results demonstrate that a fine and balanced modification/design of chemical structure can make significant performance differences and that the performance of solution-processed small-molecule-based solar cells can be comparable to or even surpass that of their polymer counterparts.

Promoting Morphology with a Favorable Density of States Using Diiodooctane to Improve Organic Photovoltaic Device Efficiency and Charge Carrier Lifetimes

DOE PAGES

Garner, Logan E.; Bera, Abhijit; Larson, Bryon W.; ...

2017-06-06

Due to the inherent challenges in probing nanoscale properties within bulk heterojunction (BHJ) active layers of organic photovoltaic (OPV) devices, the relationship between morphology and nanoscale electronic structure is not well understood. Here, we employ scanning tunneling microscopy (STM) dI/dV imaging and localized density of states (DOS) spectra to investigate the influence of additives on morphology in a high-performance OPV system. In short, we are able to correlate the use of diiodooctane (DIO) additive with significant changes to the distribution of the localized DOS, most notably a broader distribution of PCE10 polymer HOMO levels and PC70BM fullerene LUMO levels, asmore » well as significantly smaller domain sizes and significantly higher overall device efficiencies. We further correlate this data with a nearly 3-fold increase in charge carrier lifetimes in the active layer when DIO is employed, determined by time-resolved microwave conductivity (TRMC) measurements. In conclusion, the results are consistent with the growing body of literature evidence that DIO promotes the formation of a polymer/fullerene mixed phase and therefore highlight the unique information that this combination of techniques can provide when investigating OPV active layer morphology.« less

Promoting Morphology with a Favorable Density of States Using Diiodooctane to Improve Organic Photovoltaic Device Efficiency and Charge Carrier Lifetimes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garner, Logan E.; Bera, Abhijit; Larson, Bryon W.

Due to the inherent challenges in probing nanoscale properties within bulk heterojunction (BHJ) active layers of organic photovoltaic (OPV) devices, the relationship between morphology and nanoscale electronic structure is not well understood. Here, we employ scanning tunneling microscopy (STM) dI/dV imaging and localized density of states (DOS) spectra to investigate the influence of additives on morphology in a high-performance OPV system. In short, we are able to correlate the use of diiodooctane (DIO) additive with significant changes to the distribution of the localized DOS, most notably a broader distribution of PCE10 polymer HOMO levels and PC70BM fullerene LUMO levels, asmore » well as significantly smaller domain sizes and significantly higher overall device efficiencies. We further correlate this data with a nearly 3-fold increase in charge carrier lifetimes in the active layer when DIO is employed, determined by time-resolved microwave conductivity (TRMC) measurements. In conclusion, the results are consistent with the growing body of literature evidence that DIO promotes the formation of a polymer/fullerene mixed phase and therefore highlight the unique information that this combination of techniques can provide when investigating OPV active layer morphology.« less

Mesoscopic features of charge generation in organic semiconductors.

PubMed

Savoie, Brett M; Jackson, Nicholas E; Chen, Lin X; Marks, Tobin J; Ratner, Mark A

2014-11-18

CONSPECTUS: In the past two decades, organic materials have been extensively investigated by numerous research groups worldwide for implementation in organic photovoltaic (OPV) devices. The interest in organic semiconductors is spurred by their potential low cost and facile tunability, making OPV devices a potentially disruptive technology. To study OPV operating mechanisms is also to explore a knowledge gap in our general understanding of materials, because both the time scales (femtosecond to microsecond) and length scales (nanometer to micrometer) relevant to OPV functionality occupy a challenging and fascinating space between the traditional regimes of quantum chemistry and solid-state physics. New theoretical frameworks and computational tools are needed to bridge the aforementioned length and time scales, and they must satisfy the criteria of computational tractability for systems involving 10(4)-10(6) atoms, while also maintaining predictive utility. While this challenge is far from solved, advances in density functional theory (DFT) have allowed researchers to investigate the ground- and excited-state properties of many intermediate sized systems (10(2)-10(3) atoms) that provide the outlines of the larger problem. Results on these smaller systems are already sufficient to predict optical gaps and trends in valence band energies, correct erroneous interpretations of experimental data, and develop models for charge generation and transport in OPV devices. The active films of high-efficiency OPV devices are comprised of mesoscopic mixtures of electron donor (D) and electron acceptor (A) species, a "bulk-heterojunction" (BHJ) device, subject to variable degrees of structural disorder. Depending on the degree of intermolecular electronic coupling and energy level alignment, the spatial delocalization of photoexcitations and charge carriers can affect the dynamics of the solar cell. In this Account, we provide an overview of three pivotal characteristics of solar cells that possess strong delocalization dependence: (1) the exciton binding energy, (2) charge transfer at the D-A heterojunction, and (3) the energy landscape in the vicinity of the D-A heterojunction. In each case, the length scale dependence can be assessed through DFT calculations on reference systems, with a view to establishing general trends. Throughout the discussion, we draw from the experimental and theoretical literature to provide a consistent view of what is known about these properties in actual BHJ blends. A consistent interpretation of the results to date affords the following view: transient delocalization effects and resonant charge transfer at the heterojunction are capable of funneling excitations away from trap states and mediating exciton dissociation; these factors alone are capable of explaining the remarkably good charge generation currently achieved in OPV devices. The exciton binding energy likely plays a minimal role in modern OPV devices, since the presence of the heterojunction serves to bypass the costly exciton-to-free-charge transition state.

Current challenges in organic photovoltaic solar energy conversion.

PubMed

Schlenker, Cody W; Thompson, Mark E

2012-01-01

Over the last 10 years, significant interest in utilizing conjugated organic molecules for solid-state solar to electric conversion has produced rapid improvement in device efficiencies. Organic photovoltaic (OPV) devices are attractive for their compatibility with low-cost processing techniques and thin-film applicability to flexible and conformal applications. However, many of the processes that lead to power losses in these systems still remain poorly understood, posing a significant challenge for the future efficiency improvements required to make these devices an attractive solar technology. While semiconductor band models have been employed to describe OPV operation, a more appropriate molecular picture of the pertinent processes is beginning to emerge. This chapter presents mechanisms of OPV device operation, based on the bound molecular nature of the involved transient species. With the intention to underscore the importance of considering both thermodynamic and kinetic factors, recent progress in elucidating molecular characteristics that dictate photovoltage losses in heterojunction organic photovoltaics is also discussed.

Energy-cascade organic photovoltaic devices incorporating a host-guest architecture.

PubMed

Menke, S Matthew; Holmes, Russell J

2015-02-04

In planar heterojunction organic photovoltaic devices (OPVs), broad spectral coverage can be realized by incorporating multiple molecular absorbers in an energy-cascade architecture. Here, this approach is combined with a host-guest donor layer architecture previously shown to optimize exciton transport for the fluorescent organic semiconductor boron subphthalocyanine chloride (SubPc) when diluted in an optically transparent host. In order to maximize the absorption efficiency, energy-cascade OPVs that utilize both photoactive host and guest donor materials are examined using the pairing of SubPc and boron subnaphthalocyanine chloride (SubNc), respectively. In a planar heterojunction architecture, excitons generated on the SubPc host rapidly energy transfer to the SubNc guest, where they may migrate toward the dissociating, donor-acceptor interface. Overall, the incorporation of a photoactive host leads to a 13% enhancement in the short-circuit current density and a 20% enhancement in the power conversion efficiency relative to an optimized host-guest OPV combining SubNc with a nonabsorbing host. This work underscores the potential for further design refinements in planar heterojunction OPVs and demonstrates progress toward the effective separation of functionality between constituent OPV materials.

Enhanced stability of ZnO-based inverted organic photovoltaic devices by phosphonic acid modification

NASA Astrophysics Data System (ADS)

MacLeod, Bradley; Tremolet de Villers, Bertrand; Cowan, Sarah; Ratcliff, Erin; Olson, Dana

2014-03-01

Solution-processed ZnO thin films are now commonly used as n-type bottom contacts in inverted-geometry organic photovoltaics (OPVs). The use of ZnO eliminates the need for highly-reactive top-contact (air-interface) electrode material, such as calcium and aluminum which are commonly used in conventional geometries, which enables operational lifetimes of unencapsulated devices to shift from minutes or hours to days. Modification of the ZnO film by self-assembled monolayers (SAMs) has been shown to enhance performance as well as air-stability during storage. We modify ZnO with dipolar phosphonic acids and observe enhanced performance and stability. We show for the first time devices measured under continuous illumination at one-sun intensity which have significantly enhanced stability when utilizing SAM-modified ZnO. These continuous-illumination stability measurements allow us to investigate the degradation mechanisms of these more stable inverted OPV devices. This work was was supported by of the Center for Interface Science: Solar Electric Materials (CISSEM), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001084.

Intrinsic coincident linear polarimetry using stacked organic photovoltaics.

PubMed

Roy, S Gupta; Awartani, O M; Sen, P; O'Connor, B T; Kudenov, M W

2016-06-27

Polarimetry has widespread applications within atmospheric sensing, telecommunications, biomedical imaging, and target detection. Several existing methods of imaging polarimetry trade off the sensor's spatial resolution for polarimetric resolution, and often have some form of spatial registration error. To mitigate these issues, we have developed a system using oriented polymer-based organic photovoltaics (OPVs) that can preferentially absorb linearly polarized light. Additionally, the OPV cells can be made semitransparent, enabling multiple detectors to be cascaded along the same optical axis. Since each device performs a partial polarization measurement of the same incident beam, high temporal resolution is maintained with the potential for inherent spatial registration. In this paper, a Mueller matrix model of the stacked OPV design is provided. Based on this model, a calibration technique is developed and presented. This calibration technique and model are validated with experimental data, taken with a cascaded three cell OPV Stokes polarimeter, capable of measuring incident linear polarization states. Our results indicate polarization measurement error of 1.2% RMS and an average absolute radiometric accuracy of 2.2% for the demonstrated polarimeter.

Low-Temperature Process for Atomic Layer Chemical Vapor Deposition of an Al2O3 Passivation Layer for Organic Photovoltaic Cells.

PubMed

Kim, Hoonbae; Lee, Jihye; Sohn, Sunyoung; Jung, Donggeun

2016-05-01

Flexible organic photovoltaic (OPV) cells have drawn extensive attention due to their light weight, cost efficiency, portability, and so on. However, OPV cells degrade quickly due to organic damage by water vapor or oxygen penetration when the devices are driven in the atmosphere without a passivation layer. In order to prevent damage due to water vapor or oxygen permeation into the devices, passivation layers have been introduced through methods such as sputtering, plasma enhanced chemical vapor deposition, and atomic layer chemical vapor deposition (ALCVD). In this work, the structural and chemical properties of Al2O3 films, deposited via ALCVD at relatively low temperatures of 109 degrees C, 200 degrees C, and 300 degrees C, are analyzed. In our experiment, trimethylaluminum (TMA) and H2O were used as precursors for Al2O3 film deposition via ALCVD. All of the Al2O3 films showed very smooth, featureless surfaces without notable defects. However, we found that the plastic flexible substrate of an OPV device passivated with 300 degrees C deposition temperature was partially bended and melted, indicating that passivation layers for OPV cells on plastic flexible substrates need to be formed at temperatures lower than 300 degrees C. The OPV cells on plastic flexible substrates were passivated by the Al2O3 film deposited at the temperature of 109 degrees C. Thereafter, the photovoltaic properties of passivated OPV cells were investigated as a function of exposure time under the atmosphere.

Use of silane-functionalized graphene oxide in organic photovoltaic cells and organic light-emitting diodes.

PubMed

Lee, Chang Yeong; Le, Quyet Van; Kim, Cheolmin; Kim, Soo Young

2015-04-14

Graphene oxide (GO) and silane-functionalized GO (sGO) sheets obtained through a simple sonication exfoliation method are employed as hole transport layers to improve the efficiency of organic photovoltaic (OPV) cells and organic light-emitting diodes (OLED). GO was functionalized using (3-glycidyl oxypropyl)trimethoxysilane (GPTMS) and triethoxymethylsilane (MTES). The appearance of new peaks in the Fourier-transform infrared spectra of the sGOs indicates the formation of Si-O-C, Si-O-Si, Si-H, and Si-O-C moieties, which provide evidence of the addition of silane to the GO surface. Furthermore, the appearance of Si-O-Si bonds in the synchrotron radiation photoelectron spectra (SRPES) of the MTES-sGO and GPTMS-sGO samples suggests that silane groups were effectively functionalized onto the GO sheets. An OPV cell with GO layers showed a lower performance with a power conversion efficiency (PCE) of 2.06%; in contrast, OPV cells based on GPTMS-sGO and MTES-sGO have PCE values of 3.00 and 3.08%, respectively. The OLED devices based on GPTMS-sGO and MTES-sGO showed a higher maximum luminance efficiency of 13.91 and 12.77 cd A(-1), respectively, than PEDOT:PSS-based devices (12.34 cd A(-1)). The SRPES results revealed that the work functions of GO, GPTMS-sGO, and MTES-sGO were 4.8, 4.9, and 5.0 eV, respectively. Therefore, the increase in the PCE value is attributed to improved band-gap alignment. It is thought that sGO could be used as an interfacial layer in OPV and OLED devices.

On the stability of a variety of organic photovoltaic devices by IPCE and in situ IPCE analyses--the ISOS-3 inter-laboratory collaboration.

PubMed

Teran-Escobar, Gerardo; Tanenbaum, David M; Voroshazi, Eszter; Hermenau, Martin; Norrman, Kion; Lloyd, Matthew T; Galagan, Yulia; Zimmermann, Birger; Hösel, Markus; Dam, Henrik F; Jørgensen, Mikkel; Gevorgyan, Suren; Kudret, Suleyman; Maes, Wouter; Lutsen, Laurence; Vanderzande, Dirk; Würfel, Uli; Andriessen, Ronn; Rösch, Roland; Hoppe, Harald; Rivaton, Agnès; Uzunoğlu, Gülşah Y; Germack, David; Andreasen, Birgitta; Madsen, Morten V; Bundgaard, Eva; Krebs, Frederik C; Lira-Cantu, Monica

2012-09-07

This work is part of the inter-laboratory collaboration to study the stability of seven distinct sets of state-of-the-art organic photovoltaic (OPV) devices prepared by leading research laboratories. All devices have been shipped to and degraded at RISØ-DTU up to 1830 hours in accordance with established ISOS-3 protocols under defined illumination conditions. In this work, we apply the Incident Photon-to-Electron Conversion Efficiency (IPCE) and the in situ IPCE techniques to determine the relation between solar cell performance and solar cell stability. Different ageing conditions were considered: accelerated full sun simulation, low level indoor fluorescent lighting and dark storage. The devices were also monitored under conditions of ambient and inert (N(2)) atmospheres, which allows for the identification of the solar cell materials more susceptible to degradation by ambient air (oxygen and moisture). The different OPVs configurations permitted the study of the intrinsic stability of the devices depending on: two different ITO-replacement alternatives, two different hole extraction layers (PEDOT:PSS and MoO(3)), and two different P3HT-based polymers. The response of un-encapsulated devices to ambient atmosphere offered insight into the importance of moisture in solar cell performance. Our results demonstrate that the IPCE and the in situ IPCE techniques are valuable analytical methods to understand device degradation and solar cell lifetime.

Increasing Photovoltaic Performance of an Organic Cationic Chromophore by Anion Exchange

PubMed Central

Gesevičius, Donatas; Neels, Antonia; Jenatsch, Sandra; Hack, Erwin; Viani, Lucas; Athanasopoulos, Stavros; Heier, Jakob

2017-01-01

Abstract A symmetrical cyanine dye chromophore is modified with different counteranions to study the effect on crystal packing, polarizability, thermal stability, optical properties, light absorbing layer morphology, and organic photovoltaic (OPV) device parameters. Four sulfonate‐based anions and the bulky bistriflylimide anion are introduced to the 2‐[5‐(1,3‐dihydro‐1,3,3‐trimethyl‐2H‐indol‐2‐ylidene)‐1,3‐pentadien‐1‐yl]‐1,3,3‐trimethyl‐3H‐indolium chromophore using an Amberlyst A26 (OH− form) anion exchanger. Anionic charge distribution clearly correlates with device performance, whereby an average efficiency of 2% was reached in a standard bilayer organic solar. Evidence is given that the negative charge of the anion distributed over a large number of atoms is significantly more important than the size of the organic moieties of the sulfonate charge carrying group. This provides a clear strategy for future design of more efficient cyanine dyes for OPV applications. PMID:29610723

The role of the hole-extraction layer in determining the operational stability of a polycarbazole:fullerene bulk-heterojunction photovoltaic device

NASA Astrophysics Data System (ADS)

Bovill, E.; Scarratt, N.; Griffin, J.; Yi, H.; Iraqi, A.; Buckley, A. R.; Kingsley, J. W.; Lidzey, D. G.

2015-02-01

We have made a comparative study of the relative operational stability of bulk-heterojunction organic photovoltaic (OPV) devices utilising different hole transport layers (HTLs). OPV devices were fabricated based on a blend of the polymer PCDTBT with the fullerene PC70BM, and incorporated the different HTL materials PEDOT:PSS, MoOx and V2O5. Following 620 h of irradiation by light from a solar simulator, we find that devices using the PEDOT:PSS HTL retained the highest efficiency, having a projected T80 lifetime of 14 500 h.

Work-Function and Surface Energy Tunable Cyanoacrylic Acid Small-Molecule Derivative Interlayer on Planar ZnO Nanorods for Improved Organic Photovoltaic Performance.

PubMed

Ambade, Swapnil B; Ambade, Rohan B; Bagde, Sushil S; Lee, Soo-Hyoung

2016-12-28

The issue of work-function and surface energy is fundamental to "decode" the critical inorganic/organic interface in hybrid organic photovoltaics, which influences important photovoltaic events like exciton dissociation, charge transfer, photocurrent (J sc ), open-circuit voltage (V oc ), etc. We demonstrate that by incorporating an interlayer of cyanoacrylic acid small molecular layer (SML) on solution-processed, spin-coated, planar ZnO nanorods (P-ZnO NRs), higher photovoltaic (PV) performances were achieved in both inverted organic photovoltaic (iOPV) and hybrid organic photovoltaic (HOPV) devices, where ZnO acts as an "electron-transporting layer" and as an "electron acceptor", respectively. For the tuned range of surface energy from 52.5 to 33 mN/m, the power conversion efficiency (PCE) in bulk heterojunction (BHJ) iOPVs based on poly(3-hexylthiophene) (P3HT) and phenyl-C 60 -butyric acid methyl ester (PC 60 BM) increases from 3.16% to 3.68%, and that based on poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene)-2-carboxylate-2-6-diyl)] (PTB7:Th):[6,6]-phenyl C 71 butyric acid methyl ester (PC 71 BM) photoactive BHJ increases from 6.55% to 8.0%, respectively. The improved PV performance in iOPV devices is majorly attributed to enhanced photocurrents achieved as a result of reduced surface energy and greater electron affinity from the covalent attachment of the strong electron-withdrawing cyano moiety, while that in HOPV devices, where PCE increases from 0.21% to 0.79% for SML-modified devices, is ascribed to a large increase in V oc benefitted due to reduced work function effected from the presence of strong dipole moment in SML that points away from P-ZnO NRs.

Steering the Properties of MoOx Hole Transporting Layers in OPVs and OLEDs: Interface Morphology vs. Electronic Structure

PubMed Central

Marchal, Wouter; Verboven, Inge; Kesters, Jurgen; Moeremans, Boaz; De Dobbelaere, Christopher; Bonneux, Gilles; Elen, Ken; Conings, Bert; Maes, Wouter; Boyen, Hans Gerd; Deferme, Wim; Van Bael, Marlies; Hardy, An

2017-01-01

The identification, fine-tuning, and process optimization of appropriate hole transporting layers (HTLs) for organic solar cells is indispensable for the production of efficient and sustainable functional devices. In this study, the optimization of a solution-processed molybdenum oxide (MoOx) layer fabricated from a combustion precursor is carried out via the introduction of zirconium and tin additives. The evaluation of the output characteristics of both organic photovoltaic (OPV) and organic light emitting diode (OLED) devices demonstrates the beneficial influence upon the addition of the Zr and Sn ions compared to the generic MoOx precursor. A dopant effect in which the heteroatoms and the molybdenum oxide form a chemical identity with fundamentally different structural properties could not be observed, as the additives do not affect the molybdenum oxide composition or electronic band structure. An improved surface roughness due to a reduced crystallinity was found to be a key parameter leading to the superior performance of the devices employing modified HTLs. PMID:28772483

Steering the Properties of MoOx Hole Transporting Layers in OPVs and OLEDs: Interface Morphology vs. Electronic Structure.

PubMed

Marchal, Wouter; Verboven, Inge; Kesters, Jurgen; Moeremans, Boaz; De Dobbelaere, Christopher; Bonneux, Gilles; Elen, Ken; Conings, Bert; Maes, Wouter; Boyen, Hans Gerd; Deferme, Wim; Van Bael, Marlies; Hardy, An

2017-01-30

The identification, fine-tuning, and process optimization of appropriate hole transporting layers (HTLs) for organic solar cells is indispensable for the production of efficient and sustainable functional devices. In this study, the optimization of a solution-processed molybdenum oxide (MoOx) layer fabricated from a combustion precursor is carried out via the introduction of zirconium and tin additives. The evaluation of the output characteristics of both organic photovoltaic (OPV) and organic light emitting diode (OLED) devices demonstrates the beneficial influence upon the addition of the Zr and Sn ions compared to the generic MoOx precursor. A dopant effect in which the heteroatoms and the molybdenum oxide form a chemical identity with fundamentally different structural properties could not be observed, as the additives do not affect the molybdenum oxide composition or electronic band structure. An improved surface roughness due to a reduced crystallinity was found to be a key parameter leading to the superior performance of the devices employing modified HTLs.

Factors limiting device efficiency in organic photovoltaics.

PubMed

Janssen, René A J; Nelson, Jenny

2013-04-04

The power conversion efficiency of the most efficient organic photovoltaic (OPV) cells has recently increased to over 10%. To enable further increases, the factors limiting the device efficiency in OPV must be identified. In this review, the operational mechanism of OPV cells is explained and the detailed balance limit to photovoltaic energy conversion, as developed by Shockley and Queisser, is outlined. The various approaches that have been developed to estimate the maximum practically achievable efficiency in OPV are then discussed, based on empirical knowledge of organic semiconductor materials. Subsequently, approaches made to adapt the detailed balance theory to incorporate some of the fundamentally different processes in organic solar cells that originate from using a combination of two complementary, donor and acceptor, organic semiconductors using thermodynamic and kinetic approaches are described. The more empirical formulations to the efficiency limits provide estimates of 10-12%, but the more fundamental descriptions suggest limits of 20-24% to be reachable in single junctions, similar to the highest efficiencies obtained for crystalline silicon p-n junction solar cells. Closing this gap sets the stage for future materials research and development of OPV. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Crystalline Nanoporous Frameworks: a Nanolaboratory for Probing Excitonic Device Concepts.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allendorf, Mark D.; Azoulay, Jason; Ford, Alexandra Caroline

2014-09-01

Electro-optical organic materials hold great promise for the development of high-efficiency devices based on exciton formation and dissociation, such as organic photovoltaics (OPV) and organic light-emitting devices (OLEDs). However, the external quantum efficiency (EQE) of both OPV and OLEDs must be improved to make these technologies economical. Efficiency rolloff in OLEDs and inability to control morphology at key OPV interfaces both reduce EQE. Only by creating materials that allow manipulation and control of the intimate assembly and communication between various nanoscale excitonic components can we hope to first understand and then engineer the system to allow these materials to reachmore » their potential. The aims of this proposal are to: 1) develop a paradigm-changing platform for probing excitonic processes composed of Crystalline Nanoporous Frameworks (CNFs) infiltrated with secondary materials (such as a complimentary semiconductor); 2) use them to probe fundamental aspects of excitonic processes; and 3) create prototype OPVs and OLEDs using infiltrated CNF as active device components. These functional platforms will allow detailed control of key interactions at the nanoscale, overcoming the disorder and limited synthetic control inherent in conventional organic materials. CNFs are revolutionary inorganic-organic hybrid materials boasting unmatched synthetic flexibility that allow tuning of chemical, geometric, electrical, and light absorption/generation properties. For example, bandgap engineering is feasible and polyaromatic linkers provide tunable photon antennae; rigid 1-5 nm pores provide an oriented, intimate host for triplet emitters (to improve light emission in OLEDs) or secondary semiconducting polymers (creating a charge-separation interface in OPV). These atomically engineered, ordered structures will enable critical fundamental questions to be answered concerning charge transport, nanoscale interfaces, and exciton behavior that are inaccessible in disordered systems. Implementing this concept also creates entirely new dimensions for device fabrication that could both improve performance, increase durability, and reduce costs with unprecedented control of over properties. This report summarizes the key results of this project and is divided into sections based on publications that resulted from the work. We begin in Section 2 with an investigation of light harvesting and energy transfer in a MOF infiltrated with donor and acceptor molecules of the type typically used in OPV devices (thiophenes and fullerenes, respectively). The results show that MOFs can provide multiple functions: as a light harvester, as a stabilizer and organizer or the infiltrated molecules, and as a facilitator of energy transfer. Section 3 describes computational design of MOF linker groups to accomplish light harvesting in the visible and facilitate charge separation and transport. The predictions were validated by UV-visible absorption spectroscopy, demonstrating that rational design of MOFs for light-harvesting purposes is feasible. Section 4 extends the infiltration concept discussed in Section to, which we now designate as "Molecule@MOF" to create an electrically conducting framework. The tailorability and high conductivity of this material are unprecedented, meriting publication in the journal Science and spawning several Technical Advances. Section 5 discusses processes we developed for depositing MOFs as thin films on substrates, a critical enabling technology for fabricating MOF-based electronic devices. Finally, in Section 6 we summarize results showing that a MOF thin film can be used as a sensitizer in a DSSC, demonstrating that MOFs can serve as active layers in excitonic devices. Overall, this project provides several crucial proofs-of- concept that the potential of MOFs for use in optoelectronic devices that we predicted several years ago [ 3 ] can be realized in practice.« less

Heteroatom-bridged benzothiazolyls for organic solar cells: a theoretical study.

PubMed

Chen, Runfeng; Wang, Yang; Chen, Ting; Li, Huanhuan; Zheng, Chunhua; Yuan, Kai; Wang, Zhixiang; Tao, Ye; Zheng, Chao; Huang, Wei

2015-01-15

On the basis of a typical organic photovoltaic (OPV) building block of 4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (DTBT), a series of novel DTBT derivatives were designed following a heteroatom-bridging strategy to take advantage of the diversified interactions between heteroatoms and π-conjugated systems. These heteroatom-bridged DTBTs, whose outer electron-rich thiophene moieties are covalently fastened to the central electron-deficient benzothiadiazole with additional heteroatom bridges, exhibit promising features for OPV applications with rigid molecular structures, properly lain frontier molecular orbitals (FMOs), broad and intense absorption spectra, and adequate charge transport properties, as revealed by systematic theoretical calculations on molecular geometries, FMOs, absorption spectra, and relaxation and reorganization energies. The structure-property relationship investigations show that the mono-/di-heteroatom bridging is effective not only in tuning the rigidity of the molecular geometries but also in adjusting the optoelectronic properties of the resulting materials. Among the studied heteroatoms, the C and Si were found to be the most efficient in designing novel molecules for OPV applications. These theoretical insights may provide a solid basis for experimental synthesis and device investigations of the proposed heteroatom-bridged DTBTs as potential high-performance building blocks for bulk heterojunction OPV molecules.

Reticulated Organic Photovoltaics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schiros T.; Yager K.; Mannsfeld S.

2012-03-21

This paper shows how the self-assembled interlocking of two nanostructured materials can lead to increased photovoltaic performance. A detailed picture of the reticulated 6-DBTTC/C{sub 60} organic photovoltaic (OPV) heterojunction, which produces devices approaching the theoretical maximum for these materials, is presented from near edge X-ray absorption spectroscopy (NEXAFS), X-ray photoelectron spectroscopy (XPS), Grazing Incidence X-ray diffraction (GIXD) and transmission electron microscopy (TEM). The complementary suite of techniques shows how self-assembly can be exploited to engineer the interface and morphology between the cables of donor (6-DBTTC) material and a polycrystalline acceptor (C{sub 60}) to create an interpenetrating network of pure phasesmore » expected to be optimal for OPV device design. Moreover, we find that there is also a structural and electronic interaction between the two materials at the molecular interface. The data show how molecular self-assembly can facilitate 3-D nanostructured photovoltaic cells that are made with the simplicity and control of bilayer device fabrication. The significant improvement in photovoltaic performance of the reticulated heterojunction over the flat analog highlights the potential of these strategies to improve the efficiency of organic solar cells.« less

Roll-to-roll suitable short-pulsed laser scribing of organic photovoltaics and close-to-process characterization

NASA Astrophysics Data System (ADS)

Kuntze, Thomas; Wollmann, Philipp; Klotzbach, Udo; Fledderus, Henri

2017-03-01

The proper long term operation of organic electronic devices like organic photovoltaics OPV depends on their resistance to environmental influences such as permeation of water vapor. Major efforts are spent to encapsulate OPV. State of the art is sandwich-like encapsulation between two ultra-barrier foils. Sandwich encapsulation faces two major disadvantages: high costs ( 1/3 of total costs) and parasitic intrinsic water (sponge effects of the substrate foil). To fight these drawbacks, a promising approach is to use the OPV substrate itself as barrier by integration of an ultra-barrier coating, followed by alternating deposition and structuring of OPV functional layers. In effect, more functionality will be integrated into less material, and production steps are reduced in number. All processing steps must not influence the underneath barrier functionality, while all electrical functionalities must be maintained. As most reasonable structuring tool, short and ultrashort pulsed lasers USP are used. Laser machining applies to three layers: bottom electrode made of transparent conductive materials (P1), organic photovoltaic operative stack (P2) and top electrode (P3). In this paper, the machining of functional 110…250 nm layers of flexible OPV by USP laser systems is presented. Main focus is on structuring without damaging the underneath ultra-barrier layer. The close-to-process machining quality characterization is performed with the analysis tool "hyperspectral imaging" (HSI), which is checked crosswise with the "gold standard" Ca-test. It is shown, that both laser machining and quality controlling, are well suitable for R2R production of OPV.

Transition metal oxides for organic electronics: energetics, device physics and applications.

PubMed

Meyer, Jens; Hamwi, Sami; Kröger, Michael; Kowalsky, Wolfgang; Riedl, Thomas; Kahn, Antoine

2012-10-23

During the last few years, transition metal oxides (TMO) such as molybdenum tri-oxide (MoO(3) ), vanadium pent-oxide (V(2) O(5) ) or tungsten tri-oxide (WO(3) ) have been extensively studied because of their exceptional electronic properties for charge injection and extraction in organic electronic devices. These unique properties have led to the performance enhancement of several types of devices and to a variety of novel applications. TMOs have been used to realize efficient and long-term stable p-type doping of wide band gap organic materials, charge-generation junctions for stacked organic light emitting diodes (OLED), sputtering buffer layers for semi-transparent devices, and organic photovoltaic (OPV) cells with improved charge extraction, enhanced power conversion efficiency and substantially improved long term stability. Energetics in general play a key role in advancing device structure and performance in organic electronics; however, the literature provides a very inconsistent picture of the electronic structure of TMOs and the resulting interpretation of their role as functional constituents in organic electronics. With this review we intend to clarify some of the existing misconceptions. An overview of TMO-based device architectures ranging from transparent OLEDs to tandem OPV cells is also given. Various TMO film deposition methods are reviewed, addressing vacuum evaporation and recent approaches for solution-based processing. The specific properties of the resulting materials and their role as functional layers in organic devices are discussed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Exploration of Novel Materials for Development of Next Generation OPV Devices: Cooperative Research and Development Final Report, CRADA Number CRD-10-398

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olson, D.

2012-09-01

Organic-based solar cells offer the potential for low cost, scalable conversion of solar energy. This project will try to utilize the extensive organic synthetic capabilities of ConocoPhillips to produce novel acceptor and donor materials as well potentially as interface modifiers to produce improved OPV devices with greater efficiency and stability. The synthetic effort will be based on the knowledge base and modeling being done at NREL to identify new candidate materials.

Thermally stable, highly efficient, ultraflexible organic photovoltaics

PubMed Central

Xu, Xiaomin; Fukuda, Kenjiro; Karki, Akchheta; Park, Sungjun; Kimura, Hiroki; Jinno, Hiroaki; Watanabe, Nobuhiro; Yamamoto, Shuhei; Shimomura, Satoru; Kitazawa, Daisuke; Yokota, Tomoyuki; Umezu, Shinjiro; Nguyen, Thuc-Quyen; Someya, Takao

2018-01-01

Flexible photovoltaics with extreme mechanical compliance present appealing possibilities to power Internet of Things (IoT) sensors and wearable electronic devices. Although improvement in thermal stability is essential, simultaneous achievement of high power conversion efficiency (PCE) and thermal stability in flexible organic photovoltaics (OPVs) remains challenging due to the difficulties in maintaining an optimal microstructure of the active layer under thermal stress. The insufficient thermal capability of a plastic substrate and the environmental influences cannot be fully expelled by ultrathin barrier coatings. Here, we have successfully fabricated ultraflexible OPVs with initial efficiencies of up to 10% that can endure temperatures of over 100 °C, maintaining 80% of the initial efficiency under accelerated testing conditions for over 500 hours in air. Particularly, we introduce a low-bandgap poly(benzodithiophene-cothieno[3,4-b]thiophene) (PBDTTT) donor polymer that forms a sturdy microstructure when blended with a fullerene acceptor. We demonstrate a feasible way to adhere ultraflexible OPVs onto textiles through a hot-melt process without causing severe performance degradation. PMID:29666257

Effects of the charge-transfer reorganization energy on the open-circuit voltage in small-molecular bilayer organic photovoltaic devices: comparison of the influence of deposition rates of the donor.

PubMed

Lee, Chih-Chien; Su, Wei-Cheng; Chang, Wen-Chang

2016-05-14

The theoretical maximum of open-circuit voltage (VOC) of organic photovoltaic (OPV) devices has yet to be determined, and its origin remains debated. Here, we demonstrate that VOC of small-molecule OPV devices can be improved by controlling the deposition rate of a donor without changing the interfacial energy gap at the donor/acceptor interface. The measurement of external quantum efficiency and electroluminescence spectra facilitates the observation of the existence of charge transfer (CT) states. A simplified approach by reusing the reciprocity relationship for obtaining the properties of the CT states is proposed without introducing complex techniques. We compare experimental and fitting results and propose that reorganization energy is the primary factor in determining VOC instead of either the CT energy or electronic coupling term in bilayer OPV devices. Atomic force microscopy images indicate a weak molecular aggregation when a higher deposition rate is used. The results of temperature-dependent measurements suggest the importance of molecular stacking for the CT properties.

Enhancing fullerene-based solar cell lifetimes by addition of a fullerene dumbbell.

PubMed

Schroeder, Bob C; Li, Zhe; Brady, Michael A; Faria, Gregório Couto; Ashraf, Raja Shahid; Takacs, Christopher J; Cowart, John S; Duong, Duc T; Chiu, Kar Ho; Tan, Ching-Hong; Cabral, João T; Salleo, Alberto; Chabinyc, Michael L; Durrant, James R; McCulloch, Iain

2014-11-17

Cost-effective, solution-processable organic photovoltaics (OPV) present an interesting alternative to inorganic silicon-based solar cells. However, one of the major remaining challenges of OPV devices is their lack of long-term operational stability, especially at elevated temperatures. The synthesis of a fullerene dumbbell and its use as an additive in the active layer of a PCDTBT:PCBM-based OPV device is reported. The addition of only 20 % of this novel fullerene not only leads to improved device efficiencies, but more importantly also to a dramatic increase in morphological stability under simulated operating conditions. Dynamic secondary ion mass spectrometry (DSIMS) and TEM are used, amongst other techniques, to elucidate the origins of the improved morphological stability. © 2014 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Influence of Molecular Orientation on Charge-Transfer Processes at Phthalocyanine/Metal Oxide Interfaces and Relationship to Organic Photovoltaic Performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Hsiao-Chu; MacDonald, Gordon A.; Shi, Yanrong

2015-05-04

The effect of the molecular orientation distribution of the first monolayer of donor molecules at the hole-harvesting contact in an organic photovoltaic (OPV) on device efficiency was investigated. Two zinc phthalocyanine (ZnPc) phosphonic acids (PA) deposited on indium tin oxide (ITO) electrodes are compared: ZnPc(PA)4 contains PA linkers in all four quadrants, and ZnPcPA contains a PA linker in one quadrant. ZnPcPA monolayers exhibited a broad distribution of molecular orientations whereas ZnPc(PA)4 adsorption produced a monolayer with a narrower orientation distribution with the molecular plane more parallel to the ITO surface. We used potential-modulated attenuated total reflectance spectroelectrochemistry (PM-ATR) tomore » characterize the charge-transfer kinetics of these films and show that the highest rate constants correspond to ZnPc subpopulations that are oriented more parallel to the ITO surface plane. For ZnPc(PA)4, rate constants exceeded 104 s–1 and are among the highest ever reported for a surface-confined redox couple, which is attributable to both its orientation and the small ZnPc–electrode separation distance. The performance of OPVs with ITO hole-harvesting contacts modified with ZnPc(PA)4 was comparable to that achieved with highly activated bare ITO contacts, whereas for ZnPcPA-modified contacts, the OPV performance was similar to that observed with (hole-blocking) alkyl-PA modifiers. These results demonstrate the synergism between molecular structure, energetics, and dynamics at interfaces in OPVs.« less

Cylindrical Organic Solar Cells with Carbon Nanotube Charge Collectors

NASA Astrophysics Data System (ADS)

Zakhidov, Dante; Lou, Raymond; Ravi, Nav; Mielczarek, Kamil; Cook, Alexander

2009-10-01

Traditional organic photovoltaic devices (OPV) are built on a flat glass substrates coated by ITO. The maximum area covered by the solar cells is limited to a two dimensional plane. Moreover the light absorption is not maximized for a very thin photoactive layer. We suggest here a cylindrical design which has a vertical structure of optical fiber coated by OPV, with light incident from the side and from edge. The sunlight, entering via a smaller area is captured into optical fiber, which allows more sunlight to be absorbed by a cylindrical OPV overcoating with multiple reflections inside the optical fiber. Instead of using brittle ITO as a hole collecting layer in the cylindrical OPV, transparent sheets of multi-walled carbon nanotubes are applied. Their highly conductive nature and 3-D collection of carriers from the P3HT/PCBM photoactive layer allows for increased efficiency over a planar geometry while keeping the device transparent. Aluminum is used as the electron collecting layer and as a cylindrical mirror. [4pt] [1] Ulbricht, et.al, phys. stat. sol. (b) 243, No. 13, 3528 - 3532 (2006) / DOI 10.1002/pssb.200669181

Design and development of plasmonic nanostructured electrodes for ITO-free organic photovoltaic cells on rigid and highly flexible substrates

NASA Astrophysics Data System (ADS)

Richardson, Beau J.; Zhu, Leize; Yu, Qiuming

2017-04-01

Indium tin oxide (ITO) is the most common transparent electrode used in organic photovoltaics (OPVs), yet limited indium reserves and poor mechanical properties make it non-ideal for large-scale OPV production. To replace ITO, we designed, fabricated, and deployed plasmonic nanostructured electrodes in inverted OPV devices. We found that active layer absorption is significantly impacted by ZnO thickness which affects the optical field distribution inside the resonant cavity formed between the plasmonic nanostructured electrode and top electrode. High quality Cr/Au nanostructured electrodes were fabricated by nanoimprint lithography and deployed in ITO-free inverted devices on glass. Devices with thinner ZnO showed a PCE as high as 5.70% and higher J SC’s than devices on thicker ZnO, in agreement with finite-difference time-domain simulations. In addition, as the active layer was made optically thin, ITO-based devices showed diminished J SC while the resonant cavity effect from plasmonic nanostructured electrodes retained J SC. Preliminary ITO-free, flexible devices on PET showed a PCE of 1.82% and those fabricated on ultrathin and conformable Parylene substrates yielded an initial PCE over 1%. The plasmonic electrodes and device designs in this work show promise for developing highly functioning conformable devices that can be applied to numerous needs for lightweight, ubiquitous power generation.

Evaluation of the charge transfer efficiency of organic thin-film photovoltaic devices fabricated using a photoprecursor approach.

PubMed

Masuo, Sadahiro; Sato, Wataru; Yamaguchi, Yuji; Suzuki, Mitsuharu; Nakayama, Ken-ichi; Yamada, Hiroko

2015-05-01

Recently, a unique 'photoprecursor approach' was reported as a new option to fabricate a p-i-n triple-layer organic photovoltaic device (OPV) through solution processes. By fabricating the p-i-n architecture using two kinds of photoprecursors and a [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) as the donor and the acceptor, the p-i-n OPVs afforded a higher photovoltaic efficiency than the corresponding p-n devices and i-devices, while the photovoltaic efficiency of p-i-n OPVs depended on the photoprecursors. In this work, the charge transfer efficiency of the i-devices composed of the photoprecursors and PC71BM was investigated using high-sensitivity fluorescence microspectroscopy combined with a time-correlated single photon counting technique to elucidate the photovoltaic efficiency depending on the photoprecursors and the effects of the p-i-n architecture. The spatially resolved fluorescence images and fluorescence lifetime measurements clearly indicated that the compatibility of the photoprecursors with PC71BM influences the charge transfer and the photovoltaic efficiencies. Although the charge transfer efficiency of the i-device was quite high, the photovoltaic efficiency of the i-device was much lower than that of the p-i-n device. These results imply that the carrier generation and carrier transportation efficiencies can be increased by fabricating the p-i-n architecture.

Influence of SiO2 shell thickness on power conversion efficiency in plasmonic polymer solar cells with Au nanorod@SiO2 core-shell structures

PubMed Central

Zhang, Ran; Zhou, Yongfang; Peng, Ling; Li, Xue; Chen, Shufen; Feng, Xiaomiao; Guan, Yuqiao; Huang, Wei

2016-01-01

Locating core-shell metal nanoparticles into a photoactive layer or at the interface of photoactive layer/hole extraction layer is beneficial for fully employing surface plasmon energy, thus enhancing power conversion efficiency (PCE) in plasmonic organic photovoltaic devices (OPVs). Herein, we first investigated the influence of silica shell thickness in Au nanorods (NRs)@SiO2 core-shell structures on OPV performances by inserting them into poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) and thieno[3,4-b]thiophene/benzodithiophene (PTB7) interface, and amazedly found that a 2–3 nm silica shell onto Au NRs induces a highest short-circuit current density of 21.2 mA cm−2 and PCE of 9.55%. This is primarily due to an extremely strong local field and a much slower attenuation of localized surface plasmon resonance around ultrathin silica-coated Au NRs, with which the field intensity remains a high value in the active layer, thus sufficiently improves the absorption of PTB7. Our work provides a clear design concept on precise control of the shell of metal nanoparticles to realize high performances in plasmonic OPVs. PMID:27125309

Influence of SiO2 shell thickness on power conversion efficiency in plasmonic polymer solar cells with Au nanorod@SiO2 core-shell structures.

PubMed

Zhang, Ran; Zhou, Yongfang; Peng, Ling; Li, Xue; Chen, Shufen; Feng, Xiaomiao; Guan, Yuqiao; Huang, Wei

2016-04-29

Locating core-shell metal nanoparticles into a photoactive layer or at the interface of photoactive layer/hole extraction layer is beneficial for fully employing surface plasmon energy, thus enhancing power conversion efficiency (PCE) in plasmonic organic photovoltaic devices (OPVs). Herein, we first investigated the influence of silica shell thickness in Au nanorods (NRs)@SiO2 core-shell structures on OPV performances by inserting them into poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) and thieno[3,4-b]thiophene/benzodithiophene (PTB7) interface, and amazedly found that a 2-3 nm silica shell onto Au NRs induces a highest short-circuit current density of 21.2 mA cm(-2) and PCE of 9.55%. This is primarily due to an extremely strong local field and a much slower attenuation of localized surface plasmon resonance around ultrathin silica-coated Au NRs, with which the field intensity remains a high value in the active layer, thus sufficiently improves the absorption of PTB7. Our work provides a clear design concept on precise control of the shell of metal nanoparticles to realize high performances in plasmonic OPVs.

Optical effects of shadow masks on short circuit current of organic photovoltaic devices.

PubMed

Lin, Chi-Feng; Lin, Bing-Hong; Liu, Shun-Wei; Hsu, Wei-Feng; Zhang, Mi; Chiu, Tien-Lung; Wei, Mau-Kuo; Lee, Jiun-Haw

2012-03-21

In this paper, we have employed different shadow masks attached on top of organic photovoltaic (OPV) devices to study the optical effects of the former on the short circuit current (J(SC)). To rule out possible lateral electrical conduction and simplify the optical effects inside the device, a small-molecular heterojunction OPV device with a clear donor/acceptor interface was employed with a hole extraction layer exhibiting high resistance intentionally. Careful calibration with a shadow mask was employed. By attaching two layers of opaque masks in combination with a suitable holder design to shield the light from the edges and backside, the value of J(SC) approached that of the dark current, even under 1-sun radiation. With different illumination areas, we found that the photons illuminating the non-active region of the device contributed to 40% of the J(SC) by optical effect within the width of about 1 mm around the active region. When illuminating the non-active area with 12 mm to the active area, a 5.6 times improvement in the J(SC) was observed when the incident angle was 75°. With the introduction of a microstructured film onto the OPV device and an increase in the reflection from the non-active region, a 15% enhancement of the J(SC) compared to the control device was achieved.

Relation between active-layer thickness and power conversion efficiency in P3HT:PCBM inverted organic photovoltaics

NASA Astrophysics Data System (ADS)

Nakami, S.; Narioka, T.; Kobayashi, T.; Nagase, T.; Naito, H.

2017-11-01

The dependence of active-layer thickness on the power conversion efficiency (PCE) of inverted organic photovoltaics (OPVs) based on poly(3-hexylthiphene) and [6,6]-phenyl-C61-butyric acid methyl ester was investigated. When PCEs were measured immediately after device fabrication, the optimum thickness was ~100 nm. It was, however, found that thick OPVs exhibit higher PCEs a few months later, whereas thin OPVs simply degraded with time. Consequently, the optimum thickness changed with time. Considering this fact, we discuss the relationship between the active-layer thickness and PCE.

Directing energy transport in organic photovoltaic cells using interfacial exciton gates.

PubMed

Menke, S Matthew; Mullenbach, Tyler K; Holmes, Russell J

2015-04-28

Exciton transport in organic semiconductors is a critical, mediating process in many optoelectronic devices. Often, the diffusive and subdiffusive nature of excitons in these systems can limit device performance, motivating the development of strategies to direct exciton transport. In this work, directed exciton transport is achieved with the incorporation of exciton permeable interfaces. These interfaces introduce a symmetry-breaking imbalance in exciton energy transfer, leading to directed motion. Despite their obvious utility for enhanced exciton harvesting in organic photovoltaic cells (OPVs), the emergent properties of these interfaces are as yet uncharacterized. Here, directed exciton transport is conclusively demonstrated in both dilute donor and energy-cascade OPVs where judicious optimization of the interface allows exciton transport to the donor-acceptor heterojunction to occur considerably faster than when relying on simple diffusion. Generalized systems incorporating multiple exciton permeable interfaces are also explored, demonstrating the ability to further harness this phenomenon and expeditiously direct exciton motion, overcoming the diffusive limit.

Organic Optoelectronic Devices Employing Small Molecules

NASA Astrophysics Data System (ADS)

Fleetham, Tyler Blain

Organic optoelectronic devices have remained a research topic of great interest over the past two decades, particularly in the development of efficient organic photovoltaics (OPV) and organic light emitting diodes (OLED). In order to improve the efficiency, stability, and materials variety for organic optoelectronic devices a number of emitting materials, absorbing materials, and charge transport materials were developed and employed in a device setting. Optical, electrical, and photophysical studies of the organic materials and their corresponding devices were thoroughly carried out. Two major approaches were taken to enhance the efficiency of small molecule based OPVs: developing material with higher open circuit voltages or improved device structures which increased short circuit current. To explore the factors affecting the open circuit voltage (VOC) in OPVs, molecular structures were modified to bring VOC closer to the effective bandgap, DeltaE DA, which allowed the achievement of 1V VOC for a heterojunction of a select Ir complex with estimated exciton energy of only 1.55eV. Furthermore, the development of anode interfacial layer for exciton blocking and molecular templating provide a general approach for enhancing the short circuit current. Ultimately, a 5.8% PCE was achieved in a single heterojunction of C60 and a ZnPc material prepared in a simple, one step, solvent free, synthesis. OLEDs employing newly developed deep blue emitters based on cyclometalated complexes were demonstrated. Ultimately, a peak EQE of 24.8% and nearly perfect blue emission of (0.148,0.079) was achieved from PtON7dtb, which approaches the maximum attainable performance from a blue OLED. Furthermore, utilizing the excimer formation properties of square-planar Pt complexes, highly efficient and stable white devices employing a single emissive material were demonstrated. A peak EQE of over 20% for pure white color (0.33,0.33) and 80 CRI was achieved with the tridentate Pt complex, Pt-16. Furthermore, the development of a series of tetradentate Pt complexes yielded highly efficient and stable single doped white devices due to their halogen free tetradentate design. In addition to these benchmark achievements, the systematic molecular modification of both emissive and absorbing materials provides valuable structure-property relationship information that should help guide further developments in the field.

Electrical property heterogeneity at transparent conductive oxide/organic semiconductor interfaces: mapping contact ohmicity using conducting-tip atomic force microscopy.

PubMed

MacDonald, Gordon A; Veneman, P Alexander; Placencia, Diogenes; Armstrong, Neal R

2012-11-27

We demonstrate mapping of electrical properties of heterojunctions of a molecular semiconductor (copper phthalocyanine, CuPc) and a transparent conducting oxide (indium-tin oxide, ITO), on 20-500 nm length scales, using a conductive-probe atomic force microscopy technique, scanning current spectroscopy (SCS). SCS maps are generated for CuPc/ITO heterojunctions as a function of ITO activation procedures and modification with variable chain length alkyl-phosphonic acids (PAs). We correlate differences in small length scale electrical properties with the performance of organic photovoltaic cells (OPVs) based on CuPc/C(60) heterojunctions, built on these same ITO substrates. SCS maps the "ohmicity" of ITO/CuPc heterojunctions, creating arrays of spatially resolved current-voltage (J-V) curves. Each J-V curve is fit with modified Mott-Gurney expressions, mapping a fitted exponent (γ), where deviations from γ = 2.0 suggest nonohmic behavior. ITO/CuPc/C(60)/BCP/Al OPVs built on nonactivated ITO show mainly nonohmic SCS maps and dark J-V curves with increased series resistance (R(S)), lowered fill-factors (FF), and diminished device performance, especially near the open-circuit voltage. Nearly optimal behavior is seen for OPVs built on oxygen-plasma-treated ITO contacts, which showed SCS maps comparable to heterojunctions of CuPc on clean Au. For ITO electrodes modified with PAs there is a strong correlation between PA chain length and the degree of ohmicity and uniformity of electrical response in ITO/CuPc heterojunctions. ITO electrodes modified with 6-8 carbon alkyl-PAs show uniform and nearly ohmic SCS maps, coupled with acceptable CuPc/C(60)OPV performance. ITO modified with C14 and C18 alkyl-PAs shows dramatic decreases in FF, increases in R(S), and greatly enhanced recombination losses.

Chemical and Morphological Control of Interfacial Self-Doping for Efficient Organic Electronics.

PubMed

Liu, Yao; Cole, Marcus D; Jiang, Yufeng; Kim, Paul Y; Nordlund, Dennis; Emrick, Todd; Russell, Thomas P

2018-04-01

Solution-based processing of materials for electrical doping of organic semiconductor interfaces is attractive for boosting the efficiency of organic electronic devices with multilayer structures. To simplify this process, self-doping perylene diimide (PDI)-based ionene polymers are synthesized, in which the semiconductor PDI components are embedded together with electrolyte dopants in the polymer backbone. Functionality contained within the PDI monomers suppresses their aggregation, affording self-doping interlayers with controllable thickness when processed from solution into organic photovoltaic devices (OPVs). Optimal results for interfacial self-doping lead to increased power conversion efficiencies (PCEs) of the fullerene-based OPVs, from 2.62% to 10.64%, and of the nonfullerene-based OPVs, from 3.34% to 10.59%. These PDI-ionene interlayers enable chemical and morphological control of interfacial doping and conductivity, demonstrating that the conductive channels are crucial for charge transport in doped organic semiconductor films. Using these novel interlayers with efficient doping and high conductivity, both fullerene- and nonfullerene-based OPVs are achieved with PCEs exceeding 9% over interlayer thicknesses ranging from ≈3 to 40 nm. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and Characterization of Transition Metal Oxides and Dichalcogenides and Their Application in Organic Photovoltaics

NASA Astrophysics Data System (ADS)

Mendez, Diego Barrera

This Ph.D. research focused on the development of new materials for alternative renewable energy using organic photovoltaics (OPVs). The first step was to established reliable fabrication and characterization methods of organic photovoltaic devices. The reproducibility of organic photovoltaic cell performance is one of the essential issues that must be achieved before engaging serious investigations of the applications of creative and challenging ideas. Secondly, we thoroughly studied the surface chemistry of the underlying layer and its critical role on the morphology of the BHJ active layer. We showed that when the active layer (which consists of blends of poly(3-hexylthiophene) (P3HT) and phenyl-C60-butyric acid methyl ester (PCBM)) is deposited and annealed over a sol-gel ZnO electron transport layer surface made from monoethanolamine (MEA) containing precursor, PCBM clusters form during annealing and this phase segregation leads to a drastic reduction of OPV parameters due to both low charge generation and high bimolecular recombination. Rinsing the pyrolyzed ZnO films with solvents or using a ZnO recipe without MEA significantly reduced the formation of PCBM clusters and produced devices with good performance. Third, we developed new materials suitable for low-temperature processing and large-area deposition methods to be used as transport layer on OPVs. We achieved the synthesis of MoOx suspensions suitable for large area deposition, with controlled size, stoichiometry, and electronic properties using controlled oxidative dissolution of organometallic powders with H2O2 in n-butanol. The small nanoparticle diameters of ˜ 2 nm enabled solution processing of nanoparticle films on ITO with electronic properties comparable to solution processed and vacuum deposited counterparts, without the need for any post processing. We also accomplished the synthesis of transition metal dichalcogenides (TMDs) directly from precursors in solution using a versatile synthesis method. We demonstrate the ability to synthesize few-layer (˜ 2 nm) MoS2 , MoSe2, WS2, and WSe2 flakes with relatively large lateral sizes (> 2 mum) using a solvothermal method. We demonstrate that the reducing agent, 1,2-hexadecanediol is critical to ensure TMD formation and eliminate corresponding metal oxide. TEM, Raman, PESA, and Kelvin Probe measurements confirmed that all TMDs are p-type, highly crystalline, exhibit 2H phase and present hexagonal crystalline structure. In addition, thickness for all TMDs was consistent with a few-layer flakes. Finally, we studied the use of films spray casted from liquid-exfoliated MoS2 suspensions as hole transport layer for OPVs. Electrical measurements on the devices showed that FF achieved using MoS2 is identical to that using spin-coated polymeric reference material. Calculations showed that the lower Jsc observed in MoS2 devices is explained by reduced light absorption in the active layer region due to less back-reflected light in MoS2 devices. With all these results we have contributed to enable a route towards low-cost OPV and other electronics fabrication.

The origin of high PCE in PTB7 based photovoltaics: proper charge neutrality level and free energy of charge separation at PTB7/PC71BM interface

PubMed Central

Park, Soohyung; Jeong, Junkyeong; Hyun, Gyeongho; Kim, Minju; Lee, Hyunbok; Yi, Yeonjin

2016-01-01

The energy level alignments at donor/acceptor interfaces in organic photovoltaics (OPVs) play a decisive role in device performance. However, little is known about the interfacial energetics in polymer OPVs due to technical issues of the solution process. Here, the frontier ortbial line-ups at the donor/acceptor interface in high performance polymer OPVs, PTB7/PC71BM, were investigated using in situ UPS, XPS and IPES. The evolution of energy levels during PTB7/PC71BM interface formation was investigated using vacuum electrospray deposition, and was compared with that of P3HT/PC61BM. At the PTB7/PC71BM interface, the interface dipole and the band bending were absent due to their identical charge neutrality levels. In contrast, a large interfacial dipole was observed at the P3HT/PC61BM interface. The measured photovoltaic energy gap (EPVG) was 1.10 eV for PTB7/PC71BM and 0.90 eV for P3HT/PC61BM. This difference in the EPVG leads to a larger open-circuit voltage of PTB7/PC71BM than that of P3HT/PC61BM. PMID:27734957

The origin of high PCE in PTB7 based photovoltaics: proper charge neutrality level and free energy of charge separation at PTB7/PC71BM interface.

PubMed

Park, Soohyung; Jeong, Junkyeong; Hyun, Gyeongho; Kim, Minju; Lee, Hyunbok; Yi, Yeonjin

2016-10-13

The energy level alignments at donor/acceptor interfaces in organic photovoltaics (OPVs) play a decisive role in device performance. However, little is known about the interfacial energetics in polymer OPVs due to technical issues of the solution process. Here, the frontier ortbial line-ups at the donor/acceptor interface in high performance polymer OPVs, PTB7/PC 71 BM, were investigated using in situ UPS, XPS and IPES. The evolution of energy levels during PTB7/PC 71 BM interface formation was investigated using vacuum electrospray deposition, and was compared with that of P3HT/PC 61 BM. At the PTB7/PC 71 BM interface, the interface dipole and the band bending were absent due to their identical charge neutrality levels. In contrast, a large interfacial dipole was observed at the P3HT/PC 61 BM interface. The measured photovoltaic energy gap (E PVG ) was 1.10 eV for PTB7/PC 71 BM and 0.90 eV for P3HT/PC 61 BM. This difference in the E PVG leads to a larger open-circuit voltage of PTB7/PC 71 BM than that of P3HT/PC 61 BM.

Organic photovoltaic cells: from performance improvement to manufacturing processes.

PubMed

Youn, Hongseok; Park, Hui Joon; Guo, L Jay

2015-05-20

Organic photovoltaics (OPVs) have been pursued as a next generation power source due to their light weight, thin, flexible, and simple fabrication advantages. Improvements in OPV efficiency have attracted great attention in the past decade. Because the functional layers in OPVs can be dissolved in common solvents, they can be manufactured by eco-friendly and scalable printing or coating technologies. In this review article, the focus is on recent efforts to control nanomorphologies of photoactive layer and discussion of various solution-processed charge transport and extraction materials, to maximize the performance of OPV cells. Next, recent works on printing and coating technologies for OPVs to realize solution processing are reviewed. The review concludes with a discussion of recent advances in the development of non-traditional lamination and transfer method towards highly efficient and fully solution-processed OPV. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The differential impact of oral poliovirus vaccine formulation choices on serotype-specific population immunity to poliovirus transmission.

PubMed

Thompson, Kimberly M; Duintjer Tebbens, Radboud J

2015-09-17

Prior analyses demonstrated the need for some countries and the Global Polio Eradication Initiative (GPEI) to conduct additional supplemental immunization activities (SIAs) with trivalent oral poliovirus vaccine (tOPV) prior to globally-coordinated cessation of all serotype 2-containing OPV (OPV2 cessation) to prevent the creation of serotype 2 circulating vaccine-derived poliovirus (cVDPV2) outbreaks after OPV2 cessation. The GPEI continues to focus on achieving and ensuring interruption of wild poliovirus serotype 1 (WPV1) and making vaccine choices that prioritize bivalent OPV (bOPV) for SIAs, nominally to increase population immunity to serotype 1, despite an aggressive timeline for OPV2 cessation. We use an existing dynamic poliovirus transmission model of northwest Nigeria and an integrated global model for long-term poliovirus risk management to explore the impact of tOPV vs. bOPV vaccine choices on population immunity and cVDPV2 risks. Using tOPV instead of bOPV for SIAs leads to a minimal decrease in population immunity to transmission of serotypes 1 and 3 polioviruses, but a significantly higher population immunity to transmission of serotype 2 polioviruses. Failure to use tOPV in enough SIAs results in cVDPV2 emergence after OPV2 cessation in both the northwest Nigeria model and the global model. Despite perceptions to the contrary, prioritizing the use of bOPV over tOPV prior to OPV2 cessation does not significantly improve serotype 1 population immunity to transmission. Immunization leaders need to focus on all three poliovirus serotypes to appropriately manage the risks of OPV cessation in the polio endgame. Focusing on population immunity to transmission to interrupt WPV1 transmission and manage pre-OPV cessation risks of cVDPVs, all countries performing poliovirus SIAs should use tOPV up until the time of OPV2 cessation, after which time they should continue to use the OPV vaccine formulation with all remaining serotypes until coordinated global cessation of those serotypes.

High-Performing Polycarbazole Derivatives for Efficient Solution-Processing of Organic Solar Cells in Air.

PubMed

Burgués-Ceballos, Ignasi; Hermerschmidt, Felix; Akkuratov, Alexander V; Susarova, Diana K; Troshin, Pavel A; Choulis, Stelios A

2015-12-21

The application of conjugated materials in organic photovoltaics (OPVs) is usually demonstrated in lab-scale spin-coated devices that are processed under controlled inert conditions. Although this is a necessary step to prove high efficiency, testing of promising materials in air should be done in the early stages of research to validate their real potential for low-cost, solution-processed, and large-scale OPVs. Also relevant for approaching commercialization needs is the use of printing techniques that are compatible with upscaling. Here, solution processing of organic solar cells based on three new poly(2,7-carbazole) derivatives is efficiently transferred, without significant losses, to air conditions and to several deposition methods using a simple device architecture. High efficiencies in the range between 5.0 % and 6.3 % are obtained in (rigid) spin-coated, doctor-bladed, and (flexible) slot-die-coated devices, which surpass the reference devices based on poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT). In contrast, inkjet printing does not provide reliable results with the presented polymers, which is attributed to their high molecular weight. When the device area in the best-performing system is increased from 9 mm(2) to 0.7 cm(2), the efficiency drops from 6.2 % to 5.0 %. Photocurrent mapping reveals inhomogeneous current generation derived from changes in the thickness of the active layer. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metal Complexes for Organic Optoelectronic Applications

NASA Astrophysics Data System (ADS)

Huang, Liang

Organic optoelectronic devices have drawn extensive attention by over the past two decades. Two major applications for Organic optoelectronic devices are efficient organic photovoltaic devices(OPV) and organic light emitting diodes (OLED). Organic Solar cell has been proven to be compatible with the low cost, large area bulk processing technology and processed high absorption efficiencies compared to inorganic solar cells. Organic light emitting diodes are a promising approach for display and solid state lighting applications. To improve the efficiency, stability, and materials variety for organic optoelectronic devices, several emissive materials, absorber-type materials, and charge transporting materials were developed and employed in various device settings. Optical, electrical, and photophysical studies of the organic materials and their corresponding devices were thoroughly carried out. In this thesis, Chapter 1 provides an introduction to the background knowledge of OPV and OLED research fields presented. Chapter 2 discusses new porphyrin derivatives- azatetrabenzylporphyrins for OPV and near infrared OLED applications. A modified synthetic method is utilized to increase the reaction yield of the azatetrabenzylporphyrin materials and their photophysical properties, electrochemical properties are studied. OPV devices are also fabricated using Zinc azatetrabenzylporphyrin as donor materials. Pt(II) azatetrabenzylporphyrin were also synthesized and used in near infra-red OLED to achieve an emission over 800 nm with reasonable external quantum efficiencies. Chapter 3, discusses the synthesis, characterization, and device evaluation of a series of tetradentate platinum and palladium complexesfor single doped white OLED applications and RGB white OLED applications. Devices employing some of the developed emitters demonstrated impressively high external quantum efficiencies within the range of 22%-27% for various emitter concentrations. And the palladium complex, i.e. Pd3O3, enables the fabrication of stable devices achieving nearly 1000h. at 1000cd/m2 without any outcoupling enhancement while simultaneously achieving peak external quantum efficiencies of 19.9%. Chapter 4 discusses tetradentate platinum and palladium complexes as deep blue emissive materials for display and lighting applications. The platinum complex PtNON, achieved a peak external quantum efficiency of 24.4 % and CIE coordinates of (0.18, 0.31) in a device structure designed for charge confinement and the palladium complexes Pd2O2 exhibited peak external quantum efficiency of up to 19.2%.

Effects on Organic Photovoltaics Using Femtosecond-Laser-Treated Indium Tin Oxides.

PubMed

Chen, Mei-Hsin; Tseng, Ya-Hsin; Chao, Yi-Ping; Tseng, Sheng-Yang; Lin, Zong-Rong; Chu, Hui-Hsin; Chang, Jan-Kai; Luo, Chih-Wei

2016-09-28

The effects of femtosecond-laser-induced periodic surface structures (LIPSS) on an indium tin oxide (ITO) surface applied to an organic photovoltaic (OPV) system were investigated. The modifications of ITO induced by LIPPS in OPV devices result in more than 14% increase in power conversion efficiency (PCE) and short-circuit current density relative to those of the standard device. The basic mechanisms for the enhanced short-circuit current density are attributed to better light harvesting, increased scattering effects, and more efficient charge collection between the ITO and photoactive layers. Results show that higher PCEs would be achieved by laser-pulse-treated electrodes.

Efficient organic photovoltaic cells on a single layer graphene transparent conductive electrode using MoOx as an interfacial layer.

PubMed

Du, J H; Jin, H; Zhang, Z K; Zhang, D D; Jia, S; Ma, L P; Ren, W C; Cheng, H M; Burn, P L

2017-01-07

The large surface roughness, low work function and high cost of transparent electrodes using multilayer graphene films can limit their application in organic photovoltaic (OPV) cells. Here, we develop single layer graphene (SLG) films as transparent anodes for OPV cells that contain light-absorbing layers comprised of the evaporable molecular organic semiconductor materials, zinc phthalocyanine (ZnPc)/fullerene (C60), as well as a molybdenum oxide (MoO x ) interfacial layer. In addition to an increase in the optical transmittance, the SLG anodes had a significant decrease in surface roughness compared to two and four layer graphene (TLG and FLG) anodes fabricated by multiple transfer and stacking of SLGs. Importantly, the introduction of a MoO x interfacial layer not only reduced the energy barrier between the graphene anode and the active layer, but also decreased the resistance of the SLG by nearly ten times. The OPV cells with the structure of polyethylene terephthalate/SLG/MoO x /CuI/ZnPc/C60/bathocuproine/Al were flexible, and had a power conversion efficiency of up to 0.84%, which was only 17.6% lower than the devices with an equivalent structure but prepared on commercial indium tin oxide anodes. Furthermore, the devices with the SLG anode were 50% and 86.7% higher in efficiency than the cells with the TLG and FLG anodes. These results show the potential of SLG electrodes for flexible and wearable OPV cells as well as other organic optoelectronic devices.

Fabrication and Characterization of Organic Photovoltaic Cell using Keithley 2400 SMU for efficient solar cell

NASA Astrophysics Data System (ADS)

Hafeez, Hafeez Y.; Iro, Zaharaddeen S.; Adam, Bala I.; Mohammed, J.

2018-04-01

An organic solar cell device or organic photovoltaic cell (OPV) is a class of solar cell that uses conductive organic polymers or small organic molecules for light absorption and charge transport. In this study, we fabricate and characterize an organic photovoltaic cell device and estimated important parameters of the device such as Open Circuit Voltage Voc of 0.28V, Short-Circuit Current Isc of 4.0 × 10-5 A, Maximum Power Pmax of 2.4 × 10-6 W, Fill Factor of 0.214 and the energy conversion efficiency of η=0.00239% were tested using Keithley 2400,source meter under A.M 1.5 (1000/m2) illumination from a Newport Class A solar simulator. Also the I-V characteristics for OPV were drawn.

Continuous Flow Polymer Synthesis toward Reproducible Large-Scale Production for Efficient Bulk Heterojunction Organic Solar Cells.

PubMed

Pirotte, Geert; Kesters, Jurgen; Verstappen, Pieter; Govaerts, Sanne; Manca, Jean; Lutsen, Laurence; Vanderzande, Dirk; Maes, Wouter

2015-10-12

Organic photovoltaics (OPV) have attracted great interest as a solar cell technology with appealing mechanical, aesthetical, and economies-of-scale features. To drive OPV toward economic viability, low-cost, large-scale module production has to be realized in combination with increased top-quality material availability and minimal batch-to-batch variation. To this extent, continuous flow chemistry can serve as a powerful tool. In this contribution, a flow protocol is optimized for the high performance benzodithiophene-thienopyrroledione copolymer PBDTTPD and the material quality is probed through systematic solar-cell evaluation. A stepwise approach is adopted to turn the batch process into a reproducible and scalable continuous flow procedure. Solar cell devices fabricated using the obtained polymer batches deliver an average power conversion efficiency of 7.2 %. Upon incorporation of an ionic polythiophene-based cathodic interlayer, the photovoltaic performance could be enhanced to a maximum efficiency of 9.1 %. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fullerene derivatives as electron donor for organic photovoltaic cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhuang, Taojun; Wang, Xiao-Feng, E-mail: xf-wang@yz.yamagata-u.ac.jp, E-mail: ziruo@yz.yamagata-u.ac.jp; Sano, Takeshi

2013-11-11

We demonstrated the performance of unconventional, all-fullerene-based, planar heterojunction (PHJ) organic photovoltaic (OPV) cells using fullerene derivatives indene-C{sub 60} bisadduct (ICBA) and phenyl C{sub 61}-butyric acid methyl ester as the electron donors with fullerene C{sub 70} as the electron acceptor. Two different charge generation processes, including charge generation in the fullerene bulk and exciton dissociation at the donor-acceptor interface, have been found to exist in such all-fullerene-based PHJ cells and the contribution to the total photocurrent from each process is strongly dependent on the thickness of fullerene donor. The optimized 5 nm ICBA/40 nm C{sub 70} PHJ cell gives clear external quantummore » efficiency responses for the long-wavelength photons corresponding to the dissociation of strongly bound Frenkel excitons, which is hardly observed in fullerene-based single layer reference devices. This approach using fullerene as a donor material provides further possibilities for developing high performance OPV cells.« less

Long-term efficient organic photovoltaics based on quaternary bulk heterojunctions

NASA Astrophysics Data System (ADS)

Nam, Minwoo; Cha, Minjeong; Lee, Hyun Hwi; Hur, Kahyun; Lee, Kyu-Tae; Yoo, Jaehong; Han, Il Ki; Kwon, S. Joon; Ko, Doo-Hyun

2017-01-01

A major impediment to the commercialization of organic photovoltaics (OPVs) is attaining long-term morphological stability of the bulk heterojunction (BHJ) layer. To secure the stability while pursuing optimized performance, multi-component BHJ-based OPVs have been strategically explored. Here we demonstrate the use of quaternary BHJs (q-BHJs) composed of two conjugated polymer donors and two fullerene acceptors as a novel platform to produce high-efficiency and long-term durable OPVs. A q-BHJ OPV (q-OPV) with an experimentally optimized composition exhibits an enhanced efficiency and extended operational lifetime than does the binary reference OPV. The q-OPV would retain more than 72% of its initial efficiency (for example, 8.42-6.06%) after a 1-year operation at an elevated temperature of 65 °C. This is superior to those of the state-of-the-art BHJ-based OPVs. We attribute the enhanced stability to the significant suppression of domain growth and phase separation between the components via kinetic trapping effect.

Organic photovoltaic devices comprising solution-processed substituted metal-phthalocyanines and exhibiting near-IR photo-sensitivity

DOEpatents

McGrath, Dominic V.; Mayukh, Mayank; Placencia, Diogenes; Armstrong, Neal R.

2016-11-29

Organic photovoltaic (OPV) devices are disclosed. An exemplary device has first and second electrodes and an organic, photovoltaically active zone located between the first and second electrodes. The photovoltaically active zone includes an organic electron-donor material and an organic electron-acceptor material. The electron-donor material includes one or more trivalent- or tetravalent-metal phthalocyanines with alkylchalcogenide ring substituents, and is soluble in at least one organic solvent. This solubility facilitates liquid-processability of the donor material, including formation of thin-films, on an unlimited scale to form planar and bulk heterojunctions in organic OPVs. These donor materials are photovoltaically active in both visible and near-IR wavelengths of light, enabling more of the solar spectrum, for example, to be applied to producing electricity. Also disclosed are methods for producing the metalated phthalocyanines and actual devices.

Liquid eutectic GaIn as an alternative electrode for PTB7:PCBM organic solar cells

NASA Astrophysics Data System (ADS)

Thanh Hau Pham, Viet; Kieu Trinh, Thanh; Tam Nguyen Truong, Nguyen; Park, Chinho

2017-04-01

Conventional vacuum deposition process of aluminum (Al) is costly, time-consuming and difficult to apply to the large-scale production of organic photovoltaic devices (OPV). This paper reports a vacuum-free fabrication process of poly[[4,8-bis(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b‧]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thienophenediyl]:[6,6]-phenyl C71 butyric acid methyl ester (PTB7:PCBM) bulk heterojunction organic solar cell with liquid eutectic gallium-indium (EGaIn) electrode as an alternative to the common Al electrode. The insertion of a thin poly(ethylene oxide) (PEO) layer after depositing organic photoactive layer could help prevent the diffusion of liquid EGaIn into the active layer and allow the deposition of the EGaIn electrode. The PEO interfacial layer was formed by spin-coating from a mixed solvent of alcohol and water. Among different alcohol+water (methanol, ethanol, ethylene glycol, n-propanol, isopropanol, and isobutanol) mixed solvent tested, the n-propanol+water mixed solvent showed the greatest enhancement to the performance of OPVs. The improved device performance was attributed to the reactivity of mixed solvent n-propanol+water toward the surface of PTB7:PCBM active layer, which could help optimize surface morphology.

Materials Science of Electrodes and Interfaces for High-Performance Organic Photovoltaics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marks, Tobin

The science of organic photovoltaic (OPV) cells has made dramatic advances over the past three years with power conversion efficiencies (PCEs) now reaching ~12%. The upper PCE limit of light-to-electrical power conversion for single-junction OPVs as predicted by theory is ~23%. With further basic research, the vision of such devices, composed of non-toxic, earth-abundant, readily easily processed materials replacing/supplementing current-generation inorganic solar cells may become a reality. Organic cells offer potentially low-cost, roll-to-roll manufacturable, and durable solar power for diverse in-door and out-door applications. Importantly, further gains in efficiency and durability, to that competitive with inorganic PVs, will require fundamental,more » understanding-based advances in transparent electrode and interfacial materials science and engineering. This team-science research effort brought together an experienced and highly collaborative interdisciplinary group with expertise in hard and soft matter materials chemistry, materials electronic structure theory, solar cell fabrication and characterization, microstructure characterization, and low temperature materials processing. We addressed in unconventional ways critical electrode-interfacial issues underlying OPV performance -- controlling band offsets between transparent electrodes and organic active-materials, addressing current loss/leakage phenomena at interfaces, and new techniques in cost-effective low temperature and large area cell fabrication. The research foci were: 1) Theory-guided design and synthesis of advanced crystalline and amorphous transparent conducting oxide (TCO) layers which test our basic understanding of TCO structure-transport property relationships, and have high conductivity, transparency, and tunable work functions but without (or minimizing) the dependence on indium. 2) Development of theory-based understanding of optimum configurations for the interfaces between oxide electrodes/interfacial layers and OPV active layer organic molecules/polymers. 3) Exploration and perfection of new processing strategies and cell architectures for the next-generation, large-area flexible OPVs. The goal has been to develop for the solar energy community the fundamental scientific understanding needed to design, fabricate, prototype, and ultimately test high-efficiency cells incorporating these new concepts. We achieved success in all of these directions.« less

Nanoscale characterization of the electrical properties of oxide electrodes at the organic semiconductor-oxide electrode interface in organic solar cells

NASA Astrophysics Data System (ADS)

MacDonald, Gordon Alex

This dissertation focuses on characterizing the nanoscale and surface averaged electrical properties of transparent conducting oxide electrodes such as indium tin oxide (ITO) and transparent metal-oxide (MO) electron selective interlayers (ESLs), such as zinc oxide (ZnO), the ability of these materials to rapidly extract photogenerated charges from organic semiconductors (OSCs) used in organic photovoltaic (OPV) cells, and evaluating their impact on the power conversion efficiency (PCE) of OPV devices. In Chapter 1, we will introduce the fundamental principles, benefits, and the key innovations that have advanced this technology. In Chapter 2 of this dissertation, we demonstrate an innovative application of conductive probe atomic force microscopy (CAFM) to map the nanoscale electrical heterogeneity at the interface between ITO, and a well-studied OSC, copper phthalocyanine (CuPc).(MacDonald et al. (2012) ACS Nano, 6, p. 9623) In this work we collected arrays of current-voltage (J-V) curves, using a CAFM probe as the top contact of CuPc/ITO systems, to map the local J-V responses. By comparing J-V responses to known models for charge transport, we were able to determine if the local rate-limiting-step for charge transport is through the OSC (ohmic) or the CuPc/ITO interface (non-ohmic). Chapter 3 focus on the electrical property characterization of RF-magnetron sputtered ZnO (sp-ZnO) ESL films on ITO substrates. We have shown that the energetic alignment of ESLs and the OSC active materials plays a critical role in determining the PCE of OPV devices and UV light soaking sensitivity. We have used a combination of device testing, modeling, and impedance spectroscopy to characterize the effects that energetic alignment has on the charge carrier transport and distribution within the OPV device. In Chapter 4 we demonstrate that the local properties of sp-ZnO films varies as a function of the underlying ITO crystal face. We show that the local ITO crystal face determines the local nucleation and growth of the sp-ZnO films and, in turn, affects the nanoscale distribution of electrical and chemical properties. These studies have contributed to a detailed understanding of the role that electrical heterogeneity, insulating barriers and energetic alignment at MO/OSC interfaces play in OPV PCE.

Is organic photovoltaics promising for indoor applications?

NASA Astrophysics Data System (ADS)

Lee, Harrison K. H.; Li, Zhe; Durrant, James R.; Tsoi, Wing C.

2016-06-01

This work utilizes organic photovoltaics (OPV) for indoor applications, such as powering small electronic devices or wireless connected Internet of Things. Three representative polymer-based OPV systems, namely, poly(3-hexylthiophene-2,5-diyl), poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)], and poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl

Role of ultrathin metal fluoride layer in organic photovoltaic cells: mechanism of efficiency and lifetime enhancement.

PubMed

Lim, Kyung-Geun; Choi, Mi-Ri; Kim, Ji-Hoon; Kim, Dong Hun; Jung, Gwan Ho; Park, Yongsup; Lee, Jong-Lam; Lee, Tae-Woo

2014-04-01

Although rapid progress has been made recently in bulk heterojunction organic solar cells, systematic studies on an ultrathin interfacial layer at the electron extraction contact have not been conducted in detail, which is important to improve both the device efficiency and the lifetime. We find that an ultrathin BaF2 layer at the electron extraction contact strongly influences the open-circuit voltage (Voc ) as the nanomorphology evolves with increasing BaF2 thickness. A vacuum-deposited ultrathin BaF2 layer grows by island growth, so BaF2 layers with a nominal thickness less than that of single-coverage layer (≈3 nm) partially cover the polymeric photoactive layer. As the nominal thickness of the BaF2 layer increased to that of a single-coverage layer, the Voc and power conversion efficiency (PCE) of the organic photovoltaic cells (OPVs) increased but the short-circuit current remained almost constant. The fill factor and the PCE decreased abruptly as the thickness of the BaF2 layer exceeded that of a single-coverage layer, which was ascribed to the insulating nature of BaF2 . We find the major cause of the increased Voc observed in these devices is the lowered work function of the cathode caused by the reaction and release of Ba from thin BaF2 films upon deposition of Al. The OPV device with the BaF2 layer showed a slightly improved maximum PCE (4.0 %) and a greatly (approximately nine times) increased device half-life under continuous simulated solar irradiation at 100 mW cm(-2) as compared with the OPV without an interfacial layer (PCE=2.1 %). We found that the photodegradation of the photoactive layer was not a major cause of the OPV degradation. The hugely improved lifetime with cathode interface modification suggests a significant role of the cathode interfacial layer that can help to prolong device lifetimes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mechanically Compliant Electronic Materials for Wearable Photovoltaics and Human-Machine Interfaces

NASA Astrophysics Data System (ADS)

O'Connor, Timothy Francis, III

Applications of stretchable electronic materials for human-machine interfaces are described herein. Intrinsically stretchable organic conjugated polymers and stretchable electronic composites were used to develop stretchable organic photovoltaics (OPVs), mechanically robust wearable OPVs, and human-machine interfaces for gesture recognition, American Sign Language Translation, haptic control of robots, and touch emulation for virtual reality, augmented reality, and the transmission of touch. The stretchable and wearable OPVs comprise active layers of poly-3-alkylthiophene:phenyl-C61-butyric acid methyl ester (P3AT:PCBM) and transparent conductive electrodes of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) and devices could only be fabricated through a deep understanding of the connection between molecular structure and the co-engineering of electronic performance with mechanical resilience. The talk concludes with the use of composite piezoresistive sensors two smart glove prototypes. The first integrates stretchable strain sensors comprising a carbon-elastomer composite, a wearable microcontroller, low energy Bluetooth, and a 6-axis accelerometer/gyroscope to construct a fully functional gesture recognition glove capable of wirelessly translating American Sign Language to text on a cell phone screen. The second creates a system for the haptic control of a 3D printed robot arm, as well as the transmission of touch and temperature information.

Activation of Organic Photovoltaic Light Detectors Using Bend Leakage from Optical Fibers.

PubMed

Griffith, Matthew J; Willis, Matthew S; Kumar, Pankaj; Holdsworth, John L; Bezuidenhout, Henco; Zhou, Xiaojing; Belcher, Warwick; Dastoor, Paul C

2016-03-01

This work investigates the detection and subsequent utilization of leaked light from bends in a silica optical fiber using organic photovoltaic detectors. The optic power lost by single mode and multimode silica optical fibers was calibrated for bend radii between 1 and 7 mm for 532 and 633 nm light, exhibiting excellent agreement with previous theoretical solutions. The spatial location of maximum power leakage on the exterior of the fiber was found to exist in the same plane as the fiber, with a 10° offset from the normal. Two different organic photovoltaic detectors fabricated using a poly(3-hexylthiophene):indene-C60-bisadduct donor-acceptor blend cast from chloroform and chlorobenzene were fabricated to detect the leaked light. The two detectors exhibited different photovoltaic performances, predominantly due to different active layer thicknesses. Both devices showed sensitivity to leakage light, exhibiting voltages between 200 and 300 mV in response to leaked light from the fiber. The temporal responses of the devices were observed to differ, with a rise time from 10% to 90% of maximum voltage of 1430 μs for the chlorobenzene device, and a corresponding rise time of 490 μs for the higher performing chloroform device. The two OPVs were used to simultaneously detect leaked light from induced bends in the optical fiber, with the differing temporal profiles employed to create a unique time-correlated detection signal with enhanced security. The delay between detection of each OPV voltage could be systematically varied, allowing for either a programmable and secure single detection signal or triggering of multiple events with variable time resolution. The results reported in this study present exciting avenues toward the deployment of this simple and noninvasive optical detection system in a range of different applications.

Energy Migration in Organic Thin Films--From Excitons to Polarons

NASA Astrophysics Data System (ADS)

Mullenbach, Tyler K.

The rise of organic photovoltaic devices (OPVs) and organic light-emitting devices has generated interest in the physics governing exciton and polaron dynamics in thin films. Energy transfer has been well studied in dilute solutions, but there are emergent properties in thin films and greater complications due to complex morphologies which must be better understood. Despite the intense interest in energy transport in thin films, experimental limitations have slowed discoveries. Here, a new perspective of OPV operation is presented where photovoltage, instead of photocurrent, plays the fundamental role. By exploiting this new vantage point the first method of measuring the diffusion length (LD) of dark (non-luminescent) excitons is developed, a novel photodetector is invented, and the ability to watch exciton arrival, in real-time, at the donor-acceptor heterojunction is presented. Using an enhanced understanding of exciton migration in thin films, paradigms for enhancing LD by molecular modifications are discovered, and the first exciton gate is experimentally and theoretically demonstrated. Generation of polarons from exciton dissociation represents a second phase of energy migration in OPVs that remains understudied. Current approaches are capable of measuring the rate of charge carrier recombination only at open-circuit. To enable a better understanding of polaron dynamics in thin films, two new approaches are presented which are capable of measuring both the charge carrier recombination and transit rates at any OPV operating voltage. These techniques pave the way for a more complete understanding of charge carrier kinetics in molecular thin films.

Three-Dimensional Morphology Control Yielding Enhanced Hole Mobility in Air-Processed Organic Photovoltaics: Demonstration with Grazing-Incidence Wide-Angle X-ray Scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, Levi M. J.; Bhattacharya, Mithun; Wu, Qi

Polymer organic photovoltaic (OPV) device performance is defined by the three-dimensional morphology of the phase-separated domains in the active layer. Here, we determine the evolution of morphology through different stages of tailored solvent vapor and thermal annealing techniques in air-processed poly(3-hexylthiophene-2,5-diyl)/phenyl-C61-butyric acid methyl ester-based OPV blends. A comparative evaluation of the effect of solvent type used for vapor annealing was performed using grazing-incidence wide-angle X-ray scattering, atomic force microscopy, and UV–vis spectroscopy to probe the active-layer morphology. A nonhalogenated orthogonal solvent was found to impart controlled morphological features within the exciton diffusion length scales, enhanced absorbance, greater crystallinity, increased paracrystallinemore » disorder, and improved charge-carrier mobility. Low-boiling, fast-diffusing isopropanol allowed the greatest control over the nanoscale structure of the solvents evaluated and yielded a cocontinuous morphology with narrowed domains and enhanced paths for the charge carrier to reach the anode.« less

Toward Efficient Thick Active PTB7 Photovoltaic Layers Using Diphenyl Ether as a Solvent Additive.

PubMed

Zheng, Yifan; Goh, Tenghooi; Fan, Pu; Shi, Wei; Yu, Junsheng; Taylor, André D

2016-06-22

The development of thick organic photovoltaics (OPV) could increase absorption in the active layer and ease manufacturing constraints in large-scale solar panel production. However, the efficiencies of most low-bandgap OPVs decrease substantially when the active layers exceed ∼100 nm in thickness (because of low crystallinity and a short exciton diffusion length). Herein, we report the use of solvent additive diphenyl ether (DPE) that facilitates the fabrication of thick (180 nm) active layers and triples the power conversion efficiency (PCE) of conventional thienothiophene-co-benzodithiophene polymer (PTB7)-based OPVs from 1.75 to 6.19%. These results demonstrate a PCE 20% higher than those of conventional (PTB7)-based OPV devices using 1,8-diiodooctane. Morphology studies reveal that DPE promotes the formation of nanofibrillar networks and ordered packing of PTB7 in the active layer that facilitate charge transport over longer distances. We further demonstrate that DPE improves the fill factor and photocurrent collection by enhancing the overall optical absorption, reducing the series resistance, and suppressing bimolecular recombination.

CuS nanoplates from ionic liquid precursors—Application in organic photovoltaic cells

NASA Astrophysics Data System (ADS)

Kim, Yohan; Heyne, Benjamin; Abouserie, Ahed; Pries, Christopher; Ippen, Christian; Günter, Christina; Taubert, Andreas; Wedel, Armin

2018-05-01

Hexagonal p-type semiconductor CuS nanoplates were synthesized via a hot injection method from bis(trimethylsilyl)sulfide and the ionic liquid precursor bis(N-dodecylpyridinium) tetrachloridocuprate(ii). The particles have a broad size distribution with diameters between 30 and 680 nm and well-developed crystal habits. The nanoplates were successfully incorporated into organic photovoltaic (OPV) cells as hole conduction materials. The power conversion efficiency of OPV cells fabricated with the nanoplates is 16% higher than that of a control device fabricated without the nanoplates.

Is organic photovoltaics promising for indoor applications?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Harrison K. H.; Li, Zhe; Tsoi, Wing C., E-mail: w.c.tsoi@swansea.ac.uk

2016-06-20

This work utilizes organic photovoltaics (OPV) for indoor applications, such as powering small electronic devices or wireless connected Internet of Things. Three representative polymer-based OPV systems, namely, poly(3-hexylthiophene-2,5-diyl), poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′, 1′,3′-benzothiadiazole)], and poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl

Fullerene C{sub 70} as a p-type donor in organic photovoltaic cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhuang, Taojun; Wang, Xiao-Feng, E-mail: charles1976110@hotmail.com, E-mail: zrhong@ucla.edu, E-mail: kid@yz.yamagata-u.ac.jp; Sano, Takeshi

2014-09-01

Fullerenes and their derivatives have been widely used as n-type materials in organic transistor and photovoltaic devices. Though it is believed that they shall be ambipolar in nature, there have been few direct experimental proofs for that. In this work, fullerene C{sub 70}, known as an efficient acceptor, has been employed as a p-type electron donor in conjunction with 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile as an electron acceptor in planar-heterojunction (PHJ) organic photovoltaic (OPV) cells. High fill factors (FFs) of more than 0.70 were reliably achieved with the C{sub 70} layer even up to 100 nm thick in PHJ cells, suggesting the superior potentialmore » of fullerene C{sub 70} as the p-type donor in comparison to other conventional donor materials. The optimal efficiency of these unconventional PHJ cells was 2.83% with a short-circuit current of 5.33 mA/cm{sup 2}, an open circuit voltage of 0.72 V, and a FF of 0.74. The results in this work unveil the potential of fullerene materials as donors in OPV devices, and provide alternative approaches towards future OPV applications.« less

Flexible organic tandem solar modules: a story of up-scaling

NASA Astrophysics Data System (ADS)

Spyropoulos, George D.; Kubis, Peter; Li, Ning; Lucera, Luca; Salvador, Michael; Baran, Derya; Machui, Florian; Ameri, Tayebeh; Voigt, Monika M.; Brabec, Christoph J.

2014-10-01

The competition in the field of solar energy between Organic Photovoltaics (OPVs) and several Inorganic Photovoltaic technologies is continuously increasing to reach the ultimate purpose of energy supply from inexpensive and easily manufactured solar cell units. Solution-processed printing techniques on flexible substrates attach a tremendous opportunity to the OPVs for the accomplishment of low-cost and large area applications. Furthermore, tandem architectures came to boost up even more OPVs by increasing the photon-harvesting properties of the device. In this work, we demonstrate the road of realizing flexible organic tandem solar modules constructed by a fully roll-to-roll compatible processing. The modules exhibit an efficiency of 5.4% with geometrical fill factors beyond 80% and minimized interconnection-resistance losses. The processing involves low temperature (<70 °C), coating methods compatible with slot die coating and high speed and precision laser patterning.

Self-assembled nanogaps for molecular electronics.

PubMed

Tang, Qingxin; Tong, Yanhong; Jain, Titoo; Hassenkam, Tue; Wan, Qing; Moth-Poulsen, Kasper; Bjørnholm, Thomas

2009-06-17

A nanogap for molecular devices was realized using solution-based self-assembly. Gold nanorods were assembled to gold nanoparticle-coated conducting SnO2:Sb nanowires via thiol end-capped oligo(phenylenevinylene)s (OPVs). The molecular gap was easily created by the rigid molecule itself during self-assembly and the gap length was determined by the molecule length. The gold nanorods and gold nanoparticles, respectively covalently bonded at the two ends of the molecule, had very small dimensions, e.g. a width of approximately 20 nm, and hence were expected to minimize the screening effect. The ultra-long conducting SnO2:Sb nanowires provided the bridge to connect one of the electrodes of the molecular device (gold nanoparticle) to the external circuit. The tip of the atomic force microscope (AFM) was contacted onto the other electrode (gold nanorod) for the electrical measurement of the OPV device. The conductance measurement confirmed that the self-assembly of the molecules and the subsequent self-assembly of the gold nanorods was a feasible method for the fabrication of the nanogap of the molecular devices.

Probing Exciton Diffusion and Dissociation in Single-Walled Carbon Nanotube-C60 Heterojunctions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dowgiallo, Anne-Marie; Mistry, Kevin S.; Johnson, Justin C.

The efficiency of thin-film organic photovoltaic (OPV) devices relies heavily upon the transport of excitons to type-II heterojunction interfaces, where there is sufficient driving force for exciton dissociation and ultimately the formation of charge carriers. Semiconducting single-walled carbon nanotubes (SWCNTs) are strong near-infrared absorbers that form type-II heterojunctions with fullerenes such as C60. Although the efficiencies of SWCNT-fullerene OPV devices have climbed over the past few years, questions remain regarding the fundamental factors that currently limit their performance. In this study, we determine the exciton diffusion length in the C60 layer of SWCNT-C60 bilayer active layers using femtosecond transient absorptionmore » measurements. We demonstrate that hole transfer from photoexcited C60 molecules to SWCNTs can be tracked by the growth of narrow spectroscopic signatures of holes in the SWCNT 'reporter layer'. In bilayers with thick C60 layers, the SWCNT charge-related signatures display a slow rise over hundreds of picoseconds, reflecting exciton diffusion through the C60 layer to the interface. A model based on exciton diffusion with a Beer-Lambert excitation profile, as well as Monte Carlo simulations, gives the best fit to the data as a function of C60 layer thickness using an exciton diffusion length of approximately 5 nm.« less

Probing Exciton Diffusion and Dissociation in Single-Walled Carbon Nanotube-C(60) Heterojunctions.

PubMed

Dowgiallo, Anne-Marie; Mistry, Kevin S; Johnson, Justin C; Reid, Obadiah G; Blackburn, Jeffrey L

2016-05-19

The efficiency of thin-film organic photovoltaic (OPV) devices relies heavily upon the transport of excitons to type-II heterojunction interfaces, where there is sufficient driving force for exciton dissociation and ultimately the formation of charge carriers. Semiconducting single-walled carbon nanotubes (SWCNTs) are strong near-infrared absorbers that form type-II heterojunctions with fullerenes such as C60. Although the efficiencies of SWCNT-fullerene OPV devices have climbed over the past few years, questions remain regarding the fundamental factors that currently limit their performance. In this study, we determine the exciton diffusion length in the C60 layer of SWCNT-C60 bilayer active layers using femtosecond transient absorption measurements. We demonstrate that hole transfer from photoexcited C60 molecules to SWCNTs can be tracked by the growth of narrow spectroscopic signatures of holes in the SWCNT "reporter layer". In bilayers with thick C60 layers, the SWCNT charge-related signatures display a slow rise over hundreds of picoseconds, reflecting exciton diffusion through the C60 layer to the interface. A model based on exciton diffusion with a Beer-Lambert excitation profile, as well as Monte Carlo simulations, gives the best fit to the data as a function of C60 layer thickness using an exciton diffusion length of approximately 5 nm.

The Fabrication of Bulk Heterojunction P3HT: PCBM Organic Photovoltaics

NASA Astrophysics Data System (ADS)

Darwis, D.; Sesa, E.; Farhamza, D.; Iqbal

2018-05-01

Bulk heterojunction Organic photovoltaic (OPV) devices are gaining a lot of interest due to their potential for ease of processing and lower manufacturing cost sustainable energy generation. In consequence, the number of studies into the properties and characteristics of organic solar cell devices has been increased to improving their power conversion. A further advancement over past decade has shown that improved efficiency could be obtained by mixed of poly(3 - hexylthiophene) (P3HT) and [1] – phenyl - C61-butyric acid methyl ester (PCBM) as an active layer. A series of optimizations of this P3HT: PCBM blends, such as the mixture ratio variation, the annealing treatments, and solvent treatment, have been emerged to improve the efficiency of the OPV. As a result, significant improvements were achieved. Here, we report the fabrication heterojunction devices of 2.9 % efficiency. This result has been achieved using the configuration of a typical heterojunction solar cell modules consists of layered glass/ITO/PEDOT: PSS/active layer/cathode interlayer

Optical, electrical, and magnetic field studies of organic materials for light emitting diodes and photovoltaic applications

NASA Astrophysics Data System (ADS)

Basel, Tek Prasad

We studied optical, electrical, and magnetic field responses of films and devices based on organic semiconductors that are used for organic light emitting diodes (OLEDs) and photovoltaic (OPV) solar cell applications. Our studies show that the hyperfine interaction (HFI)-mediated spin mixing is the key process underlying various magnetic field effects (MFE) and spin transport in aluminum tris(8-hydroxyquinoline)[Alq3]-based OLEDs and organic spin-valve (OSV). Conductivity-detected magnetic resonance in OLEDs and magneto-resistance (MR) in OSVs show substantial isotope dependence. In contrast, isotope-insensitive behavior in the magneto-conductance (MC) of same devices is explained by the collision of spin ½ carriers with triplet polaron pairs. We used steady state optical spectroscopy for studying the energy transfer dynamics in films and OLEDs based on host-guest blends of the fluorescent polymer and phosphorescent molecule. We have also studied the magnetic-field controlled color manipulation in these devices, which provide a strong proof for the `polaron-pair' mechanism underlying the MFE in organic devices. The critical issue that hampers organic spintronics device applications is significant magneto-electroluminescence (MEL) at room temperature (RT). Whereas inorganic spin valves (ISVs) show RT magneto-resistance, MR>80%, however, the devices do not exhibit electroluminescence (EL). In contrast, OLEDs show substantive EL emission, and are particularly attractive because of their flexibility, low cost, and potential for multicolor display. We report a conceptual novel hybrid organic/inorganic spintronics device (h-OLED), where we employ both ISV with large MR at RT, and OLED that has efficient EL emission. We investigated the charge transfer process in an OPV solar cell through optical, electrical, and magnetic field measurements of thin films and devices based on a low bandgap polymer, PTB7 (fluorinated poly-thienothiophene-benzodithiophene). We found that one of the major losses that limit the power conversion efficiency of OPV devices is the formation of triplet excitons in the polymer through recombination of charge-transfer (CT) excitons at the interface, and presented a method to suppress the dissociation of CT states by incorporating the spin ½ additive, galvinoxyl in the bulk heterojunction architecture of the active organic blend layer.

Impact of enterovirus and other enteric pathogens on oral polio and rotavirus vaccine performance in Bangladeshi infants.

PubMed

Taniuchi, Mami; Platts-Mills, James A; Begum, Sharmin; Uddin, Md Jashim; Sobuz, Shihab U; Liu, Jie; Kirkpatrick, Beth D; Colgate, E Ross; Carmolli, Marya P; Dickson, Dorothy M; Nayak, Uma; Haque, Rashidul; Petri, William A; Houpt, Eric R

2016-06-08

Oral polio vaccine (OPV) and rotavirus vaccine (RV) exhibit poorer performance in low-income settings compared to high-income settings. Prior studies have suggested an inhibitory effect of concurrent non-polio enterovirus (NPEV) infection, but the impact of other enteric infections has not been comprehensively evaluated. In urban Bangladesh, we tested stools for a broad range of enteric viruses, bacteria, parasites, and fungi by quantitative PCR from infants at weeks 6 and 10 of life, coincident with the first OPV and RV administration respectively, and examined the association between enteropathogen quantity and subsequent OPV serum neutralizing titers, serum rotavirus IgA, and rotavirus diarrhea. Campylobacter and enterovirus (EV) quantity at the time of administration of the first dose of OPV was associated with lower OPV1-2 serum neutralizing titers, while enterovirus quantity was also associated with diminished rotavirus IgA (-0.08 change in log titer per tenfold increase in quantity; P=0.037), failure to seroconvert (OR 0.78, 95% CI: 0.64-0.96; P=0.022), and breakthrough rotavirus diarrhea (OR 1.34, 95% CI: 1.05-1.71; P=0.020) after adjusting for potential confounders. These associations were not observed for Sabin strain poliovirus quantity. In this broad survey of enteropathogens and oral vaccine performance we find a particular association between EV carriage, particularly NPEV, and OPV immunogenicity and RV protection. Strategies to reduce EV infections may improve oral vaccine responses. ClinicalTrials.gov Identifier: NCT01375647. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Highly Efficient Porphyrin-Based OPV/Perovskite Hybrid Solar Cells with Extended Photoresponse and High Fill Factor.

PubMed

Gao, Ke; Zhu, Zonglong; Xu, Bo; Jo, Sae Byeok; Kan, Yuanyuan; Peng, Xiaobin; Jen, Alex K-Y

2017-12-01

Employing a layer of bulk-heterojunction (BHJ) organic semiconductors on top of perovskite to further extend its photoresponse is considered as a simple and promising way to enhance the efficiency of perovskite-based solar cells, instead of using tandem devices or near infrared (NIR)-absorbing Sn-containing perovskites. However, the progress made from this approach is quite limited because very few such hybrid solar cells can simultaneously show high short-circuit current (J SC ) and fill factor (FF). To find an appropriate NIR-absorbing BHJ is essential for highly efficient, organic, photovoltaics (OPV)/perovskite hybrid solar cells. The materials involved in the BHJ layer not only need to have broad photoresponse to increase J SC , but also possess suitable energy levels and high mobility to afford high V OC and FF. In this work, a new porphyrin is synthesized and blended with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) to function as an efficient BHJ for OPV/perovskite hybrid solar cells. The extended photoresponse, well-matched energy levels, and high hole mobility from optimized BHJ morphology afford a very high power conversion efficiency (PCE) (19.02%) with high V oc , J SC , and FF achieved simultaneously. This is the highest value reported so far for such hybrid devices, which demonstrates the feasibility of further improving the efficiency of perovskite devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of MoOx interlayer on the maximum achievable open-circuit voltage in organic photovoltaic cells

NASA Astrophysics Data System (ADS)

Zou, Yunlong; Holmes, Russell

2013-03-01

Transition metal oxides including molybdenum oxide (MoOx) are characterized by large work functions and deep energy levels relative to the organic semiconductors used in photovoltaic cells (OPVs). These materials have been used in OPVs as interlayers between the indium-tin-oxide anode and the active layers to increase the open-circuit voltage (VOC) and power conversion efficiency. We examine the role of MoOx in determining the maximum achievable VOC in planar heterojunction OPVs based on the donor-acceptor pairing of boron subphthalocyanine chloride (SubPc) and C60. While causing minor changes in VOC at room temperature, the inclusion of MoOx significantly changes the temperature dependence of VOC. Devices containing no interlayer show a maximum VOC\\ of 1.2 V, while devices containing MoOx show no saturation in VOC, reaching a value of >1.4 V at 110 K. We propose that the MoOx-SubPc interface forms a dissociating Schottky junction that provides an additional contribution to VOC at low temperature. Separate measurements of photoluminescence confirm that excitons in SubPc can be quenched by MoOx. Charge transfer at this interface is by hole extraction from SubPc to MoOx, and this mechanism favors donors with a deep highest occupied molecular orbital (HOMO) energy level. Consistent with this expectation, the temperature dependence of VOC for devices constructed using a donor with a shallower HOMO level, e.g. copper phthalocyanine, is independent of the presence of MoOx.

Fabrication of three-dimensional hybrid nanostructure-embedded ITO and its application as a transparent electrode for high-efficiency solution processable organic photovoltaic devices.

PubMed

Kim, Jeong Won; Jeon, Hwan-Jin; Lee, Chang-Lyoul; Ahn, Chi Won

2017-03-02

Well-aligned, high-resolution (10 nm), three-dimensional (3D) hybrid nanostructures consisting of patterned cylinders and Au islands were fabricated on ITO substrates using an ion bombardment process and a tilted deposition process. The fabricated 3D hybrid nanostructure-embedded ITO maintained its excellent electrical and optical properties after applying a surface-structuring process. The solution processable organic photovoltaic device (SP-OPV) employing a 3D hybrid nanostructure-embedded ITO as the anode displayed a 10% enhancement in the photovoltaic performance compared to the photovoltaic device prepared using a flat ITO electrode, due to the improved charge collection (extraction and transport) efficiency as well as light absorbance by the photo-active layer.

Melt-processing of small molecule organic photovoltaics via bulk heterojunction compatibilization.

PubMed

Rahmanudin, Aiman; Yao, Liang; Jeanbourquin, Xavier A; Liu, Yongpeng; Sekar, Arvindh; Ripaud, Emilie; Sivula, Kevin

2018-05-21

Melt-processing of organic semiconductors (OSCs) is a promising environmentally-friendly technique that can alleviate dependence on toxic chlorinated solvents. While melt-processed single-component OSC devices ( e.g. field-effect-transistors) have been demonstrated, multi-component bulk heterojunctions (BHJs) for organic photovoltaics (OPVs) remain a challenge. Herein, we demonstrate a strategy that affords tunable BHJ phase segregation and domain sizes from a single-phase homogeneous melt by employing strongly-crystalline small-molecule OSCs together with a customized molecular compatibilizing (MCP) additive. An optimized photoactive BHJ with 50 wt% MCP achieved a device power conversion efficiency of ca. 1% after melting the active layer at 240 °C (15 min, followed by slow cooling) before deposition of the top electrode. BHJ morphology characterization using atomic force and Kelvin probe microscopy, X-ray diffraction, and photo-luminescence measurements further demonstrate the trade-off between free charge generation and transport with respect to MCP loading in the BHJ. In addition, a functional OPV was also obtained from the melt-processing of dispersed micron-sized solid BHJ particles into a smooth and homogeneous thin-film by using the MCP approach. These results demonstrate that molecular compatibilization is a key prerequisite for further developments towards true solvent-free melt-processed BHJ OPV systems.

Synthesis of phthalocyanine derivatives as materials for organic photovoltaic cells

NASA Astrophysics Data System (ADS)

Collazo-Ramos, Aura

Organic photovoltaics (OPVs) are used to convert sunlight into electricity by using thin films of organic semiconductors. OPVs have the potential to produce low cost, lightweight, flexible devices with an eased manufacturing process. This technology contains the potential to increase the use of clean, sustainable solar energy, helping manage the global energy and environmental crisis that results majorly from the constant use of fossil fuels as an energy source. The ability to modulate the physical properties of organic molecules by tuning their chemical structure is an advantage for OPVs. Phthalocyanines (Pcs) are highly pi-conjugated synthetic porphyrin analogs that have been explored as active layer components in OPVs due to their high extinction coefficients and hole mobilities. The Pc structure can be modified by the introduction of metals in the core and the incorporation of substituents into the periphery. These modifications tend to tune the solubility, photophysical properties and condensed phase organization of Pcs. The research work in this dissertation describes improved methods towards substituted Pc derivatives addressing: (1) the use of mass spectrometry techniques for Pcs characterization, (2) efforts to achieve materials with near-infrared (NIR) absorption, and (3) the potential of Pc as electron-acceptor materials. Herein, the synthesis of a series of asymmetric and symmetric metallated Pcs has been established, which resulted in interesting chemical, photophysical and electrochemical properties. The materials investigated in this thesis increase the potential of Pcs as organic semiconductors for OPVs.

Lessons From Globally Coordinated Cessation of Serotype 2 Oral Poliovirus Vaccine for the Remaining Serotypes

PubMed Central

Duintjer Tebbens, Radboud J.

2017-01-01

Abstract Background. Comparing model expectations with the experience of oral poliovirus vaccine (OPV) containing serotype 2 (OPV2) cessation can inform risk management for the expected cessation of OPV containing serotypes 1 and 3 (OPV13). Methods. We compare the expected post-OPV2-cessation OPV2-related viruses from models with the evidence available approximately 6 months after OPV2 cessation. We also model the trade-offs of use vs nonuse of monovalent OPV (mOPV) for outbreak response considering all 3 serotypes. Results. Although too early to tell definitively, the observed die-out of OPV2-related viruses in populations that attained sufficiently intense trivalent OPV (tOPV) use prior to OPV2 cessation appears consistent with model expectations. As expected, populations that did not intensify tOPV use prior to OPV2 cessation show continued circulation of serotype 2 vaccine-derived polioviruses (VDPVs). Failure to aggressively use mOPV to respond to circulating VDPVs results in a high risk of uncontrolled outbreaks that would require restarting OPV. Conclusions. Ensuring a successful endgame requires more aggressive OPV cessation risk management than has occurred to date for OPV2 cessation. This includes maintaining high population immunity to transmission up until OPV13 cessation, meeting all prerequisites for OPV cessation, and ensuring sufficient vaccine supply to prevent and respond to outbreaks. PMID:28838198

Lessons From Globally Coordinated Cessation of Serotype 2 Oral Poliovirus Vaccine for the Remaining Serotypes.

PubMed

Thompson, Kimberly M; Duintjer Tebbens, Radboud J

2017-07-01

Comparing model expectations with the experience of oral poliovirus vaccine (OPV) containing serotype 2 (OPV2) cessation can inform risk management for the expected cessation of OPV containing serotypes 1 and 3 (OPV13). We compare the expected post-OPV2-cessation OPV2-related viruses from models with the evidence available approximately 6 months after OPV2 cessation. We also model the trade-offs of use vs nonuse of monovalent OPV (mOPV) for outbreak response considering all 3 serotypes. Although too early to tell definitively, the observed die-out of OPV2-related viruses in populations that attained sufficiently intense trivalent OPV (tOPV) use prior to OPV2 cessation appears consistent with model expectations. As expected, populations that did not intensify tOPV use prior to OPV2 cessation show continued circulation of serotype 2 vaccine-derived polioviruses (VDPVs). Failure to aggressively use mOPV to respond to circulating VDPVs results in a high risk of uncontrolled outbreaks that would require restarting OPV. Ensuring a successful endgame requires more aggressive OPV cessation risk management than has occurred to date for OPV2 cessation. This includes maintaining high population immunity to transmission up until OPV13 cessation, meeting all prerequisites for OPV cessation, and ensuring sufficient vaccine supply to prevent and respond to outbreaks. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Strong photocurrent enhancements in plasmonic organic photovoltaics by biomimetic nanoarchitectures with efficient light harvesting.

PubMed

Leem, Jung Woo; Kim, Sehwan; Park, Chihyun; Kim, Eunkyoung; Yu, Jae Su

2015-04-01

We propose the biomimetic moth-eye nanoarchitectures as a novel plasmonic light-harvesting structure for further enhancing the solar-generated photocurrents in organic photovoltaics (OPVs). The full moth-eye nanoarchitectures are composed of two-dimensional hexagonal periodic grating arrays on surfaces of both the front zinc oxide (ZnO) and rear active layers, which are prepared by a simple and cost-effective soft imprint nanopatterning technique. For the 380 nm period ZnO and 650 nm period active gratings (i.e., ZnO(P380)/Active(P650)), the poly(3-hexylthiophene-2,5-diyl):indene-C60 bis-adduct (P3HT:ICBA)-based plasmonic OPVs exhibit an improvement of the absorption spectrum compared to the pristine OPVs over a broad wavelength range of 350-750 nm, showing absorption enhancement peaks at wavelengths of ∼370, 450, and 670 nm, respectively. This leads to a considerable increase of short-circuit current density (Jsc) from 10.9 to 13.32 mA/cm(2), showing a large Jsc enhancement percentage of ∼22.2%. As a result, the strongly improved power conversion efficiency (PCE) of 6.28% is obtained compared to that (i.e., PCE = 5.12%) of the pristine OPVs. For the angle-dependent light-absorption characteristics, the plasmonic OPVs with ZnO(P380)/Active(P650) have a better absorption performance than that of the pristine OPVs at incident angles of 20-70°. For optical absorption characteristics and near-field intensity distributions of plasmonic OPVs, theoretical analyses are also performed by a rigorous coupled-wave analysis method, which gives a similar tendency with the experimentally measured data.

Materials and Devices | Photovoltaic Research | NREL

Science.gov Websites

Polycrystalline Thin-Film PV Cadmium telluride (CdTe) solar cells Copper indium gallium diselenide (CIGS) solar cells Perovskite and Organic PV Perovskite solar cells Perovskite Patent Portfolio Organic PV (OPV ) solar cells Advanced Materials, Devices, and Concepts We explore new PV materials using high-throughput

COST OF PRIMARY HEALTH CARE IN PAKISTAN.

PubMed

Malik, Muhammad Ashar; Gul, Wahid; Iqbal, Saleem Perwaiz; Abrejo, Farina

2015-01-01

Detailed cost analysis is an important tool for review of health policy and reforms. We provide an estimate of cost of service and its detailed breakup on out-door patient visits (OPV) to basic health units (BHU) in Pakistan. Six BHUs were randomly selected from each of the five districts in Khyber Pukhtonkhawa (KPK) and two agencies in Federally Administered Tribal Areas (FATA) of Pakistan for this study. Actual expenditure data and utilization data in the year 2005-06 of 42 BHUs was collected from selected district health offices in KPK and FATA. Costs were estimated for outpatient visits to BHUs. Perspective on cost estimates was district-based health planning and management of BHUs. Average recurring cost was PKR.245 (USD 4.1) per OPV to BHU. Staff salaries constituted 90% of recurrent cost. On the average there were 16 OPV per day to the BHUs. CONCLUDION: Recurrent cost per OPV has doubled from the previous estimates of cost of OPV in Baluchistan. The estimated recurrent cost was six times higher than average consultation charges with the private general practitioner (GP) in the country (i.e., PKR 50/ GP consultation). Performance of majority of the BHUs was much lower than the performance target (50 patients per day) set in the sixth five-year plan of the government of Pakistan. The Government of Pakistan may use these analyses to revisit the performance target, staffinL and location of BHUs.

Predicting transport regime and local electrostatic environment from Coulomb blockade diamond sizes

NASA Astrophysics Data System (ADS)

Olsen, Stine T.; Hansen, Thorsten; Mikkelsen, Kurt V.

2017-03-01

Electron transport through a molecule is often described in one of the two regimes: the coherent tunnelling regime or the Coulomb blockade regime. The twilight zone of the two regimes still possesses many unsolved questions. A theoretical analysis of the oligophenylenevinylene OPV3 experiments by Bjørnholm and co-workers is performed. The experiments showed how two OPV3 derivatives performed very differently despite the strong similarity of the molecular structure, hence the experimental data showed two different transport mechanisms. The different transport mechanisms of the two OPV3 derivatives are explained from quantum mechanical calculations of the molecular redox energies and from the experimentally accessible window size.

Flexible ITO-free organic solar cells applying aqueous solution-processed V2O5 hole transport layer: An outdoor stability study

NASA Astrophysics Data System (ADS)

Lima, F. Anderson S.; Beliatis, Michail J.; Roth, Bérenger; Andersen, Thomas R.; Bortoti, Andressa; Reyna, Yegraf; Castro, Eryza; Vasconcelos, Igor F.; Gevorgyan, Suren A.; Krebs, Frederik C.; Lira-Cantu, Mónica

2016-02-01

Solution processable semiconductor oxides have opened a new paradigm for the enhancement of the lifetime of thin film solar cells. Their fabrication by low-cost and environmentally friendly solution-processable methods makes them ideal barrier (hole and electron) transport layers. In this work, we fabricate flexible ITO-free organic solar cells (OPV) by printing methods applying an aqueous solution-processed V2O5 as the hole transport layer (HTL) and compared them to devices applying PEDOT:PSS. The transparent conducting electrode was PET/Ag/PEDOT/ZnO, and the OPV configuration was PET/Ag/PEDOT/ZnO/P3HT:PC60BM/HTL/Ag. Outdoor stability analyses carried out for more than 900 h revealed higher stability for devices fabricated with the aqueous solution-processed V2O5.

Investigations into Performance and Lifetime Enhancements of OPV Devices: Cooperative Research and Development Final Report, CRADA Number CRD-08-263

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ginley, D.

2014-06-01

To evaluate Plextronics new additives and derivatives in lithium-ion Battery Applications, Plextronics will provide to NREL, a starting point, including materials and initial data for proof of concept. The central focus of this project is to acertain the nature of the efficacy of the Plextronics additives through physical and electrical characterization, including evaluations of new derivatives, system evaluations on batteries made with Plexcore and to study long term cycling performance differences. The initial focus is to establish Plexcore mode of action to support the commercialization of the first commercial evaluations of Plexcore in Sept. 2013.

Optimization of Organic Solar Cells: Materials, Devices and Interfaces

NASA Astrophysics Data System (ADS)

Zhou, Nanjia

Due to the increasing demand for sustainable clean energy, photovoltaic cells have received intensified attention in the past decade in both academia and industry. Among the types of cells, organic photovoltaic (OPV) cells offer promise as alternatives to conventional inorganic-type solar cells owning to several unique advantages such as low material and fabrication cost. To maximize power conversion efficiencies (PCEs), extensive research efforts focus on frontier molecular orbital (FMO) energy engineering of photoactive materials. Towards this objective, a series of novel donor polymers incorporating a new building block, bithiophene imide (BTI) group are developed, with narrow bandgap and low-lying highest occupied molecular orbital (HOMO) energies to increase short circuit current density, Jsc, and open circuit voltage, Voc.. Compared to other PV technologies, OPVs often suffer from large internal recombination loss and relatively low fill factors (FFs) <70%. Through a combination of materials design and device architecture optimization strategies to improve both microscopic and macroscopic thin film morphology, OPVs with PCEs up to 8.7% and unprecedented FF approaching 80% are obtained. Such high FF are close to those typically achieved in amorphous Si solar cells. Systematic variations of polymer chemical structures lead to understanding of structure-property relationships between polymer geometry and the resulting blend film morphology characteristics which are crucial for achieving high local mobilities and long carrier lifetimes. Instead of using fullerene as the acceptors, an alternative type of OPV is developed employing a high electron mobility polymer, P(NDI2OD-T2), as the acceptor. To improve the all-polymer blend film morphology, the influence of basic solvent properties such as solvent boiling point and solubility on polymer phase separation and charge transport properties is investigated, yielding to a high PCE of 2.7% for all-polymer solar cells. To take advantages of the inherent mechanical flexibility associated with organic materials, the development of transparent, flexible substrates to replace the conventionally used polycrystalline ITO electrodes is highly desirable. Employing an ultraflexible amorphous zinc indium tin oxide (a-ZITO) transparent conducting oxide (TCO), highly efficient OPVs with similar PCEs to rigid ones are obtained. Furthermore, these cells show no significant PCE reduction under controlled bending test.

Nanoscale structure, dynamics and power conversion efficiency correlations in small molecule and oligomer-based photovoltaic devices

PubMed Central

Szarko, Jodi M.; Guo, Jianchang; Rolczynski, Brian S.; Chen, Lin X.

2011-01-01

Photovoltaic functions in organic materials are intimately connected to interfacial morphologies of molecular packing in films on the nanometer scale and molecular levels. This review will focus on current studies on correlations of nanoscale morphologies in organic photovoltaic (OPV) materials with fundamental processes relevant to photovoltaic functions, such as light harvesting, exciton splitting, exciton diffusion, and charge separation (CS) and diffusion. Small molecule photovoltaic materials will be discussed here. The donor and acceptor materials in small molecule OPV devices can be fabricated in vacuum-deposited, multilayer, crystalline thin films, or spin-coated together to form blended bulk heterojunction (BHJ) films. These two methods result in very different morphologies of the solar cell active layers. There is still a formidable debate regarding which morphology is favored for OPV optimization. The morphology of the conducting films has been systematically altered; using variations of the techniques above, the whole spectrum of film qualities can be fabricated. It is possible to form a highly crystalline material, one which is completely amorphous, or an intermediate morphology. In this review, we will summarize the past key findings that have driven organic solar cell research and the current state-of-the-art of small molecule and conducting oligomer materials. We will also discuss the merits and drawbacks of these devices. Finally, we will highlight some works that directly compare the spectra and morphology of systematically elongated oligothiophene derivatives and compare these oligomers to their polymer counterparts. We hope this review will shed some new light on the morphology differences of these two systems. PMID:22110870

Influence of oral polio vaccines on performance of the monovalent and pentavalent rotavirus vaccines.

PubMed

Patel, Manish; Steele, A Duncan; Parashar, Umesh D

2012-04-27

In recent years, two live, oral rotavirus vaccines have been successfully tested in developing and industrialized countries, and both vaccines are now recommended by the World Health Organization for all children worldwide. Both immunogenicity and efficacy of these rotavirus vaccines has been lower in developing compared to industrialized settings. We reviewed the data on the effect of trivalent OPV on the immunogenicity and efficacy of two rotavirus vaccines currently recommended by the WHO. While rotavirus vaccines have not affected immune responses to OPV, in general, the immune responses (i.e., antibody levels) to rotavirus vaccination were lower when rotavirus vaccines were co-administered with OPV. Limited data suggests that the interference is greater after the first dose of OPV, presumably because the first dose is associated with greatest intestinal replication of vaccine polio virus strains, and this interference is largely overcome with subsequent rotavirus vaccine doses. Despite the lower immunogenicity, one large efficacy study in middle income Latin American countries showed no decrease in protective efficacy of rotavirus vaccine in infants receiving concurrent OPV. While these data are encouraging and support simultaneous administration of rotavirus vaccines and OPV, additional evidence should be gathered as rotavirus vaccines are used more widely in developing country settings, where OPV is routinely used, rather than inactivated polio vaccine. Published by Elsevier Ltd.

Effect of Aggregation on Squaraine Fullerene Bulk-Heterojunction Organic Photovoltaic Devices

NASA Astrophysics Data System (ADS)

Jalan, Ishita

Organic photovoltaics (OPV) offer great promise as a low-cost renewable energy source, the relative low efficiency still challenges its commercialization potential. Small conjugated molecules like Squaraine (SQ) molecules show promising advancement in organic photovoltaics (OPV). Advantages of SQ over other materials is that it has a high extinction coefficient (>105), decent photo-stability, good synthetic reproducibility, and tunable molecular structure. With small chemical modifications, the squaraines can have substantial impact on photophysical properties and aggregation pattern, and thus on operational OPV efficiency. The squaraine molecule that will be studied in this work is a symmetric aniline-based squaraine with n-hexyl chain on the molecular arm with di hydroxyl substituents on the aniline, this will be referred to DHSQ(OH) 2. In this work, the assignment of the monomer and aggregate peak is discussed. It is known that crystallinity is important for efficient charge transport and exciton diffusion in the BHJ, this thesis focuses on thermal and solvent vapor annealing the as-cast films to reduce the amorphous regions. It is observed that crystallinity is improved but often at the expense of larger crystal size. Therefore, to achieve optimal OPV efficiency, this tradeoff is controlled to improve the crystallinity while maintaining a small, highly mixed BHJ morphology.

Efficiency enhancement and angle-dependent color change in see-through organic photovoltaics using distributed Bragg reflectors

NASA Astrophysics Data System (ADS)

Dong, Wan Jae; Lo, Nhat-Truong; Jung, Gwan Ho; Ham, Juyoung; Lee, Jong-Lam

2016-03-01

A distributed Bragg reflector (DBR) is conducted as a bottom reflector in see-through organic photovoltaics (OPVs) with an active layer of poly(3-hexylthiophene) and phenyl-C61-butyric acid methyl ester (P3HT:PCBM). The DBR consists of alternative layers of the high- and low-refractive index materials of Ta2O5 (n = 2.16) and SiO2 (n = 1.46). The DBR selectively reflects the light within a specific wavelength region (490 nm-630 nm) where the absorbance of P3HT:PCBM is maximum. The see-through OPVs fabricated on DBR exhibit efficiency enhancement by 31% compared to the device without DBR. Additionally, the angle-dependent transmittance of DBR is analysed using optical simulation and verified by experimental results. As the incident angle of light increases, peak of reflectance shifts to shorter wavelength and the bandwidth gets narrower. This unique angle-dependent optical properties of DBR allows the facile color change of see-through OPVs.

Organic photovoltaics: elucidating the ultra-fast exciton dissociation mechanism in disordered materials.

PubMed

Heitzer, Henry M; Savoie, Brett M; Marks, Tobin J; Ratner, Mark A

2014-07-14

Organic photovoltaics (OPVs) offer the opportunity for cheap, lightweight and mass-producible devices. However, an incomplete understanding of the charge generation process, in particular the timescale of dynamics and role of exciton diffusion, has slowed further progress in the field. We report a new Kinetic Monte Carlo model for the exciton dissociation mechanism in OPVs that addresses the origin of ultra-fast (<1 ps) dissociation by incorporating exciton delocalization. The model reproduces experimental results, such as the diminished rapid dissociation with increasing domain size, and also lends insight into the interplay between mixed domains, domain geometry, and exciton delocalization. Additionally, the model addresses the recent dispute on the origin of ultra-fast exciton dissociation by comparing the effects of exciton delocalization and impure domains on the photo-dynamics.This model provides insight into exciton dynamics that can advance our understanding of OPV structure-function relationships. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Role of FRET in Non-Fullerene Organic Solar Cells: Implications for Molecular Design.

PubMed

Gautam, Bhoj R; Younts, Robert; Carpenter, Joshua; Ade, Harald; Gundogdu, Kenan

2018-04-19

Non-fullerene acceptors (NFAs) have been demonstrated to be promising candidates for highly efficient organic photovoltaic (OPV) devices. The tunability of absorption characteristics of NFAs can be used to make OPVs with complementary donor-acceptor absorption to cover a broad range of the solar spectrum. However, both charge transfer from donor to acceptor moieties and energy (energy) transfer from high-bandgap to low-bandgap materials are possible in such structures. Here, we show that when charge transfer and exciton transfer processes are both present, the coexistence of excitons in both domains can cause a loss mechanism. Charge separation of excitons in a low-bandgap material is hindered due to exciton population in the larger bandgap acceptor domains. Our results further show that excitons in low-bandgap material should have a relatively long lifetime compared to the transfer time of excitons from higher bandgap material in order to contribute to the charge separation. These observations provide significant guidance for design and development of new materials in OPV applications.

Combining Fullerenes and Zwitterions in non-Conjugated Polymer Interlayers to Raise Solar Cell Efficiency.

PubMed

Liu, Yao; Sheri, Madhu; Cole, Marcus D; Emrick, Todd; Russell, Thomas P

2018-06-12

Polymer zwitterions were synthesized by nucleophilic ring-opening of 3,3'-(but-2-ene-1,4-diyl)bis(1,2-oxathiolane 2,2-dioxide) (a bis-sultone) with functional perylene diimide (PDI) or fullerene monomers. Integration of these polymers into solar cell devices as cathode interlayers boosted efficiencies of fullerene-based organic photovoltaics (OPVs) from 2.75% to 10.74%, and of non-fullerene-based OPVs from 4.25% to 10.10%, demonstrating the versatility of these interlayer materials in OPVs. The fullerene-containing polymer zwitterion (C60-PZ) showed a higher interfacial dipole (∆) value and electron mobility than its PDI counterpart (PDI-PZ), affording solar cells with high efficiency. The power of PDI-PZ and C60-PZ to improve electron injection and extraction processes when positioned between metal electrodes and organic semiconductors highlights their promise to overcome energy barriers at the hard-soft materials interface of organic electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Implementation of coordinated global serotype 2 oral poliovirus vaccine cessation: risks of inadvertent trivalent oral poliovirus vaccine use.

PubMed

Duintjer Tebbens, Radboud J; Hampton, Lee M; Thompson, Kimberly M

2016-06-01

The endgame for polio eradication includes coordinated global cessation of oral poliovirus vaccine (OPV), starting with the cessation of vaccine containing OPV serotype 2 (OPV2) by switching all trivalent OPV (tOPV) to bivalent OPV (bOPV). The logistics associated with this global switch represent a significant undertaking, with some possibility of inadvertent tOPV use after the switch. We used a previously developed poliovirus transmission and OPV evolution model to explore the relationships between the extent of inadvertent tOPV use, the time after the switch of the inadvertent tOPV use and corresponding population immunity to serotype 2 poliovirus transmission, and the ability of the inadvertently introduced viruses to cause a serotype 2 circulating vaccine-derived poliovirus (cVDPV2) outbreak in a hypothetical population. We then estimated the minimum time until inadvertent tOPV use in a supplemental immunization activity (SIA) or in routine immunization (RI) can lead to a cVDPV2 outbreak in realistic populations with properties like those of northern India, northern Pakistan and Afghanistan, northern Nigeria, and Ukraine. At low levels of inadvertent tOPV use, the minimum time after the switch for the inadvertent use to cause a cVDPV2 outbreak decreases sharply with increasing proportions of children inadvertently receiving tOPV. The minimum times until inadvertent tOPV use in an SIA or in RI can lead to a cVDPV2 outbreak varies widely among populations, with higher basic reproduction numbers, lower tOPV-induced population immunity to serotype 2 poliovirus transmission prior to the switch, and a lower proportion of transmission occurring via the oropharyngeal route all resulting in shorter times. In populations with the lowest expected immunity to serotype 2 poliovirus transmission after the switch, inadvertent tOPV use in an SIA leads to a cVDPV2 outbreak if it occurs as soon as 9 months after the switch with 0.5 % of children aged 0-4 years inadvertently receiving tOPV, and as short as 6 months after the switch with 10-20 % of children aged 0-1 years inadvertently receiving tOPV. In the same populations, inadvertent tOPV use in RI leads to a cVDPV2 outbreak if 0.5 % of OPV RI doses given use tOPV instead of bOPV for at least 20 months after the switch, with the minimum length of use dropping to at least 9 months if inadvertent tOPV use occurs in 50 % of OPV RI doses. Efforts to ensure timely and complete tOPV withdrawal at all levels, particularly from locations storing large amounts of tOPV, will help minimize risks associated with the tOPV-bOPV switch. Under-vaccinated populations with poor hygiene become at risk of a cVDPV2 outbreak in the event of inadvertent tOPV use the soonest after the tOPV-bOPV switch and therefore should represent priority areas to ensure tOPV withdrawal from all OPV stocks.

Health and economic consequences of different options for timing the coordinated global cessation of the three oral poliovirus vaccine serotypes.

PubMed

Thompson, Kimberly M; Duintjer Tebbens, Radboud J

2015-09-17

World leaders remain committed to globally-coordinated oral poliovirus vaccine (OPV) cessation following successful eradication of wild polioviruses, but the best timing and strategy for implementation depend on existing and emerging conditions. Using an existing integrated global poliovirus risk management model, we explore alternatives to the current timing plan of coordinated cessation of each OPV serotype (i.e., OPV1, OPV2, and OPV3 cessation for serotypes 1, 2, and 3, respectively). We assume the current timing plan involves OPV2 cessation in 2016 followed by OPV1 and OPV3 cessation in 2019 and we compare this to alternative timing options, including cessation of all three serotypes in 2018 or 2019, and cessation of both OPV2 and OPV3 in 2017 followed by OPV1 in 2019. If Supplemtal Immunization Activity frequency remains sufficiently high through cessation of the last OPV serotype, then all OPV cessation timing options prevent circulating vaccine-derived poliovirus (cVDPV) outbreaks after OPV cessation of any serotype. The various OPV cessation timing options result in relatively modest differences in expected vaccine-associated paralytic poliomyelitis cases and expected total of approximately 10-13 billion polio vaccine doses used. However, the expected amounts of vaccine of different OPV formulations needed changes dramatically with each OPV cessation timing option. Overall health economic impacts remain limited for timing options that only change the OPV formulation but preserve the currently planned year for cessation of the last OPV serotype and the global introduction of inactivated poliovirus vaccine (IPV) introduction. Earlier cessation of the last OPV serotype or later global IPV introduction yield approximately $1 billion in incremental net benefits due to saved vaccination costs, although the logistics of implementation of OPV cessation remain uncertain and challenging. All countries should maintain the highest possible levels of population immunity to transmission for each poliovirus serotype prior to the coordinated cessation of the OPV serotype to manage cVDPV risks. If OPV2 cessation gets delayed, then global health leaders should consider other OPV cessation timing options.

Nanoscale observation of organic thin film by atomic force microscopy

NASA Astrophysics Data System (ADS)

Mochizuki, Shota; Uruma, Takeshi; Satoh, Nobuo; Saravanan, Shanmugam; Soga, Tetsuo

2017-08-01

Organic photovoltaics (OPVs) fabricated using organic semiconductors and hybrid solar cells (HSCs) based on organic semiconductors/quantum dots (QDs) have been attracting significant attention owing to their potential use in low-cost solar energy-harvesting applications and flexible, light-weight, colorful, large-area devices. In this study, we observed and evaluated the surface of a photoelectric conversion layer (active layer) of the OPVs and HSCs based on phenyl-C61-butyric acid methyl ester (PCBM), poly(3-hexylthiophene) (P3HT), and zinc oxide (ZnO) nanoparticles. The experiment was performed using atomic force microscopy (AFM) combined with a frequency modulation detector (FM detector) and a contact potential difference (CPD) detection circuit. We experimentally confirmed the changes in film thickness and surface potential, as affected by the ZnO nanoparticle concentration. From the experimental results, we confirmed that ZnO nanoparticles possibly affect the structures of PCBM and P3HT. Also, we prepared an energy band diagram on the basis of the observation results, and analyzed the energy distribution inside the active layer.

Implementation of coordinated global serotype 2 oral poliovirus vaccine cessation: risks of potential non-synchronous cessation.

PubMed

Duintjer Tebbens, Radboud J; Hampton, Lee M; Thompson, Kimberly M

2016-05-26

The endgame for polio eradication involves coordinated global cessation of oral poliovirus vaccine (OPV) with cessation of serotype 2 OPV (OPV2 cessation) implemented in late April and early May 2016 and cessation of serotypes 1 and 3 OPV (OPV13 cessation) currently planned for after 2018. The logistics associated with globally switching all use of trivalent OPV (tOPV) to bivalent OPV (bOPV) represent a significant undertaking, which may cause some complications, including delays that lead to different timing of the switch across shared borders. Building on an integrated global model for long-term poliovirus risk management, we consider the expected vulnerability of different populations to transmission of OPV2-related polioviruses as a function of time following the switch. We explore the relationship between the net reproduction number (Rn) of OPV2 at the time of the switch and the time until OPV2-related viruses imported from countries still using OPV2 can establish transmission. We also analyze some specific situations modeled after populations at high potential risk of circulating serotype 2 vaccine-derived poliovirus (cVDPV2) outbreaks in the event of a non-synchronous switch. Well-implemented tOPV immunization activities prior to the tOPV to bOPV switch (i.e., tOPV intensification sufficient to prevent the creation of indigenous cVDPV2 outbreaks) lead to sufficient population immunity to transmission to cause die-out of any imported OPV2-related viruses for over 6 months after the switch in all populations in the global model. Higher Rn of OPV2 at the time of the switch reduces the time until imported OPV2-related viruses can establish transmission and increases the time during which indigenous OPV2-related viruses circulate. Modeling specific connected populations suggests a relatively low vulnerability to importations of OPV2-related viruses that could establish transmission in the context of a non-synchronous switch from tOPV to bOPV, unless the gap between switch times becomes very long (>6 months) or a high risk of indigenous cVDPV2s already exists in the importing and/or the exporting population. Short national discrepancies in the timing of the tOPV to bOPV switch will likely not significantly increase cVDPV2 risks due to the insurance provided by tOPV intensification efforts, although the goal to coordinate national switches within the globally agreed April 17-May 1, 2016 time window minimized the risks associated with cross-border importations.

Synthetic principles directing charge transport in low-band-gap dithienosilole-benzothiadiazole copolymers.

PubMed

Beaujuge, Pierre M; Tsao, Hoi Nok; Hansen, Michael Ryan; Amb, Chad M; Risko, Chad; Subbiah, Jegadesan; Choudhury, Kaushik Roy; Mavrinskiy, Alexei; Pisula, Wojciech; Brédas, Jean-Luc; So, Franky; Müllen, Klaus; Reynolds, John R

2012-05-30

Given the fundamental differences in carrier generation and device operation in organic thin-film transistors (OTFTs) and organic photovoltaic (OPV) devices, the material design principles to apply may be expected to differ. In this respect, designing organic semiconductors that perform effectively in multiple device configurations remains a challenge. Following "donor-acceptor" principles, we designed and synthesized an analogous series of solution-processable π-conjugated polymers that combine the electron-rich dithienosilole (DTS) moiety, unsubstituted thiophene spacers, and the electron-deficient core 2,1,3-benzothiadiazole (BTD). Insights into backbone geometry and wave function delocalization as a function of molecular structure are provided by density functional theory (DFT) calculations at the B3LYP/6-31G(d,p) level. Using a combination of X-ray techniques (2D-WAXS and XRD) supported by solid-state NMR (SS-NMR) and atomic force microscopy (AFM), we demonstrate fundamental correlations between the polymer repeat-unit structure, molecular weight distribution, nature of the solubilizing side-chains appended to the backbones, and extent of structural order attainable in p-channel OTFTs. In particular, it is shown that the degree of microstructural order achievable in the self-assembled organic semiconductors increases largely with (i) increasing molecular weight and (ii) appropriate solubilizing-group substitution. The corresponding field-effect hole mobilities are enhanced by several orders of magnitude, reaching up to 0.1 cm(2) V(-1) s(-1) with the highest molecular weight fraction of the branched alkyl-substituted polymer derivative in this series. This trend is reflected in conventional bulk-heterojunction OPV devices using PC(71)BM, whereby the active layers exhibit space-charge-limited (SCL) hole mobilities approaching 10(-3) cm(2) V(-1) s(-1), and yield improved power conversion efficiencies on the order of 4.6% under AM1.5G solar illumination. Beyond structure-performance correlations, we observe a large dependence of the ionization potentials of the polymers estimated by electrochemical methods on polymer packing, and expect that these empirical results may have important consequences on future material study and device applications.

Modeling Emerging Solar Cell Materials and Devices

NASA Astrophysics Data System (ADS)

Thongprong, Non

Organic photovoltaics (OPVs) and perovskite solar cells are emerging classes of solar cell that are promising for clean energy alternatives to fossil fuels. Understanding fundamental physics of these materials is crucial for improving their energy conversion efficiencies and promoting them to practical applications. Current density-voltage (JV) curves; which are important indicators of OPV efficiency, have direct connections to many fundamental properties of solar cells. They can be described by the Shockley diode equation, resulting in fitting parameters; series and parallel resistance (Rs and Rp), diode saturation current ( J0) and ideality factor (n). However, the Shockley equation was developed specifically for inorganic p-n junction diodes, so it lacks physical meanings when it is applied to OPVs. Hence, the puRposes of this work are to understand the fundamental physics of OPVs and to develop new diode equations in the same form as the Shockley equation that are based on OPV physics. We develop a numerical drift-diffusion simulation model to study bilayer OPVs, which will be called the drift-diffusion for bilayer interface (DD-BI) model. The model solves Poisson, drift-diffusion and current-continuity equations self-consistently for charge densities and potential profiles of a bilayer device with an organic heterojunction interface described by the GWWF model. We also derive new diode equations that have JV curves consistent with the DD-BI model and thus will be called self-consistent diode (SCD) equations. Using the DD-BI and the SCD model allows us to understand working principles of bilayer OPVs and physical definitions of the Shockley parameters. Due to low carrier mobilities in OPVs, space charge accumulation is common especially near the interface and electrodes. Hence, quasi-Fermi levels (i.e. chemical potentials), which depend on charge densities, are modified around the interface, resulting in a splitting of quasi-Fermi levels that works as a driving potential for the heterojunction diode. This brings about the meaning of R s as the resistance that gives rise to the diode voltage equal to the interface quasi-Fermi level splitting instead of the voltage between the electrodes. Quasi-Fermi levels that drop near the electrodes because of unmatched electrode work functions or due to charge injection can also increase Rs. Furthermore, we are able to study dissociation and recombination rates of bound charge pairs across the interface (i.e. polaron pairs or PPs) and arrive at the physical meaning of Rp as recombination resistance of PPs. In the dark, PP density is very low, so Rp is possibly caused by a tunneling leakage current at the interface. Ideality factors are parameters that depend on the split of quasi-Fermi levels and the ratio of recombination rate to recombination rate at equilibrium. Even though they are related to trap characteristics as normally understood, their relations are complicated and careful inte Rpretations of fitted ideality factors are needed. Our models are successfully applied to actual devices, and useful physics can be deduced, for example differences between the Shockley parameters under dark and illumination conditions. Another puRpose of this thesis is to study electronic properties of CsSnBr3 perovskite and processes of growing the perovskite film using an epitaxy technique. Calculation results using density functional theory reveal that a CsSnBr3 film that is grown on a NaCl(100) substrate can undergo a phase transition to CsSn 2Br5, which is a wide-bandgap semiconductor material. Actual mechanisms of the transition and the interface between CsSnBr3 and CsSn2Br5are interesting for future studies.

[Genetic improvement of breeding materials in tropical and sub- tropical maize].

PubMed

Sansern, Jampatong; Chaba, Jampatong

2011-12-01

In the present study, 122 maize local cultivars and adapted exotic germplasm from Thailand were used to develop open pollinate varieties (OPVs) using modified ear-to-row scheme, top-cross or test-cross programmes. Ten new maize OPVs with distinct characters were created based on the precise breeding objectives and directional design. The selection of breeding materials was based upon three factors: elite performance, broad adaptability, and genetic diversity. The synthesizing system provided four features: genetic mixing and recombination, equal comparable genetic contribution, mild selection pressure, and maximum intermating for genetic equilibrium (i.e., the female traits were close for the genetic com-positions). Subsequently, Suwan 1 composite and its deritives (Suwan 2, Suwan 3 composite, Suwan 5 and KS24 synthetics), KS6 and KS28 synthetics with the dent type of different origins, and Caripeno DMR composite, KS23, and KS27 synthetics with the dent type of Non-Suwan 1 origin were developed. These OPVs had been improved for 2~13 cycles using S1 recurrent selection method. About 50 inbred lines were developed from these OPVs, and 16 elite single (three-way) crosses were combined and released from these inbred lines. At present, at least one parental inbred line of all the tropical hybrids was derived from Suwan (KS) germplasm in Thailand. Based on the theory of the synthesizing OPVs and developing inbred lines, this paper discussed the genetic moderate diversity, relationship, heterotic group, and patterns for synthesizing OPVs, and inspiration for composed OPVs to heterosis breeding.

Mutations in the novel gene FOPV are associated with familial autosomal dominant and non-familial obliterative portal venopathy.

PubMed

Besmond, Claude; Valla, Dominique; Hubert, Laurence; Poirier, Karine; Grosse, Brigitte; Guettier, Catherine; Bernard, Olivier; Gonzales, Emmanuel; Jacquemin, Emmanuel

2018-02-01

Obliterative portal venopathy (OPV) is characterized by lesions of portal vein intrahepatic branches and is thought to be responsible for many cases of portal hypertension in the absence of cirrhosis or obstruction of large portal or hepatic veins. In most cases the cause of OPV remains unknown. The aim was to identify a candidate gene of OPV. Whole exome sequencing was performed in two families, including 6 patients with OPV. Identified mutations were confirmed by Sanger sequencing and expression of candidate gene transcript was studied by real time qPCR in human tissues. In both families, no mutations were identified in genes previously reported to be associated with OPV. In each family, we identified a heterozygous mutation (c.1783G>A, p.Gly595Arg and c.4895C>T, p.Thr1632Ile) in a novel gene located on chromosome 4, that we called FOPV (Familial Obliterative Portal Venopathy), and having a cDNA coding for 1793 amino acids. The FOPV mutations segregated with the disease in families and the pattern of inheritance was suggestive of autosomal dominant inherited OPV, with incomplete penetrance and variable expressivity. In silico analysis predicted a deleterious effect of each mutant and mutations concerned highly conserved amino acids in mammals. A deleterious heterozygous FOPV missense mutation (c.4244T>C, p.Phe1415Ser) was also identified in a patient with non-familial OPV. Expression study in liver veins showed that FOPV transcript was mainly expressed in intrahepatic portal vein. This report suggests that FOPV mutations may have a pathogenic role in some cases of familial and non-familial OPV. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Physical effects of DCNQI derivatives doping as an N type organic semiconductor in organic photovoltaic cell performance.

PubMed

Lee, Joo Hyung; Oh, Se Young

2014-08-01

In the previous work, we have reported that organic photovoltaic (OPV) cells using DMDCNQI as an n-type second dopant material showed a high power conversion efficiency (PCE). In the present work, we have synthesized a novel DHDCNQI with long alkyl chains to improve the compatibility between the DHDCNQI dopant molecule and host P3HT polymer. We have fabricated OPV cells consisting of ITO/PEDOT:PSS/P3HT:PCBM:DHDCNQI/Al. We have investigated the characteristics of theses OPV cells using DCNQI derivative dopants from the measurements of the incident photon-to-current collection efficiency and photocurrent. The OPV cell using 3 wt% DHDCNQI exhibited a high PCE of 3.29% due to the high charge separation efficiency, good compatibility and low trap site effect.

Obliterative portal venopathy: A histopathologic finding associated with chronic antibody-mediated rejection in pediatric liver allografts.

PubMed

Guerra, Marjorie-Anne R; Naini, Bita V; Scapa, Jason V; Reed, Elaine F; Busuttil, Ronald W; Cheng, Elaine Y; Farmer, Douglas G; Vargas, Jorge H; Venick, Robert S; McDiarmid, Sue V; Wozniak, Laura J

2018-03-01

The significance of post-transplant HLA DSA and chronic AMR in LT is an emerging field of study. Although OPV has previously been described as a histopathologic finding in DSA-positive adult LT recipients, it was not included in the recent Banff criteria for chronic AMR. Our aim was to describe the association between OPV and chronic AMR in pediatric LT recipients. A retrospective review of 67 liver biopsies performed between November 2014 and April 2016 in 45 pediatric LT recipients identified four patients with OPV. Clinical status, liver biochemistry, the presence of DSA, and available non-HLA antibody testing, as well as histopathologic features of chronic AMR, were assessed. All four patients with OPV had class II DSA and histopathologic features of chronic AMR based on the Banff criteria. Two patients were noted to have non-HLA antibodies. Three patients are undergoing treatment with IVIG but have persistent DSA. Two patients have graft failure and are awaiting retransplantation. In conclusion, OPV is a histopathologic finding associated with chronic AMR in pediatric LT recipients. Further studies are needed to elucidate whether OPV is reversible and/or amenable to medical therapy. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Computational screening of organic materials towards improved photovoltaic properties

NASA Astrophysics Data System (ADS)

Dai, Shuo; Olivares-Amaya, Roberto; Amador-Bedolla, Carlos; Aspuru-Guzik, Alan; Borunda, Mario

2015-03-01

The world today faces an energy crisis that is an obstruction to the development of the human civilization. One of the most promising solutions is solar energy harvested by economical solar cells. Being the third generation of solar cell materials, organic photovoltaic (OPV) materials is now under active development from both theoretical and experimental points of view. In this study, we constructed a parameter to select the desired molecules based on their optical spectra performance. We applied it to investigate a large collection of potential OPV materials, which were from the CEPDB database set up by the Harvard Clean Energy Project. Time dependent density functional theory (TD-DFT) modeling was used to calculate the absorption spectra of the molecules. Then based on the parameter, we screened out the top performing molecules for their potential OPV usage and suggested experimental efforts toward their synthesis. In addition, from those molecules, we summarized the functional groups that provided molecules certain spectrum capability. It is hoped that useful information could be mined out to provide hints to molecular design of OPV materials.

Optoelectronic Properties of Conjugated Block Copolymer with Flexible Linking Group

NASA Astrophysics Data System (ADS)

Hu, Zhiqi; Verduzco, Rafael

State-of-the-art organic photovoltaics (OPVs) are prepared by depositing a disordered, co-continuous donor and acceptor blend. While optimization of material processing has produced significant improvements in performance, a fundamental understanding of charge separation and recombination at the donor/acceptor interface is lacking. Block copolymers with donor and acceptor polymer blocks provide an opportunity for controlling the donor-accepter interfacial structure and understanding its relationship to charge separation and photovoltaic performance. Here, we report the synthesis and characterization of donor-linker-acceptor block copolymers for use in OPVs. A series of poly(3-hexylthiophene)-block- poly((9,9-dioctylfluorene)-2,7-diyl-alt-[4,7-bis(thiophen-5-yl)-2,1,3-benzothiadiazole]-2',2''-diyl) (P3HT-linkerPFTBT) are synthesized with flexible oligo-ethylene glycol (PEG) linkers. Photoluminescence measurements demonstrate that the insertion of a non-conjugated linker has a significant impact on energy transfer between the two blocks, and the block copolymers are used as additives for bulk heterojunction OPVs. This work provides insight into the charge separation process and demonstrates a technique for tailoring the donor-accepter interface in OPVs.

Polio endgame: the global switch from tOPV to bOPV.

PubMed

Garon, Julie; Seib, Katherine; Orenstein, Walter A; Ramirez Gonzalez, Alejandro; Chang Blanc, Diana; Zaffran, Michel; Patel, Manish

2016-06-01

Globally, polio cases have reached an all-time low, and type 2 poliovirus (one of three) is eradicated. Oral polio vaccine (OPV) has been the primary tool, however, in rare cases, OPV induces paralysis. In 2013, the World Health Assembly endorsed the phased withdrawal of OPV and introduction of inactivated poliovirus vaccine (IPV) into childhood routine immunization schedules. Type 2 OPV will be withdrawn through a globally synchronized "switch" from trivalent OPV (all three types) to bivalent OPV (types 1 and 3). The switch will happen in 155 OPV-using countries between April 17(th) and May 1(st), 2016. Planned activities to reduce type 2 outbreak risks post-switch include the following: tOPV campaigns to increase type 2 immunity prior to the switch, monovalent OPV2 stockpiling to respond to outbreaks should they occur, containment of both wild and vaccine type 2 viruses, enhanced acute flaccid paralysis (AFP) and environmental surveillance, outbreak response protocols, and ensured access to IPV and bivalent OPV.

Conjugated Polymer Zwitterions: Efficient Interlayer Materials in Organic Electronics.

PubMed

Liu, Yao; Duzhko, Volodimyr V; Page, Zachariah A; Emrick, Todd; Russell, Thomas P

2016-11-15

Conjugated polymer zwitterions (CPZs) are neutral, hydrophilic, polymer semiconductors. The pendent zwitterions, viewed as side chain dipoles, impart solubility in polar solvents for solution processing, and open opportunities as interfacial components of optoelectronic devices, for example, between metal electrodes and organic semiconductor active layers. Such interlayers are crucial for defining the performance of organic electronic devices, e.g., field-effect transistors (OFETs), light-emitting diodes (OLEDs), and photovoltaics (OPVs), all of which consist of multilayer structures. The interlayers reduce the Schottky barrier height and thus improve charge injection in OFETs and OLEDs. In OPVs, the interlayers serve to increase the built-in electric potential difference (V bi ) across the active layer, ensuring efficient extraction of photogenerated charge carriers. In general, polar and even charged electronically active polymers have gained recognition for their ability to modify metal/semiconductor interfaces to the benefit of organic electronics. While conjugated polyelectrolytes (CPEs) as interlayer materials are well-documented, open questions remain about the role of mobile counterions in CPE-containing devices. CPZs possess the processing advantages of CPEs, but as neutral molecules lack any potential complications associated with counterions. The electronic implications of CPZs on metal electrodes stem from the orientation of the zwitterion dipole moment in close proximity to the metal surface, and the resultant surface-induced polarization. This generates an interfacial dipole (Δ) at the CPZ/metal interface, altering the work function of the electrode, as confirmed by ultraviolet photoelectron spectroscopy (UPS), and improving device performance. An ideal cathode interlayer would reduce electrode work function, have orthogonal processability to the active layer, exhibit good film forming properties (i.e., wettability/uniformity), prevent exciton quenching, possess optimal electron affinity that neither limits the work function reduction nor impedes the charge extraction, transport electrons selectively, and exhibit long-term stability. Our recent discoveries show that CPZs achieve many of these attributes, and are poised for further expansion and development in the interfacial science of organic electronics. This Account reviews a recent collaboration that began with the synthesis of CPZs and a study of their structural and electronic properties on metals, then extended to their application as interlayer materials for OPVs. We discuss CPZ structure-property relationships based on several material platforms, ranging from homopolymers to copolymers, and from materials with intrinsic p-type conjugated backbones to those with intrinsic n-type conjugated backbones. We discuss key components of such interlayers, including (i) the origin of work function reduction of CPZ interlayers on metals; (ii) the role of the frontier molecular orbital energy levels and their trade-offs in optimizing electronic and device properties; and (iii) the role of polymer conductivity type and the magnitude of charge carrier mobility. Our motivation is to present our prior use and current understanding of CPZs as interlayer materials in organic electronics, and describe outstanding issues and future potential directions.

Near room-temperature direct encapsulation of organic photovoltaics by plasma-based deposition techniques

DOE PAGES

Perrotta, Alberto; Fuentes-Hernandez, Canek; Khan, Talha M.; ...

2016-12-02

Plasma-assisted atomic layer deposition (ALD) is used for the deposition of environmental barriers directly onto organic photovoltaic devices (OPVs) at near room temperature (30 °C). To study the effect of the ALD process on the organic materials forming the device, the precursor diffusion and intermixing at the interface during the growth of different plasma- assisted ALD inorganic barriers (i.e. Al2O3 and TiO2) onto the organic photoactive layer (P3HT:ICBA) was investigated. Depth profile x-ray photoelectron spectroscopy was used to analyze the composition of the organic/inorganic interface to investigate the infiltration of the plasma-assisted ALD precursors into the photoactive layer as amore » function of the precursor dimension, the process temperature, and organic layer morphology. The free volume in the photoactive layer accessible to the ALD precursor was characterized by means of ellipsometric porosimetry (EP) and spectroscopic ellipsometry as a function of temperature. The organic layer is shown to exhibit free volume broadening at high temperatures, increasing the infiltration depth of the ALD precursor into the photoactive layer. Furthermore, based on previous investigations, the intrinsic permeation properties of the inorganic layers deposited by plasma-assisted ALD were predicted from the nano-porosity content as measured by EP and found to be in the 10-6 gm-2 d-1 range. Insight from our studies was used to design and fabricate multilayer barriers synthesized at near-room temperature by plasma-assisted ALD in combination with plasma-enhanced CVD onto organic photovoltaic (OPVs) devices. Encapsulated OPVs displayed shelf-lifetimes up to 1400 h at ambient conditions.« less

Structure-Processing Relationships in Solution Processable Polymer Thin Film Transistors and Small Molecule Bulk Heterojunction Solar Cells

NASA Astrophysics Data System (ADS)

Perez, Louis A.

A regio-regular (RR) conjugated copolymer based on cyclopenta[2,1-b:3,4- b]dithiophene (CDT) and pyridal[2,1,3]thiadiazole (PT) structural units was prepared by using polymerization reactions involving reactants specifically designed to avoid random orientation of the asymmetric PT heterocycle. Compared to its regio-irregular (RI) counterpart, the RR polymer exhibits a two orders of magnitude increase in hole mobility from 0.005 to 0.6 cm2V -1s-1. To probe the reason for this difference in mobility, we examined the crystalline structure and its orientation in thin films of both copolymers as a function of depth via grazing incidence wide angle X-ray scattering (GIWAXS). In the RI film, the pi-pi stacking direction of the crystallites is mainly perpendicular to the substrate normal (edge-on orientation) while in the RR film the crystallites adopt a mixed pi-pi stacking orientation in the center of the film as well as near the interface between the polymer and the dielectric layer. These results demonstrate that control of backbone regularity is another important design criterion to consider in the synthesis and optimization of new conjugated copolymers with asymmetric structural units. Solution processed organic photovoltaic devices (OPVs) have emerged as a promising sustainable energy technology due to their ease of fabrication, potential to enable low-cost manufacturing, and ability to be incorporated onto light-weight flexible substrates. To date, the most efficacious OPV device architecture, the bulk heterojunction (BHJ), consists of a blend of a light-harvesting conjugated organic electron donating molecule and a strong electron-accepting compound (usually a soluble fullerene derivative e.g. [6,6]-phenyl C71 butyric acid methyl ester (PC71BM). BHJ layer morphology, which has been shown to be highly dependent on processing, has a significant effect on OPV performance. It is postulated that optimal BHJ morphologies consist of discrete bicontinuous nanoscale domains of each moiety, on the order of the exciton diffusion length, which extend vertically from each electrode, thereby increasing the surface area of the domains and forming continuous conducting pathways for efficient charge extraction and transfer. An optimal morphology, however, is seldom achieved during film formation; therefore, a number of processing techniques, such as thermal and sol vent annealing, and the addition of solvent additives to the casting solution have been explored to control the morphology in order to attain the multiple structural requirements. Solvent additive processing, a technique that is used in most record performing polymer:fullerene BHJ solar cell devices, involves the addition of small volumes of a high boiling point liquid to the BHJ casting solu- tion. Solvent additive processing, with 1,8-diiodooctane (DIO) as the additive, has recently been employed in solution processable small molecule (SPSM) BHJ systems, showing similar drastic effects on several device metrics and ultimately the power conversion efficiency (PCE). A recent SPSM study delineates how the volume of solvent additive used affects device performance: when 0.4 v/v% of DIO was used, the PCE increased from 1.8 to 7%, while a deterioration in the PCE to less than 1% occurred when only 1 v/v% of DIO was used. Several structural characterization techniques, such as grazing incidence wide and small-angle X-ray scattering (GIWAXS and GISAXS), and energy filtered transmission electron microscopy (EF-TEM), were used to investigate structure-processing-property relationships in additive-treated SPSM BHJ films and were correlated to device performance. Scattering experiments showed that the use of additives had several effects on the structure of the BHJ at multiple length scales: e.g. the number and orientation of SPSM crystallites, different pi-pi stacking distances, and the nano-scale domain size. Additionally, EF-TEM further verified the effect of additives on the domain size and was complemented with tomographic reconstructions to provide a 3D representation of the BHJ morphology due to solvent additive processing. Finally, in situ GIWAXS was also performed to investigate the kinetics of crystallite formation during and shortly after spin-casting. The additive was shown to induce a complex structural evolution effect on the microstructure of SPSMs by inciting the formation of a metastable polymorph and enhanced crystalline quality of the SPSM during and shortly after casting, whereas the non-additive treated SPSM structure was static after initial crystallite formation. The results from this study have important implications for future optimization and design of solvent additive processed SPSM BHJ blends for OPV devices.

Maintenance and Intensification of Bivalent Oral Poliovirus Vaccine Use Prior to its Coordinated Global Cessation

PubMed Central

Tebbens, Radboud J Duintjer; Hampton, Lee M; Wassilak, Steven G F; Pallansch, Mark A; Cochi, Stephen L; Thompson, Kimberly M

2017-01-01

Objective To examine the impact of different bivalent oral poliovirus vaccine (bOPV) supplemental immunization activity (SIA) strategies on population immunity to serotype 1 and 3 poliovirus transmission and circulating vaccine-derived poliovirus (cVDPV) risks before and after globally-coordinated cessation of serotype 1 and 3 oral poliovirus vaccine (OPV13 cessation). Methods We adapt mathematical models that previously informed vaccine choices ahead of the trivalent oral poliovirus vaccine to bOPV switch to estimate the population immunity to serotype 1 and 3 poliovirus transmission needed at the time of OPV13 cessation to prevent subsequent cVDPV outbreaks. We then examine the impact of different frequencies of SIAs using bOPV in high risk populations on population immunity to serotype 1 and 3 transmission, on the risk of serotype 1 and 3 cVDPV outbreaks, and on the vulnerability to any imported bOPV-related polioviruses. Results Maintaining high population immunity to serotype 1 and 3 transmission using bOPV SIAs significantly reduces 1) the risk of outbreaks due to imported serotype 1 and 3 viruses, 2) the emergence of indigenous cVDPVs before or after OPV13 cessation, and 3) the vulnerability to bOPV-related polioviruses in the event of non-synchronous OPV13 cessation or inadvertent bOPV use after OPV13 cessation. Conclusion Although some reduction in global SIA frequency can safely occur, countries with suboptimal routine immunization coverage should each continue to conduct at least one annual SIA with bOPV, preferably more, until global OPV13 cessation. Preventing cVDPV risks after OPV13 cessation requires investments in bOPV SIAs now through the time of OPV13 cessation. PMID:28690915

Enhancement in Organic Photovoltaic Efficiency through the Synergistic Interplay of Molecular Donor Hydrogen Bonding and -Stacking

DOE PAGES

Shewmon, Nathan; Watkins, Davita; Galindo, Johan; ...

2015-07-20

For organic photovoltaic (OPV) cells based on the bulk heterojunction (BHJ) structure, it remains challenging to rationally control the degree of phase separation and percolation within blends of donors and acceptors to secure optimal charge separation and transport. Reported is a bottom-up, supramolecular approach to BHJ OPVs wherein tailored hydrogen bonding (H-bonding) interactions between π-conjugated electron donor molecules encourage formation of vertically aligned donor π-stacks while simultaneously suppressing lateral aggregation; the programmed arrangement facilitates fine mixing with fullerene acceptors and efficient charge transport. The approach is illustrated using conventional linear or branched quaterthiophene donor chromophores outfitted with terminal functional groupsmore » that are either capable or incapable of self-complementary H-bonding. When applied to OPVs, the H-bond capable donors yield a twofold enhancement in power conversion efficiency relative to the comparator systems, with a maximum external quantum efficiency of 64%. H-bond promoted assembly results in redshifted absorption (in neat films and donor:C 60 blends) and enhanced charge collection efficiency despite disparate donor chromophore structure. Both features positively impact photocurrent and fill factor in OPV devices. Film structural characterization by atomic force microscopy, transmission electron microscopy, and grazing incidence wide angle X-ray scattering reveals a synergistic interplay of lateral H-bonding interactions and vertical π-stacking for directing the favorable morphology of the BHJ.« less

Paralytic poliomyelitis associated with Sabin monovalent and bivalent oral polio vaccines in Hungary.

PubMed

Estívariz, Concepción F; Molnár, Zsuzsanna; Venczel, Linda; Kapusinszky, Beatrix; Zingeser, James A; Lipskaya, Galina Y; Kew, Olen M; Berencsi, György; Csohán, Agnes

2011-08-01

Historical records of patients with vaccine-associated paralytic poliomyelitis (VAPP) in Hungary during 1961-1981 were reviewed to assess the risk of VAPP after oral polio vaccine (OPV) administration. A confirmed VAPP case was defined as a diagnosis of paralytic poliomyelitis and residual paralysis at 60 days in a patient with an epidemiologic link to the vaccine. Archived poliovirus isolates were retested using polymerase chain reaction and sequencing of the viral protein 1 capsid region. This review confirmed 46 of 47 cases previously reported as VAPP. Three cases originally linked to monovalent OPV (mOPV) 3 and one case linked to mOPV1 presented after administration of bivalent OPV 1 + 3 (bOPV). The adjusted VAPP risk per million doses administered was 0.18 for mOPV1 (2 cases/11.13 million doses), 2.96 for mOPV3 (32 cases/10.81 million doses), and 12.82 for bOPV (5 cases/390,000 doses). Absence of protection from immunization with inactivated poliovirus vaccine or exposure to OPV virus from routine immunization and recent injections could explain the higher relative risk of VAPP in Hungarian children. In polio-endemic areas in which mOPV3 and bOPV are needed to achieve eradication, the higher risk of VAPP would be offset by the high risk of paralysis due to wild poliovirus and higher per-dose efficacy of mOPV3 and bOPV compared with trivalent OPV.

Quantum Mechanical Calculations of Free Energy and Open-Circuit Voltage in Lattice Modeled Organic Photovoltaic Devices

NASA Astrophysics Data System (ADS)

Lankevich, Vladimir; Bittner, Eric

In organic photovoltaic devices (OPVs), initially bound electron and hole can take many different paths to dissociate and become free charge carriers. This leads to the increase in their density of states and therefore increase in the entropy of the system. Accurate description of the energy barriers that charges have to overcome, therefore requires calculation of the free energy. Free energy of an OPV is directly related to its open-circuit voltage and depends only on few important parameters such as average life-time of a charge-transfer state, average energy of the charge-transfer state and energetic disorder in the system. We extend these ideas to the quantum mechanical simulations of the dissociation in the lattice modeled bulk-heterojunction system. We observe average excitonic and free energies that agree with theoretical predictions and the number of experimental results from previous studies. We study effects of the energy disorder and importance of the dimensionality and morphology in materials such as polymer-fullerene blends.

Modeling the dynamics of oral poliovirus vaccine cessation.

PubMed

Thompson, Kimberly M; Duintjer Tebbens, Radboud J

2014-11-01

Oral poliovirus vaccine (OPV) results in an ongoing burden of poliomyelitis due to vaccine-associated paralytic poliomyelitis and circulating vaccine-derived polioviruses (cVDPVs). This motivates globally coordinated OPV cessation after wild poliovirus eradication. We modeled poliovirus transmission and OPV evolution to characterize the interaction between population immunity, OPV-related virus prevalence, and the emergence of cVDPVs after OPV cessation. We explored strategies to prevent and manage cVDPVs for countries that currently use OPV for immunization and characterized cVDPV emergence risks and OPV use for outbreak response. Continued intense supplemental immunization activities until OPV cessation represent the best strategy to prevent cVDPV emergence after OPV cessation in areas with insufficient routine immunization coverage. Policy makers must actively manage population immunity before OPV cessation to prevent cVDPVs and aggressively respond if prevention fails. Sufficiently aggressive response with OPV to interrupt transmission of the cVDPV outbreak virus will lead to die-out of OPV-related viruses used for response in the outbreak population. Further analyses should consider the risk of exportation to other populations of the outbreak virus and any OPV used for outbreak response. OPV cessation can successfully eliminate all circulating live polioviruses in a population. The polio end game requires active risk management. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Bio-Based Transparent Conductive Film Consisting of Polyethylene Furanoate and Silver Nanowires for Flexible Optoelectronic Devices.

PubMed

Lam, Jeun-Yan; Shih, Chien-Chung; Lee, Wen-Ya; Chueh, Chu-Chen; Jang, Guang-Way; Huang, Cheng-Jyun; Tung, Shih-Huang; Chen, Wen-Chang

2018-05-30

Exploiting biomass has raised great interest as an alternative to the fossil resources for environmental protection. In this respect, polyethylene furanoate (PEF), one of the bio-based polyesters, thus reveals a great potential to replace the commonly used polyethylene terephthalate (PET) on account of its better mechanical, gas barrier, and thermal properties. Herein, a bio-based, flexible, conductive film is successfully developed by coupling a PEF plastic substrate with silver nanowires (Ag NWs). Besides the appealing advantage of renewable biomass, PEF also exhibits a good transparency around 90% in the visible wavelength range, and its constituent polar furan moiety is revealed to enable an intense interaction with Ag NWs to largely enhance the adhesion of Ag NWs grown above, as exemplified by the superior bending and peeling durability than the currently prevailing PET substrate. Finally, the efficiency of conductive PEF/Ag NWs film in fabricating efficient flexible organic thin-film transistor and organic photovoltaic (OPV) is demonstrated. The OPV device achieves a power conversion efficiency of 6.7%, which is superior to the device based on ITO/PEN device, manifesting the promising merit of the bio-based PEF for flexible electronic applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recent Advance in Organic Spintronics and Magnetic Field Effect

NASA Astrophysics Data System (ADS)

Valy Vardeny, Z.

2013-03-01

In this talk several important advances in the field of Organic Spintronics and magnetic field effect (MFE) of organic films and optoelectronic devices that have occurred during the past two years from the Utah group will be surveyed and discussed. (i) Organic Spintronics: We demonstrated spin organic light emitting diode (spin-OLED) using two FM injecting electrodes, where the electroluminescence depends on the mutual orientation of the electrode magnetization directions. This development has opened up research studies into organic spin-valves (OSV) in the space-charge limited current regime. (ii) Magnetic field effect: We demonstrated that the photoinduced absorption spectrum in organic films (where current is not involved) show pronounced MFE. This unravels the underlying mechanism of the MFE in organic devices, to be more in agreement with the field of MFE in Biochemistry. (iii) Spin effects in organic optoelectronic devices: We demonstrated that certain spin 1/2 radical additives to donor-acceptor blends substantially enhance the power conversion efficiency of organic photovoltaic (OPV) solar cells. This effect shows that studies of spin response and MFE in OPV devices are promising. In collaboration with T. Nguyen, E. Ehrenfreund, B. Gautam, Y. Zhang and T. Basel. Supported by the DOE grant 04ER46109 ; NSF Grant # DMR-1104495 and MSF-MRSEC program DMR-1121252 [2,3].

Efficient Vacuum-Deposited Ternary Organic Solar Cells with Broad Absorption, Energy Transfer, and Enhanced Hole Mobility.

PubMed

Shim, Hyun-Sub; Moon, Chang-Ki; Kim, Jihun; Wang, Chun-Kai; Sim, Bomi; Lin, Francis; Wong, Ken-Tsung; Seo, Yongsok; Kim, Jang-Joo

2016-01-20

The use of multiple donors in an active layer is an effective way to boost the efficiency of organic solar cells by broadening their absorption window. Here, we report an efficient vacuum-deposited ternary organic photovoltaic (OPV) using two donors, 2-((2-(5-(4-(diphenylamino)phenyl)thieno[3,2-b]thiophen-2-yl)thiazol-5-yl)methylene)malononitrile (DTTz) for visible absorption and 2-((7-(5-(dip-tolylamino)thiophen-2-yl)benzo[c]-[1,2,5]thiadiazol-4-yl)methylene)malononitrile (DTDCTB) for near-infrared absorption, codeposited with C70 in the ternary layer. The ternary device achieved a power conversion efficiency of 8.02%, which is 23% higher than that of binary OPVs. This enhancement is the result of incorporating two donors with complementary absorption covering wavelengths of 350 to 900 nm with higher hole mobility in the ternary layer than that of binary layers consisting of one donor and C70, combined with energy transfer from the donor with lower hole mobility (DTTz) to that with higher mobility (DTDCTB). This structure fulfills all the requirements for efficient ternary OPVs.

Perylene Diimide Based ``Nanofabric'' Thin Films for Organic Photovoltaic Cells

NASA Astrophysics Data System (ADS)

Carter, Austin; Park, June Hyoung; Min, Yong; Epstein, Arthur

2011-03-01

We report progress in using a perylene diimide (PDI) nanofabric as an effective electron accepting nanostructure for organic photovoltaics (OPV). A key challenge in OPV continues to be the recovery of electrons after charge separation due to the relatively poor mobility of C60 and related materials. A series of PDI compounds and complexes have been synthesized and used to fabricate nanofibers and thin films using solution and vacuum deposition techniques. Overlaping PDI-based nanofibers form a fast electron-transporting ``nanofabric'' that has been characterized (AFM, PL, UV-vis, etc.) and can be blended with electron donating materials. A solution-processible OPV configuration containing a nanofabric heterojunction (FHJ) of poly(3-hexylthiophene) and the PDI nanofabric was investigated. We observed a significant improvement in power-conversion efficiency due in part to expansion of the interfacial area and the presence of high mobility electron pathways to the LiF/Al electrode. This work is supported by the Wright Center for Photovoltaic Innovation and Commercialization, the Institute for Materials Research and the Center for Affordable Nanoengineering of Polymeric Biomedical Devices.

Use of a Novel Real-Time PCR Assay To Detect Oral Polio Vaccine Shedding and Reversion in Stool and Sewage Samples after a Mexican National Immunization Day▿

PubMed Central

Troy, Stephanie B.; Ferreyra-Reyes, Leticia; Huang, ChunHong; Mahmud, Nadim; Lee, Yu-Jin; Canizales-Quintero, Sergio; Flaster, Harry; Báez-Saldaña, Renata; García-García, Lourdes; Maldonado, Yvonne

2011-01-01

During replication, oral polio vaccine (OPV) can revert to neurovirulence and cause paralytic poliomyelitis. In individual vaccinees, it can acquire specific revertant point mutations, leading to vaccine-associated paralytic poliomyelitis (VAPP). With longer replication, OPV can mutate into vaccine-derived poliovirus (VDPV), which causes poliomyelitis outbreaks similar to those caused by wild poliovirus. After wild poliovirus eradication, safely phasing out vaccination will likely require global use of inactivated polio vaccine (IPV) until cessation of OPV circulation. Mexico, where children receive routine IPV but where OPV is given biannually during national immunization days (NIDs), provides a natural setting to study the duration of OPV circulation in a population primarily vaccinated with IPV. We developed a real-time PCR assay to detect and distinguish revertant and nonrevertant OPV serotype 1 (OPV-1), OPV-2, and OPV-3 from RNA extracted directly from stool and sewage. Stool samples from 124 children and 8 1-liter sewage samples from Orizaba, Veracruz, Mexico, collected 6 to 13 weeks after a NID were analyzed. Revertant OPV-1 was found in stool at 7 and 9 weeks, and nonrevertant OPV-2 and OPV-3 were found in stool from two children 10 weeks after the NID. Revertant OPV-1 and nonrevertant OPV-2 and -3 were detected in sewage at 6 and 13 weeks after the NID. Our real-time PCR assay was able to detect small amounts of OPV in both stool and sewage and to distinguish nonrevertant and revertant serotypes and demonstrated that OPV continues to circulate at least 13 weeks after a NID in a Mexican population routinely immunized with IPV. PMID:21411577

Photo annealing effect on p-doped inverted organic solar cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lafalce, Evan; Toglia, Patrick; Lewis, Jason E.

2014-06-28

We report the transient positive photo annealing effect in which over 600% boost of power conversion efficiency was observed in inverted organic photovoltaic devices (OPV) made from P3HT/PCBM by spray method, after 2 hrs of constant solar AM 1.5 irradiation at low temperature. This is opposite to usual photodegradation of OPV, and cannot be explained by thermal activation alone since the mere temperature effect could only account for 30% of the enhancement. We have investigated the temperature dependence, cell geometry, oxygen influence, and conclude that, for p-doped active layer at room temperature, the predominant mechanism is photo-desorption of O{sub 2}, whichmore » eliminates electron traps and reduces space charge screening. As temperature decreases, thermal activation and deep trap-state filling start to show noticeable effect on the enhancement of photocurrent at intermediate low temperature (T = 125 K). At very low temperature, the dominant mechanism for photo annealing is trap-filling, which significantly reduces recombination between free and trapped carriers. At all temperature, photo annealing effect depends on illumination direction from cathode or anode. We also explained the large fluctuation of photocurrent by the capture/reemit of trapped electrons from shallow electron traps of O{sub 2}{sup -} generated by photo-doping. Our study has demonstrated the dynamic process of photo-doping and photo-desorption, and shown that photo annealing in vacuum can be an efficient method to improve OPV device efficiency.« less

On the role of local charge carrier mobility in the charge separation mechanism of organic photovoltaics.

PubMed

Yoshikawa, Saya; Saeki, Akinori; Saito, Masahiko; Osaka, Itaru; Seki, Shu

2015-07-21

Although the charge separation (CS) and transport processes that compete with geminate and non-geminate recombination are commonly regarded as the governing factors of organic photovoltaic (OPV) efficiency, the details of the CS mechanism remain largely unexplored. Here we provide a systematic investigation on the role of local charge carrier mobility in bulk heterojunction films of ten different low-bandgap polymers and polythiophene analogues blended with methanofullerene (PCBM). By correlating with the OPV performances, we demonstrated that the local mobility of the blend measured by time-resolved microwave conductivity is more important for the OPV output than those of the pure polymers. Furthermore, the results revealed two separate trends for crystalline and semi-crystalline polymers. This work offers guidance in the design of high-performance organic solar cells.

Copper Mesh Templated by Breath-Figure Polymer Films as Flexible Transparent Electrodes for Organic Photovoltaic Devices.

PubMed

Zhou, Weixin; Chen, Jun; Li, Yi; Wang, Danbei; Chen, Jianyu; Feng, Xiaomiao; Huang, Zhendong; Liu, Ruiqing; Lin, Xiujing; Zhang, Hongmei; Mi, Baoxiu; Ma, Yanwen

2016-05-04

Metal mesh is a significant candidate of flexible transparent electrodes to substitute the current state-of-the-art material indium tin oxide (ITO) for future flexible electronics. However, there remains a challenge to fabricate metal mesh with order patterns by a bottom-up approach. In this work, high-quality Cu mesh transparent electrodes with ordered pore arrays are prepared by using breath-figure polymer films as template. The optimal Cu mesh films present a sheet resistance of 28.7 Ω·sq(-1) at a transparency of 83.5%. The work function of Cu mesh electrode is tuned from 4.6 to 5.1 eV by Ag deposition and the following short-time UV-ozone treatment, matching well with the PSS (5.2 eV) hole extraction layer. The modified Cu mesh electrodes show remarkable potential as a substitute of ITO/PET in the flexible OPV and OLED devices. The OPV cells constructed on our Cu mesh electrodes present a similar power conversion efficiency of 2.04% as those on ITO/PET electrodes. The flexible OLED prototype devices can achieve a brightness of 10 000 cd at an operation voltage of 8 V.

Doped Interlayers for Improved Selectivity in Bulk Herterojunction Organic Photovoltaic Devices

DOE PAGES

Mauger, Scott A.; Glasser, Melodie P.; Tremolet de Villers, Bertrand J.; ...

2016-01-21

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is less selective for holes in inverted-architecture organic photovoltaic (OPV) than it is in a conventional-architecture OPV device due differences between the interfacial-PSS concentration at the top and bottom of the PEDOT:PSS layer. In this work, thin layers of polysulfonic acids are inserted between the P3HT:ICBA bulk heterojunction (BHJ) active layer and PEDOT:PSS to create a higher concentration of acid at this interface and, therefore, mimic the distribution of materials present in a conventional device. Upon thermal annealing, this acid layer oxidizes P3HT, creating a thin p-type interlayer of P3HT+/acid- on top of the BHJ. Using x-raymore » absorption spectroscopy, Kelvin probe and ellipsometry measurements, this P3HT+/acid- layer is shown to be insoluble in water, indicating it remains intact during the subsequent deposition of PEDOT:PSS. Current density - voltage measurements show this doped interlayer reduces injected dark current while increasing both open-circuit voltage and fill factor through the creation of a more hole selective BHJ-PEDOT:PSS interface.« less

Molecular Structure Controlled Transitions between Free-Charge Generation and Trap Formation in a Conjugated Copolymer Series

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pandit, Bill; Jackson, Nicholas E.; Zheng, Tianyue

2016-03-03

Charge transfer copolymers, where each repeating unit has at least one “donor” and one “acceptor” block, have played important roles in recent advances in organic photovoltaic (OPV) devices, however design criteria for these materials are still not completely clear. Here we show that the well-recognized LUMO-LUMO energy off-set design criterion for OPV materials using a fullerene acceptor is challenged in a series of copolymers, PTRn (n = 3, 5, 7 and 9), where n is the number of fused aromatic rings in the “donor” block and thienothiophene is the “acceptor” block in each repeating unit. Photoexcitation dynamics of PTRn copolymersmore » in solution and BHJ (bulk heterojunction) films demonstrated that local push-pull interactions between the “donor” block and the “acceptor” block weakens with increasing n, whereas the LUMO-LUMO off-set between the polymer and PC71BM (Phenyl-C71-butyric acid methyl ester) increases. Such a counter intuitive trend can be explained by local energetics of each repeating unit as a function of n. The energetic changes transform the copolymer with strong local charge transfer character for efficient hole-electron separation to localized hole-electron pairs with low mobility, despite the apparent increase of the polymer/PC71BM LUMO-LUMO off-set. This suggests the importance of local charge transfer character in these copolymers in the initial exciton splitting dynamics, which could ultimately be reflected in the device performance.« less

Achieving high seroprevalence against polioviruses in Sri Lanka--results from a serological survey, 2014.

PubMed

Gamage, Deepa; Palihawadana, Paba; Mach, Ondrej; Weldon, William C; Oberste, Steven M; Sutter, Roland W

2015-12-01

The immunization program in Sri Lanka consistently reaches >90% coverage with oral poliovirus vaccines (OPV), and no polio supplementary vaccination campaigns have been conducted since 2003. We evaluated serological protection against polioviruses in children. A cross-sectional community-based survey was performed in three districts of Sri Lanka (Colombo, Badulla, and Killinochi). Randomly selected children in four age groups (9-11 months, 3-4 years, 7-9 years, and 15 years) were tested for poliovirus neutralizing antibodies. All 400 enrolled children completed the study. The proportion of seropositive children for poliovirus Type 1 and Type 2 was >95% for all age groups; for poliovirus Type 3 it was 95%, 90%, 77%, and 75% in the respective age groups. The vaccination coverage in our sample based on vaccination cards or parental recall was >90% in all age groups. Most Sri Lankan children are serologically protected against polioviruses through routine immunization only. This seroprevalence survey provided baseline data prior to the anticipated addition of inactivated poliovirus vaccine (IPV) into the Sri Lankan immunization program and the switch from trivalent OPV (tOPV) to bivalent OPV (bOPV). Copyright © 2015 Ministry of Health, Saudi Arabia. Published by Elsevier Ltd. All rights reserved.

Immunity status of adults and children against poliomyelitis virus type 1 strains CHAT and Sabin (LSc-2ab) in Germany.

PubMed

Eggers, Maren; Terletskaia-Ladwig, Elena; Rabenau, Holger F; Doerr, Hans W; Diedrich, Sabine; Enders, Gisela; Enders, Martin

2010-12-09

In October 2007, the working group CEN/TC 216 of the European Committee for standardisation suggested that the Sabin oral poliovirus vaccine type 1 strain (LSc-2ab) presently used for virucidal tests should be replaced by another attenuated vaccine poliovirus type 1 strain, CHAT. Both strains were historically used as oral vaccines, but the Sabin type 1 strain was acknowledged to be more attenuated. In Germany, vaccination against poliomyelitis was introduced in 1962 using the oral polio vaccine (OPV) containing Sabin strain LSc-2ab. The vaccination schedule was changed from OPV to an inactivated polio vaccine (IPV) containing wild polio virus type 1 strain Mahoney in 1998. In the present study, we assessed potential differences in neutralising antibody titres to Sabin and CHAT in persons with a history of either OPV, IPV, or OPV with IPV booster. Neutralisation poliovirus antibodies against CHAT and Sabin 1 were measured in sera of 41 adults vaccinated with OPV. Additionally, sera from 28 children less than 10 years of age and immunised with IPV only were analysed. The neutralisation assay against poliovirus was performed according to WHO guidelines. The neutralisation activity against CHAT in adults with OPV vaccination history was significantly lower than against Sabin poliovirus type 1 strains (Wilcoxon signed-rank test P < 0.025). In eight sera, the antibody titres measured against CHAT were less than 8, although the titre against Sabin 1 varied between 8 and 64. Following IPV booster, anti-CHAT antibodies increased rapidly in sera of CHAT-negative adults with OPV history. Sera from children with IPV history neutralised CHAT and Sabin 1 strains equally. The lack of neutralising antibodies against the CHAT strain in persons vaccinated with OPV might be associated with an increased risk of reinfection with the CHAT polio virus type 1, and this implies a putative risk of transmission of the virus to polio-free communities. We strongly suggest that laboratory workers who were immunised with OPV receive a booster vaccination with IPV before handling CHAT in the laboratory.

Considerations for the Full Global Withdrawal of Oral Polio Vaccine After Eradication of Polio.

PubMed

Hampton, Lee M; du Châtellier, Gaël Maufras; Fournier-Caruana, Jacqueline; Ottosen, Ann; Rubin, Jennifer; Menning, Lisa; Farrell, Margaret; Shendale, Stephanie; Patel, Manish

2017-07-01

Eliminating the risk of polio from vaccine-derived polioviruses is essential for creating a polio-free world, and eliminating that risk will require stopping use of all oral polio vaccines (OPVs) once all types of wild polioviruses have been eradicated. In many ways, the experience with the global switch from trivalent OPV (tOPV) to bivalent OPV (bOPV) can inform the eventual full global withdrawal of OPV. Significant preparation will be needed for a thorough, synchronized, and full withdrawal of OPV, and such preparation would be aided by setting a reasonably firm date for OPV withdrawal as far in advance as possible, ideally at least 24 months. A shorter lead time would provide valuable flexibility for decisions about when to stop use of OPV in the context of uncertainty about whether or not all types of wild polioviruses had been eradicated, but it might increase the cost of OPV withdrawal. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Disposing of Excess Vaccines After the Withdrawal of Oral Polio Vaccine

PubMed Central

Ramirez Gonzalez, Alejandro; Dolan, Samantha B.; Garon, Julie; Veira, Chantal Laroche; Hampton, Lee M.; Chang Blanc, Diana; Patel, Manish M.

2017-01-01

Abstract Until recently, waste management for national immunization programs was limited to sharps waste, empty vaccine vials, or vaccines that had expired or were no longer usable. However, because wild-type 2 poliovirus has been eradicated, the World Health Organization’s (WHO’s) Strategic Advisory Group of Experts on Immunization deemed that all countries must simultaneously cease use of the type 2 oral polio vaccine and recommended that all countries and territories using oral polio vaccine (OPV) “switch” from trivalent OPV (tOPV; types 1, 2, and 3 polioviruses) to bivalent OPV (bOPV; types 1 and 3 polioviruses) during a 2-week period in April 2016. Use of tOPV after the switch would risk outbreaks of paralysis related to type 2–circulating vaccine-derived poliovirus (cVDPV2). To minimize risk of vaccine-derived polio countries using OPV were asked to dispose of all usable, unexpired tOPV after the switch to bOPV. In this paper, we review the rationale for tOPV disposal and describe the global guidelines provided to countries for the safe and appropriate disposal of tOPV. These guidelines gave countries flexibility in implementing this important task within the confines of their national regulations, capacities, and resources. Steps for appropriate disposal of tOPV included removal of all tOPV vials from the cold chain, placement in appropriate bags or containers, and disposal using a recommended approach (ie, autoclaving, boiling, chemical inactivation, incineration, or encapsulation) followed by burial or transportation to a designated waste facility. This experience with disposal of tOPV highlights the adaptability of national immunization programs to new procedures, and identifies gaps in waste management policies and strategies with regard to disposal of unused vaccines. The experience also provides a framework for future policies and for developing programmatic guidance for the ultimate disposal of all OPV after the eradication of polio. PMID:28838168

New Insights into the Molecular Dynamics of P3HT:PCBM Bulk Heterojunction: A Time-of-Flight Quasi-Elastic Neutron Scattering Study.

PubMed

Guilbert, Anne A Y; Zbiri, Mohamed; Jenart, Maud V C; Nielsen, Christian B; Nelson, Jenny

2016-06-16

The molecular dynamics of organic semiconductor blend layers are likely to affect the optoelectronic properties and the performance of devices such as solar cells. We study the dynamics (5-50 ps) of the poly(3-hexylthiophene) (P3HT): phenyl-C61-butyric acid methyl ester (PCBM) blend by time-of-flight quasi-elastic neutron scattering, at temperatures in the range 250-360 K, thus spanning the glass transition temperature region of the polymer and the operation temperature of an OPV device. The behavior of the QENS signal provides evidence for the vitrification of P3HT upon blending, especially above the glass transition temperature, and the plasticization of PCBM by P3HT, both dynamics occurring on the picosecond time scale.

Tuning domain size and crystallinity in isoindigo/PCBM organic solar cells via solution shearing

DOE PAGES

Gu, Kevin L.; Zhou, Yan; Gu, Xiaodan; ...

2016-11-01

Despite having achieved the long sought-after performance of 10% power conversion efficiency, high performance organic photovoltaics (OPVs) are still mostly constrained to lab scale devices fabricated by spin coating. Efforts to produce printed OPVs lag considerably behind, and the sensitivity to different fabrication methods highlights the need to develop a comprehensive understanding of the processing-morphology relationship in printing methods. Here we present a systematic experimental investigation of a model low bandgap polymer/fullerene system, poly-isoindigo thienothiophene/PC 61BM, using a lab-scale analogue to roll-to-roll coating as the fabrication tool in order to understand the impact of processing parameters on morphological evolution. Wemore » report that domain size and polymer crystallinity can be tuned by a factor of two by controlling the temperature and coating speed. Lower fabrication temperature simultaneously decreased the phase separation domain size and increased the relative degree of crystallinity in those domains, leading to improved photocurrent. We conclude that domain size in isoindigo/PCBM is dictated by spontaneous phase separation rather than crystal nucleation and growth. Moreover we present a model to describe the temperature dependence of domain size formation in our system, which demonstrates that morphology is not necessarily strictly dependent on the evaporation rate, but rather on the interplay between evaporation and diffusion during the printing process.« less

Excitons and the lifetime of organic semiconductor devices.

PubMed

Forrest, Stephen R

2015-06-28

While excitons are responsible for the many beneficial optical properties of organic semiconductors, their non-radiative recombination within the material can result in material degradation due to the dumping of energy onto localized molecular bonds. This presents a challenge in developing strategies to exploit the benefits of excitons without negatively impacting the device operational stability. Here, we will briefly review the fundamental mechanisms leading to excitonic energy-driven device ageing in two example devices: blue emitting electrophosphorescent organic light emitting devices (PHOLEDs) and organic photovoltaic (OPV) cells. We describe strategies used to minimize or even eliminate this fundamental device degradation pathway. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Novel hole transport materials for organic light emitting devices

NASA Astrophysics Data System (ADS)

Shi, Jianmin; Forsythe, Eric; Morton, David

2008-08-01

Organic electronic devices generally have a layered structure with organic materials sandwiched between an anode and a cathode, such organic electronic devices of organic light-emitting diode (OLED), organic photovoltaic (OPV), organic thin-film transistor (OTFT). There are many advantages of these organic electronic devices as compared to silicon-based devices. However, one of key challenge for an organic electronic device is to minimize the charge injection barrier from electrodes to organic materials and improve the charge transport mobility. In order to overcome these circumstances, there are many approaches including, designing organic materials with minimum energy barriers and improving charge transport mobility. Ideally organic materials or complex with Ohmic contact will be the most desired.

Counterbalancing of morphology and conductivity of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate based flexible devices.

PubMed

Jang, Woongsik; Ahn, Sunyong; Park, Soyun; Park, Jong Hyeok; Wang, Dong Hwan

2016-12-01

The importance of conductive polymer electrodes with a balance between the morphology and electrical conductivity for flexible organic photovoltaic properties has been demonstrated. Highly transparent PEDOT:PSS anodes with controlled conductivity and surface properties were realized by insertion of dimethyl sulfoxide (DMSO) and a fluorosurfactant (Zonyl) as efficient additives and used for flexible organic photovoltaic cells (OPVs) which are based on a bulk-heterojunction of polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7):[6,6]phenyl-C 71 -butyric acid methyl ester (PC 71 BM). We investigated the correlation between the electrical properties of PEDOT:PSS electrodes and their influences on the surface morphology of the active materials (PTB7:PC 71 BM). When the device was prepared from the PEDOT:PSS layer functioning as an anode of OPV through an optimized ratio of 5 vol% of DMSO and 0.1 wt% of fluorosurfactant, the devices exhibited improved fill factor (FF) due to the enhanced coverage of PEDOT:PSS films. These results correlate with reduced photoluminescence and increased charge extraction as seen through Raman spectroscopy and electrical analysis, respectively. The conductive polymer electrode with the balance between the morphology and electrical conductivity can be a useful replacement for brittle electrodes such as those made of indium tin oxide (ITO) as they are more resistant to cracking and bending conditions, which will contribute to the long-term operation of flexible devices.

Improved performance of organic solar cells with solution processed hole transport layer

NASA Astrophysics Data System (ADS)

Bhargav, Ranoo; Gairola, S. P.; Patra, Asit; Naqvi, Samya; Dhawan, S. K.

2018-06-01

This work is based on Cobalt Oxide as solution processed, inexpensive and effective hole transport layer (HTL) for efficient organic photovoltaic applications (OPVs). In Organic solar cell (OSC) devices ITO coated glass substrate used as a transparent anode electrode for light incident, HTL material Co3O4 dissolve in DMF solvent deposited on anode electrode, after that active layer material (donor/acceptor) deposited on to HTL and finally Al were deposited by thermal evaporation used as cathode electrode. These devices were fabricated with PCDTBT well known low band gap donor material in OSCs and blended with PC71BM as an acceptor material using simplest device structure ITO/Co3O4/active layer/Al at ambient conditions. The power conversion efficiencies (PCEs) based on Co3O4 and PEDOT:PSS have been achieved to up to 3.21% and 1.47% with PCDTBT respectively. In this study we reported that the devices fabricated with Co3O4 showed better performance as compare to the devices fabricated with well known and most studied solution processed HTL material PEDOT:PSS under identical environmental conditions. The surface morphology of the HTL film was characterized by (AFM). Lastly, we have provided Co3O4 as an efficient hole transport material HTL for solution processed organic photovoltaic applications.

Implementing the Synchronized Global Switch from Trivalent to Bivalent Oral Polio Vaccines-Lessons Learned From the Global Perspective.

PubMed

Ramirez Gonzalez, Alejandro; Farrell, Margaret; Menning, Lisa; Garon, Julie; Everts, Hans; Hampton, Lee M; Dolan, Samantha B; Shendale, Stephanie; Wanyoike, Sarah; Veira, Chantal Laroche; Châtellier, Gaël Maufras du; Kurji, Feyrouz; Rubin, Jennifer; Boualam, Liliane; Chang Blanc, Diana; Patel, Manish

2017-07-01

In 2015, the Global Commission for the Certification of Polio Eradication certified the eradication of type 2 wild poliovirus, 1 of 3 wild poliovirus serotypes causing paralytic polio since the beginning of recorded history. This milestone was one of the key criteria prompting the Global Polio Eradication Initiative to begin withdrawal of oral polio vaccines (OPV), beginning with the type 2 component (OPV2), through a globally synchronized initiative in April and May 2016 that called for all OPV using countries and territories to simultaneously switch from use of trivalent OPV (tOPV; containing types 1, 2, and 3 poliovirus) to bivalent OPV (bOPV; containing types 1 and 3 poliovirus), thus withdrawing OPV2. Before the switch, immunization programs globally had been using approximately 2 billion tOPV doses per year to immunize hundreds of millions of children. Thus, the globally synchronized withdrawal of tOPV was an unprecedented achievement in immunization and was part of a crucial strategy for containment of polioviruses. Successful implementation of the switch called for intense global coordination during 2015-2016 on an unprecedented scale among global public health technical agencies and donors, vaccine manufacturers, regulatory agencies, World Health Organization (WHO) and United Nations Children's Fund (UNICEF) regional offices, and national governments. Priority activities included cessation of tOPV production and shipment, national inventories of tOPV, detailed forecasting of tOPV needs, bOPV licensing, scaling up of bOPV production and procurement, developing national operational switch plans, securing funding, establishing oversight and implementation committees and teams, training logisticians and health workers, fostering advocacy and communications, establishing monitoring and validation structures, and implementing waste management strategies. The WHO received confirmation that, by mid May 2016, all 155 countries and territories that had used OPV in 2015 had successfully withdrawn OPV2 by ceasing use of tOPV in their national immunization programs. This article provides an overview of the global efforts and challenges in successfully implementing this unprecedented global initiative, including (1) coordination and tracking of key global planning milestones, (2) guidance facilitating development of country specific plans, (3) challenges for planning and implementing the switch at the global level, and (4) best practices and lessons learned in meeting aggressive switch timelines. Lessons from this monumental public health achievement by countries and partners will likely be drawn upon when bOPV is withdrawn after polio eradication but also could be relevant for other global health initiatives with similarly complex mandates and accelerated timelines. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Supramolecular liquid crystalline π-conjugates: the role of aromatic π-stacking and van der Waals forces on the molecular self-assembly of oligophenylenevinylenes.

PubMed

Goel, Mahima; Jayakannan, M

2010-10-07

Here, we report a unique design strategy to trace the role of aromatic π-stacking and van der Waals interactions on the molecular self-organization of π-conjugated building blocks in a single system. A new series of bulky oligophenylenevinylenes (OPVs) bearing a tricyclodecanemethylene (TCD) unit in the aromatic π-core with flexible long methylene chains (n = 0-12 and 16) in the longitudinal position were designed and synthesized. The OPVs were found to be liquid crystalline, and their enthalpies of phase transitions (also entropies) showed odd-even oscillation with respect to the number of carbon atoms in alkyl chains. OPVs with an even number of methylene units in the side chains showed higher enthalpies with respect to their highly packed solid structures compared to odd-numbered ones. Polarized light microscopic analysis confirmed the formation of cholesteric liquid crystalline (LC) phases of fan shaped textures with focal conics in OPVs with 5 ≤ n ≤ 9. OPVs with longer alkyl chains (OPV-10 to OPV-12) produced a birefringence pattern consisting of dark and bright ring-banded suprastructures. The melting temperature followed a sigmoidal trend, indicating the transformation of molecular self-organization in OPVs from solid to ring-banded suprastructures via cholesteric LC intermediates. At longer alkyl chain lengths, the van der Waals interactions among the alkyl chains became predominant and translated the mesogenic effect across the lamellae; as a consequence, the lamellae underwent twisted self-organization along the radial growth direction of the spherulites to produce bright and dark bands. Scanning electron microscope (SEM) analysis of cholesteric LC and ring-banded textures strongly supported the existence of twisted lamellae in the OPVs with ring-banded textures. Variable temperature X-ray diffraction analysis confirmed the reversibility of the molecular self-organization in the solid state and also showed the existence of the higher ordered lamellar structure in ring-banded OPVs. Photophysical characterizations such as excitation, emission, and time resolved fluorescence decay measurements were employed to trace molecular self-organization in their liquid crystalline phases. The emission spectra of the OPV samples showed odd-even oscillation in their emission wavelengths with respect to the length of alkyl chains. Highly packed even-OPVs showed more blue shift compared to that of less crystalline odd-OPVs. Time dependent fluorescence decay of OPVs followed a biexponential fit, and their lifetimes (τ(1) and τ(2) values) revealed that the decay is faster for odd-OPVs compared to even-OPVs. Among all the OPVs, the τ(2) values for OPV-8 and OPV-12 were found to be much higher, indicating their high luminescent characteristics. In a nut shell, bulky liquid crystalline OPV chromophores were cleverly utilized, for the first time, to probe the aromatic π-stacking versus van der Waals interactions on the molecular self-organization of π-conjugated system.

Computational assessment of organic photovoltaic candidate compounds

NASA Astrophysics Data System (ADS)

Borunda, Mario; Dai, Shuo; Olivares-Amaya, Roberto; Amador-Bedolla, Carlos; Aspuru-Guzik, Alan

2015-03-01

Organic photovoltaic (OPV) cells are emerging as a possible renewable alternative to petroleum based resources and are needed to meet our growing demand for energy. Although not as efficient as silicon based cells, OPV cells have as an advantage that their manufacturing cost is potentially lower. The Harvard Clean Energy Project, using a cheminformatic approach of pattern recognition and machine learning strategies, has ranked a molecular library of more than 2.6 million candidate compounds based on their performance as possible OPV materials. Here, we present a ranking of the top 1000 molecules for use as photovoltaic materials based on their optical absorption properties obtained via time-dependent density functional theory. This computational search has revealed the molecular motifs shared by the set of most promising molecules.

Effect of passively transferred anti-poliovirus antibodies on seroconversion.

PubMed

Bavdekar, S B; Naik, S; Nadkarni, S S; Kamat, J R; Deshpande, J M; Vaswani, L K

1999-01-01

A prospective study enrolling 50 mother-infant pairs was undertaken to determine the effect of maternal antibodies on poliovirus antibody titres and seroconversion rates in infants and to determine the difference in titres and seroconversion rates following three and five doses of oral poliovaccine (OPV). Cord blood samples and samples collected 4 weeks after 3rd and 5th doses of trivalent oral poliovaccine were processed for estimation of anti-poliovirus antibody titres. These were expressed as geometric mean titres (GMT). Significance was analyzed using unpaired 't' test. The relationship between maternal antibody titres and seroconversion was determined by correlation coefficient test. Post OPV5 titres were significantly higher than post OPV3 titres for type 1 and type 2 polioviruses. Seroconversion rates against type 1, 2 and 3 polioviruses were 92.9%, 100.0% and 92.9% following OPV3 and 100.0%, 100.0% and 93.2% following OPV5. The cord blood titres did not have any relation to post-OPV3 or post-OPV5 titres. Although there is significant passive transfer of poliovirus antibodies across the placenta, this does not affect titres achieved after immunization. Post-OPV5 titres against type 1 and type 2 viruses are significantly higher than post-OPV3 titres. The seroconversion rates following OPV5 are higher than those obtained post-OPV3 but this difference is not statistically significant.

Determinants of monovalent oral polio vaccine mutagenesis in vaccinated elderly people.

PubMed

Boot, Hein J; Sonsma, Jan; van Nunen, Femke; Abbink, Frithjofna; Kimman, Tjeerd G; Buisman, Anne-Marie

2007-06-11

Live oral poliovirus vaccine (OPV) strains can mutate and recombine during replication in the host. Trivalent OPV has long been used to restrain wild-type poliovirus in developing countries. However, recently WHO advocates using monovalent OPV (mOPV) to finally eradicate poliovirus world-wide. We analysed polioviruses recovered from the faeces of 101 elderly patients (divided into three groups by immune status) challenged with mOPV-1 or mOPV-3. A high number of nucleotide mutations was found in the viral capsid-protein-encoding regions. Some of these mutations caused amino acid changes in or near regions with neutralizing epitopes, especially in mOPV-1-derived strains. The quantities of mutations in recovered poliovirus strains correlated with prevaccination immune status (seronegatives have more mutations) and excretion duration. Duration of excretion appears to be the dominant factor for the accumulation of mutations in mOPV-derived strains in vaccinated elderly people.

Polio endgame: the global introduction of inactivated polio vaccine.

PubMed

Patel, Manish; Zipursky, Simona; Orenstein, Walt; Garon, Julie; Zaffran, Michel

2015-05-01

In 2013, the World Health Assembly endorsed a plan that calls for the ultimate withdrawal of oral polio vaccines (OPV) from all immunization programs globally. The withdrawal would begin in a phased manner with removal of the type 2 component of OPV in 2016 through a global switch from trivalent OPV to bivalent OPV (containing only types 1 and 3). To mitigate risks associated with immunity gaps after OPV type 2 withdrawal, the WHO Strategic Advisory Group of Experts has recommended that all 126 OPV-only using countries introduce at least one dose of inactivated polio vaccine into routine immunization programs by end-2015, before the trivalent OPV-bivalent OPV switch. The introduction of inactivated polio vaccine would reduce risks of reintroduction of type 2 poliovirus by providing some level of seroprotection, facilitating interruption of transmission if outbreaks occur, and accelerating eradication by boosting immunity to types 1 and 3 polioviruses.

Technical Note: Nanometric organic photovoltaic thin film detectors for dose monitoring in diagnostic x-ray imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elshahat, Bassem; Gill, Hardeep Singh; Kumar, Jayant

2015-07-15

Purpose: To fabricate organic photovoltaic (OPV) cells with nanometric active layers sensitive to ionizing radiation and measure their dosimetric characteristics in clinical x-ray beams in the diagnostic tube potential range of 60–150 kVp. Methods: Experiments were designed to optimize the detector’s x-ray response and find the best parameter combination by changing the active layer thickness and the area of the electrode. The OPV cell consisted of poly (3-hexylthiophene-2,5-diyl): [6,6]-phenyl C{sub 61} butyric acid methyl ester photoactive donor and acceptor semiconducting organic materials sandwiched between an aluminum electrode as an anode and an indium tin oxide electrode as a cathode. Themore » authors measured the radiation-induced electric current at zero bias voltage in all fabricated OPV cells. Results: The net OPV current as a function of beam potential (kVp) was proportional to kVp{sup −0.5} when normalized to x-ray tube output, which varies with kVp. Of the tested configurations, the best combination of parameters was 270 nm active layer thicknesses with 0.7 cm{sup 2} electrode area, which provided the highest signal per electrode area. For this cell, the measured current ranged from approximately 0.7 to 2.4 nA/cm{sup 2} for 60–150 kVp, corresponding to about 0.09 nA–0.06 nA/mGy air kerma, respectively. When compared to commercial amorphous silicon thin film photovoltaic cells irradiated under the same conditions, this represents 2.5 times greater sensitivity. An additional 40% signal enhancement was observed when a 1 mm layer of plastic scintillator was attached to the cells’ beam-facing side. Conclusions: Since both OPVs can be produced as flexible devices and they do not require external bias voltage, they open the possibility for use as thin film in vivo detectors for dose monitoring in diagnostic x-ray imaging.« less

Improving Device Efficiencies in Organic Photovoltaics through the Manipulation of Device Architectures and the Development of Low-Bandgap Materials

NASA Astrophysics Data System (ADS)

Rice, Andrew Hideo

Over the past two decades, vast amounts of research have been conducted in the pursuit of suitable organic semiconductors to replace inorganic materials in electronic applications due to their advantages of being lightweight, flexible, and solution-processible. However, before organic photovoltaics (OPVs) can be truly competitive and commercially viable, their efficiencies must be improved significantly. In this examination, we pursue higher efficiency OPVs in two different ways. Our attempts focus on 1) altering the microstructure of devices to improve charge dissociation, charge transport, and our understanding of how these devices function, and 2) tailoring materials to achieve optimal band gaps and energy levels for use in organic electronics. First, we demonstrate how the vertical morphology of bulk heterojunction (BHJ) solar cells, with an active layer consisting of self-assembled poly(3-hexylthiophene) (P3HT) nanowires and (6,6)-phenyl C61-butyric acid methyl ester (PCBM), can be beneficially influenced. Most device fabrication routes using similar materials employ an annealing step to influence active layer morphology, but this process can create an unfavorable phase migration where P3HT is driven toward the cathode. In contrast, we demonstrate devices that exhibit an increase in relative fullerene concentration at the top of the active layer by introducing the donor phase as a solid nanowire in the active layer solution and altering the pre-spin drying time. X-ray photoelectron spectroscopy (XPS) and conductive and photoconductive atomic force microscopy (cAFM and pcAFM) provide detailed information about how the surface of the active layer can be influenced; this is done by tracking the concentration and alignment of P3HT and PCBM domains. Using this new procedure, devices are made with power conversion efficiencies surpassing 2%. Additionally, we show that nanowires grown in the presence of the fullerene perform differently than those that are grown and mixed separately; exposure to the nanowire during self-assembly may allow the fullerene to coat nanowire surfaces and influence the photocurrent within the device. Furthermore, because we are able to carefully control the regioregularity of our P3HT, we are able to produce a series of nanowires with regioregularities ranging between 93% and 99%. X-ray diffraction (XRD) shows that as the regioregularity of the polymer increases, the coherent domain size along the long-axis of the nanowires also becomes larger. When organic field effect transistors (OFETs) are made from these materials, the hole mobility of the nanowire films also has a positive correlation with regioregularity. As the domains within the nanowires grow larger, the frequency of domain boundaries decreases, allowing charges to percolate more efficiently along the nanowire. Additionally, we show that by introducing C60 into the active layer of P3HT:PCBM devices, we can modulate the crystal habit of the PCBM domains. Using optical microscopy and UV-vis absorption spectroscopy, we demonstrate that C60 additions alter the crystal morphology and greatly reduce the size of fullerene crystallites that are observed after extended annealing times and under aggressive aging conditions. We also show by fabricating organic field-effect transistors (OFETs) from PCBM:C60 blends that the incorporation of C60 does not adversely affect the electron mobility in these films. Finally, we show that as C60 is incorporated into P3HT:PCBM OPVs, devices become more thermally stable and do not degrade in performance as rapidly as traditional P3HT:PCBM blends. Lastly, the synthesis of four alternating copolymers using benzo[2,1- b;3,4-b']dithiophene (BDP) as the common donor unit is presented. Incorporating BDP, which consists of fused dithiophene units with a benzene ring, into these polymers should produce a low-lying highest occupied molecular orbital (HOMO) energy level. Low-lying HOMO levels are desirable to produce high open circuit voltages (V OC) in organic BHJ photovoltaic devices. The preliminary results of their performance in solar cells, using PCBM as the electron acceptor, is presented. The VOC values follow the expected trend: increasing with decreasing HOMO level of the polymer. High VOC values of 0.81 and 0.82 V have been obtained from two polymers: PBDPBT and PBDPDPP. The highest initial power conversion efficiency (PCE) achieved in these unoptimized devices was 1.11% due to relatively low JSC values. The variation observed in the J SC values between the four polymers is discussed. Device performance is expected to increase with optimization of processing conditions for the devices.

Kinetics of Poliovirus Shedding following Oral Vaccination as Measured by Quantitative Reverse Transcription-PCR versus Culture

PubMed Central

Begum, Sharmin; Uddin, Md Jashim; Platts-Mills, James A.; Liu, Jie; Kirkpatrick, Beth D.; Chowdhury, Anwarul H.; Jamil, Khondoker M.; Haque, Rashidul; Petri, William A.; Houpt, Eric R.

2014-01-01

Amid polio eradication efforts, detection of oral polio vaccine (OPV) virus in stool samples can provide information about rates of mucosal immunity and allow estimation of the poliovirus reservoir. We developed a multiplex one-step quantitative reverse transcription-PCR (qRT-PCR) assay for detection of OPV Sabin strains 1, 2, and 3 directly in stool samples with an external control to normalize samples for viral quantity and compared its performance with that of viral culture. We applied the assay to samples from infants in Dhaka, Bangladesh, after the administration of trivalent OPV (tOPV) at weeks 14 and 52 of life (on days 0 [pre-OPV], +4, +11, +18, and +25 relative to vaccination). When 1,350 stool samples were tested, the sensitivity and specificity of the quantitative PCR (qPCR) assay were 89 and 91% compared with culture. A quantitative relationship between culture+/qPCR+ and culture−/qPCR+ stool samples was observed. The kinetics of shedding revealed by qPCR and culture were similar. qPCR quantitative cutoffs based on the day +11 or +18 stool samples could be used to identify the culture-positive shedders, as well as the long-duration or high-frequency shedders. Interestingly, qPCR revealed that a small minority (7%) of infants contributed the vast majority (93 to 100%) of the total estimated viral excretion across all subtypes at each time point. This qPCR assay for OPV can simply and quantitatively detect all three Sabin strains directly in stool samples to approximate shedding both qualitatively and quantitatively. PMID:25378579

Buta-1,3-diyne-Based π-Conjugated Polymers for Organic Transistors and Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eckstein, Brian J.; Melkonyan, Ferdinand S.; Zhou, Nanjia

We report the synthesis and characterization of new alkyl-substituted 1,4-di(thiophen-2-yl)buta-1,3-diyne (R-DTB) donor building blocks, based on the -C≡C-C≡C- conjugative pathway, and their incorporation with thienyl-diketopyrrolopyrrole (R'-TDPP) acceptor units into π-conjugated PTDPP-DTB polymers (P1-P4). The solubility of the new polymers strongly depends on the DTB and DPP solubilizing (R and R', respectively) substituents. Thus, solution processable and high molecular weight PDPP-DTB polymers are achieved for P3 (R = n-C12H25, R' = 2- butyloctyl) and P4 (R = 2-ethylhexyl, R' = 2-butyloctyl). Systematic studies of P3 and P4 physicochemical properties are carried using optical spectroscopy, cyclic voltammetry, and thermal analysis, revealing characteristicmore » features of the dialkynyl motif. For the first time, optoelectronic devices (OFETs, OPVs) are fabricated with 1,3-butadiyne containing organic semiconductors. OFET hole mobilities and record OPV power conversion efficiencies for acetylenic organic materials approach 0.1 cm2/(V s) and 4%, respectively, which can be understood from detailed thin-film morphology and microstructural characterization using AFM, TEM, XRD, and GIWAXS methodologies. Importantly, DTB-based polymers (P3 and P4) exhibit, in addition to stabilization of frontier molecular orbitals and to -C≡C-C≡C- relief of steric torsions, discrete morphological pliability through thermal annealing and processing additives. The advantageous materials properties and preliminary device performance reported here demonstrate the promise of 1,3-butadiyne-based semiconducting polymers.« less

Interference of Monovalent, Bivalent, and Trivalent Oral Poliovirus Vaccines on Monovalent Rotavirus Vaccine Immunogenicity in Rural Bangladesh

PubMed Central

Emperador, Devy M.; Velasquez, Daniel E.; Estivariz, Concepcion F.; Lopman, Ben; Jiang, Baoming; Parashar, Umesh; Anand, Abhijeet; Zaman, Khalequ

2016-01-01

Background Trivalent oral poliovirus vaccine (OPV) is known to interfere with monovalent rotavirus vaccine (RV1) immunogenicity. The interference caused by bivalent and monovalent OPV formulations, which will be increasingly used globally in coming years, has not been examined. We conducted a post hoc analysis to assess the effect of coadministration of different OPV formulations on RV1 immunogenicity. Methods Healthy infants in Matlab, Bangladesh, were randomized to receive 3 doses of monovalent OPV type 1 or bivalent OPV types 1 and 3 at either 6, 8, and 10 or 6, 10, and 14 weeks of age or trivalent OPV at 6, 10, and 14 weeks of age. All infants received 2 doses of RV1 at about 6 and 10 weeks of age. Concomitant administration was defined as RV1 and OPV given on the same day; staggered administration as RV1 and OPV given ≥1 day apart. Rotavirus seroconversion was defined as a 4-fold rise in immunoglobulin A titer from before the first RV1 dose to ≥3 weeks after the second RV1 dose. Results There were no significant differences in baseline RV1 immunogenicity among the 409 infants included in the final analysis. Infants who received RV1 and OPV concomitantly, regardless of OPV formulation, were less likely to seroconvert (47%; 95% confidence interval, 39%–54%) than those who received both vaccines staggered ≥1 day (63%; 57%–70%; P < .001). For staggered administration, we found no evidence that the interval between RV1 and OPV administration affected RV1 immunogenicity. Conclusions Coadministration of monovalent, bivalent, or trivalent OPV seems to lower RV1 immunogenicity. Clinical Trials Registration NCT01633216. PMID:26349548

Systematic Review of Mucosal Immunity Induced by Oral and Inactivated Poliovirus Vaccines against Virus Shedding following Oral Poliovirus Challenge

PubMed Central

Hird, Thomas R.; Grassly, Nicholas C.

2012-01-01

Inactivated poliovirus vaccine (IPV) may be used in mass vaccination campaigns during the final stages of polio eradication. It is also likely to be adopted by many countries following the coordinated global cessation of vaccination with oral poliovirus vaccine (OPV) after eradication. The success of IPV in the control of poliomyelitis outbreaks will depend on the degree of nasopharyngeal and intestinal mucosal immunity induced against poliovirus infection. We performed a systematic review of studies published through May 2011 that recorded the prevalence of poliovirus shedding in stool samples or nasopharyngeal secretions collected 5–30 days after a “challenge” dose of OPV. Studies were combined in a meta-analysis of the odds of shedding among children vaccinated according to IPV, OPV, and combination schedules. We identified 31 studies of shedding in stool and four in nasopharyngeal samples that met the inclusion criteria. Individuals vaccinated with OPV were protected against infection and shedding of poliovirus in stool samples collected after challenge compared with unvaccinated individuals (summary odds ratio [OR] for shedding 0.13 (95% confidence interval [CI] 0.08–0.24)). In contrast, IPV provided no protection against shedding compared with unvaccinated individuals (summary OR 0.81 [95% CI 0.59–1.11]) or when given in addition to OPV, compared with individuals given OPV alone (summary OR 1.14 [95% CI 0.82–1.58]). There were insufficient studies of nasopharyngeal shedding to draw a conclusion. IPV does not induce sufficient intestinal mucosal immunity to reduce the prevalence of fecal poliovirus shedding after challenge, although there was some evidence that it can reduce the quantity of virus shed. The impact of IPV on poliovirus transmission in countries where fecal-oral spread is common is unknown but is likely to be limited compared with OPV. PMID:22532797

Recent progress of high performance polymer OLED and OPV materials for organic printed electronics.

PubMed

Sekine, Chizu; Tsubata, Yoshiaki; Yamada, Takeshi; Kitano, Makoto; Doi, Shuji

2014-06-01

The development of organic printed electronics has been expanding to a variety of applications and is expected to bring innovations to our future life. Along with this trend, high performance organic materials with cost-efficient fabrication processes and specific features such as thin, light weight, bendable, and low power consumption are required. A variety of organic materials have been investigated in the development of this field. The basic guidelines for material design and the recent progress of polymer-based organic light-emitting diodes (OLEDs) and organic photovoltaic cells (OPVs) are reported.

Recent progress of high performance polymer OLED and OPV materials for organic printed electronics

PubMed Central

Sekine, Chizu; Tsubata, Yoshiaki; Yamada, Takeshi; Kitano, Makoto; Doi, Shuji

2014-01-01

The development of organic printed electronics has been expanding to a variety of applications and is expected to bring innovations to our future life. Along with this trend, high performance organic materials with cost-efficient fabrication processes and specific features such as thin, light weight, bendable, and low power consumption are required. A variety of organic materials have been investigated in the development of this field. The basic guidelines for material design and the recent progress of polymer-based organic light-emitting diodes (OLEDs) and organic photovoltaic cells (OPVs) are reported. PMID:27877671

Recent progress of high performance polymer OLED and OPV materials for organic printed electronics

NASA Astrophysics Data System (ADS)

Sekine, Chizu; Tsubata, Yoshiaki; Yamada, Takeshi; Kitano, Makoto; Doi, Shuji

2014-06-01

The development of organic printed electronics has been expanding to a variety of applications and is expected to bring innovations to our future life. Along with this trend, high performance organic materials with cost-efficient fabrication processes and specific features such as thin, light weight, bendable, and low power consumption are required. A variety of organic materials have been investigated in the development of this field. The basic guidelines for material design and the recent progress of polymer-based organic light-emitting diodes (OLEDs) and organic photovoltaic cells (OPVs) are reported.

Monitoring and Validation of the Global Replacement of tOPV with bOPV, April–May 2016

PubMed Central

Hampton, Lee M.; Shendale, Stephanie; Menning, Lisa; Gonzalez, Alejandro Ramirez; Garon, Julie; Dolan, Samantha B.; du Châtellier, Gaël Maufras; Wanyoike, Sarah; Chang Blanc, Diana; Patel, Manish M.

2017-01-01

Abstract The phased withdrawal of oral polio vaccine (OPV) associated with the Polio Eradication and Endgame Strategic Plan 2013-2018 began with the synchronized global replacement of trivalent OPV (tOPV) with bivalent OPV (bOPV) during April - May 2016, a transition referred to as the “switch.” The World Health Organization’s (WHO) Strategic Advisory Group of Experts (SAGE) on Immunization recommended conducting this synchronized switch in all 155 OPV-using countries and territories (which collectively administered several hundred million doses of tOPV each year via several hundred thousand facilities) to reduce risks of re-emergence of vaccine-derived polioviruses. Safe execution of this switch required implementation of an associated independent monitoring strategy, the primary objective of which was verification that tOPV was no longer available for administration post-switch. This strategy had to be both practical and rigorous such that tOPV withdrawal could be reasonably employed and confirmed in all countries and territories within a discreet timeframe. Following these principles, WHO recommended that designated monitors in each of the 155 countries and territories visit all vaccine stores as well as a 10% sample of highest-risk health facilities within two weeks of the national switch date, removing any tOPV vials found. National governments were required to provide the WHO with formal validation of execution and monitoring of the switch. In practice, all countries reported cessation of tOPV by 12 May 2016 and 95% of countries and territories submitted detailed monitoring data to WHO. According to these data, 272 out of 276 (99%) national stores, 3,741 out of 3.968 (94%) regional stores, 16,144 out of 22,372 (72%) district level stores, and 143,050 out of 595,401 (24%) of health facilities were monitored. These data, along with field reports suggest that monitoring and validation of the switch was efficient and effective, and that the strategies used during the process could be adapted to future stages of OPV withdrawal. PMID:28838162

Organic semiconductor crystals.

PubMed

Wang, Chengliang; Dong, Huanli; Jiang, Lang; Hu, Wenping

2018-01-22

Organic semiconductors have attracted a lot of attention since the discovery of highly doped conductive polymers, due to the potential application in field-effect transistors (OFETs), light-emitting diodes (OLEDs) and photovoltaic cells (OPVs). Single crystals of organic semiconductors are particularly intriguing because they are free of grain boundaries and have long-range periodic order as well as minimal traps and defects. Hence, organic semiconductor crystals provide a powerful tool for revealing the intrinsic properties, examining the structure-property relationships, demonstrating the important factors for high performance devices and uncovering fundamental physics in organic semiconductors. This review provides a comprehensive overview of the molecular packing, morphology and charge transport features of organic semiconductor crystals, the control of crystallization for achieving high quality crystals and the device physics in the three main applications. We hope that this comprehensive summary can give a clear picture of the state-of-art status and guide future work in this area.

Consortium for Nanomaterials for Aerospace Commerce and Technology (CONTACT)

DTIC Science & Technology

2013-02-01

108 47 Absorption mechanism in tandem OPVs and absorption spectra of common organic materials...different protection mechanisms in the humid air of terrestrial environments and the dry vacuum of space. From these initial successes, a range of...confinement based materials enable the ability to manipulate and enhance the optical, electrical, thermal and noise mechanisms to optimize device

Pyridyl-Amides as a Multimode Self-Assembly Driver for the Design of a Stimuli-Responsive π-Gelator.

PubMed

Kartha, Kalathil K; Praveen, Vakayil K; Babu, Sukumaran Santhosh; Cherumukkil, Sandeep; Ajayaghosh, Ayyappanpillai

2015-10-01

An oligo(p-phenylenevinylene) (OPV) derivative connected to pyridyl end groups through an amide linkage (OPV-Py) resulted in a multistimuli-responsive π-gelator. When compared to the corresponding OPV π-gelator terminated by a phenyl-amide (OPV-Ph), the aggregation properties of OPV-Py were found to be significantly different, leading to multistimuli gelation and other morphological properties. The pyridyl moiety in OPV-Py initially interferes with the amide H-bonded assembly and gelation, however, protonation of the pyridyl moiety with trifluoroacetic acid (TFA) facilitated the formation of amide H-bonded assembly leading to gelation, which is reversible by the addition of N,N-diisopropyethylamine (DiPEA). Interestingly, addition of Ag(+) ions to a solution of OPV-Py facilitated the formation of a metallo-supramolecular assembly leading to gelation. Surprisingly, ultrasound-induced gelation was observed when OPV-Py was mixed with a dicarboxylic acid (A1). A detailed study using different spectroscopic and microscopic experimental techniques revealed the difference in the mode of assembly in the two molecules and the multistimuli-responsive nature of the OPV-Py gelation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Does oral polio vaccine have non-specific effects on all-cause mortality? Natural experiments within a randomised controlled trial of early measles vaccine.

PubMed

Aaby, Peter; Andersen, Andreas; Martins, Cesário L; Fisker, Ane B; Rodrigues, Amabelia; Whittle, Hilton C; Benn, Christine S

2016-12-23

BCG and measles vaccine (MV) may have beneficial non-specific effects (NSEs). If an unplanned intervention with a vaccine (a natural experiment) modifies the estimated effect in a randomised controlled trial (RCT), this suggests NSEs. We used this approach to test NSEs of triple oral polio vaccine (OPV). During an RCT of 2 doses of MV at 4.5 and 9 months versus 1 dose of MV at 9 months of age, we experienced 2 natural experiments with OPV. We assessed whether these OPV experiments modified the effect of 2-dose MV in the MV trial. MV RCT conducted in urban Guinea-Bissau 2003-2009. Natural experiments with OPV due to missing vaccine and the implementation of OPV campaigns. Changes in the mortality rate ratio (MRR) for 2-dose MV versus 1-dose MV. First, the MRR (2-dose/1-dose MV) overall was 0.70 (0.52 to 0.94), but the MRR was 1.04 (0.53 to 2.04) when OPV at birth (OPV0) was not given, suggesting that early priming with OPV was important for the effect of 2-dose MV. The effect of OPV0 depended on age of administration; the MRR (2-dose/1-dose MV) was 0.45 (0.29 to 0.71) for children receiving OPV0 in the first week of life, but 3.63 (0.87 to 15.2) for those receiving OPV0 after the first month of life (p=0.007, test of no interaction). Second, campaign-OPV may have reduced the difference between the randomisation groups since the MRR (2-dose/1-dose MV) was 0.60 (0.42 to 0.85) for children who had not received campaign-OPV before RCT-enrolment versus 0.72 (0.23 to 2.31) and 1.42 (0.70 to 2.90) for children who had received 1 or 2 doses of campaign-OPV-before-enrolment, respectively. Bissau had no polio infection during this trial, so OPV0 and campaign-OPV may have NSEs since they modified the effect of 2-dose MV in an RCT. Different interventions may interact to a much larger effect than usually assumed. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Copper thiocyanate: An attractive hole transport/extraction layer for use in organic photovoltaic cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Treat, Neil D., E-mail: neil.treat@imperial.ac.uk, E-mail: t.anthopoulos@imperial.ac.uk; Stingelin, Natalie; Yaacobi-Gross, Nir

2015-07-06

We report the advantageous properties of the inorganic molecular semiconductor copper(I) thiocyanate (CuSCN) for use as a hole collection/transport layer (HTL) in organic photovoltaic (OPV) cells. CuSCN possesses desirable HTL energy levels [i.e., valence band at −5.35 eV, 0.35 eV deeper than poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS)], which produces a 17% increase in power conversion efficiency (PCE) relative to PEDOT:PSS-based devices. In addition, a two-fold increase in shunt resistance for the solar cells measured in dark conditions is achieved. Ultimately, CuSCN enables polymer:fullerene based OPV cells to achieve PCE > 8%. CuSCN continues to offer promise as a chemically stable and straightforward replacement for the commonly usedmore » PEDOT:PSS.« less

Inactivated poliovirus vaccine given alone or in a sequential schedule with bivalent oral poliovirus vaccine in Chilean infants: a randomised, controlled, open-label, phase 4, non-inferiority study.

PubMed

O'Ryan, Miguel; Bandyopadhyay, Ananda S; Villena, Rodolfo; Espinoza, Mónica; Novoa, José; Weldon, William C; Oberste, M Steven; Self, Steve; Borate, Bhavesh R; Asturias, Edwin J; Clemens, Ralf; Orenstein, Walter; Jimeno, José; Rüttimann, Ricardo; Costa Clemens, Sue Ann

2015-11-01

Bivalent oral poliovirus vaccine (bOPV; types 1 and 3) is expected to replace trivalent OPV (tOPV) globally by April, 2016, preceded by the introduction of at least one dose of inactivated poliovirus vaccine (IPV) in routine immunisation programmes to eliminate vaccine-associated or vaccine-derived poliomyelitis from serotype 2 poliovirus. Because data are needed on sequential IPV-bOPV schedules, we assessed the immunogenicity of two different IPV-bOPV schedules compared with an all-IPV schedule in infants. We did a randomised, controlled, open-label, non-inferiority trial with healthy, full-term (>2·5 kg birthweight) infants aged 8 weeks (± 7 days) at six well-child clinics in Santiago, Chile. We used supplied lists to randomly assign infants (1:1:1) to receive three polio vaccinations (IPV by injection or bOPV as oral drops) at age 8, 16, and 24 weeks in one of three sequential schedules: IPV-bOPV-bOPV, IPV-IPV-bOPV, or IPV-IPV-IPV. We did the randomisation with blocks of 12 stratified by study site. All analyses were done in a masked manner. Co-primary outcomes were non-inferiority of the bOPV-containing schedules compared with the all-IPV schedule for seroconversion (within a 10% margin) and antibody titres (within two-thirds log2 titres) to poliovirus serotypes 1 and 3 at age 28 weeks, analysed in the per-protocol population. Secondary outcomes were seroconversion and titres to serotype 2 and faecal shedding for 4 weeks after a monovalent OPV type 2 challenge at age 28 weeks. Safety analyses were done in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT01841671, and is closed to new participants. Between April 25 and August 1, 2013, we assigned 570 infants to treatment: 190 to IPV-bOPV-bOPV, 192 to IPV-IPV-bOPV, and 188 to IPV-IPV-IPV. 564 (99%) were vaccinated and included in the intention-to-treat cohort, and 537 (94%) in the per-protocol analyses. In the IPV-bOPV-bOPV, IPV-IPV-bOPV, and IPV-IPV-IPV groups, respectively, the proportions of children with seroconversion to type 1 poliovirus were 166 (98·8%) of 168, 95% CI 95·8-99·7; 178 (100%), 97·9-100·0; and 175 (100%), 97·9-100·0. Proportions with seroconvsion to type 3 poliovirus were 163 (98·2%) of 166, 94·8-99·4; 177 (100%), 97·9-100·0, and 172 (98·9%) of 174, 95·9-99·7. Non-inferiority was thus shown for the bOPV-containing schedules compared with the all-IPV schedule, with no significant differences between groups. In the IPV-bOPV-bOPV, IPV-IPV-bOPV, and IPV-IPV-IPV groups, respectively, the proportions of children with seroprotective antibody titres to type 1 poliovirus were 168 (98·8%) of 170, 95% CI 95·8-99·7; 181 (100%), 97·9-100·0; and 177 (100%), 97·9-100·0. Proportions to type 3 poliovirus were 166 (98·2%) of 169, 94·9-99·4; 180 (100%), 97·9-100·0; and 174 (98·9%) of 176, 96·0-99·7. Non-inferiority comparisons could not be done for this outcome because median titres for the groups receiving OPV were greater than the assay's upper limit of detection (log2 titres >10·5). The proportions of children seroconverting to type 2 poliovirus in the IPV-bOPV-bOPV, IPV-IPV-bOPV, and IPV-IPV-IPV groups, respectively, were 130 (77·4%) of 168, 95% CI 70·5-83·0; 169 (96·0%) of 176, 92·0-98·0; and 175 (100%), 97·8-100. IPV-bOPV schedules resulted in almost a 0·3 log reduction of type 2 faecal shedding compared with the IPV-only schedule. No participants died during the trial; 81 serious adverse events were reported, of which one was thought to be possibly vaccine-related (intestinal intussusception). Seroconversion rates against polioviruses types 1 and 3 were non-inferior in sequential schedules containing IPV and bOPV, compared with an all-IPV schedule, and proportions of infants with protective antibodies were high after all three schedules. One or two doses of bOPV after IPV boosted intestinal immunity for poliovirus type 2, suggesting possible cross protection. Additionally, there was evidence of humoral priming for type 2 from one dose of IPV. Our findings could give policy makers flexibility when choosing a vaccination schedule, especially when trying to eliminate vaccine-associated and vaccine-derived poliomyelitis. Bill & Melinda Gates Foundation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Poliovirus vaccination during the endgame: insights from integrated modeling.

PubMed

Duintjer Tebbens, Radboud J; Thompson, Kimberly M

2017-06-01

Managing the polio endgame requires access to sufficient quantities of poliovirus vaccines. After oral poliovirus vaccine (OPV) cessation, outbreaks may occur that require outbreak response using monovalent OPV (mOPV) and/or inactivated poliovirus vaccine. Areas covered: We review the experience and challenges with managing vaccine supplies in the context of the polio endgame. Building on models that explored polio endgame risks and the potential mOPV needs to stop outbreaks from live poliovirus reintroductions, we conceptually explore the potential demands for finished and bulk mOPV doses from a stockpile in the context of limited shelf-life of finished vaccine and time delays to convert bulk to finished vaccine. Our analysis suggests that the required size of the mOPV stockpile varies by serotype, with the highest expected needs for serotype 1 mOPV. Based on realizations of poliovirus risks after OPV cessation, the stockpile required to eliminate the chance of a stock-out appears considerably larger than the currently planned mOPV stockpiles. Expert commentary: The total required stockpile size depends on the acceptable probability of a stock-out, and increases with longer times to finish bulk doses and shorter shelf-lives of finished doses. Successful polio endgame management will require careful attention to poliovirus vaccine supplies.

Virologic Monitoring of Poliovirus Type 2 after Oral Poliovirus Vaccine Type 2 Withdrawal in April 2016 - Worldwide, 2016-2017.

PubMed

Diop, Ousmane M; Asghar, Humayun; Gavrilin, Evgeniy; Moeletsi, Nicksy Gumede; Benito, Gloria Rey; Paladin, Fem; Pattamadilok, Sirima; Zhang, Yan; Goel, Ajay; Quddus, Arshad

2017-05-26

The Global Polio Eradication Initiative (GPEI) has made substantial progress since its launch in 1988; only 37 wild poliovirus type 1 (WPV1) cases were detected in 2016, the lowest annual count ever. Wild poliovirus type 3 has not been detected since November 2012, and wild poliovirus type 2 was officially declared eradicated in September 2015. This success is attributable to the wide use of live oral poliovirus vaccines (OPVs). Since 2001, numerous outbreaks were caused by the emergence of genetically divergent vaccine-derived polioviruses (VDPVs) whose genetic drift from the parental OPV strains indicates prolonged replication or circulation (1). In 2015, circulating VDPV type 2 (cVDPV2) outbreaks were detected in five countries worldwide (Nigeria, Pakistan, Guinea, Burma, and South Sudan), and VDPV2 single events were reported in 22 countries. These events prompted the GPEI to withdraw the type 2 component (Sabin2) of trivalent OPV (tOPV) in a globally coordinated, synchronized manner in April 2016 (2,3), at which time all OPV-using countries switched to using bivalent OPV (bOPV), containing Sabin types 1 and 3. This report details for the first time the virologic tracking of elimination of a live vaccine that has been withdrawn from routine and mass immunization systems worldwide (3). To secure elimination, further monitoring is warranted to detect any use of tOPV or monovalent OPV type 2 (mOPV2).

Refusal of oral polio vaccine in northwestern Pakistan: a qualitative and quantitative study.

PubMed

Murakami, Hitoshi; Kobayashi, Makoto; Hachiya, Masahiko; Khan, Zahir S; Hassan, Syed Q; Sakurada, Shinsaku

2014-03-10

Refusal of the oral polio vaccine (OPV) is a difficulty faced by the Polio Eradication Initiative (PEI) in multiple endemic areas, including the Khyber Pakhtunkhwa Province (KPP), Pakistan. In 2007, we investigated community perceptions of the OPV and estimated the prevalence of OPV refusal in three districts in Swat Valley, KPP, a polio-endemic area. Qualitative data concerning community perceptions were collected by focus group discussions among lady health workers (LHWs) and mothers with children <1 year old and by key informant interviews with local health managers and officials. Quantitative data collection followed using a questionnaire survey of 200 LHWs and a cluster sampling survey of 210 mothers (per district) with children <1 year old. The qualitative assessments identified the grounded theory of OPV refusal involving facts known by the residents that are related to the OPV (too frequent OPV campaigns, an OPV boycott in northern Nigeria in 2003 and that birth control is viewed as is against Islam), the local interpretations of these facts (perceptions that OPV contained birth control or pork, that OPV was a foreign/central plot against Muslims, and that the vaccination was against the Hadith and the fate determined by God) and different manifestations of OPV refusal. Among the three districts studied, the proportion of LHWs who encountered OPV refusal ranged from 0 to 33%, whereas among the districts, the proportions of mothers unwilling to give OPV to their children ranged from 0.5 to 5.7%. Refusal of other injectable vaccines was almost equally prevalent for reasons that were very similar. The PEI needs to reflect local value system in the path to polio eradication in the studied districts in the Swat Valley. The religious and cultural values as well as the interpretation of the international political situation are of particular importance. Copyright © 2014 Elsevier Ltd. All rights reserved.

Interference of Monovalent, Bivalent, and Trivalent Oral Poliovirus Vaccines on Monovalent Rotavirus Vaccine Immunogenicity in Rural Bangladesh.

PubMed

Emperador, Devy M; Velasquez, Daniel E; Estivariz, Concepcion F; Lopman, Ben; Jiang, Baoming; Parashar, Umesh; Anand, Abhijeet; Zaman, Khalequ

2016-01-15

Trivalent oral poliovirus vaccine (OPV) is known to interfere with monovalent rotavirus vaccine (RV1) immunogenicity. The interference caused by bivalent and monovalent OPV formulations, which will be increasingly used globally in coming years, has not been examined. We conducted a post hoc analysis to assess the effect of coadministration of different OPV formulations on RV1 immunogenicity. Healthy infants in Matlab, Bangladesh, were randomized to receive 3 doses of monovalent OPV type 1 or bivalent OPV types 1 and 3 at either 6, 8, and 10 or 6, 10, and 14 weeks of age or trivalent OPV at 6, 10, and 14 weeks of age. All infants received 2 doses of RV1 at about 6 and 10 weeks of age. Concomitant administration was defined as RV1 and OPV given on the same day; staggered administration as RV1 and OPV given ≥1 day apart. Rotavirus seroconversion was defined as a 4-fold rise in immunoglobulin A titer from before the first RV1 dose to ≥3 weeks after the second RV1 dose. There were no significant differences in baseline RV1 immunogenicity among the 409 infants included in the final analysis. Infants who received RV1 and OPV concomitantly, regardless of OPV formulation, were less likely to seroconvert (47%; 95% confidence interval, 39%-54%) than those who received both vaccines staggered ≥1 day (63%; 57%-70%; P < .001). For staggered administration, we found no evidence that the interval between RV1 and OPV administration affected RV1 immunogenicity. Coadministration of monovalent, bivalent, or trivalent OPV seems to lower RV1 immunogenicity. NCT01633216. Published by Oxford University Press for the Infectious Diseases Society of America 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Immunogenicity and safety evaluation of bivalent types 1 and 3 oral poliovirus vaccine by comparing different poliomyelitis vaccination schedules in China: A randomized controlled non-inferiority clinical trial.

PubMed

Qiu, Jingjun; Yang, Yunkai; Huang, Lirong; Wang, Ling; Jiang, Zhiwei; Gong, Jian; Wang, Wei; Wang, Hongyan; Guo, Shaohong; Li, Chanjuan; Wei, Shuyuan; Mo, Zhaojun; Xia, Jielai

2017-06-03

The type 2 component of the oral poliovirus vaccine is targeted for global withdrawal through a switch from the trivalent oral poliovirus vaccine (tOPV) to a bivalent oral poliovirus vaccine (bOPV). The switch is intended to prevent paralytic polio caused by circulating vaccine-derived poliovirus type 2. We aimed to assess the immunogenicity and safety profile of 6 vaccination schedules with different sequential doses of inactivated poliovirus vaccine (IPV), tOPV, or bOPV. A randomized controlled trial was conducted in China in 2015. Healthy newborn babies randomly received one of the following 6 vaccination schedules: cIPV-bOPV-bOPV(I-B-B), cIPV-tOPV-tOPV(I-T-T), cIPV-cIPV-bOPV(I-I-B), cIPV-cIPV-tOPV(I-I-T), cIPV-cIPV-cIPV(I-I-I), or tOPV-tOPV-tOPV(T-T-T). Doses were administered sequentially at 4-6 week intervals after collecting baseline blood samples. Patients were proactively followed up for observation of adverse events after the first dose and 30 days after all doses. The primary study objective was to investigate the immunogenicity and safety profile of different vaccine schedules, evaluated by seroconversion, seroprotection and antibody titer against poliovirus types 1, 2, and 3 in the per-protocol population. Of 600 newborn babies enrolled, 504 (84.0%) were included in the per-protocol population. For type 1 poliovirus, the differences in the seroconversion were 1.17% (95% CI = -2.74%, 5.08%) between I-B-B and I-T-T and 0.00% (95% CI: -6.99%, 6.99%) between I-I-B and I-I-T; for type 3 poliovirus, differences in the seroconversion were 3.49% (95% CI: -1.50%, 8.48%) between I-B-B and I-T-T and -2.32% (95% CI: -5.51%, 0.86%) between I-I-B and I-I-T. The non-inferiority conclusion was achieved in both poliovirus type 1 and 3 with the margin of -10%. Of 24 serious adverse events reported, no one was vaccine-related. The vaccination schedules with bOPV followed by one or 2 doses of IPV were recommended to substitute for vaccinations involving tOPV without compromising the immunogenicity and safety in the Chinese population. The findings will be essential for policy formulation by national and global authorities to facilitate polio elimination.

"Supersaturated" self-assembled charge-selective interfacial layers for organic solar cells.

PubMed

Song, Charles Kiseok; Luck, Kyle A; Zhou, Nanjia; Zeng, Li; Heitzer, Henry M; Manley, Eric F; Goldman, Samuel; Chen, Lin X; Ratner, Mark A; Bedzyk, Michael J; Chang, Robert P H; Hersam, Mark C; Marks, Tobin J

2014-12-24

To achieve densely packed charge-selective organosilane-based interfacial layers (IFLs) on the tin-doped indium oxide (ITO) anodes of organic photovoltaic (OPV) cells, a series of Ar2N-(CH2)n-SiCl3 precursors with Ar = 3,4-difluorophenyl, n = 3, 6, 10, and 18, was synthesized, characterized, and chemisorbed on OPV anodes to serve as IFLs. To minimize lateral nonbonded -NAr2···Ar2N- repulsions which likely limit IFL packing densities in the resulting self-assembled monolayers (SAMs), precursor mixtures having both small and large n values are simultaneously deposited. These "heterogeneous" SAMs are characterized by a battery of techniques: contact angle measurements, X-ray reflectivity, X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy (UPS), cyclic voltammetry, and DFT computation. It is found that the headgroup densities of these "supersaturated" heterogeneous SAMs (SHSAMs) are enhanced by as much as 17% versus their homogeneous counterparts. Supersaturation significantly modifies the IFL properties including the work function (as much as 16%) and areal dipole moment (as much as 49%). Bulk-heterojunction OPV devices are fabricated with these SHSAMs: ITO/IFL/poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][2-[[(2-ethylhexyl)oxy]carbonyl]-3-fluorothieno[3,4-b]thiophenediyl

Can the Dielectric Constant of Fullerene Derivatives Be Enhanced by Side-Chain Manipulation? A Predictive First-Principles Computational Study.

PubMed

Sami, Selim; Haase, Pi A B; Alessandri, Riccardo; Broer, Ria; Havenith, Remco W A

2018-04-19

The low efficiency of organic photovoltaic (OPV) devices has often been attributed to the strong Coulombic interactions between the electron and hole, impeding the charge separation process. Recently, it has been argued that by increasing the dielectric constant of materials used in OPVs, this strong interaction could be screened. In this work, we report the application of periodic density functional theory together with the coupled perturbed Kohn-Sham method to calculate the electronic contribution to the dielectric constant for fullerene C 60 derivatives, a ubiquitous class of molecules in the field of OPVs. The results show good agreement with experimental data when available and also reveal an important undesirable outcome when manipulating the side chain to maximize the static dielectric constant: in all cases, the electronic contribution to the dielectric constant decreases as the side chain increases in size. This information should encourage both theoreticians and experimentalists to further investigate the relevance of contributions to the dielectric constant from slower processes like vibrations and dipolar reorientations for facilitating the charge separation, because electronically, enlarging the side chain of conventional fullerene derivatives only lowers the dielectric constant, and consequently, their electronic dielectric constant is upper bound by the one of C 60 .

Can the Dielectric Constant of Fullerene Derivatives Be Enhanced by Side-Chain Manipulation? A Predictive First-Principles Computational Study

PubMed Central

2018-01-01

The low efficiency of organic photovoltaic (OPV) devices has often been attributed to the strong Coulombic interactions between the electron and hole, impeding the charge separation process. Recently, it has been argued that by increasing the dielectric constant of materials used in OPVs, this strong interaction could be screened. In this work, we report the application of periodic density functional theory together with the coupled perturbed Kohn–Sham method to calculate the electronic contribution to the dielectric constant for fullerene C60 derivatives, a ubiquitous class of molecules in the field of OPVs. The results show good agreement with experimental data when available and also reveal an important undesirable outcome when manipulating the side chain to maximize the static dielectric constant: in all cases, the electronic contribution to the dielectric constant decreases as the side chain increases in size. This information should encourage both theoreticians and experimentalists to further investigate the relevance of contributions to the dielectric constant from slower processes like vibrations and dipolar reorientations for facilitating the charge separation, because electronically, enlarging the side chain of conventional fullerene derivatives only lowers the dielectric constant, and consequently, their electronic dielectric constant is upper bound by the one of C60. PMID:29561616

“Supersaturated” Self-Assembled Charge-Selective Interfacial Layers for Organic Solar Cells

DOE PAGES

Song, Charles Kiseok; Luck, Kyle A.; Zhou, Nanjia; ...

2014-11-24

Here, to achieve densely packed charge-selective organosilane-based interfacial layers (IFLs) on the tin-doped indium oxide (ITO) anodes of organic photovoltaic (OPV) cells, a series of Ar 2N-(CH 2) n-SiCl3 precursors with Ar = 3,4-difluorophenyl, n = 3, 6, 10, and 18, was synthesized, characterized, and chemisorbed on OPV anodes to serve as IFLs. To minimize lateral nonbonded -NAr 2···Ar 2N- repulsions which likely limit IFL packing densities in the resulting self-assembled monolayers (SAMs), precursor mixtures having both small and large n values are simultaneously deposited. These “heterogeneous” SAMs are characterized by a battery of techniques: contact angle measurements, X-ray reflectivity,more » X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy (UPS), cyclic voltammetry, and DFT computation. It is found that the headgroup densities of these “supersaturated” heterogeneous SAMs (SHSAMs) are enhanced by as much as 17% versus their homogeneous counterparts. Supersaturation significantly modifies the IFL properties including the work function (as much as 16%) and areal dipole moment (as much as 49%). Bulk-heterojunction OPV devices are fabricated with these SHSAMs: ITO/IFL/poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2- b:4,5- b']dithiophene-2,6-diyl][2-[[(2-ethylhexyl)oxy]carbonyl]-3-fluorothieno[3,4-b]thiophenediyl

Vaccine-induced mucosal immunity to poliovirus: analysis of cohorts from an open-label, randomised controlled trial in Latin American infants.

PubMed

Wright, Peter F; Connor, Ruth I; Wieland-Alter, Wendy F; Hoen, Anne G; Boesch, Austin W; Ackerman, Margaret E; Oberste, M Steven; Gast, Chris; Brickley, Elizabeth B; Asturias, Edwin J; Rüttimann, Ricardo; Bandyopadhyay, Ananda S

2016-12-01

Identification of mechanisms that limit poliovirus replication is crucial for informing decisions aimed at global polio eradication. Studies of mucosal immunity induced by oral poliovirus (OPV) or inactivated poliovirus (IPV) vaccines and mixed schedules thereof will determine the effectiveness of different vaccine strategies to block virus shedding. We used samples from a clinical trial of different vaccination schedules to measure intestinal immunity as judged by neutralisation of virus and virus-specific IgA in stools. In the FIDEC trial, Latin American infants were randomly assigned to nine groups to assess the efficacy of two schedules of bivalent OPV (bOPV) and IPV and challenge with monovalent type 2 OPV, and stools samples were collected. We selected three groups of particular interest-the bOPV control group (serotypes 1 and 3 at 6, 10, and 14 weeks), the trivalent attenuated OPV (tOPV) control group (tOPV at 6, 10, and 14 weeks), and the bOPV-IPV group (bOPV at 6, 10, and 14 weeks plus IPV at 14 weeks). Neutralising activity and poliovirus type-specific IgA were measured in stool after a monovalent OPV type 2 challenge at 18 weeks of age. Mucosal immunity was measured by in-vitro neutralisation of a type 2 polio pseudovirus (PV2). Neutralisation titres and total and poliovirus-type-specific IgG and IgA concentrations in stools were assessed in samples collected before challenge and 2 weeks after challenge from all participants. 210 infants from Guatemala and Dominican Republic were included in this analysis. Of 38 infants tested for mucosal antibody in the tOPV group, two were shedding virus 1 week after challenge, compared with 59 of 85 infants receiving bOPV (p<0·0001) and 53 of 87 infants receiving bOPV-IPV (p<0·0001). Mucosal type 2 neutralisation and type-specific IgA were noted primarily in response to tOPV. An inverse correlation was noted between virus shedding and both serum type 2 neutralisation at challenge (p<0·0001) and mucosal type 2 neutralisation at challenge (p<0·0001). Mucosal type-2-specific antibodies can be measured in stool and develop in response to receipt of OPV type 2 either in the primary vaccine series or at challenge. These mucosal antibodies influence the amount of virus that is shed in an established infection. Bill & Melinda Gates Foundation. Copyright © 2016 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY license. Published by Elsevier Ltd.. All rights reserved.

Synthesis and Characterization of Metal-Organic Frameworks (MOFs) for Photon Collection and Energy Transfer

NASA Astrophysics Data System (ADS)

So, Monica C.

Projected global energy demand is widely believed to reach 30 TW by 2050. Currently, fossil fuels collectively represent over 80% of our total energy supply, while only 10% come from renewable sources. To meet future demands, however, we must maximize our use of renewable resources while minimizing our dependence on fossil fuels. While there are many sources of renewable energy, solar energy is one of the most abundant; in fact, the sun delivers up to 67 TW of power annually, which exceeds the projected energy demand in 2050. While there are multiple ways to convert sunlight to electricity, organic photovoltaics (OPVs) has the shortest energy payback time; this is the time required for the PV module to generate the equivalent amount of energy that originally was used to manufacture the PV module. OPVs show promise for light-to-electrical energy conversion with the best performing cells having power conversion efficiencies of 8%, but the theoretical maximum is at 32%. If efficiencies can be increased to even a fraction of the way to ˜16%, OPVs would be more cost-competitive with their inorganic counterparts. However, there are four major challenges in improving OPV performance. These include (a) poor light harvesting, due to a limited range of absorbance of visible light, (b) inefficient exciton splitting into holes and electrons, due to the limited diffusion length of excitons (typically ca. 10 nm), (c) increased recombination of separated charges at the donor/acceptor interface, and (d) inefficient collection of charges at the active layer/electrode interface (i.e. partial electrical shorting). OPVs constructed from conventional materials and architectures involve conflicting design requirements; this makes it impossible to address all four problems simultaneously. The projects described in this dissertation involve the design, synthesis, and characterization of a new class of OPV materials that have the potential to overcome the problems with conventional cells. To address problem (a), we incorporated antenna molecules (i.e. perylene diimides) to expand light collection and then transfer energy to the primary chromophores. To address problem (b), we observed that excitons can achieve up to 2,025 hops in a porphyrin-based metal-organic framework (MOF) single crystal within its 3 ns lifetime. By precisely aligning the chromophores in the MOF, we showed that long-distance exciton transport (i.e. ultra-fast, sequential hopping) was consistent with the well-established Forster theory. To address problems (c) and (d), we introduced MOF components one step at a time to optimize optical path length and crystal-thickness. This allowed us to incorporate MOFs (normally bulk crystals) into a MOF film. The approach exploited both MOF chemistry and layer-by-layer (LbL) assembly of crystalline MOFs in a highly controlled fashion on functional surfaces. We also incorporated good light-harvesting molecules as struts in MOFs to increase the visible absorption. Designing MOF-based OPVs can provide insight into solar energy conversion. This can potentially lead to much higher efficiencies, based on the simultaneous resolution of the four challenges hindering OPV performance.

The detection of Vaccinia virus confirms the high circulation of Orthopoxvirus in buffaloes living in geographical isolation, Marajó Island, Brazilian Amazon.

PubMed

Franco-Luiz, Ana Paula Moreira; Fagundes Pereira, Alexandre; de Oliveira, Cairo Henrique Sousa; Barbosa, José Diomedes; Oliveira, Danilo Bretas; Bonjardim, Cláudio Antônio; Ferreira, Paulo César Peregrino; de Souza Trindade, Giliane; Abrahão, Jônatas Santos; Kroon, Erna Geessien

2016-06-01

In Brazil, serologic evidence of Orthopoxvirus (OPV) circulation showed positivity around 20% in cattle, humans, monkeys and rodents. Although OPV seropositivity has been described in buffalo herds in southeastern Brazil, no Vaccinia virus (VACV) (member of genus OPV) outbreaks in buffalo herds have been described in this country. This study aimed to investigate the detection of anti-OPV antibodies and to study the OPV genome in Brazilian buffalo herds. Our results demonstrated a high OPV seropositivity in buffalo herds on Marajó Island and molecular data confirmed the circulation of VACV. The geographical isolation conditionmight be a sine qua non condition to explain our results. Copyright © 2016. Published by Elsevier Ltd.

Electronic structure and charge transfer excited states of endohedral fullerene containing electron donoracceptor complexes utilized in organic photovoltaics

NASA Astrophysics Data System (ADS)

Amerikheirabadi, Fatemeh

Organic Donor-Acceptor complexes form the main component of the organic photovoltaic devices (OPVs). The open circuit voltage of OPVs is directly related to the charge transfer excited state energies of these complexes. Currently a large number of different molecular complexes are being tested for their efficiency in photovoltaic devices. In this work, density functional theory as implemented in the NRLMOL code is used to investigate the electronic structure and related properties of these donor-acceptor complexes. The charge transfer excitation energies are calculated using the perturbative delta self-consistent field method recently developed in our group as the standard time dependent density functional approaches fail to accurately provide them. The model photovoltaics systems analyzed are as follows: Sc3N C 80--ZnTPP, Y3 N C80-- ZnTPP and Sc3 N C80-- ZnPc. In addition, a thorough analysis of the isolated donor and acceptor molecules is also provided. The studied acceptors are chosen from a class of fullerenes named trimetallic nitride endohedral fullerenes. These molecules have shown to possess advantages as acceptors such as long lifetimes of the charge-separated states.

Electron Acceptors Based on α-Substituted Perylene Diimide (PDI) for Organic Solar Cells

DOE PAGES

Zhao, Donglin; Wu, Qinghe; Cai, Zhengxu; ...

2016-02-20

The ortho-position functionalized perylene diimide derivatives (αPPID, αPBDT) were synthesized and used as the electron acceptors in nonfullerene organic photovoltaics. Due to the good planarity of ortho-position functionalized PDI, the αPPID and αPBDT show strong tendency to form aggregate because of their enhanced intermolecular pie-pie interaction. Moreover, they maintain the pure domains and the same packing order as in the pure film if they are blended with PBT7-TH and the SCLC measurement also shows the high electron mobility. The inverted OPVs employing αPDI-based compounds as acceptor and PBT7-TH as the donor give the highest PCE of 4.92 % for αPBDTmore » based device and 3.61 % for αPPID based device, which is 39 % and 4 % higher than that for their counterpart βPBDT and βPPID. The charge separation study shows the more efficient exciton dissociation at interfaces between PDI based compounds and PBT7-TH. In conclusion, the results suggest that compared to beta-substituted ones, alpha-substituted PDI derivatives are more promising electron acceptors for OPV.« less

Magnetic field effect in organic films and devices

NASA Astrophysics Data System (ADS)

Gautam, Bhoj Raj

In this work, we focused on the magnetic field effect in organic films and devices, including organic light emitting diodes (OLEDs) and organic photovoltaic (OPV) cells. We measured magnetic field effect (MFE) such as magnetoconductance (MC) and magneto-electroluminescence (MEL) in OLEDs based on several pi- conjugated polymers and small molecules for fields |B|<100 mT. We found that both MC(B) and MEL(B) responses in bipolar devices and MC(B) response in unipolar devices are composed of two B-regions: (i) an 'ultra-small' region at |B| < 1-2 mT, and (ii) a monotonic response region at |B| >˜2mT. Magnetic field effect (MFE) measured on three isotopes of Poly (dioctyloxy) phenylenevinylene (DOO-PPV) showed that both regular and ultra-small effects are isotope dependent. This indicates that MFE response in OLED is mainly due to the hyperfine interaction (HFI). We also performed spectroscopy of the MFE including magneto-photoinduced absorption (MPA) and magneto-photoluminescence (MPL) at steady state conditions in several systems. This includes pristine Poly[2-methoxy-5-(2-ethylhexyl-oxy)-1,4-phenylene-vinylene] (MEH-PPV) films, MEH-PPV films subjected to prolonged illumination, and MEH-PPV/[6,6]-Phenyl C61 butyric acid methyl ester (PCBM) blend, as well as annealed and pristine C60 thin films. For comparison, we also measured MC and MEL in organic diodes based on the same materials. By directly comparing the MPA and MPL responses in films to MC and MEL in organic diodes based on the same active layers, we are able to relate the MFE in organic diodes to the spin densities of the excitations formed in the device, regardless of whether they are formed by photon absorption or carrier injection from the electrodes. We also studied magneto-photocurrent (MPC) and power conversion efficiency (PCE) of a 'standard' Poly (3-hexylthiophene)/PCBM device at various Galvinoxyl radical wt%. We found that the MPC reduction with Galvinoxyl wt% follows the same trend as that of the PCE enhancement. In addition, we also measured the MPC response of a series of OPV cells. We attribute the observed broad MPC to short-lived charge transfer complex species, where spin mixing is caused by the difference, Deltag of the donor/acceptor g factors; whereas narrow MPC is due to HFI within long-lived polaron-pairs.

Vaccine-derived polioviruses.

PubMed

Agol, Vadim I

2006-06-01

The Sabin oral poliovaccine (OPV) is extremely efficacious and safe, despite its inherent genetic instability. While reversion to nearly wild-type phenotype regularly occurs soon after the onset of OPV reproduction in the gastro-intestinal tract of vaccine recipients or their contacts, this is usually not a big problem, provided the vaccine is used either for mass vaccination or in populations with a relatively high level of anti-polio immunity. However, if these conditions are not met, the vaccine viruses are likely to be converted into highly transmissible agents with a nearly wild-type level of neurovirulence. Moreover, OPV viruses may persist and evolve even in adequately immunized populations. The current strategy for the "endgame" of poliovirus eradication envisions cessation of OPV usage shortly after the last isolation of a wild poliovirus. If implemented, this strategy would result in rapid growth of non-immune human populations at the time when OPV derivatives would very likely be persisting. Therefore, the planned cessation of OPV vaccination is associated with a very high, and in the author's opinion, unacceptable risk of polio outbreaks caused by OPV derivatives. The only currently available tool to curb such outbreaks is OPV, which should have been used at a global scale. Safe discontinuation of OPV vaccination will be possible only after an efficient new vaccine or an anti-poliovirus drug is available. To achieve this goal, stimulation of poliovirus research and elimination of organizational and financial obstacles preventing it are needed.

Toxicological analysis and anti-inflammatory effects of essential oil from Piper vicosanum leaves.

PubMed

Hoff Brait, Débora Regina; Mattos Vaz, Márcia Soares; da Silva Arrigo, Jucicléia; Borges de Carvalho, Luciana Noia; Souza de Araújo, Flávio Henrique; Vani, Juliana Miron; da Silva Mota, Jonas; Cardoso, Claudia Andrea Lima; Oliveira, Rodrigo Juliano; Negrão, Fábio Juliano; Kassuya, Cândida Aparecida Leite; Arena, Arielle Cristina

2015-12-01

This study assessed the anti-inflammatory effects of the essential oil from Piper vicosanum leaves (OPV) and evaluated the toxicological potential of this oil through acute toxicity, genotoxicity and mutagenicity tests. The acute toxicity of OPV was evaluated following oral administration to female rats at a single dose of 2 g/kg b.w. To evaluate the genotoxic and mutagenic potential, male mice were divided into five groups: I: negative control; II: positive control; III: 500 mg/kg of OPV; IV: 1000 mg/kg of OPV; V: 2000 mg/kg of OPV. The anti-inflammatory activity of OPV was evaluated in carrageenan-induced pleurisy and paw edema models in rats. No signs of acute toxicity were observed, indicating that the LD50 of this oil is greater than 2000 mg/kg. In the comet assay, OPV did not increase the frequency or rate of DNA damage in groups treated with any of the doses assessed compared to that in the negative control group. In the micronucleus test, the animals treated did not exhibit any cytotoxic or genotoxic changes in peripheral blood erythrocytes. OPV (100 and 300 mg/kg) significantly reduced edema formation and inhibited leukocyte migration analyzed in the carrageenan-induced edema and pleurisy models. These results show that OPV has anti-inflammatory potential without causing acute toxicity or genotoxicity. Copyright © 2015 Elsevier Inc. All rights reserved.

Transmissibility and persistence of oral polio vaccine viruses: implications for the global poliomyelitis eradication initiative.

PubMed

Fine, P E; Carneiro, I A

1999-11-15

The global poliomyelitis eradication initiative has been a tremendous success, with current evidence suggesting that wild poliovirus will cease to circulate anywhere in the world soon after the year 2000. As the goal of wild poliovirus eradication is approached, concern has been raised about the potential for persistent transmission of oral polio vaccine (OPV) viruses, as these viruses are known to revert toward wild-type neurovirulence. This paper has been extracted from a document prepared for the World Health Organization on the implications of OPV transmissibility for the strategy of stopping OPV vaccination after global eradication of wild polioviruses. The authors review the empirical evidence on OPV transmissibility available from household and community transmission studies and from mass-vaccination experiences. They then consider theoretical measures of transmissibility and persistence for wild and OPV viruses (secondary attack rate, basic reproduction number, and critical populations' size), to assess whether transmissibility of OPV viruses is sufficient to allow persistence of these viruses after cessation of vaccination. The findings indicate that OPV viruses could persist under various plausible circumstances, and that this potential should be a major consideration when planning the cessation of OPV vaccination.

The polio endgame: rationale behind the change in immunisation.

PubMed

Garon, Julie; Patel, Manish

2017-04-01

The decades long effort to eradicate polio is nearing the final stages and oral polio vaccine (OPV) is much to thank for this success. As cases of wild poliovirus continue to dwindle, cases of paralysis associated with OPV itself have become a concern. As type-2 poliovirus (one of three) has been certified eradicated and a large proportion of OPV-related paralysis is caused by the type-2 component of OPV, the World Health Assembly endorsed the phased withdrawal of OPV and the introduction of inactivated polio vaccine (IPV) into routine immunisation schedules as a crucial step in the polio endgame plan. The rapid pace of IPV scale-up and uptake required adequate supply, planning, advocacy, training and operational readiness. Similarly, the synchronised switch from trivalent OPV (all three types) to bivalent OPV (types 1 and 3) involved an unprecedented level of global coordination and country commitment. The important shift in vaccination policy seen through global IPV introduction and OPV withdrawal represents an historical milestone reached in the polio eradication effort. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Humoral and intestinal immunity induced by new schedules of bivalent oral poliovirus vaccine and one or two doses of inactivated poliovirus vaccine in Latin American infants: an open-label randomised controlled trial.

PubMed

Asturias, Edwin J; Bandyopadhyay, Ananda S; Self, Steve; Rivera, Luis; Saez-Llorens, Xavier; Lopez, Eduardo; Melgar, Mario; Gaensbauer, James T; Weldon, William C; Oberste, M Steven; Borate, Bhavesh R; Gast, Chris; Clemens, Ralf; Orenstein, Walter; O'Ryan G, Miguel; Jimeno, José; Clemens, Sue Ann Costa; Ward, Joel; Rüttimann, Ricardo

2016-07-09

Replacement of the trivalent oral poliovirus vaccine (tOPV) with bivalent types 1 and 3 oral poliovirus vaccine (bOPV) and global introduction of inactivated poliovirus vaccine (IPV) are major steps in the polio endgame strategy. In this study, we assessed humoral and intestinal immunity in Latin American infants after three doses of bOPV combined with zero, one, or two doses of IPV. This open-label randomised controlled multicentre trial was part of a larger study. 6-week-old full-term infants due for their first polio vaccinations, who were healthy on physical examination, with no obvious medical conditions and no known chronic medical disorders, were enrolled from four investigational sites in Colombia, Dominican Republic, Guatemala, and Panama. The infants were randomly assigned by permuted block randomisation (through the use of a computer-generated list, block size 36) to nine groups, of which five will be discussed in this report. These five groups were randomly assigned 1:1:1:1 to four permutations of schedule: groups 1 and 2 (control groups) received bOPV at 6, 10, and 14 weeks; group 3 (also a control group, which did not count as a permutation) received tOPV at 6, 10, and 14 weeks; group 4 received bOPV plus one dose of IPV at 14 weeks; and group 5 received bOPV plus two doses of IPV at 14 and 36 weeks. Infants in all groups were challenged with monovalent type 2 vaccine (mOPV2) at 18 weeks (groups 1, 3, and 4) or 40 weeks (groups 2 and 5). The primary objective was to assess the superiority of bOPV-IPV schedules over bOPV alone, as assessed by the primary endpoints of humoral immunity (neutralising antibodies-ie, seroconversion) to all three serotypes and intestinal immunity (faecal viral shedding post-challenge) to serotype 2, analysed in the per-protocol population. Serious and medically important adverse events were monitored for up to 6 months after the study vaccination. This study is registered with ClinicalTrials.gov, number NCT01831050, and has been completed. Between May 20, 2013, and Aug 15, 2013, 940 eligible infants were enrolled and randomly assigned to the five treatment groups (210 to group 1, 210 to group 2, 100 to group 3, 210 to group 4, and 210 to group 5). One infant in group 1 was not vaccinated because their parents withdrew consent after enrolment and randomisation, so 939 infants actually received the vaccinations. Three doses of bOPV or tOPV elicited type 1 and 3 seroconversion rates of at least 97·7%. Type 2 seroconversion occurred in 19 of 198 infants (9·6%, 95% CI 6·2-14·5) in the bOPV-only groups, 86 of 88 (97·7%, 92·1-99·4) in the tOPV-only group (p<0·0001 vs bOPV-only), and 156 of 194 (80·4%, 74·3-85·4) infants in the bOPV-one dose of IPV group (p<0·0001 vs bOPV-only). A further 20 of 193 (10%) infants in the latter group seroconverted 1 week after mOPV2 challenge, resulting in around 98% of infants being seropositive against type 2. After a bOPV-two IPV schedule, all 193 infants (100%, 98·0-100; p<0·0001 vs bOPV-only) seroconverted to type 2. IPV induced small but significant decreases in a composite serotype 2 viral shedding index after mOPV2 challenge. 21 serious adverse events were reported in 20 patients during the study, including two that were judged to be possibly related to the vaccines. Most of the serious adverse events (18 [86%] of 21) and 24 (80%) of the 30 important medical events reported were infections and infestations. No deaths occurred during the study. bOPV provided humoral protection similar to tOPV against polio serotypes 1 and 3. After one or two IPV doses in addition to bOPV, 80% and 100% of infants seroconverted, respectively, and the vaccination induced a degree of intestinal immunity against type 2 poliovirus. Bill & Melinda Gates Foundation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Toward mass producible ordered bulk heterojunction organic photovoltaic devices.

PubMed

Kim, Taeyong; Yoon, Hyunsik; Song, Hyung-Jun; Haberkorn, Niko; Cho, Younghyun; Sung, Seung Hyun; Lee, Chang Hee; Char, Kookheon; Theato, Patrick

2012-12-13

A strategy to fabricate nanostructured poly(3-hexylthiophene) (P3HT) films for organic photovoltaic (OPV) cells by a direct transfer method from a reusable soft replica mold is presented. The flexible polyfluoropolyether (PFPE) replica mold allows low-pressure and low- temperature process condition for the successful transfer of nanostructured P3HT films onto PEDOT/PSS-coated ITO substrates. To reduce the fabrication cost of masters in large area, we employed well-ordered anodic aluminum oxide (AAO) as a template. Also, we provide a method to fabricate reversed nanostructures by exploiting the self-replication of replica molds. The concept of the transfer method in low temperature with a flexible and reusable replica mold obtained from an AAO template will be a firm foundation for a low-cost fabrication process of ordered OPVs. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solution-Processable Low-Molecular Weight Extended Arylacetylenes: Versatile p-Type Semiconductors for Field-Effect Transistors and Bulk Heterojunction Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silvestri, Fabio; Marrocchi, Assunta; Seri, Mirko

2010-04-08

We report the synthesis and characterization of a series of five extended arylacetylenes, 9,10-bis-{[m,p-bis(hexyloxy)phenyl]ethynyl}-anthracene (A-P6t, 1), 9,10-bis-[(p-{[m,p-bis(hexyloxy) phenyl]ethynyl}phenyl)ethynyl]-anthracene (PA-P6t, 2), 4,7-bis-{[m,p-bis(hexyloxy)phenyl]ethynyl}-2,1,3-benzothiadiazole (BTZ-P6t, 5), 4,7-bis(5-{[m,p-bis(hexyloxy)phenyl]ethynyl}thien-2-yl)-2,1,3-benzothiadiazole (TBTZ-P6t, 6), and 7,7'-({[m,p-bis(hexyloxy)phenyl]ethynyl}-2,1,3-benzothiadiazol-4,4'-ethynyl)-2,5-thiophene (BTZT-P6t, 7), and two arylvinylenes, 9,10-bis-{(E)-[m,p-bis(hexyloxy)phenyl]vinyl}-anthracene (A-P6d, 3), 9,10-bis-[(E)-(p-{(E)-[m,p-bis(hexyloxy)phenyl]vinyl}phenyl)vinyl]-anthracene (PA-P6d, 4). Trends in optical absorption spectra and electrochemical redox processes are first described. Next, the thin-film microstructures and morphologies of films deposited from solution under various conditions are investigated, and organic field-effect transistors (OFETs) and bulk heterojunction photovoltaic (OPV) cells fabricated. We find that substituting acetylenic for olefinic linkers on the molecular cores significantly enhances device performance. OFET measurements reveal that allmore » seven of the semiconductors are FET-active and, depending on the backbone architecture, the arylacetylenes exhibit good p-type mobilities (μ up to ~0.1 cm 2 V -1 s -1) when optimum film microstructural order is achieved. OPV cells using [6,6]-phenyl C 61-butyric acid methyl ester (PCBM) as the electron acceptor exhibit power conversion efficiencies (PCEs) up to 1.3% under a simulated AM 1.5 solar irradiation of 100 mW/cm 2. These results demonstrate that arylacetylenes are promising hole-transport materials for p-channel OFETs and promising donors for organic solar cells applications. A direct correlation between OFET arylacetylene hole mobility and OPV performance is identified and analyzed.« less

[The spread of the wild Poliovirus in the rural environment, the case of the Adzopé health district, Côte d'Ivoire].

PubMed

Akoua-Koffi, C G; Nekouressi, G; Tieoulou, L; Guillot, S; Faye-Kette, H; Ehouman, A

2004-05-01

Wild Poliovirus spreading in rural environment in Adzopé, Côte d'Ivoire In order to determine the level of wild Poliovirus spreading among rural children in an endemic poliomyelitis country 469 stools samples, from children aged between three weeks and twelve years old were processed according to WHO procedures for transportation, conservation, isolation and identification of Poliovirus. Intratypic differenciation was performed by an antigenic method using monoclonal antibodies and a genomic RFLP (Restriction Fragment Length Polymorphism). 50 Poliovirus strains (10.7%) were isolated and analyzed: 15 vaccine-like Poliovirus type 1 (30%), 30 vaccine-like Poliovirus type 2 (60%), 4 vaccine-like Poliovirus type 3 (8%) and one wild Poliovirus type 3 (2%). As expected, in the major cases the duration of post-vaccinal viral excretion did not exceed two months. However, in 14% of cases, it varied between 3 and 9 months after the third OPV dose. This long excretion could be due to an inefficient local intestinal immunity or no local immunity at all, in spite of the three OPV doses. These results argue in favor of an increase of the number of OPV doses in such endemic zones. Moreover, OPV strains are well-known to revert to pathogenicity in vaccinees, therefore, the long term excretion of pathogenic OPV derived strains by a certain amount of vaccinees needs to be considered quite seriously.

Community transmission of type 2 poliovirus after cessation of trivalent oral polio vaccine in Bangladesh: an open-label cluster-randomised trial and modelling study.

PubMed

Taniuchi, Mami; Famulare, Michael; Zaman, Khalequ; Uddin, Md Jashim; Upfill-Brown, Alexander M; Ahmed, Tahmina; Saha, Parimalendu; Haque, Rashidul; Bandyopadhyay, Ananda S; Modlin, John F; Platts-Mills, James A; Houpt, Eric R; Yunus, Mohammed; Petri, William A

2017-10-01

Trivalent oral polio vaccine (tOPV) was replaced worldwide from April, 2016, by bivalent types 1 and 3 oral polio vaccine (bOPV) and one dose of inactivated polio vaccine (IPV) where available. The risk of transmission of type 2 poliovirus or Sabin 2 virus on re-introduction or resurgence of type 2 poliovirus after this switch is not understood completely. We aimed to assess the risk of Sabin 2 transmission after a polio vaccination campaign with a monovalent type 2 oral polio vaccine (mOPV2). We did an open-label cluster-randomised trial in villages in the Matlab region of Bangladesh. We randomly allocated villages (clusters) to either: tOPV at age 6 weeks, 10 weeks, and 14 weeks; or bOPV at age 6 weeks, 10 weeks, and 14 weeks and either one dose of IPV at age 14 weeks or two doses of IPV at age 14 weeks and 18 weeks. After completion of enrolment, we implemented an mOPV2 vaccination campaign that targeted 40% of children younger than 5 years, regardless of enrolment status. The primary outcome was Sabin 2 incidence in the 10 weeks after the campaign in per-protocol infants who did not receive mOPV2, as assessed by faecal shedding of Sabin 2 by reverse transcriptase quantitative PCR (RT-qPCR). The effect of previous immunity on incidence was also investigated with a dynamical model of poliovirus transmission to observe prevalence and incidence of Sabin 2 virus. This trial is registered at ClinicalTrials.gov, number NCT02477046. Between April 30, 2015, and Jan 14, 2016, individuals from 67 villages were enrolled to the study. 22 villages (300 infants) were randomly assigned tOPV, 23 villages (310 infants) were allocated bOPV and one dose of IPV, and 22 villages (329 infants) were assigned bOPV and two doses of IPV. Faecal shedding of Sabin 2 in infants who did not receive the mOPV2 challenge did not differ between children immunised with bOPV and one or two doses of IPV and those who received tOPV (15 of 252 [6%] vs six of 122 [4%]; odds ratio [OR] 1·29, 95% CI 0·45-3·72; p=0·310). However, faecal shedding of Sabin 2 in household contacts was increased significantly with bOPV and one or two doses of IPV compared with tOPV (17 of 751 [2%] vs three of 353 [1%]; OR 3·60, 95% CI 0·82-15·9; p=0·045). Dynamical modelling of within-household incidence showed that immunity in household contacts limited transmission. In this study, simulating 1 year of tOPV cessation, Sabin 2 transmission was higher in household contacts of mOPV2 recipients in villages receiving bOPV and either one or two doses of IPV, but transmission was not increased in the community as a whole as shown by the non-significant difference in incidence among infants. Dynamical modelling indicates that transmission risk will be higher with more time since cessation. Bill & Melinda Gates Foundation. Copyright © 2017 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.

Morphology characterization of organic solar cell materials and blends

NASA Astrophysics Data System (ADS)

Roehling, John Daniel

The organization of polymers and fullerenes, both in their pure states and mixed together, have a large impact on their macroscopic properties. For mixtures used in organic solar cells, the morphology of the mixture has a very large impact upon the mixture's ability to efficiently convert sunlight into useful electrical energy. Understanding how the morphology can change under certain processing conditions and in turn, affect the characteristics of the solar cell is therefore important to improving the function of organic solar cells. Conventional poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) solar cells have served as a staple system to study organic solar cell function for nearly a decade. Much of the understanding of how to make these "poorly"conductive organic materials efficiently convert sunlight into electricity has come from the study of P3HT:PCBM. It has long been understood that in order for a polymer:fullerene (electron donor and acceptor, respectively) mixture to function well as a solar cell, two major criteria for the morphology must be met; first, the interface between the two materials must be large to efficiently create charges, and secondly, there must be continous pathways through the "pure" materials for charges to be efficiently collected at the electrodes. This makes it advantageous for OPV materials to phase-separate into interconnected domains with very small domain sizes, a structure that P3HT:PCBM seems to naturally self-assemble. Despite P3HT:PCBM's ability to reach an optimal morphology, a complete understanding of exactly how the morphology affects device performance has not been realized. Completely different morphological models can end up predicting the same device performance characteristics. Much of the problem comes from the assumed morphology within a particular model, which can often be incorrect. The problem lies in the fact that obtaining real, accurate morphological information is difficult. An often neglected morphological feature is the existence of a third mixed phase, which is often unaccounted for because much about its composition and location are poorly understood. Obtaining this information and measuring the full morphology of OPV layers would therefore enable further understanding of device function. It is the aim of this thesis to demonstrate a technique which can measure the morphology of OPV layers accurately, accounting for the third phase and its composition. By using a scanning transmission electron microscope (STEM) in conjunction with electron tomography (ET) and an easily resolved fullerene component, the morphology of P3HT:fullerene layers are herein investigated. The combination of materials and techniques are demonstrated to accurately measure the morphology, illustrated by results which corroborate previous studies in the literature. It will be shown that not only can the position of each of the three phases present be measured, but their compositions can also be determined. Through this technique, morphologies formed under different processing conditions are quantitatively compared. The technique reveals differences between conventional processing methods that are not obvious through other measurements. Differences in the materials distribution throughout the thickness of the layer are also demonstrated and shown to give implications toward device function. Additionally, the precise changes in morphology which occur from different processing conditions are determined and shown to have a significant impact upon the properties of an OPV layer as a solar energy harvester. Not only does the morphology of the mixed materials affect the solar cell properties, but the local structure of the component materials themselves can strongly influence the macroscopic properties. By removing the fullerene component and forming pure domains of P3HT, the effects of internal structure on the properties of P3HT and how the structure is formed is also herein investigated. Through these techniques, the morphology and structure of different organic solar cell mixtures can now be thoroughly investigated. Through this work and future studies, the exact effects of morphology can be more fully understood. With the availability of accurate morphological data, it may now be possible to decouple morphology from other factors which govern device function.

Analysis of the aging/stability process of organic solar cells based on PTB7:[70]PCBM and an alternative free-vacuum deposited cathode: the effect of active layer scaling

NASA Astrophysics Data System (ADS)

Barreiro-Argüelles, Denisse; Ramos-Ortiz, Gabriel; Maldonado, José-Luis L.; Romero-Borja, Daniel; Meneses-Nava, Marco-Antonio; Pérez-Gutiérrez, Enrique

2017-08-01

The PV performance and aging/stability of organic photovoltaic (OPV) devices based on the well-known system PTB7:[70]PCBM and an alternative air-stable electrode deposited at room conditions are fully studied when the active area is scaled by a factor of 25. On the other hand, the aging/stability processes were also studied through single diode model, impedance spectroscopy and light-beam induced current (LBIC) measurements in accordance with the established ISOS-D1 (dark storage) and ISOS-L1 (illumination conditions) protocols. Results are a good indication that the alternative cathode Field's metal (FM) cathode works as an encapsulating material and provides excellent PV performance comparable with the common and costly high-vacuum evaporated Al cathode.

Immunogenicity and safety evaluation of bivalent types 1 and 3 oral poliovirus vaccine by comparing different poliomyelitis vaccination schedules in China: A randomized controlled non-inferiority clinical trial

PubMed Central

Qiu, Jingjun; Yang, Yunkai; Huang, Lirong; Wang, Ling; Jiang, Zhiwei; Gong, Jian; Wang, Wei; Wang, Hongyan; Guo, Shaohong; Li, Chanjuan; Wei, Shuyuan; Mo, Zhaojun; Xia, Jielai

2017-01-01

ABSTRACT Background: The type 2 component of the oral poliovirus vaccine is targeted for global withdrawal through a switch from the trivalent oral poliovirus vaccine (tOPV) to a bivalent oral poliovirus vaccine (bOPV). The switch is intended to prevent paralytic polio caused by circulating vaccine-derived poliovirus type 2. We aimed to assess the immunogenicity and safety profile of 6 vaccination schedules with different sequential doses of inactivated poliovirus vaccine (IPV), tOPV, or bOPV. Methods: A randomized controlled trial was conducted in China in 2015. Healthy newborn babies randomly received one of the following 6 vaccination schedules: cIPV-bOPV-bOPV(I-B-B), cIPV-tOPV-tOPV(I-T-T), cIPV-cIPV-bOPV(I-I-B), cIPV-cIPV-tOPV(I-I-T), cIPV-cIPV-cIPV(I-I-I), or tOPV-tOPV-tOPV(T-T-T). Doses were administered sequentially at 4–6 week intervals after collecting baseline blood samples. Patients were proactively followed up for observation of adverse events after the first dose and 30 days after all doses. The primary study objective was to investigate the immunogenicity and safety profile of different vaccine schedules, evaluated by seroconversion, seroprotection and antibody titer against poliovirus types 1, 2, and 3 in the per-protocol population. Results: Of 600 newborn babies enrolled, 504 (84.0%) were included in the per-protocol population. For type 1 poliovirus, the differences in the seroconversion were 1.17% (95% CI = −2.74%, 5.08%) between I-B-B and I-T-T and 0.00% (95% CI: −6.99%, 6.99%) between I-I-B and I-I-T; for type 3 poliovirus, differences in the seroconversion were 3.49% (95% CI: −1.50%, 8.48%) between I-B-B and I-T-T and −2.32% (95% CI: −5.51%, 0.86%) between I-I-B and I-I-T. The non-inferiority conclusion was achieved in both poliovirus type 1 and 3 with the margin of −10%. Of 24 serious adverse events reported, no one was vaccine-related. Conclusions: The vaccination schedules with bOPV followed by one or 2 doses of IPV were recommended to substitute for vaccinations involving tOPV without compromising the immunogenicity and safety in the Chinese population. The findings will be essential for policy formulation by national and global authorities to facilitate polio elimination. PMID:28362135

The Dual Role of Disorder on the Dissociation of Interfacial Charge Transfer Excitons

NASA Astrophysics Data System (ADS)

Shi, Liang; Lee, Chee-Kong; Willard, Adam

In organic-based photovoltaics (OPV), dissociation of neutral photo-excitations (i.e., Frenkel excitons) into free charge carriers requires the excitons to overcome binding energy that can significantly exceed thermal energies. The inability of bound charges to overcome this large binding energy has been implicated as a primary source of efficiency loss in OPVs. Despite the potential impact on the performance of organic solar cells much remains to be understood about the microscopic mechanism of exciton dissociation in OPV materials. Here we explore the role of static molecular disorder in mediating this charge dissociation process. Using a simple lattice model of exciton dynamics we demonstrate that random spatial variations in the energetic landscape can mitigate the effects of the exciton binding energy by lowering the free energy barrier. By considering the competition between this thermodynamic effect and the disorder-induced slowing of dissociation kinetics we demonstrate that exciton dissociation yields are expected to depend non-monotonically on the degree of static disorder. We conclude that a certain amount of molecular-scale disorder is desirable in order to optimize the performance of organic photovoltaic materials.

Key issues in the persistence of poliomyelitis in Nigeria: a case-control study.

PubMed

Mangal, Tara D; Aylward, R Bruce; Mwanza, Michael; Gasasira, Alex; Abanida, Emmanuel; Pate, Muhammed A; Grassly, Nicholas C

2014-02-01

The completion of poliomyelitis eradication is a global emergency for public health. In 2012, more than 50% of the world's cases occurred in Nigeria following an unanticipated surge in incidence. We aimed to quantitatively analyse the key factors sustaining transmission of poliomyelitis in Nigeria and to calculate clinical efficacy estimates for the oral poliovirus vaccines (OPV) currently in use. We used acute flaccid paralysis (AFP) surveillance data from Nigeria collected between January, 2001, and December, 2012, to estimate the clinical efficacies of all four OPVs in use and combined this with vaccination coverage to estimate the effect of the introduction of monovalent and bivalent OPV on vaccine-induced serotype-specific population immunity. Vaccine efficacy was determined using a case-control study with CIs based on bootstrap resampling. Vaccine efficacy was also estimated separately for north and south Nigeria, by age of the children, and by year. Detailed 60-day follow-up data were collected from children with confirmed poliomyelitis and were used to assess correlates of vaccine status. We also quantitatively assessed the epidemiology of poliomyelitis and programme performance and considered the reasons for the high vaccine refusal rate along with risk factors for a given local government area reporting a case. Against serotype 1, both monovalent OPV (median 32.1%, 95% CI 26.1-38.1) and bivalent OPV (29.5%, 20.1-38.4) had higher clinical efficacy than trivalent OPV (19.4%, 16.1-22.8). Corresponding data for serotype 3 were 43.2% (23.1-61.1) and 23.8% (5.3-44.9) compared with 18.0% (14.1-22.1). Combined with increases in coverage, this factor has boosted population immunity in children younger than age 36 months to a record high (64-69% against serotypes 1 and 3). Vaccine efficacy in northern states was estimated to be significantly lower than in southern states (p≤0.05). The proportion of cases refusing vaccination decreased from 37-72% in 2008 to 21-51% in 2012 for routine and supplementary immunisation, and most caregivers cited ignorance of either vaccine importance or availability as the main reason for missing routine vaccinations (32.1% and 29.6% of cases, respectively). Multiple regression analyses highlighted associations between the age of the mother, availability of OPV at health facilities, and the primary source of health information and the probability of receiving OPV (all p<0.05). Although high refusal rates, low OPV campaign awareness, and heterogeneous population immunity continued to support poliomyelitis transmission in Nigeria at the end of 2012, overall population immunity had improved due to new OPV formulations and improvements in programme delivery. Bill & Melinda Gates Foundation Vaccine Modeling Initiative, Royal Society. Copyright © 2014 Mangal et al. Open Access article distributed under the terms of CC BY-NC-SA. Published by .. All rights reserved.

Does oral polio vaccine at birth affect the size of the thymus? Observations within a randomized trial.

PubMed

Eriksen, Helle Brander; Lund, Najaaraq; Biering-Sørensen, Sofie; Correia, Cizete; Barbosa, Amarildo; Andersen, Andreas; Aaby, Peter; Jeppesen, Dorthe L; Benn, Christine Stabell

2014-05-30

There is increasing evidence that vaccines have an effect on general mortality which goes beyond specific disease protection. Oral polio vaccine (OPV) is widely used in low-income countries, but in observational studies in Guinea-Bissau we observed that not receiving OPV at birth was associated with reduced overall male infant mortality and enhanced immune response to BCG vaccine. We therefore initiated a randomized trial to test the overall effect of OPV at birth (OPV0). A small thymic gland is a predictor of mortality in high-mortality settings. Within the trial we aimed to test whether no-OPV0 was associated with increased thymic size. In 511 normal birth weight infants who were randomized to receive or not receive OPV0, thymic index and thymus/weight index were measured before randomization and after 2 weeks (N=49), 4 weeks (N=308) or 6 weeks (N=27). The association between OPV0 and the log transformed thymic size indicators were analyzed in ANCOVA models with thymic size at follow-up as the outcome and adjusting for thymic size at enrollment and age at follow-up. Estimates were reported as geometric mean ratios (GMR) with 95% confidence intervals, comparing no-OPV0 to OPV0. No-OPV0 was not associated with thymic index after 2 weeks (GMR: 1.14 (0.99-1.30)), after 4 weeks (GMR: 0.98 (0.93-1.05)) or after 6 weeks (GMR: 1.00 (0.81-1.23)). However, no-OPV0 was associated with increased thymus/weight index after 2 weeks (GMR: 1.22 (1.06-1.40)), but the effect was not seen after 4 weeks (GMR: 0.97 (0.92-1.03)) and 6 weeks (GMR: 0.99 (0.82-1.19)). There were no strong sex-differences. Overall there was no effect on thymic size of OPV0 when administered with BCG. The results could indicate that if an effect occurs, it is only within the first weeks after vaccination. Copyright © 2014 Elsevier Ltd. All rights reserved.

An economic analysis of poliovirus risk management policy options for 2013-2052.

PubMed

Duintjer Tebbens, Radboud J; Pallansch, Mark A; Cochi, Stephen L; Wassilak, Steven G F; Thompson, Kimberly M

2015-09-24

The Global Polio Eradication Initiative plans for coordinated cessation of oral poliovirus vaccine (OPV) after interrupting all wild poliovirus (WPV) transmission, but many questions remain related to long-term poliovirus risk management policies. We used an integrated dynamic poliovirus transmission and stochastic risk model to simulate possible futures and estimate the health and economic outcomes of maintaining the 2013 status quo of continued OPV use in most developing countries compared with OPV cessation policies with various assumptions about global inactivated poliovirus vaccine (IPV) adoption. Continued OPV use after global WPV eradication leads to continued high costs and/or high cases. Global OPV cessation comes with a high probability of at least one outbreak, which aggressive outbreak response can successfully control in most instances. A low but non-zero probability exists of uncontrolled outbreaks following a poliovirus reintroduction long after OPV cessation in a population in which IPV-alone cannot prevent poliovirus transmission. We estimate global incremental net benefits during 2013-2052 of approximately $16 billion (US$2013) for OPV cessation with at least one IPV routine immunization dose in all countries until 2024 compared to continued OPV use, although significant uncertainty remains associated with the frequency of exportations between populations and the implementation of long term risk management policies. Global OPV cessation offers the possibility of large future health and economic benefits compared to continued OPV use. Long-term poliovirus risk management interventions matter (e.g., IPV use duration, outbreak response, containment, continued surveillance, stockpile size and contents, vaccine production site requirements, potential antiviral drugs, and potential safer vaccines) and require careful consideration. Risk management activities can help to ensure a low risk of uncontrolled outbreaks and preserve or further increase the positive net benefits of OPV cessation. Important uncertainties will require more research, including characterizing immunodeficient long-term poliovirus excretor risks, containment risks, and the kinetics of outbreaks and response in an unprecedented world without widespread live poliovirus exposure.

Cross-sectional serologic assessment of immunity to poliovirus infection in high-risk areas of northern India.

PubMed

Bahl, Sunil; Estívariz, Concepción F; Sutter, Roland W; Sarkar, Bidyut K; Verma, Harish; Jain, Vibhor; Agrawal, Ashutosh; Rathee, Mandeep; Shukla, Hemant; Pathyarch, Surendra K; Sethi, Raman; Wannemuehler, Kathleen A; Jafari, Hamid; Deshpande, Jagadish M

2014-11-01

The objectives of this survey were to assess the seroprevalence of antibodies to poliovirus types 1 and 3 and the impact of bivalent (types 1 and 3) oral poliovirus vaccine (bOPV) use in immunization campaigns in northern India. In August 2010, a 2-stage stratified cluster sampling method identified infants aged 6-7 months in high-risk blocks for wild poliovirus infection. Vaccination history, weight and length, and serum were collected to test for neutralizing antibodies to poliovirus types 1, 2, and 3. Seroprevalences of antibodies to poliovirus types 1, 2, and 3 were 98% (95% confidence interval [CI], 97%-99%), 66% (95% CI, 62%-69%), and 77% (95% CI, 75%-79%), respectively, among 664 infants from Bihar and 616 infants from Uttar Pradesh. Infants had received a median of 3 bOPV doses and 2 monovalent type 1 OPV (mOPV1) doses through campaigns and 3 trivalent OPV (tOPV) doses through routine immunization. Among subjects with 0 tOPV doses, the seroprevalences of antibodies to type 3 were 50%, 77%, and 82% after 2, 3, and 4 bOPV doses, respectively. In multivariable analysis, malnutrition was associated with a lower seroprevalence of type 3 antibodies. This study confirmed that replacing mOPV1 with bOPV in campaigns was successful in maintaining very high population immunity to type 1 poliovirus and substantially decreasing the immunity gap to type 3 poliovirus. Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Possible global strategies for stopping polio vaccination and how they could be harmonized.

PubMed

Cochi, S L; Sutter, R W; Aylward, R B

2001-01-01

One of the challenges of the polio eradication initiative over the next few years will be the formulation of an optimal strategy for stopping poliovirus vaccination after global certification of polio eradication has been accomplished. This strategy must maximize the benefits and minimize the risks. A number of strategies are currently under consideration, including: (i) synchronized global discontinuation of use of oral poliovirus vaccine (OPV); (ii) regional or subregional coordinated OPV discontinuation; and (iii) moving from trivalent to bivalent or monovalent OPV. Other options include moving from OPV to global use of IPV for an interim period before cessation of IPV use (to eliminate circulation of vaccine-derived poliovirus, if necessary) or development of new OPV strains that are not transmissible. Each of these strategies is associated with specific advantages (financial benefits for OPV discontinuation) and disadvantages (cost of switch to IPV) and inherent uncertainties (risk of continued poliovirus circulation in certain populations or prolonged virus replication in immunodeficient persons). An ambitious research agenda addresses the remaining questions and issues. Nevertheless, several generalities are already clear. Unprecedented collaboration between countries, regions, and indeed the entire world will be required to implement a global OPV discontinuation strategy Regulatory approval will be needed for an interim bivalent OPV or for monovalent OPV in many countries. Manufacturers will need sufficient lead time to produce sufficient quantities of IPV Finally, the financial implications for any of these strategies need to be considered. Whatever strategy is followed it will be necessary to stockpile supplies of a poliovirus-containing vaccine (most probably all three types of monovalent OPV), and to develop contingency plans to respond should an outbreak of polio occur after stopping vaccination.

India's Research Contributions Towards Polio Eradication (1965-2015).

PubMed

John, T Jacob

2016-08-07

Pioneering research has been conducted in India during the past five decades, comprehensively covering epidemiology of poliovirus infection and of polio, efficacy and effectiveness of oral and inactivated polio vaccines (OPV, IPV) as well as pathogenesis of wild and vaccine polioviruses. It was estimated, based on epidemiology data, that India had a very heavy burden of polio, with average 500-1000 cases per day. Prevention was an urgent need, but OPV showed unacceptably low vaccine efficacy (VE) for poliovirus types 1 and 3. Having learned that response to sequential doses followed arithmetic pattern and not prime-boost principle, multiple doses were tested and found to be a simple intervention to increase VE. Eventually this knowledge became critical for polio eradication. Indian research demonstrated that monovalent OPV (mOPV) had nearly three timed higher VE than trivalent OPV (tOPV). Eventually, mOPV type 1 became essential to interrupt wild type 1 infection in many locations where the VE of tOPV was very low. Indian research pointed to the epidemiologic importance of direct person-to-person spread of wild polio viruses and the need and potential of IPV to prevent and control polio. Research on vaccine responses led to the understanding that OPV would become wild-like through back mutations and to the definition of eradication as interrupting transmission of both wild and vaccine-derived polioviruses. By asking and answering the right questions insequence, Indian polio research presaged and guided polio eradication.

Monovalent type-1 oral poliovirus vaccine given at short intervals in Pakistan: a randomised controlled, four-arm, open-label, non-inferiority trial.

PubMed

Mir, Fatima; Quadri, Farheen; Mach, Ondrej; Ahmed, Imran; Bhatti, Zaid; Khan, Asia; Rehman, Najeeb Ur; Durry, Elias; Salama, Maha; Oberste, Steven M; Weldon, William C; Sutter, Roland W; Zaidi, Anita K M

2015-08-01

Supplementary immunisation activities with oral poliovirus vaccines (OPVs) are usually separated by 4 week intervals; however, shorter intervals have been used in security-compromised areas and for rapid outbreak responses. We assessed the immunogenicity of monovalent type-1 oral poliovirus vaccine (mOPV1) given at shorter than usual intervals in Karachi, Pakistan. This was a multicentre, randomised, controlled, four-arm, open-label, non-inferiority trial done at five primary health-care centres in low-income communities in and around Karachi, Pakistan. Eligible participants were healthy newborn babies with a birthweight of at least 2·5 kg, for whom informed consent was provided by their parent or guardian, and lived less than 30 km from the study clinic. After receiving a birth dose of trivalent OPV, we enrolled and randomly assigned newborn babies (1:1:1:1) to receive two doses of mOPV1 with an interval of 1 week (mOPV1-1 week), 2 weeks (mOPV1-2 weeks), or 4 weeks (mOPV1-4 weeks) between doses, or two doses of bivalent OPV (bOPV) with an interval of 4 weeks between doses (bOPV-4 weeks). We gave the first study dose of OPV at age 6 weeks. We did the randomisation with a centrally generated, computerised allocation sequence with blocks of 16; participants' families and study physicians could not feasibly be masked to the allocations. Trial participants were excluded from local supplementary immunisation activities during the study period. The primary outcome was non-inferiority (within a 20% margin) between groups in seroconversion to type-1 poliovirus. The primary and safety analyses were done in the per-protocol population of infants who received all three doses of vaccine. This trial is registered with ClinicalTrials.gov, number NCT01586572, and is closed to new participants. Between March 1, 2012, and May 31, 2013, we enrolled 1009 newborn babies, and randomly assigned 829 (82%) to treatment. 554 (67%) of the 829 babies were included in the per-protocol analysis. Proportions of seroconversion to type-1 poliovirus were 107/135 (79%, 95% CI 72·4-86·1) with mOPV1-1 week, 108/135 (80%, 73·2-86·8) with mOPV1-2 weeks, 129/148 (87%, 80·9-92·0) with mOPV1-4 weeks, and 107/136 (79%, 71·8-85·6) with bOPV-4 weeks. Non-inferiority was shown between groups and no significant differences were noted. Ten participants died during the trial. Seven of these deaths occurred during the lead-in period before randomisation (two from diarrhoea, five from unknown causes). Three infants died from sepsis after random assignment. No deaths were attributed to the procedures or vaccines. Additionally, we noted no events of vaccine-associated paralysis. We identified no significant differences in responses to mOPV1 given with shorter intervals between doses than with the standard 4 week intervals. The short-interval strategy could be particularly beneficial when temporary windows of opportunity for safe access can be granted in areas of conflict--eg, during cease-fire periods. In such situations, we recommend shortening the interval between OPV doses to 7 days. World Health Organization. Copyright © 2015 World Health Organization. Published by Elsevier Ltd/Inc/BV. All rights reserved. Published by Elsevier Ltd.. All rights reserved.

Molecular analyses of oral polio vaccine samples.

PubMed

Poinar, H; Kuch, M; Pääbo, S

2001-04-27

It has been suggested that the human immunodeficiency virus (HIV), and thus the acquired immunodeficiency syndrome (AIDS) it causes, was inadvertently introduced to humans by the use of an oral polio vaccine (OPV) during a vaccination campaign launched by the Wistar Institute, Philadelphia, PA, USA, in the Belgian Congo in 1958 and 1959. The "OPV/AIDS hypothesis" suggests that the OPV used in this campaign was produced in chimpanzee kidney epithelial cell cultures rather than in monkey kidney cell cultures, as stated by H. Koprowski and co-workers, who produced the OPV. If chimpanzee cells were indeed used, this would lend support to the OPV/AIDS hypothesis, since chimpanzees harbor a simian immunodeficiency virus, widely accepted to be the origin of HIV-1. We analyzed several early OPV pools and found no evidence for the presence of chimpanzee DNA; by contrast, monkey DNA is present.

Hetero Bis-Addition of Spiro-Acetalized or Cyclohexanone Ring to 58π Fullerene Impacts Solubility and Mobility Balance in Polymer Solar Cells.

PubMed

Mikie, Tsubasa; Saeki, Akinori; Ikuma, Naohiko; Kokubo, Ken; Seki, Shu

2015-06-17

Fullerene bis-adducts are increasingly being studied to gain a high open circuit voltage (Voc) in bulk heterojunction organic photovoltaics (OPVs). We designed and synthesized homo and hetero bis-adduct [60]fullerenes by combining fused cyclohexanone or a five-membered spiro-acetalized unit (SAF5) with 1,2-dihydromethano (CH2), indene, or [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). These new eight 56π fullerenes showed a rational rise of the lowest unoccupied molecular orbital (LUMO). We perform a systematic study on the electrochemical property, solubility, morphology, and space-charge-limited current (SCLC) mobility. The best power conversion efficiency (PCE) of 4.43% (average, 4.36%) with the Voc of 0.80 V was obtained for poly(3-hexylthiophene) (P3HT) blended with SAF5/indene hetero bis-adduct, which is a marked advancement in PCE compared to the 0.9% of SAF5 monoadduct. More importantly, we elucidate an important role of mobility balance between hole and electron that correlates with the device PCEs. Besides, an empirical equation to extrapolate the solubilities of hetero bis-adducts is proposed on the basis of those of counter monoadducts. Our work offers a guide to mitigate barriers for exploring a large number of hetero bis-adduct fullerenes for efficient OPVs.

[Circulating vaccine-derived poliovirus type 2 outbreak in Democratic Republic of Congo 2011-2012].

PubMed

Bazira, L; Coulibaly, T; Mayenga, M; Ncharre, C; Yogolelo, R; Mbule, A; Moudzeo, H; Lwamba, P; Mulumba, A W; Cabore, J

2015-10-01

According to the WHO records of 2013, the incidence of poliomyelitis was reduced by more than 99%, the number of endemic countries decreased from 125 in 1988 to 3 in 2013 and over 10 million cases were prevented from poliomyelitis thanks to the intensive use of Oral polio vaccine (OPV). However, the emergence of circulating vaccine-derived poliovirus strains (cVDPV), causing serious epidemics like the wild poliovirus, is a major challenge on the final straight towards the goal of eradication and OPV cessation. This paper describes the cVDPVoutbreak that occurred in the Democratic Republic of Congo (DRC) from November 2011 to April 2012. All children under 15 years of age with acute flaccid paralysis (AFP) and confirmed presence of cVDPV in the stool samples were included. Thirty (30) children, all from the administrative territories of Bukama and Malemba Nkulu in the Katanga Province (south-east DRC), were reported. The virus responsible was the cVDPV type 2 (0.7% -3.5% divergent from the reference Sabin 2 strain) in 29 children (97%) and the ambiguous vaccine-derived poliovirus strain (0.7% divergent) was confirmed in one case (3%), a boy seventeen months old and already vaccinated four times with OPV. Twentyfive children (83%) were protected by any of the routine EPI vaccines and 3 children (10%) had never received any dose of OPV. In reaction, DRC has conducted five local campaigns over a period of 10 months (from January to October 2012) and the epidemic was stopped after the second round performed in March 2012. As elsewhere in similar conditions, low immunization coverage, poor sanitation conditions and the stop of the use of OPV2 have favoured the emergence of the third cVDPV epidemic in DRC. The implementation of the Strategic Plan for Polio eradication and endgame strategic plan 2013-2018 will prevent the emergence of cVDPV and set up the conditions for a coordinated OPV phase out.

A developing country perspective on vaccine-associated paralytic poliomyelitis.

PubMed

John, T Jacob

2004-01-01

When the Expanded Programme on Immunization was established and oral poliovirus vaccine (OPV) was introduced for developing countries to use exclusively, national leaders of public health had no opportunity to make an informed choice between OPV and the inactivated poliovirus vaccine (IPV). Today, as progress is made towards the goal of global eradication of poliomyelitis attributable to wild polioviruses, all developing countries where OPV is used face the risk of vaccine-associated paralytic poliomyelitis (VAPP). Until recently, awareness of VAPP has been poor and quantitative risk analysis scanty but it is now well known that the continued use of OPV perpetuates the risk of VAPP. Discontinuation or declining immunization coverage of OPV will increase the risk of emergence of circulating vaccine-derived polioviruses (cVDPV) that re-acquire wild virus-like properties and may cause outbreaks of polio. To eliminate the risk of cVDPV, either very high immunization coverage must be maintained as long as OPV is in use, or IPV should replace OPV. Stopping OPV without first achieving high immunization coverage with IPV is unwise on account of the possibility of emergence of cVDPV. Increasing numbers of developed nations prefer IPV, and manufacturing capacities have not been scaled up, so its price remains prohibitively high and unaffordable by developing countries, where, in addition, large-scale field experience with IPV is lacking. Under these circumstances, a policy shift to increase the use of IPV in national immunization programmes in developing countries is a necessary first step; once IPV coverage reaches high levels (over 85%), the withdrawal of OPV may begin.

Panoramic View of Electrochemical Pseudocapacitor and Organic Solar Cell Research in Molecularly Engineered Energy Materials (MEEM)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aguirre, Jordan C.; Ferreira, Amy; Ding, Hong

2014-07-09

Our program on capacitive energy storage is a comprehensive one that combines experimental and computational components to achieve a fundamental understanding of charge storage processes in redox-based materials, specifically transition metal oxides. Some of the highlights of this program are the identification of intercalation pseudocapacitance in Nb2O5, which enables high energy density to be achieved at high rates, and the development of a new route for synthesizing mesoporous films in which preformed nanocrystal building blocks are used in combination with polymer templating. The resulting material architectures have large surface areas and enable electrolyte access to the redox active pore walls,more » while the interconnected mesoporous film provides good electronic conductivity. Select first-principles density-functional theory studies of prototypical pseudocapacitor materials are reviewed, providing insight into the key physical and chemical features involved in charge transfer and ion diffusion. Rigorous multiscale physical models and numerical tools have been developed and used to reproduce electrochemical properties of carbon-based electrochemical capacitors with the ultimate objective of facilitating the optimization of electrode design. For the organic photovoltaic (OPV) program, our focus has been ongoing beyond the trial-and-error Edisonian approaches that have been responsible for the increase in power conversion efficiency of blend-cast (BC) bulk heterojunction blends of polymers and fullerenes. Our first approach has been to use molecular self-assembly to create the ideal nanometer-scale architecture using thermodynamics rather than relying on the kinetics of spontaneous phase segregation. We have created fullerenes that self-assemble into one-dimensional stacks and have shown that use of these self-assembled fullerenes lead to dramatically enhanced OPV performance relative to fullerenes that do not assemble. We also have created self-assembling conjugated polymers that form gels based on electrically continuous cross-linked micelles in solution, opening the possibility for water-processable “green” production of OPVs based on these materials. Our second approach has been to avoid kinetic control over phase separation by using a sequential processing (SqP) technique to deposit the polymer and fullerene materials in separate deposition steps. The polymer layer is deposited first, using solvents and deposition conditions that optimize the polymer crystallinity for swelling and hole mobility. The fullerene layer is then deposited in a second step from a solvent that swells the polymer but does not dissolve it, allowing the fullerene to penetrate into the polymer underlayer to the desired degree. Careful comparison of composition- and thickness-matched BC and SqP devices shows that SqP not only produces more efficient devices but also leads to devices that behave more consistently.« less

The global switch from trivalent oral polio vaccine (tOPV) to bivalent oral polio vaccine (bOPV): facts, experiences and lessons learned from the south-south zone; Nigeria, April 2016.

PubMed

Bassey, Bassey Enya; Braka, Fiona; Vaz, Rui Gama; Komakech, William; Maleghemi, Sylvester Toritseju; Koko, Richard; Igbu, Thompson; Ireye, Faith; Agwai, Sylvester; Akpan, Godwin Ubong; Tegegne, Sisay Gashu; Mohammed, Abdul-Aziz Garba; Okocha-Ejeko, Angela

2018-01-27

The globally synchronized switch from trivalent Oral Polio Vaccine (tOPV) to bivalent Oral Polio Vaccine (bOPV) took place in Nigeria on April 18th 2016. The country is divided into six geopolitical zones. This study reports the experiences and lessons learned from the switch process in the six states that make up Nigeria's south-south geopolitical zone. This was a descriptive retrospective review of Nigeria's switch plan and structures used for implementing the tOPV-bOPV switch in the south-south zone. Nigeria's National Polio Emergency Operation Centre (NPEOC) protocols, global guidelines and reports from switch supervisors during the switch were used to provide background information for this study. Quantitative data were derived from reviewing switch monitoring and validation documents as submitted to the NPEOC RESULTS: The switch process took place in all 3078 Health Facilities (HFs) and 123 Local Government Areas (LGAs) that make up the six states in the zone. A total of $139,430 was used for this process. The 'healthcare personnel' component received the highest budgetary allocation (59%) followed by the 'logistics' component (18%). Akwa Ibom state was allocated the highest number of healthcare personnel and hence received the most budgetary allocation compared to the six states (total healthcare personnel = 458, total budgetary allocation = $17,428). Validation of the switch process revealed that eight HFs in Bayelsa, Cross-River, Edo and Rivers states still possessed tOPV in cold-chain while six HFs in Cross-River and Rivers states had tOPV out of cold-chain but without the 'do not use' sticker. Akwa-Ibom was the only state in the zone to have bOPV and Inactivated Polio Vaccine (IPV) available in all its HFs monitored. The Nigerian tOPV-bOPV switch was successful. For future Oral Polio Vaccine (OPV) withdrawals, implementation of the switch plan would be more feasible with an earlier dissemination of funds from global donor organizations, which would greatly aid timely planning and preparations. Increased budgetary allocation to the 'logistics' component to accommodate unexpected hikes in transportation prices and the general inefficiencies with power supply in the country is also advised.

Community Circulation Patterns of Oral Polio Vaccine Serotypes 1, 2, and 3 After Mexican National Immunization Weeks

PubMed Central

Troy, Stephanie B.; Ferreyra-Reyes, Leticia; Huang, ChunHong; Sarnquist, Clea; Canizales-Quintero, Sergio; Nelson, Christine; Báez-Saldaña, Renata; Holubar, Marisa; Ferreira-Guerrero, Elizabeth; García-García, Lourdes; Maldonado, Yvonne A.

2014-01-01

Background. With wild poliovirus nearing eradication, preventing circulating vaccine-derived poliovirus (cVDPV) by understanding oral polio vaccine (OPV) community circulation is increasingly important. Mexico, where OPV is given only during biannual national immunization weeks (NIWs) but where children receive inactivated polio vaccine (IPV) as part of their primary regimen, provides a natural setting to study OPV community circulation. Methods. In total, 216 children and household contacts in Veracruz, Mexico, were enrolled, and monthly stool samples and questionnaires collected for 1 year; 2501 stool samples underwent RNA extraction, reverse transcription, and real-time polymerase chain reaction (PCR) to detect OPV serotypes 1, 2, and 3. Results. OPV was detected up to 7 months after an NIW, but not at 8 months. In total, 35% of samples collected from children vaccinated the prior month, but only 4% of other samples, contained OPV. Although each serotype was detected in similar proportions among OPV strains shed as a result of direct vaccination, 87% of OPV acquired through community spread was serotype 2 (P < .0001). Conclusions. Serotype 2 circulates longer and is transmitted more readily than serotypes 1 or 3 after NIWs in a Mexican community primarily vaccinated with IPV. This may be part of the reason why most isolated cVDPV has been serotype 2. PMID:24367038

Oral and Inactivated Poliovirus Vaccines in the Newborn: A review

PubMed Central

Mateen, Farrah J.; Shinohara, Russell T.; Sutter, Roland W.

2015-01-01

Background Oral poliovirus vaccine (OPV) remains the vaccine-of-choice for routine immunization and supplemental immunization activities (SIAs) to eradicate poliomyelitis globally. Recent data from India suggested lowerthanexpected immunogenicity of an OPV birth dose, prompting a review of the immunogenicity of OPV or inactivated poliovirus vaccine (IPV) when administered at birth. Methods We evaluated the seroconversion and reported adverse events among infants given a single birth dose (given ≤7 days of life) of OPV or IPV through a systematic review of published articles and conference abstracts from 1959-2011 in any language found on PubMed, Google Scholar, or reference lists of selected articles. Results 25 articles from 13 countries published between1959 and 2011 documented seroconversion rates in newborns following an OPV dose given within the first seven days of life. There were 10 studies that measured seroconversion rates between 4 and 8 weeks of a single birth dose of TOPV, using an umbilical cord blood draw at the time of birth to establish baseline antibody levels. The percentage of newborns who seroconverted at 8 weeks range 6-42% for poliovirus type 1, 2-63% for type 2, and 1-35% for type 3). For mOPV type 1, seroconversion ranged from 10-76%; mOPV type 3, the range was 12-58%; and for the one study reporting bOPV, it was 20% for type 1 and 7% for type 3. There were four studies of IPV in newborns with a seroconversion rate of 8-100% for serotype 1, 15-100% for serotype 2, and 15-94% for serotype 3, measured at 4-6 weeks of life. No serious adverse events related to newborn OPV or IPV dosing were reported, including no cases of acute flaccid paralysis. Conclusions There is great variability of the immunogenicity of a birth dose of OPV for reasons largely unknown. Our review confirms the utility of a birth dose of OPV, particularly in countries where early induction of polio immunity is imperative. IPV has higher seroconversion rates in newborns and may be a superior choice in countries which can afford IPV, but there have been studies of an IPV dose for newborns. PMID:22728224

Multifunctional organic thin films and their electronic/optical properties

NASA Astrophysics Data System (ADS)

Shao, Yan

The concept of multifunctional organic thin films and their electronic/optical properties has been applied to organic functional device design, fabrication, and characterization. The organic devices involve organic light-emitting diodes (OLEDs) and organic photovoltaic devices (OPV) in this dissertation. In the research of graded junction structure of OLEDs, two kinds of naturally-formed graded junction (NFGJ) structures, sharp and shallow graded junctions, can be formed using single thermal evaporation boat loaded with uniformly mixed charge transport and light-emitting materials. OLEDs with NFGJ have been demonstrated in Chapter 3; the performance is comparable to the heterojunction OLEDs, but with better device lifetime. A novel method to prepare highly uniform mixed organic solid solutions through a high temperature and high-pressure fusion process has been demonstrated in Chapter 4. A series of fused organic solid solution (FOSS) compounds with NPD doped with different organic emitting dopants were prepared and DSC technique was utilized to determine the thermal characteristics. For the first time, the schematic phase diagram for this binary system has been obtained. High performance OLEDs of single color and white emission were fabricated and the device properties were characterized. In Chapter 5, an efficient photovoltaic heterojunction of tetracene and fullerene has been investigated and high performance organic solar cells have been demonstrated by thermal deposition and successive heat treatment. The preliminary conclusion for this enhancement is discussed and supported by atomic force microscopy images, absorption spectra and x-ray diffraction analysis. Additionally, an effective organic photovoltaic heterojunction based on the typical triplet material PtOEP was demonstrated. It is believed that introducing appropriate organic materials with long exciton lifetime is a very promising way to improve photovoltaic performance.

Investigation of ITO free transparent conducting polymer based electrode

NASA Astrophysics Data System (ADS)

Sharma, Vikas; Sapna, Sachdev, Kanupriya

2016-05-01

The last few decades have seen a significant improvement in organic semiconductor technology related to solar cell, light emitting diode and display panels. The material and structure of the transparent electrode is one of the major concerns for superior performance of devices such as OPV, OLED, touch screen and LCD display. Commonly used ITO is now restricted due to scarcity of indium, its poor mechanical properties and rigidity, and mismatch of energy levels with the active layer. Nowadays DMD (dielectric-metal-dielectric) structure is one of the prominent candidates as alternatives to ITO based electrode. We have used solution based spin coated polymer layer as the dielectric layer with silver thin film embedded in between to make a polymer-metal-polymer (PMP) structure for TCE applications. The PMP structure shows low resistivity (2.3 x 10-4Ω-cm), high carrier concentration (2.9 x 1021 cm-3) and moderate transparency. The multilayer PMP structure is characterized with XRD, AFM and Hall measurement to prove its suitability for opto-electronic device applications.

An Alternative Anionic Polyelectrolyte for Aqueous PEDOT Dispersions: Toward Printable Transparent Electrodes.

PubMed

Hofmann, Anna I; Smaal, Wiljan T T; Mumtaz, Muhammad; Katsigiannopoulos, Dimitrios; Brochon, Cyril; Schütze, Falk; Hild, Olaf R; Cloutet, Eric; Hadziioannou, Georges

2015-07-13

Organic conducting polymers are promising electrode materials for printable organic electronics. One of the most studied conducting polymers is PSS, which is sufficiently conductive and transparent, but which shows some drawbacks, such as hygroscopicity and acidity. A new approach to stabilize PEDOT in aqueous dispersions involves the replacement of PSS with a basic polyanion based on a polystyrene backbone with (trifluoromethylsulfonyl)imide (TSFI) side groups. The PSTFSIK dispersions were obtained by oxidative polymerization of EDOT in an aqueous PSTFSIK solution and were characterized with regard to their composition, morphology, doping, rheological behavior, and optoelectronic performance. The PSTFSIK dispersions showed excellent printability and good optoelectronic performance (238 Ohm sq(-1) at 91% transmittance, σ>260 S cm(-1)) and were successfully integrated as flexible electrodes in OLED and OPV devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Shedding of Oral Poliovirus Vaccine (OPV) by HIV-Infected and -Uninfected Mothers of OPV-Vaccinated Zimbabwean Infants.

PubMed

Holubar, Marisa; Troy, Stephanie B; Nathoo, Kusum; Stranix-Chibanda, Lynda; Musingwini, Georgina; Srinivas, Nivedita; Huang, ChunHong; Junn, Alexandra; Halpern, Meira S; Maldonado, Yvonne A

2017-03-01

Community circulation of oral poliovirus vaccine (OPV) likely begins with household transmission. We analyzed stool collected from Zimbabwean mothers who were infected with human immunodeficiency virus (HIV) and those who were uninfected with HIV 1 to 24 weeks after infant oral poliovirus vaccination. Overall, only 5% of the mothers had detectable OPV (16 of 304) despite high infant shedding rates. OPV shedding was similar between HIV-infected mothers and those who were uninfected (11 [6.4%] of 171 vs 5 [3.8%] of 133, respectively) and between mothers of HIV-infected infants and those of uninfected infants (2 [3.5%] of 57 vs 9 [6.3%] of 144, respectively). Mothers of vaccinated infants are unlikely to shed OPV, even when they are infected with HIV. © Published by Oxford University Press on behalf of The Journal of the Pediatric Infectious Diseases Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Extensive Penetration of Evaporated Electrode Metals into Fullerene Films: Intercalated Metal Nanostructures and Influence on Device Architecture.

PubMed

Zhang, Guangye; Hawks, Steven A; Ngo, Chilan; Schelhas, Laura T; Scholes, D Tyler; Kang, Hyeyeon; Aguirre, Jordan C; Tolbert, Sarah H; Schwartz, Benjamin J

2015-11-18

Although it is known that evaporated metals can penetrate into films of various organic molecules that are a few nanometers thick, there has been little work aimed at exploring the interaction of the common electrode metals used in devices with fullerene derivatives, such as organic photovoltaics (OPVs) or perovskite solar cells that use fullerenes as electron transport layers. In this paper, we show that when commonly used electrode metals (e.g., Au, Ag, Al, Ca, etc.) are evaporated onto films of fullerene derivatives (such as [6,6]-phenyl-C61-butyric acid methyl ester (PCBM)), the metal penetrates many tens of nanometers into the fullerene layer. This penetration decreases the effective electrical thickness of fullerene-based sandwich structure devices, as measured by the device's geometric capacitance, and thus significantly alters the device physics. For the case of Au/PCBM, the metal penetrates a remarkable 70 nm into the fullerene, and we see penetration of similar magnitude in a wide variety of fullerene derivative/evaporated metal combinations. Moreover, using transmission electron microscopy to observed cross-sections of the films, we show that when gold is evaporated onto poly(3-hexylthiophene) (P3HT)/PCBM sequentially processed OPV quasi-bilayers, Au nanoparticles with diameters of ∼3-20 nm are formed and are dispersed entirely throughout the fullerene-rich overlayer. The plasmonic absorption and scattering from these nanoparticles are readily evident in the optical transmission spectrum, demonstrating that the interpenetrated metal significantly alters the optical properties of fullerene-rich active layers. This opens a number of possibilities in terms of contact engineering and light management so that metal penetration in devices that use fullerene derivatives could be used to advantage, making it critical that researchers are aware of the electronic and optical consequences of exposing fullerene-derivative films to evaporated electrode metals.

Water Based Inkjet Material Deposition Of Donor-Acceptor Nanoparticles For Usage In Organic Photovoltaics

NASA Astrophysics Data System (ADS)

Penmetcha, Anirudh Raju

Significant efficiency increases are being made for bulk heterojunction organic photovoltaic prototype devices with world records at 11%. However the chlorinated solvents most frequently used in prototype manufacture would cause local health and safety concerns or large scale environmental pollution upon expansion of these techniques for commercialization. Moreover, research to bridge prototype and large-scale production of these solar cells is still in its infancy. Most prototype devices are made in inert glove box environments using spin-coating. There is a need to develop a non-toxic ink and incorporate it into a material deposition system that can be used in mass production. In this thesis, P3HT:PCBM organic photovoltaic devices were fabricated with the help of inkjet printing. P3HT:PCBM blends were dissolved in organic solvent systems, and this solution was used as the ink for the printer. The "coffee-ring effect" as well as the effect of inkjet printing parameters on film formation were highlighted - thus the inkjet printing method was validated as a stepping stone between lab-scale production of OPVs and large-scale roll-to-roll manufacturing. To address the need of a non-toxic ink, P3HT:PCBM blends were then dispersed in water, using the miniemulsion method. The nanoparticles were characterized for their size, as well as the blending between the P3HT and PCBM within the nanoparticle. These dispersions were then converted into inks. Finally, these nanoparticle inks were inkjet-printed to fabricate OPV devices. Based on the results obtained here, tentative "next steps" have been outlined in order to improve upon this research work, in the future.

Eco-friendly graphene synthesis on Cu foil electroplated by reusing Cu etchants

PubMed Central

Kwon, Ki Chang; Ham, Juyoung; Kim, Sungjun; Lee, Jong-Lam; Kim, Soo Young

2014-01-01

Graphene film grown by chemical vapor deposition using Cu substrate is promising for industrial applications. After etching the Cu substrate, which is essential step in graphene transfer process, the etchant solution must be chemically treated to prevent water pollution. Here we investigated that a method of reusing Cu etchant used to synthesize graphene, the synthesis of graphene on the resulting reused Cu films (R-G), and the application of R-G to organic light-emitting diodes (OLEDs) and organic photovoltaic cells (OPVs). The turn-on voltage of OLEDs based on the R-G electrode was 4.2 V, and the efficiencies of OPVs based on the R-G electrode were 5.9–5.95%, that are similar to or better than those of the indium-tin-oxide-based devices. These results suggest that the reusing of Cu foil by the electroplating method could reduce the cost of graphene synthesis, thus opening a wide range of applications in graphene electronics. PMID:24777344

Diketopyrrolopyrrole-based polymer:fullerene nanoparticle films with thermally stable morphology for organic photovoltaic applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holmes, Natalie P.; Vaughan, Ben; Williams, Evan L.

Polymer:fullerene nanoparticles (NPs) offer two key advantages over bulk heterojunction (BHJ) films for organic photovoltaics (OPVs), water-processability and potentially superior morphological control. Once an optimal active layer morphology is reached, maintaining this morphology at OPV operating temperatures is key to the lifetime of a device. Here in this paper we study the morphology of the PDPP-TNT (poly{3,6-dithiophene-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-naphthalene}):PC 71BM ([6,6]-phenyl C 71 butyric acid methyl ester) NP system and then compare the thermal stability of NP and BHJ films to the common poly(3-hexylthiophene) (P3HT): phenyl C 61 butyric acid methyl ester (PC 61BM) system. We find that material T g playsmore » a key role in the superior thermal stability of the PDPP-TNT:PC 71BM system; whereas for the P3HT:PC 61BM system, domain structure is critical.« less

Effects of the Terminal Structure, Purity, and Molecular Weight of an Amorphous Conjugated Polymer on Its Photovoltaic Characteristics.

PubMed

Kuwabara, Junpei; Yasuda, Takeshi; Takase, Naoto; Kanbara, Takaki

2016-01-27

The photovoltaic characteristics of an amorphous polymer containing EDOT and fluorene units were investigated. In particular, the effects of the terminal structure, residual amount of Pd, and molecular weight were systematically investigated. Direct arylation polycondensation of EDOT followed by an established purification method readily afforded polymers with different terminal structures, Pd contents, and molecular weights. Of these factors, the terminal structure of the polymer was a crucial factor affecting the photovoltaic characteristics. For example, the polymer with a Br terminal had a PCE of 2.9% in bulk-heterojunction organic photovoltaics (BHJ OPVs) with a fullerene derivative, whereas the polymer without a Br terminal had a PCE of 4.6% in the same cell configuration. The decreased Pd residues and high molecular weights of the polymers increased the long-term stability of the devices. Moreover, BHJ OPVs containing the high-molecular-weight polymer could be fabricated with an environmentally friendly nonhalogenated solvent.

Primary and booster vaccination with an inactivated poliovirus vaccine (IPV) is immunogenic and well-tolerated in infants and toddlers in China.

PubMed

Li, Rongcheng; Li, Chang Gui; Li, Yanping; Liu, Youping; Zhao, Hong; Chen, Xiaoling; Kuriyakose, Sherine; Van Der Meeren, Olivier; Hardt, Karin; Hezareh, Marjan; Roy-Ghanta, Sumita

2016-03-14

Replacing live-attenuated oral poliovirus vaccines (OPV) with inactivated poliovirus vaccines (IPV) is part of the global strategy to eradicate poliomyelitis. China was declared polio-free in 2000 but continues to record cases of vaccine-associated-poliomyelitis and vaccine-derived-poliovirus outbreaks. Two pilot safety studies and two larger immunogenicity trials evaluated the non-inferiority of IPV (Poliorix™, GSK Vaccines, Belgium) versus OPV in infants and booster vaccination in toddlers primed with either IPV or OPV in China. In pilot safety studies, 25 infants received 3-dose IPV primary vaccination (Study A, www.clinicaltrial.gov NCT00937404) and 25 received an IPV booster after priming with three OPV doses (Study B, NCT01021293). In the randomised, controlled immunogenicity and safety trial (Study C, NCT00920439), infants received 3-dose primary vaccination with IPV (N=541) or OPV (N=535) at 2,3,4 months of age, and a booster IPV dose at 18-24 months (N=470, Study D, NCT01323647: extension of study C). Blood samples were collected before and one month post-dose-3 and booster. Reactogenicity was assessed using diary cards. Serious adverse events (SAEs) were captured throughout each study. Study A and B showed that IPV priming and IPV boosting (after OPV) was safe. Study C: One month post-dose-3, all IPV and ≥ 98.3% OPV recipients had seroprotective antibody titres towards each poliovirus type. The immune response elicited by IPV was non-inferior to Chinese OPV. Seroprotective antibody titres persisted in ≥ 94.7% IPV and ≥ 96.1% OPV recipients at 18-24 months (Study D). IPV had a clinically acceptable safety profile in all studies. Grade 3 local and systemic reactions were uncommon. No SAEs were related to IPV administration. Trivalent IPV is non-inferior to OPV in terms of seroprotection (in the Chinese vaccination schedule) in infant and toddlers, with a clinically acceptable safety profile. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Introduction of inactivated poliovirus vaccine leading into the polio eradication endgame strategic plan; Hangzhou, China, 2010-2014.

PubMed

Liu, Yan; Wang, Jun; Liu, Shijun; Du, Jian; Wang, Liang; Gu, Wenwen; Xu, Yuyang; Zuo, Shuyan; Xu, Erping; An, Zhijie

2017-03-01

China's Expanded Program on Immunization (EPI) has provided 4 doses of oral poliovirus vaccine (OPV) since the 1970s. Inactivated poliovirus vaccine (IPV) became available in 2010 in Hangzhou as a private-sector, parent-chosen alternative to OPV. In 2015, WHO recommended that countries with all-OPV vaccination schedules introduce at least one dose of IPV, to mitigate risk associated with the withdrawal of type 2 OPV. We analyzed polio vaccine coverage and utilization in Hangzhou to determine patterns of IPV use and the occurrence of vaccine-associated paralytic polio (VAPP) in the various patterns identified. Children born between 2010 and 2014 and registered in Hangzhou's Immunization Information System (HZIIS) were included. VAPP cases were detected through the acute flaccid paralysis surveillance system. We used descriptive epidemiological methods to determine IPV and OPV usage patterns and VAPP occurrence. HZIIS data from 566,894 children were analyzed. Coverage levels of polio vaccine were greater than 92% for each birth cohort. Percentages of children using OPV-only, IPV-only, and IPV/OPV sequential schedules were 70.57%, 27.01% and 2.41%, respectively. IPV-only schedule utilization increased by birth cohort regardless of geographical area or whether the child was locally-born. The highest use of an all-IPV schedule (79.85%) was among urban, locally-born children in the 2014 birth cohort. Five VAPP cases were identified during the study years; all cases occurred following the first polio vaccine dose, which was always OPV for the cases. Type 2 vaccine virus was isolated from 2 VAPP cases, and type 2 and type 3 vaccine virus was isolated from one VAPP case. The incidence of VAPP in the 2010-2014 birth cohorts was 3.76 per 1million doses of OPV. Children in Hangzhou had high polio vaccination coverage. IPV-only schedule use increased by year, and was highest in urban areas among locally-born children. All cases of VAPP were associated with the first dose of OPV. Copyright © 2017 Elsevier Ltd. All rights reserved.

The risk of type 2 oral polio vaccine use in post-cessation outbreak response.

PubMed

McCarthy, Kevin A; Chabot-Couture, Guillaume; Famulare, Michael; Lyons, Hil M; Mercer, Laina D

2017-10-04

Wild type 2 poliovirus was last observed in 1999. The Sabin-strain oral polio vaccine type 2 (OPV2) was critical to eradication, but it is known to revert to a neurovirulent phenotype, causing vaccine-associated paralytic poliomyelitis. OPV2 is also transmissible and can establish circulating lineages, called circulating vaccine-derived polioviruses (cVDPVs), which can also cause paralytic outbreaks. Thus, in April 2016, OPV2 was removed from immunization activities worldwide. Interrupting transmission of cVDPV2 lineages that survive cessation will require OPV2 in outbreak response, which risks seeding new cVDPVs. This potential cascade of outbreak responses seeding VDPVs, necessitating further outbreak responses, presents a critical risk to the OPV2 cessation effort. The EMOD individual-based disease transmission model was used to investigate OPV2 use in outbreak response post-cessation in West African populations. A hypothetical outbreak response in northwest Nigeria is modeled, and a cVDPV2 lineage is considered established if the Sabin strain escapes the response region and continues circulating 9 months post-response. The probability of this event was investigated in a variety of possible scenarios. Under a broad range of scenarios, the probability that widespread OPV2 use in outbreak response (~2 million doses) establishes new cVDPV2 lineages in this model may exceed 50% as soon as 18 months or as late as 4 years post-cessation. The risk of a cycle in which outbreak responses seed new cVDPV2 lineages suggests that OPV2 use should be managed carefully as time from cessation increases. It is unclear whether this risk can be mitigated in the long term, as mucosal immunity against type 2 poliovirus declines globally. Therefore, current programmatic strategies should aim to minimize the possibility that continued OPV2 use will be necessary in future years: conducting rapid and aggressive outbreak responses where cVDPV2 lineages are discovered, maintaining high-quality surveillance in all high-risk settings, strengthening the use of the inactivated polio vaccine as a booster in the OPV2-exposed and in routine immunization, and gaining access to currently inaccessible areas of the world to conduct surveillance.

Polio elimination in Nigeria: A review.

PubMed

Nasir, Usman Nakakana; Bandyopadhyay, Ananda Sankar; Montagnani, Francesca; Akite, Jacqueline Elaine; Mungu, Etaluka Blanche; Uche, Ifeanyi Valentine; Ismaila, Ahmed Mohammed

2016-03-03

Nigeria has made tremendous strides towards eliminating polio and has been free of wild polio virus (WPV) for more than a year as of August 2015. However, sustained focus towards getting rid of all types of poliovirus by improving population immunity and enhancing disease surveillance will be needed to ensure it sustains the polio-free status. We reviewed the pertinent literature including published and unpublished, official reports and working documents of the Global Polio Eradication Initiative (GPEI) partners as well as other concerned organizations. The literature were selected based on the following criteria: published in English Language, published after year 2000, relevant content and conformance to the theme of the review and these were sorted accordingly. The challenges facing the Polio Eradication Initiative (PEI) in Nigeria were found to fall into 3 broad categories viz failure to vaccinate, failure of the Oral Polio Vaccine (OPV) and epidemiology of the virus. Failure to vaccinate resulted from insecurity, heterogeneous political support, programmatic limitation in implementation of vaccination campaigns, poor performance of vaccination teams in persistently poor performing Local Government areas and sporadic vaccine refusals in Northern Nigeria. Sub optimal effectiveness of OPV in some settings as well as the rare occurrence of VDPVs associated with OPV type 2 in areas of low immunization coverage were also found to be key issues. Some of the innovations which helped to manage the threats to the PEI include a strong government accountability frame work, change from type 2 containing OPV to bi valent OPVs for supplementary immunization activities (SIA), enhancing environmental surveillance in key states (Sokoto, Kano and Borno) along with an overall improvement in SIA quality. There has been an improvement in coverage of routine immunization and vaccination campaigns, which has resulted in Nigeria being removed from the list of endemic countries following an absence of new cases for an entire year as of September 2015. However, the last mile remains to be crossed and there is need to further improve and sustain the momentum to complete the journey toward polio elimination.

Polio elimination in Nigeria: A review

PubMed Central

Nasir, Usman Nakakana; Bandyopadhyay, Ananda Sankar; Montagnani, Francesca; Akite, Jacqueline Elaine; Mungu, Etaluka Blanche; Uche, Ifeanyi Valentine; Ismaila, Ahmed Mohammed

2016-01-01

abstract Nigeria has made tremendous strides towards eliminating polio and has been free of wild polio virus (WPV) for more than a year as of August 2015. However, sustained focus towards getting rid of all types of poliovirus by improving population immunity and enhancing disease surveillance will be needed to ensure it sustains the polio-free status. We reviewed the pertinent literature including published and unpublished, official reports and working documents of the Global Polio Eradication Initiative (GPEI) partners as well as other concerned organizations. The literature were selected based on the following criteria: published in English Language, published after year 2000, relevant content and conformance to the theme of the review and these were sorted accordingly. The challenges facing the Polio Eradication Initiative (PEI) in Nigeria were found to fall into 3 broad categories viz failure to vaccinate, failure of the Oral Polio Vaccine (OPV) and epidemiology of the virus. Failure to vaccinate resulted from insecurity, heterogeneous political support, programmatic limitation in implementation of vaccination campaigns, poor performance of vaccination teams in persistently poor performing Local Government areas and sporadic vaccine refusals in Northern Nigeria. Sub optimal effectiveness of OPV in some settings as well as the rare occurrence of VDPVs associated with OPV type 2 in areas of low immunization coverage were also found to be key issues. Some of the innovations which helped to manage the threats to the PEI include a strong government accountability frame work, change from type 2 containing OPV to bi valent OPVs for supplementary immunization activities (SIA), enhancing environmental surveillance in key states (Sokoto, Kano and Borno) along with an overall improvement in SIA quality. There has been an improvement in coverage of routine immunization and vaccination campaigns, which has resulted in Nigeria being removed from the list of endemic countries following an absence of new cases for an entire year as of September 2015. However, the last mile remains to be crossed and there is need to further improve and sustain the momentum to complete the journey toward polio elimination. PMID:26383769

Quantifying low-frequency revertants in oral poliovirus vaccine using next generation sequencing.

PubMed

Sarcey, Eric; Serres, Aurélie; Tindy, Fabrice; Chareyre, Audrey; Ng, Siemon; Nicolas, Marine; Vetter, Emmanuelle; Bonnevay, Thierry; Abachin, Eric; Mallet, Laurent

2017-08-01

Spontaneous reversion to neurovirulence of live attenuated oral poliovirus vaccine (OPV) serotype 3 (chiefly involving the n.472U>C mutation), must be monitored during production to ensure vaccine safety and consistency. Mutant analysis by polymerase chain reaction and restriction enzyme cleavage (MAPREC) has long been endorsed by the World Health Organization as the preferred in vitro test for this purpose; however, it requires radiolabeling, which is no longer supported by many laboratories. We evaluated the performance and suitability of next generation sequencing (NGS) as an alternative to MAPREC. The linearity of NGS was demonstrated at revertant concentrations equivalent to the study range of 0.25%-1.5%. NGS repeatability and intermediate precision were comparable across all tested samples, and NGS was highly reproducible, irrespective of sequencing platform or analysis software used. NGS was performed on OPV serotype 3 working seed lots and monovalent bulks (n=21) that were previously tested using MAPREC, and which covered the representative range of vaccine production. Percentages of 472-C revertants identified by NGS and MAPREC were comparable and highly correlated (r≥0.80), with a Pearson correlation coefficient of 0.95585 (p<0.0001). NGS demonstrated statistically equivalent performance to that of MAPREC for quantifying low-frequency OPV serotype 3 revertants, and offers a valid alternative to MAPREC. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Solution Processed Organic Photovoltaic Cells Using D-A-D-A-D Type Small Molecular Donor Materials with Benzodithiophene and Diketopyrrolopyrrole Units.

PubMed

Park, Sangman; Nam, So Yeon; Suh, Dong Hack; Lee, Jaemin; Lee, Changjin; Yoon, Sung Cheol

2016-03-01

Organic photovoltaic Cells (OPVs) have been considered to be a next-generation energy source to overcome exhaustion of resources. Currently, OPVs are developed based on two types of donor material with polymer and small molecule. Polymeric donor materials have shown better power conversion efficiency (PCE) than small molecular donor materials, since it's easy to control the morphology of photoactive film. However, the difficulty in synthetic reproducibility and purification of polymeric donor were main drawback to overcome. And then, recently small molecule donor materials have been overcome bad morphology of OPVs film by using appropriate alkyl substituents and relatively long conjugation system. In this study, we designed and synthesized D-A-D-A-D type small molecular donor materials containing alternatively linked benzodithiophene (BDT) and diketopyrrolopyrrole (DPP) units. Also, we studied on the effect of photovoltaic performance of prepared small molecular D-A-D-A-D type donor with variation of thiophene links and with/without hexyl substituent. Our small molecular donors showed HOMO energy levels from -5.26 to -5.34 eV and optical bandgaps from 1.70 to 1.87 eV by CV (cyclic voltammetry) and UV/Vis spectroscopy, respectively. Finally, 3.4% of PCE can be obtained using a mixture of BDT(DPP)2-T2 and PCBM as an active layer with a Voc of 0.78 V, a Jsc of 9.72 mA/cm2, and a fill factor of 0.44 under 100 mW/cm2 AM 1.5G simulated light. We will discuss the performance of D-A-D-A-D type small molecular donor based OPVs with variation of both terminal substituents.

DNA fingerprinting of maize seed lots to establish genetic purity using SSR markers.

USDA-ARS?s Scientific Manuscript database

Most countries in sub-Saharan Africa (SSA) grow open pollinated maize varieties (OPVs) because seed of maize OPVs can be recycled for several seasons with minimal yield reduction due to inbreeding as compared to hybrids. However, OPVs are heterogeneous, and some local seed suppliers attempt to take ...

Update on Vaccine-Derived Polioviruses - Worldwide, January 2015-May 2016.

PubMed

Jorba, Jaume; Diop, Ousmane M; Iber, Jane; Sutter, Roland W; Wassilak, Steven G; Burns, Cara C

2016-08-05

In 1988, the World Health Assembly resolved to eradicate poliomyelitis worldwide (1). One of the main tools used in polio eradication efforts has been the live, attenuated, oral poliovirus vaccine (OPV) (2), an inexpensive vaccine easily administered by trained volunteers. OPV might require several doses to induce immunity, but provides long-term protection against paralytic disease. Through effective use of OPV, the Global Polio Eradication Initiative (GPEI) has brought wild polioviruses to the threshold of eradication (1). However, OPV use, particularly in areas with low routine vaccination coverage, is associated with the emergence of genetically divergent vaccine-derived polioviruses (VDPVs) whose genetic drift from the parental OPV strains indicates prolonged replication or circulation (3). VDPVs can emerge among immunologically normal vaccine recipients and their contacts as well as among persons with primary immunodeficiencies (PIDs). Immunodeficiency-associated VDPVs (iVDPVs) can replicate for years in some persons with PIDs. In addition, circulating vaccine-derived polioviruses (cVDPVs) (3) can emerge in areas with low OPV coverage and can cause outbreaks of paralytic polio. This report updates previous summaries regarding VDPVs (4).

Estimated Effect of Inactivated Poliovirus Vaccine Campaigns, Nigeria and Pakistan, January 2014-April 2016.

PubMed

Shirreff, George; Wadood, Mufti Zubair; Vaz, Rui Gama; Sutter, Roland W; Grassly, Nicholas C

2017-02-01

In 2014, inactivated poliovirus vaccine (IPV) campaigns were implemented in Nigeria and Pakistan after clinical trials showed that IPV boosts intestinal immunity in children previously given oral poliovirus vaccine (OPV). We estimated the effect of these campaigns by using surveillance data collected during January 2014-April 2016. In Nigeria, campaigns with IPV and trivalent OPV (tOPV) substantially reduced the incidence of poliomyelitis caused by circulating serotype-2 vaccine-derived poliovirus (incidence rate ratio [IRR] 0.17 for 90 days after vs. 90 days before campaigns, 95% CI 0.04-0.78) and the prevalence of virus in environmental samples (prevalence ratio [PR] 0.16, 95% CI 0.02-1.33). Campaigns with tOPV alone resulted in similar reductions (IRR 0.59, 95% CI 0.18-1.97; PR 0.45, 95% CI 0.21-0.95). In Pakistan, the effect of IPV+tOPV campaigns on wild-type poliovirus was not significant. Results suggest that administration of IPV alongside OPV can decrease poliovirus transmission if high vaccine coverage is achieved.

Systematization of the Introduction of IPV and Switch from tOPV to bOPV in the Americas

PubMed Central

Thrush, Elizabeth; Jauregui, Barbara

2017-01-01

Abstract The synchronized introduction of the inactivated polio vaccine (IPV) and the switch from trivalent oral polio vaccine (tOPV) to bivalent oral polio vaccine (bOPV) has constituted an effort without precedents, and with astonishing results. Within the established time frame, all countries in our region managed to carry out the decision, planning, and introduction of this vaccine and subsequent switch to their national immunization schedules. The purpose of this article is to systematize the process of IPV introduction and switch in Latin America and the Caribbean, which constitutes an important piece in the documentation of the polio legacy in the Americas. Regional level as well as country perspectives and viewpoints are described. Analyzing and summarizing the lessons learned from the introduction of IPV and the switch from tOPV to bOPV can be useful for the introduction of new vaccines in the Pan American Health Organization (PAHO) region and in other regions of the world, and to help our own region successfully carry out another synchronized vaccine introduction in the future, if necessary. PMID:28838161

Estimated Effect of Inactivated Poliovirus Vaccine Campaigns, Nigeria and Pakistan, January 2014–April 2016

PubMed Central

Shirreff, George; Wadood, Mufti Zubair; Vaz, Rui Gama; Sutter, Roland W.

2017-01-01

In 2014, inactivated poliovirus vaccine (IPV) campaigns were implemented in Nigeria and Pakistan after clinical trials showed that IPV boosts intestinal immunity in children previously given oral poliovirus vaccine (OPV). We estimated the effect of these campaigns by using surveillance data collected during January 2014–April 2016. In Nigeria, campaigns with IPV and trivalent OPV (tOPV) substantially reduced the incidence of poliomyelitis caused by circulating serotype-2 vaccine–derived poliovirus (incidence rate ratio [IRR] 0.17 for 90 days after vs. 90 days before campaigns, 95% CI 0.04–0.78) and the prevalence of virus in environmental samples (prevalence ratio [PR] 0.16, 95% CI 0.02–1.33). Campaigns with tOPV alone resulted in similar reductions (IRR 0.59, 95% CI 0.18–1.97; PR 0.45, 95% CI 0.21–0.95). In Pakistan, the effect of IPV+tOPV campaigns on wild-type poliovirus was not significant. Results suggest that administration of IPV alongside OPV can decrease poliovirus transmission if high vaccine coverage is achieved. PMID:27861118

Coarse-Grained Molecular Simulation of the Hierarchical Self-Assembly of π-Conjugated Optoelectronic Peptides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mansbach, Rachael A.; Ferguson, Andrew L.

Self-assembled aggregates of peptides containing aromatic groups possess optoelectronic properties that make them attractive targets for the fabrication of biocompatible electronics. Molecular-level understanding of how the microscopic peptide chemistry influences the properties of the aggregates is vital for rational peptide design. We construct a coarse-grained model of Asp-Phe-Ala-Gly-OPV3-Gly-Ala-Phe-Asp (DFAG-OPV3-GAFD) peptides containing OPV3 (distyrylbenzene) π-conjugated cores explicitly parameterized against all-atom calculations and perform molecular dynamics simulations of the self-assembly of hundreds of molecules over hundreds of nanoseconds. We observe a hierarchical assembly mechanism wherein ~2-8 peptides assemble into stacks with aligned aromatic cores that subsequently form elliptical aggregates and ultimately amore » branched network with a fractal dimensionality of ~1.5. The assembly dynamics are well described by a Smoluchowski coagulation process for which we extract rate constants from the molecular simulations to both furnish insight into the microscopic assembly kinetics and extrapolate our aggregation predictions to time and length scales beyond the reach of molecular simulation. Lastly, this study presents new molecular-level understanding of the morphology and dynamics of the spontaneous self-assembly of DFAG-OPV3-GAFD peptides and establishes a systematic protocol to develop coarse-grained models of optoelectronic peptides for the exploration and design of π-conjugated peptides with tunable optoelectronic properties.« less

Coarse-Grained Molecular Simulation of the Hierarchical Self-Assembly of π-Conjugated Optoelectronic Peptides

DOE PAGES

Mansbach, Rachael A.; Ferguson, Andrew L.

2017-02-10

Self-assembled aggregates of peptides containing aromatic groups possess optoelectronic properties that make them attractive targets for the fabrication of biocompatible electronics. Molecular-level understanding of how the microscopic peptide chemistry influences the properties of the aggregates is vital for rational peptide design. We construct a coarse-grained model of Asp-Phe-Ala-Gly-OPV3-Gly-Ala-Phe-Asp (DFAG-OPV3-GAFD) peptides containing OPV3 (distyrylbenzene) π-conjugated cores explicitly parameterized against all-atom calculations and perform molecular dynamics simulations of the self-assembly of hundreds of molecules over hundreds of nanoseconds. We observe a hierarchical assembly mechanism wherein ~2-8 peptides assemble into stacks with aligned aromatic cores that subsequently form elliptical aggregates and ultimately amore » branched network with a fractal dimensionality of ~1.5. The assembly dynamics are well described by a Smoluchowski coagulation process for which we extract rate constants from the molecular simulations to both furnish insight into the microscopic assembly kinetics and extrapolate our aggregation predictions to time and length scales beyond the reach of molecular simulation. Lastly, this study presents new molecular-level understanding of the morphology and dynamics of the spontaneous self-assembly of DFAG-OPV3-GAFD peptides and establishes a systematic protocol to develop coarse-grained models of optoelectronic peptides for the exploration and design of π-conjugated peptides with tunable optoelectronic properties.« less

Assessing the stability of polio eradication after the withdrawal of oral polio vaccine

PubMed Central

Selinger, Christian; McCarthy, Kevin A.; Eckhoff, Philip A.; Chabot-Couture, Guillaume

2018-01-01

The oral polio vaccine (OPV) contains live-attenuated polioviruses that induce immunity by causing low virulence infections in vaccine recipients and their close contacts. Widespread immunization with OPV has reduced the annual global burden of paralytic poliomyelitis by a factor of 10,000 or more and has driven wild poliovirus (WPV) to the brink of eradication. However, in instances that have so far been rare, OPV can paralyze vaccine recipients and generate vaccine-derived polio outbreaks. To complete polio eradication, OPV use should eventually cease, but doing so will leave a growing population fully susceptible to infection. If poliovirus is reintroduced after OPV cessation, under what conditions will OPV vaccination be required to interrupt transmission? Can conditions exist in which OPV and WPV reintroduction present similar risks of transmission? To answer these questions, we built a multi-scale mathematical model of infection and transmission calibrated to data from clinical trials and field epidemiology studies. At the within-host level, the model describes the effects of vaccination and waning immunity on shedding and oral susceptibility to infection. At the between-host level, the model emulates the interaction of shedding and oral susceptibility with sanitation and person-to-person contact patterns to determine the transmission rate in communities. Our results show that inactivated polio vaccine (IPV) is sufficient to prevent outbreaks in low transmission rate settings and that OPV can be reintroduced and withdrawn as needed in moderate transmission rate settings. However, in high transmission rate settings, the conditions that support vaccine-derived outbreaks have only been rare because population immunity has been high. Absent population immunity, the Sabin strains from OPV will be nearly as capable of causing outbreaks as WPV. If post-cessation outbreak responses are followed by new vaccine-derived outbreaks, strategies to restore population immunity will be required to ensure the stability of polio eradication. PMID:29702638

Eradicating poliomyelitis: India's journey from hyperendemic to polio-free status

PubMed Central

John, T. Jacob; Vashishtha, Vipin M.

2013-01-01

India's success in eliminating wild polioviruses (WPVs) has been acclaimed globally. Since the last case on January 13, 2011 success has been sustained for two years. By early 2014 India could be certified free of WPV transmission, if no indigenous transmission occurs, the chances of which is considered zero. Until early 1990s India was hyperendemic for polio, with an average of 500 to 1000 children getting paralysed daily. In spite of introducing trivalent oral poliovirus vaccine (tOPV) in the Expanded Programme on Immunization (EPI) in 1979, the burden of polio did not fall below that of the pre-EPI era for a decade. One of the main reasons was the low vaccine efficacy (VE) of tOPV against WPV types 1 and 3. The VE of tOPV was highest for type 2 and WPV type 2 was eliminated in 1999 itself as the average per-capita vaccine coverage reached 6. The VE against types 1 and 3 was the lowest in Uttar Pradesh and Bihar, where the force of transmission of WPVs was maximum on account of the highest infant-population density. Transmission was finally interrupted with sustained and extraordinary efforts. During the years since 2004 annual pulse polio vaccination campaigns were conducted 10 times each year, virtually every child was tracked and vaccinated - including in all transit points and transport vehicles, monovalent OPV types 1 and 3 were licensed and applied in titrated campaigns according to WPV epidemiology and bivalent OPV (bOPV, with both types 1 and 3) was developed and judiciously deployed. Elimination of WPVs with OPV is only phase 1 of polio eradication. India is poised to progress to phase 2, with introduction of inactivated poliovirus vaccine (IPV), switch from tOPV to bOPV and final elimination of all vaccine-related and vaccine-derived polioviruses. True polio eradication demands zero incidence of poliovirus infection, wild and vaccine. PMID:23760372

Eradicating poliomyelitis: India's journey from hyperendemic to polio-free status.

PubMed

John, T Jacob; Vashishtha, Vipin M

2013-05-01

India's success in eliminating wild polioviruses (WPVs) has been acclaimed globally. Since the last case on January 13, 2011 success has been sustained for two years. By early 2014 India could be certified free of WPV transmission, if no indigenous transmission occurs, the chances of which is considered zero. Until early 1990s India was hyperendemic for polio, with an average of 500 to 1000 children getting paralysed daily. In spite of introducing trivalent oral poliovirus vaccine (tOPV) in the Expanded Programme on Immunization (EPI) in 1979, the burden of polio did not fall below that of the pre-EPI era for a decade. One of the main reasons was the low vaccine efficacy (VE) of tOPV against WPV types 1 and 3. The VE of tOPV was highest for type 2 and WPV type 2 was eliminated in 1999 itself as the average per-capita vaccine coverage reached 6. The VE against types 1 and 3 was the lowest in Uttar Pradesh and Bihar, where the force of transmission of WPVs was maximum on account of the highest infant-population density. Transmission was finally interrupted with sustained and extraordinary efforts. During the years since 2004 annual pulse polio vaccination campaigns were conducted 10 times each year, virtually every child was tracked and vaccinated - including in all transit points and transport vehicles, monovalent OPV types 1 and 3 were licensed and applied in titrated campaigns according to WPV epidemiology and bivalent OPV (bOPV, with both types 1 and 3) was developed and judiciously deployed. Elimination of WPVs with OPV is only phase 1 of polio eradication. India is poised to progress to phase 2, with introduction of inactivated poliovirus vaccine (IPV), switch from tOPV to bOPV and final elimination of all vaccine-related and vaccine-derived polioviruses. True polio eradication demands zero incidence of poliovirus infection, wild and vaccine.

Knowledge Domain and Emerging Trends in Organic Photovoltaic Technology: A Scientometric Review Based on CiteSpace Analysis.

PubMed

Xiao, Fengjun; Li, Chengzhi; Sun, Jiangman; Zhang, Lianjie

2017-01-01

To study the rapid growth of research on organic photovoltaic (OPV) technology, development trends in the relevant research are analyzed based on CiteSpace software of text mining and visualization in scientific literature. By this analytical method, the outputs and cooperation of authors, the hot research topics, the vital references and the development trend of OPV are identified and visualized. Different from the traditional review articles by the experts on OPV, this work provides a new method of visualizing information about the development of the OPV technology research over the past decade quantitatively.

Knowledge Domain and Emerging trends in Organic Photovoltaic Technology: A Scientometric Review Based on CiteSpace Analysis

NASA Astrophysics Data System (ADS)

Xiao, Fengjun; Li, Chengzhi; Sun, Jiangman; Zhang, Lianjie

2017-09-01

To study the rapid growth of research on organic photovoltaic (OPV) technology, development trends in the relevant research are analyzed based on CiteSpace software of text mining and visualization in scientific literature. By this analytical method, the outputs and cooperation of authors, the hot research topics, the vital references and the development trend of OPV are identified and visualized. Different from the traditional review articles by the experts on OPV, this work provides a new method of visualizing information about the development of the OPV technology research over the past decade quantitatively.

Chemically Functionalized Conjugated Oligoelectrolyte Nanoparticles for Enhancement of Current Generation in Microbial Fuel Cells.

PubMed

Zhao, Cui-e; Chen, Jia; Ding, Yuanzhao; Wang, Victor Bochuan; Bao, Biqing; Kjelleberg, Staffan; Cao, Bin; Loo, Say Chye Joachim; Wang, Lianhui; Huang, Wei; Zhang, Qichun

2015-07-08

Water-soluble conjugated oligoelectrolyte nanoparticles (COE NPs), consisting of a cage-like polyhedral oligomeric silsesquioxanes (POSS) core equipped at each end with pendant groups (oligo(p-phenylenevinylene) electrolyte, OPVE), have been designed and demonstrated as an efficient strategy in increasing the current generation in Escherichia coli microbial fuel cells (MFCs). The as-prepared COE NPs take advantage of the structure of POSS and the optical properties of the pendant groups, OPVE. Confocal laser scanning microscopy showed strong photoluminescence of the stained cells, indicating spontaneous accumulation of COE NPs within cell membranes. Moreover, the electrochemical performance of the COE NPs is superior to that of an established membrane intercommunicating COE, DSSN+ in increasing current generation, suggesting that these COE NPs thus hold great potential to boost the performance of MFCs.

Vaccine Poliovirus Shedding and Immune Response to Oral Polio Vaccine in HIV-Infected and -Uninfected Zimbabwean Infants

PubMed Central

Troy, Stephanie B.; Musingwini, Georgina; Halpern, Meira S.; Huang, ChunHong; Stranix-Chibanda, Lynda; Kouiavskaia, Diana; Shetty, Avinash K.; Chumakov, Konstantin; Nathoo, Kusum; Maldonado, Yvonne A.

2013-01-01

Background. With prolonged replication, attenuated polioviruses used in oral polio vaccine (OPV) can mutate into vaccine-derived poliovirus (VDPV) and cause poliomyelitis outbreaks. Individuals with primary humoral immunodeficiencies can become chronically infected with vaccine poliovirus, allowing it to mutate into immunodeficiency-associated VDPV (iVDPV). It is unclear if children perinatally infected with the human immunodeficiency virus (HIV), who have humoral as well as cellular immunodeficiencies, might be sources of iVDPV. Methods. We conducted a prospective study collecting stool and blood samples at multiple time points from Zimbabwean infants receiving OPV according to the national schedule. Nucleic acid extracted from stool was analyzed by real-time polymerase chain reaction for OPV serotypes. Results. We analyzed 825 stool samples: 285 samples from 92 HIV-infected children and 540 from 251 HIV-uninfected children. Poliovirus shedding was similar after 0–2 OPV doses but significantly higher in the HIV-infected versus uninfected children after ≥3 OPV doses, particularly within 42 days of an OPV dose, independent of seroconversion status. HIV infection was not associated with prolonged or persistent poliovirus shedding. HIV infection was associated with significantly lower polio seroconversion rates. Conclusions. HIV infection is associated with decreased mucosal and humoral immune responses to OPV but not the prolonged viral shedding required to form iVDPV. PMID:23661792

Narrow Gap, High Mobility, and Stable Pi Conjugated Polymers

DTIC Science & Technology

2012-09-20

wide-angle X-ray scattering (2D-WAXS) of P5.1 (extruded at 210oC). This trend is reflected in conventional bulk- heterojunction OPV devices as shown...Additives in Molecular Bulk Heterojunction Solar Cells Using a bithiophene capped, isoindigo core, DAD molecule as the donor phase, and PCBM as the...PCE values of 3.7% as illustrated in Figure 11. Figure 11. Combining interface control using MoOx as an electron transport material and PDMS

Systematization of the Introduction of IPV and Switch from tOPV to bOPV in the Americas.

PubMed

Pedreira, Cristina; Thrush, Elizabeth; Jauregui, Barbara

2017-07-01

The synchronized introduction of the inactivated polio vaccine (IPV) and the switch from trivalent oral polio vaccine (tOPV) to bivalent oral polio vaccine (bOPV) has constituted an effort without precedents, and with astonishing results. Within the established time frame, all countries in our region managed to carry out the decision, planning, and introduction of this vaccine and subsequent switch to their national immunization schedules.The purpose of this article is to systematize the process of IPV introduction and switch in Latin America and the Caribbean, which constitutes an important piece in the documentation of the polio legacy in the Americas. Regional level as well as country perspectives and viewpoints are described. Analyzing and summarizing the lessons learned from the introduction of IPV and the switch from tOPV to bOPV can be useful for the introduction of new vaccines in the Pan American Health Organization (PAHO) region and in other regions of the world, and to help our own region successfully carry out another synchronized vaccine introduction in the future, if necessary. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Cost analysis of post-polio certification immunization policies.

PubMed Central

Sangrujee, Nalinee; Cáceres, Victor M.; Cochi, Stephen L.

2004-01-01

OBJECTIVE: An analysis was conducted to estimate the costs of different potential post-polio certification immunization policies currently under consideration, with the objective of providing this information to policy-makers. METHODS: We analyzed three global policy options: continued use of oral poliovirus vaccine (OPV); OPV cessation with optional inactivated poliovirus vaccine (IPV); and OPV cessation with universal IPV. Assumptions were made on future immunization policy decisions taken by low-, middle-, and high-income countries. We estimated the financial costs of each immunization policy, the number of vaccine-associated paralytic poliomyelitis (VAPP) cases, and the global costs of maintaining an outbreak response capacity. The financial costs of each immunization policy were based on estimates of the cost of polio vaccine, its administration, and coverage projections. The costs of maintaining outbreak response capacity include those associated with developing and maintaining a vaccine stockpile in addition to laboratory and epidemiological surveillance. We used the period 2005-20 as the time frame for the analysis. FINDINGS: OPV cessation with optional IPV, at an estimated cost of US$ 20,412 million, was the least costly option. The global cost of outbreak response capacity was estimated to be US$ 1320 million during 2005-20. The policy option continued use of OPV resulted in the highest number of VAPP cases. OPV cessation with universal IPV had the highest financial costs, but it also had the least number of VAPP cases. Sensitivity analyses showed that global costs were sensitive to assumptions on the cost of the vaccine. Analysis also showed that if the price per dose of IPV was reduced to US$ 0.50 for low-income countries, the cost of OPV cessation with universal IPV would be the same as the costs of continued use of OPV. CONCLUSION: Projections on the vaccine price per dose and future coverage rates were major drivers of the global costs of post-certification polio immunization. The break-even price of switching to IPV compared with continuing with OPV immunizations is US$ 0.50 per dose of IPV. However, this doses not account for the cost of vaccine-derived poliovirus cases resulting from the continued use of OPV. In addition to financial costs, risk assessments related to the re-emergence of polio will be major determinants of policy decisions. PMID:15106295

Preventing Vaccine-Derived Poliovirus Emergence during the Polio Endgame

PubMed Central

Burns, Cara C.; Lyons, Hil; Blake, Isobel M.; Oberste, M. Steven; Kew, Olen M.; Grassly, Nicholas C.

2016-01-01

Reversion and spread of vaccine-derived poliovirus (VDPV) to cause outbreaks of poliomyelitis is a rare outcome resulting from immunisation with the live-attenuated oral poliovirus vaccines (OPVs). Global withdrawal of all three OPV serotypes is therefore a key objective of the polio endgame strategic plan, starting with serotype 2 (OPV2) in April 2016. Supplementary immunisation activities (SIAs) with trivalent OPV (tOPV) in advance of this date could mitigate the risks of OPV2 withdrawal by increasing serotype-2 immunity, but may also create new serotype-2 VDPV (VDPV2). Here, we examine the risk factors for VDPV2 emergence and implications for the strategy of tOPV SIAs prior to OPV2 withdrawal. We first developed mathematical models of VDPV2 emergence and spread. We found that in settings with low routine immunisation coverage, the implementation of a single SIA increases the risk of VDPV2 emergence. If routine coverage is 20%, at least 3 SIAs are needed to bring that risk close to zero, and if SIA coverage is low or there are persistently “missed” groups, the risk remains high despite the implementation of multiple SIAs. We then analysed data from Nigeria on the 29 VDPV2 emergences that occurred during 2004−2014. Districts reporting the first case of poliomyelitis associated with a VDPV2 emergence were compared to districts with no VDPV2 emergence in the same 6-month period using conditional logistic regression. In agreement with the model results, the odds of VDPV2 emergence decreased with higher routine immunisation coverage (odds ratio 0.67 for a 10% absolute increase in coverage [95% confidence interval 0.55−0.82]). We also found that the probability of a VDPV2 emergence resulting in poliomyelitis in >1 child was significantly higher in districts with low serotype-2 population immunity. Our results support a strategy of focused tOPV SIAs before OPV2 withdrawal in areas at risk of VDPV2 emergence and in sufficient number to raise population immunity above the threshold permitting VDPV2 circulation. A failure to implement this risk-based approach could mean these SIAs actually increase the risk of VDPV2 emergence and spread. PMID:27384947

Photovoltaic materials and devices 2016

DOE PAGES

Sopori, Bhushan; Basnyat, Prakash; Mehta, Vishal

2016-01-01

Photovoltaic energy continues to grow with about 59 GW of solar PV installed in 2015. While most of the PV production (about 93%) was Si wafer based, both CdTe and CI(G)S are growing in their shares. There is also continued progress at the laboratory scale in OPV and dye sensitized solar cells. As the market grows, emphasis on reducing the cost of modules and systems continues to grow. This is the fourth special issue of this journal that is dedicated to gathering selected papers on recent advances in materials, devices, and modules/PV systems. This issue contains sixteen papers on variousmore » aspects of photovoltaics. As a result, these fall in four broad categories of novel materials, device design and fabrication, modules, and systems.« less

Synthesis of poly(benzothiadiazole-co-dithienobenzodithiophenes) and effect of thiophene insertion for high-performance polymer solar cells.

PubMed

Yun, Hui-Jun; Lee, Yun-Ji; Yoo, Seung-Jin; Chung, Dae Sung; Kim, Yun-Hi; Kwon, Soon-Ki

2013-09-23

We describe herein the synthesis of novel donor-acceptor conjugated polymers with dithienobenzodithiophenes (DTBDT) as the electron donor and 2,1,3-benzothiadiazole as the electron acceptor for high-performance organic photovoltaics (OPVs). We studied the effects of strategically inserting thiophene into the DTBDT as a substituent on the skeletal structure on the opto-electronic performances of fabricated devices. From UV/Vis absorption, electrochemical, and field-effect transistor analyses, we found that the thiophene-containing DTBDT derivative can substantially increase the orbital overlap area between adjacent conjugated chains and thus dramatically enhance charge-carrier mobility up to 0.55 cm(2)  V(-1)  s(-1). The outstanding charge-transport characteristics of this polymer allowed the realization of high-performance organic solar cells with a power conversion efficiency (PCE) of 5.1 %. Detailed studies on the morphological factors that enable the maximum PCE of the polymer solar cells are discussed along with a hole/electron mobility analysis based on the space-charge-limited current model. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

3D reconstruction modeling of bulk heterojunction organic photovoltaic cells: Effect of the complexity of the boundary on the morphology

NASA Astrophysics Data System (ADS)

Kim, Sung-Jin; Jeong, Daun; Kim, SeongMin; Choi, Yeong Suk; Ihn, Soo-Ghang; Yun, Sungyoung; Lim, Younhee; Lee, Eunha; Park, Gyeong-Su

2016-02-01

Although the morphology of the active layer in bulk heterojunction organic photovoltaic (BHJ-OPV) cells is critical for determining the quantum efficiency (QE), predicting the real QE for a 3-dimensional (3D) morphology has long been difficult because structural information on the composition complexity of donor (D): acceptor (A) blends with small domain size is limited to 2D observations via various image-processing techniques. To overcome this, we reconstruct the 3D morphology by using an isotropic statistical approach based on 2D energy-filtered transmission electron microscopy (EF-TEM) images. This new reconstruction method is validated to obtain the internal QE by using a dynamic Monte Carlo simulation in the BHJ-OPV system with different additives such as 4 vol% 1-chloronaphthalene (CN) and 4 vol% 1,8-diiodooctane (DIO) (compared to the case of no additive); the resulting trend is compared with the experimental QE. Therefore, our developed method can be used to predict the real charge transport performance in the OPV system accurately.

Impact on electronic structure of donor/acceptor blend in organic photovoltaics by decontamination of molybdenum-oxide surface

NASA Astrophysics Data System (ADS)

Ito, Yuta; Akaike, Kouki; Fukuda, Takeshi; Sato, Daisuke; Fuse, Takuya; Iwahashi, Takashi; Ouchi, Yukio; Kanai, Kaname

2018-05-01

Molybdenum oxide (MoOx) is widely used as the hole-transport layer in bulk-heterojunction organic photovoltaics (BHJ-OPVs). During the fabrication of solution-processed BHJ-OPVs on vacuum-deposited MoOx film, the film must be exposed to N2 atmosphere in a glove box, where the donor/acceptor blends are spin-coated from a mixed solution. Employing photoelectron spectroscopy, we reveal that the exposure of the MoOx film to such atmosphere contaminates the MoOx surface. Annealing the contaminated MoOx film at 160 °C for 5 min, prior to spin-coating the blend film, can partially remove the carbon and oxygen adsorbed on the MoOx surface during the exposure of MoOx. However, the contamination layer on the MoOx surface does not affect the energy-level alignment at the interface between MoOx and the donor/acceptor blend. Hence, significant improvement in the performance of BHJ-OPVs by mildly annealing the MoOx layer, which was previously reported, can be explained by the reduction of undesired contamination.

High Efficiency Near-Infrared and Semitransparent Non-Fullerene Acceptor Organic Photovoltaic Cells.

PubMed

Li, Yongxi; Lin, Jiu-Dong; Che, Xiaozhou; Qu, Yue; Liu, Feng; Liao, Liang-Sheng; Forrest, Stephen R

2017-11-29

The absence of near-infrared (NIR) solar cells with high open circuit voltage (V oc ) and external quantum efficiency (EQE) has impeded progress toward achieving organic photovoltaic (OPV) power conversion efficiency PCE > 15%. Here we report a small energy gap (1.3 eV), chlorinated nonfullerene acceptor-based solar cell with PCE = 11.2 ± 0.4%, short circuit current of 22.5 ± 0.6 mA cm -2 , V oc = 0.70 ± 0.01 V and fill factor of 0.71 ± 0.02, which is the highest performance reported to date for NIR single junction OPVs. Importantly, the EQE of this NIR solar cell reaches 75%, between 650 and 850 nm while leaving a transparency window between 400 and 600 nm. The semitransparent OPV using an ultrathin (10 nm) Ag cathode shows PCE = 7.1 ± 0.1%, with an average visible transmittance of 43 ± 2%, Commission d'Eclairage chromaticity coordinates of (0.29, 0.32) and a color rendering index of 91 for simulated AM1.5 illumination transmitted through the cell.

Fluorinated copper phthalocyanine nanowires for enhancing interfacial electron transport in organic solar cells.

PubMed

Yoon, Seok Min; Lou, Sylvia J; Loser, Stephen; Smith, Jeremy; Chen, Lin X; Facchetti, Antonio; Marks, Tobin J; Marks, Tobin

2012-12-12

Zinc oxide is a promising candidate as an interfacial layer (IFL) in inverted organic photovoltaic (OPV) cells due to the n-type semiconducting properties as well as chemical and environmental stability. Such ZnO layers collect electrons at the transparent electrode, typically indium tin oxide (ITO). However, the significant resistivity of ZnO IFLs and an energetic mismatch between the ZnO and the ITO layers hinder optimum charge collection. Here we report that inserting nanoscopic copper hexadecafluorophthalocyanine (F(16)CuPc) layers, as thin films or nanowires, between the ITO anode and the ZnO IFL increases OPV performance by enhancing interfacial electron transport. In inverted P3HT:PC(61)BM cells, insertion of F(16)CuPc nanowires increases the short circuit current density (J(sc)) versus cells with only ZnO layers, yielding an enhanced power conversion efficiency (PCE) of ∼3.6% vs ∼3.0% for a control without the nanowire layer. Similar effects are observed for inverted PTB7:PC(71)BM cells where the PCE is increased from 8.1% to 8.6%. X-ray scattering, optical, and electrical measurements indicate that the performance enhancement is ascribable to both favorable alignment of the nanowire π-π stacking axes parallel to the photocurrent flow and to the increased interfacial layer-active layer contact area. These findings identify a promising strategy to enhance inverted OPV performance by inserting anisotropic nanostructures with π-π stacking aligned in the photocurrent flow direction.

Investigation of ITO free transparent conducting polymer based electrode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Vikas; Sapna,; Sachdev, Kanupriya

2016-05-23

The last few decades have seen a significant improvement in organic semiconductor technology related to solar cell, light emitting diode and display panels. The material and structure of the transparent electrode is one of the major concerns for superior performance of devices such as OPV, OLED, touch screen and LCD display. Commonly used ITO is now restricted due to scarcity of indium, its poor mechanical properties and rigidity, and mismatch of energy levels with the active layer. Nowadays DMD (dielectric-metal-dielectric) structure is one of the prominent candidates as alternatives to ITO based electrode. We have used solution based spin coatedmore » polymer layer as the dielectric layer with silver thin film embedded in between to make a polymer-metal-polymer (PMP) structure for TCE applications. The PMP structure shows low resistivity (2.3 x 10{sup −4}Ω-cm), high carrier concentration (2.9 x 10{sup 21} cm{sup −3}) and moderate transparency. The multilayer PMP structure is characterized with XRD, AFM and Hall measurement to prove its suitability for opto-electronic device applications.« less

An electron-deficient small molecule accessible from sustainable synthesis and building blocks for use as a fullerene alternative in organic photovoltaics.

PubMed

McAfee, Seth M; Topple, Jessica M; Payne, Abby-Jo; Sun, Jon-Paul; Hill, Ian G; Welch, Gregory C

2015-04-27

An electron-deficient small molecule accessible from sustainable isoindigo and phthalimide building blocks was synthesized via optimized synthetic procedures that incorporate microwave-assisted synthesis and a heterogeneous catalyst for Suzuki coupling, and direct heteroarylation carbon-carbon bond forming reactions. The material was designed as a non-fullerene acceptor with the help of DFT calculations and characterized by optical, electronic, and thermal analysis. Further investigation of the material revealed a differing solid-state morphology with the use of three well-known processing conditions: thermal annealing, solvent vapor annealing and small volume fractions of 1,8-diiodooctane (DIO) additive. These unique morphologies persist in the active layer blends and have demonstrated a distinct influence on device performance. Organic photovoltaic-bulk heterojunction (OPV-BHJ) devices show an inherently high open circuit voltage (Voc ) with the best power conversion efficiency (PCE) cells reaching 1.0 V with 0.4 v/v % DIO as a processing additive. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transgenic mice as an alternative to monkeys for neurovirulence testing of live oral poliovirus vaccine: validation by a WHO collaborative study.

PubMed Central

Dragunsky, Eugenia; Nomura, Tatsuji; Karpinski, Kazimir; Furesz, John; Wood, David J.; Pervikov, Yuri; Abe, Shinobu; Kurata, Takeshi; Vanloocke, Olivier; Karganova, Galina; Taffs, Rolf; Heath, Alan; Ivshina, Anna; Levenbook, Inessa

2003-01-01

OBJECTIVE: Extensive WHO collaborative studies were performed to evaluate the suitability of transgenic mice susceptible to poliovirus (TgPVR mice, strain 21, bred and provided by the Central Institute for Experimental Animals, Japan) as an alternative to monkeys in the neurovirulence test (NVT) of oral poliovirus vaccine (OPV). METHODS: Nine laboratories participated in the collaborative study on testing neurovirulence of 94 preparations of OPV and vaccine derivatives of all three serotypes in TgPVR21 mice. FINDINGS: Statistical analysis of the data demonstrated that the TgPVR21 mouse NVT was of comparable sensitivity and reproducibility to the conventional WHO NVT in simians. A statistical model for acceptance/rejection of OPV lots in the mouse test was developed, validated, and shown to be suitable for all three vaccine types. The assessment of the transgenic mouse NVT is based on clinical evaluation of paralysed mice. Unlike the monkey NVT, histological examination of central nervous system tissue of each mouse offered no advantage over careful and detailed clinical observation. CONCLUSIONS: Based on data from the collaborative studies the WHO Expert Committee for Biological Standardization approved the mouse NVT as an alternative to the monkey test for all three OPV types and defined a standard implementation process for laboratories that wish to use the test. This represents the first successful introduction of transgenic animals into control of biologicals. PMID:12764491

Evolution of the Sabin Vaccine into Pathogenic Derivatives without Appreciable Changes in Antigenic Properties: Need for Improvement of Current Poliovirus Surveillance▿

PubMed Central

Yakovenko, Maria L.; Korotkova, Ekaterina A.; Ivanova, Olga E.; Eremeeva, Tatyana P.; Samoilovich, Elena; Uhova, Iryna; Gavrilin, Gene V.; Agol, Vadim I.

2009-01-01

The Sabin oral polio vaccine (OPV) may evolve into pathogenic viruses, causing sporadic cases and outbreaks of poliomyelitis. Such vaccine-derived polioviruses (VDPV) generally exhibit altered antigenicity. The current paradigm to distinguish VDPV from OPV and wild polioviruses is to characterize primarily those poliovirus isolates that demonstrate deviations from OPV in antigenic and genetic intratypic differentiation (ITD) tests. Here we report on two independent cases of poliomyelitis caused by VDPVs with “Sabin-like” properties in several ITD assays. The results suggest the existence of diverse pathways of OPV evolution and necessitate improvement of poliovirus surveillance, which currently potentially misses this class of VDPV. PMID:19129444

Evolution of the Sabin vaccine into pathogenic derivatives without appreciable changes in antigenic properties: need for improvement of current poliovirus surveillance.

PubMed

Yakovenko, Maria L; Korotkova, Ekaterina A; Ivanova, Olga E; Eremeeva, Tatyana P; Samoilovich, Elena; Uhova, Iryna; Gavrilin, Gene V; Agol, Vadim I

2009-04-01

The Sabin oral polio vaccine (OPV) may evolve into pathogenic viruses, causing sporadic cases and outbreaks of poliomyelitis. Such vaccine-derived polioviruses (VDPV) generally exhibit altered antigenicity. The current paradigm to distinguish VDPV from OPV and wild polioviruses is to characterize primarily those poliovirus isolates that demonstrate deviations from OPV in antigenic and genetic intratypic differentiation (ITD) tests. Here we report on two independent cases of poliomyelitis caused by VDPVs with "Sabin-like" properties in several ITD assays. The results suggest the existence of diverse pathways of OPV evolution and necessitate improvement of poliovirus surveillance, which currently potentially misses this class of VDPV.

Polio vaccination: past, present and future.

PubMed

Bandyopadhyay, Ananda S; Garon, Julie; Seib, Katherine; Orenstein, Walter A

2015-01-01

Live attenuated oral polio vaccine (OPV) and inactivated polio vaccine (IPV) are the tools being used to achieve eradication of wild polio virus. Because OPV can rarely cause paralysis and generate revertant polio strains, IPV will have to replace OPV after eradication of wild polio virus is certified to sustain eradication of all polioviruses. However, uncertainties remain related to IPV's ability to induce intestinal immunity in populations where fecal-oral transmission is predominant. Although substantial effectiveness and safety data exist on the use and delivery of OPV and IPV, several new research initiatives are currently underway to fill specific knowledge gaps to inform future vaccination policies that would assure polio is eradicated and eradication is maintained.

The role of routine polio immunization in the post-certification era.

PubMed Central

Sutter, Roland W.; Cáceres, Victor M.; Mas Lago, Pedro

2004-01-01

The role of routine vaccination against poliomyelitis for the post-certification era remains an important area for policy decision-making. Two critical decisions need to be taken: first, to continue or discontinue vaccination with the live attenuated oral poliovirus vaccine (OPV); and second, if OPV is to be discontinued, whether vaccination with inactivated poliovirus vaccine (IPV) is needed. Four potential vaccination scenarios can be constructed: stop all polio vaccination; continue with current vaccination policies (OPV, IPV, or sequential schedule); discontinue OPV, but continue IPV universally; or discontinue OPV, but continue IPV in selected countries. All possible scenarios require continued investments in a surveillance and response strategy, including a stockpile of polio vaccine. Continuing vaccination would limit the savings that could be applied to the control of other health priorities. This report reviews the key issues associated with each scenario, highlights the advantages and disadvantages of each scenario, and outlines the major challenges for policy decision-making. PMID:15106298

Phenotypic and genomic analysis of serotype 3 Sabin poliovirus vaccine produced in MRC-5 cell substrate.

PubMed

Alirezaie, Behnam; Taqavian, Mohammad; Aghaiypour, Khosrow; Esna-Ashari, Fatemeh; Shafyi, Abbas

2011-05-01

The cell substrate has a pivotal role in live virus vaccines production. It is necessary to evaluate the effects of the cell substrate on the properties of the propagated viruses, especially in the case of viruses which are unstable genetically such as polioviruses, by monitoring the molecular and phenotypical characteristics of harvested viruses. To investigate the presence/absence of mutation(s), the near full-length genomic sequence of different harvests of the type 3 Sabin strain of poliovirus propagated in MRC-5 cells were determined. The sequences were compared with genomic sequences of different virus seeds, vaccines, and OPV-like isolates. Nearly complete genomic sequencing results, however, revealed no detectable mutations throughout the genome RNA-plaque purified (RSO)-derived monopool of type 3 OPVs manufactured in MRC-5. Thirty-six years of experience in OPV production, trend analysis, and vaccine surveillance also suggest that: (i) different monopools of serotype 3 OPV produced in MRC-5 retained their phenotypic characteristics (temperature sensitivity and neuroattenuation), (ii) MRC-5 cells support the production of acceptable virus yields, (iii) OPV replicated in the MRC-5 cell substrate is a highly efficient and safe vaccine. These results confirm previous reports that MRC-5 is a desirable cell substrate for the production of OPV. Copyright © 2011 Wiley-Liss, Inc.

Enhancement in Open-Circuit Voltage in Organic Solar Cells by Using Ladder-Type Nonfullerene Acceptors.

PubMed

Cai, Zhengxu; Zhao, Donglin; Sharapov, Valerii; Awais, Mohammad A; Zhang, Na; Chen, Wei; Yu, Luping

2018-04-25

The open-circuit voltage ( V oc ) loss has always been a major factor in lowering power conversion efficiencies (PCEs) in bulk heterojunction organic photovoltaic cells (OPVs). A method to improve the V oc is indispensable to achieve high PCEs. In this paper, we investigated a series of perylene diimide-based ladder-type molecules as electron acceptors in nonfullerene OPVs. The D-A ladder-type structures described here lock our π-systems into a planar structure and eliminate bond twisting associated with linear conjugated systems. This enlarges the interface energy gap (Δ E DA ), extends electronic delocalization, and hence improves the V oc . More importantly, these devices showed an increase in V oc without compromising either the J sc or the FF. C5r exhibited a strong intermolecular interaction and a PCE value of 6.1%. Moreover, grazing-incident wide-angle X-ray scattering analysis and atomic force microscopy images suggested that our fused-ring acceptors showed a suitable domain size and uniform blend films, which were not affected by their rigid molecular structures.

A molecular heterojunction of zinc phthalocyanine and peanut-shaped fullerene polymer: A density functional study

NASA Astrophysics Data System (ADS)

Tanikawa, Kousei; Ohno, Kaoru; Noda, Yusuke; Ono, Shota; Kuwahara, Riichi; Takashima, Akito; Nakaya, Masato; Onoe, Jun

2017-10-01

We have performed first-principles density functional calculations of a molecular heterojunction of a zinc phthalocyanine (ZnPc) molecule and a peanut-shaped fullerene polymer (PSFP) made from several coalesced cross-linked C60 molecules. The PSFP has many isomers and all have both spatially localized (near ZnPc) and metallic conducting levels. Here we consider four typical isomers. From the resulting electronic structure, we discuss the applicability of these isomers to organic photovoltaics (OPV), electrodes, and light harvesting materials. If one of the isomers called T3, which has the largest energy gap, is used together with ZnPc for OPV, this system shows more than 20% energy conversion efficiency.

Is there any Exciton (bottleneck) in an Excitonic Solar Cell: Revisiting the Prospects of Single-Semiconductor OPV

NASA Astrophysics Data System (ADS)

Alam, Muhammad

2014-03-01

The discovery dye sensitized and bulk heterojunction (BHJ) solar cells in early 1990s introduced a new class of PV technology that rely on (i) distributed photogeneration of excitons, (ii) dissociation of excitons into free carriers by the heterojunction between two organic semiconductors (OSC), and (iii) collection of free carriers through electron and hole transport layers. The success of the approach is undisputed: the highest efficiency OPV cells have all relied on variants of BHJ approach. Yet, three concerns related to the use of a pair of OSCs, namely, low Voc, process sensitivity, and reliability, suggest that the technology may never achieve efficiency-variability-reliability metrics comparable to inorganic solar cells. This encourages a reconsideration of the prospects of Single semiconductor OPV (SS-OPV), a system presumably doomed by the exciton bottleneck. In this talk, we use an inverted SS-OPV to demonstrate how the historical SS-OPV experiments may have been misinterpreted. No one disputes the signature of excitons in polymer under narrowband excitation, but our experiments show that exciton dissociation need not be a bottleneck for OPV under broadband solar illumination. We demonstrate that an alternate collection-limited theory consistently interprets the classical and new experiments, resolves puzzles such as efficiency loss with increasing light intensity, and voltage-dependent reverse photo-current, etc. The theory and experiments suggest a new ``perovskite-like'' strategy to efficiency-variability-reliability of organic solar cells. The work was supported by the Columbia DOE-EFRC (DE-SC0001085) and NSF-NCN (EEC-0228390).

A density functional theory (DFT) and time-dependent density functional theory (TDDFT) study on optical transitions in oligo(p-phenylenevinylene)-fullerene dyads and the applicability to resonant energy transfer.

PubMed

Toivonen, Teemu L J; Hukka, Terttu I

2007-06-07

The optical transitions of three different size oligo(p-phenylenevinylene)-fullerene dyads (OPV(n)-MPC(60); n = 2-4) and of the corresponding separate molecules are studied using density functional theory (DFT) and time-dependent density functional theory. The DFT is used to determine the geometries and the electronic structures of the ground states. Transition energies and excited-state structures are obtained from the TDDFT calculations. Resonant energy transfer from OPV(n) to MPC(60) is also studied and the Fermi golden rule is used, along with two simple models to describe the electronic coupling to calculate the energy transfer rates. The hybrid-type PBE0 functional is used with a split-valence basis set augmented with a polarization function (SV(P)) in calculations and the calculated results are compared to the corresponding experimental results. The calculated PBE0 spectra of the OPV(n)-MPC(60) dyads correspond to the experimental spectra very well and are approximately sums of the absorption spectra of the separate OPV(n) and MPC(60) molecules. Also, the absorption energies of OPV(n) and MPC(60) and the emission energies of OPV(n) are predicted well with the PBE0 functional. The PBE0 calculated resonant energy transfer rates are in a good agreement with the experimental rates and show the existence of many possible pathways for energy transfer from the first excited singlet states of the OPV(n) molecules to the MPC(60) molecule.

New designs and characterization techniques for thin-film solar cells

NASA Astrophysics Data System (ADS)

Pang, Yutong

This thesis presents a fundamentally new thin-film photovoltaic design and develops several novel characterization techniques that improve the accuracy of thin-film solar cell computational models by improving the accuracy of the input data. We first demonstrate a novel organic photovoltaic (OPV) design, termed a "Slot OPV", in which the active layer is less than 50 nm; We apply the principles of slot waveguides to confine light within the active layer. According to our calculation, the guided-mode absorption for a 10nm thick active layer equal to the absorption of normal incidence on an OPV with a 100nm thick active layer. These results, together with the expected improvement in charge extraction for ultrathin layers, suggest that slot OPVs can be designed with greater power conversion efficiency than today's state-of-art OPV architectures if practical challenges, such as the efficient coupling of light into these modes, can be overcome. The charge collection probability, i.e. the probability that charges generated by absorption of a photon are successfully collected as current, is a critical feature for all kinds of solar cells. While the electron-beam-induced current (EBIC) method has been used in the past to successfully reconstruct the charge collection probability, this approach is destructive and requires time-consuming sample preparation. We demonstrate a new nondestructive optoelectronic method to reconstruct the charge collection probability by analyzing the internal quantum efficiency (IQE) data that are measured on copper indium gallium diselenide (CIGS) thin-film solar cells. We further improve the method with a parameter-independent regularization approach. Then we introduce the Self-Constrained Ill-Posed Inverse Problem (SCIIP) method, which improves the signal-to-noise of the solution by using the regularization method with system constraints and optimization via an evolutionary algorithm. For a thin-film solar cell optical model to be an accurate representation of reality, the measured refractive index profile of the solar cell used as input to the model must also be accurate. We describe a new method for reconstructing the depth-dependent refractive-index profile with high spatial resolution in thin photoactive layers. This novel technique applies to any thin film, including the photoactive layers of a broad range of thin-film photovoltaics. Together, these methods help us improve the measurement accuracy of the depth profile within thin-film photovoltaics for optical and electronic properties such as refractive index and charge collection probability, which is critical to the understanding, modeling, and optimization of these devices.

Update on vaccine-derived polioviruses - worldwide, July 2012-December 2013.

PubMed

Diop, Ousmane M; Burns, Cara C; Wassilak, Steven G; Kew, Olen M

2014-03-21

In 1988, the World Health Assembly resolved to eradicate poliomyelitis worldwide. One of the main tools used in polio eradication efforts has been live, attenuated oral poliovirus vaccine (OPV), an inexpensive vaccine easily administered by trained volunteers. OPV might require several doses to induce immunity, but then it provides long-term protection against paralytic disease through durable humoral immunity. Rare cases of vaccine-associated paralytic poliomyelitis can occur among immunologically normal OPV recipients, their contacts, and persons who are immunodeficient. In addition, vaccine-derived polioviruses (VDPVs) can emerge in areas with low OPV coverage to cause polio outbreaks and can replicate for years in persons who have primary, B-cell immunodeficiencies. This report updates previous surveillance summaries and describes VDPVs detected worldwide during July 2012-December 2013. Those include a new circulating VDPV (cVDPV) outbreak identified in Pakistan in 2012, with spread to Afghanistan; an outbreak in Afghanistan previously identified in 2009 that continued into 2013; a new outbreak in Chad that spread to Cameroon, Niger, and northeastern Nigeria; and an outbreak that began in Somalia in 2008 that continued and spread to Kenya in 2013. A large outbreak in Nigeria that was identified in 2005 was nearly stopped by the end of 2013. Additionally, 10 newly identified persons in eight countries were found to excrete immunodeficiency-associated VDPVs (iVDPVs), and VDPVs were found among immunocompetent persons and environmental samples in 13 countries. Because the majority of VDPV isolates are type 2, the World Health Organization has developed a plan for coordinated worldwide replacement of trivalent OPV (tOPV) with bivalent OPV (bOPV; types 1 and 3) by 2016, preceded by introduction of at least 1 dose of inactivated poliovirus vaccine (IPV) containing all three poliovirus serotypes into routine immunization schedules worldwide to ensure high population immunity to all polioviruses.

Harnessing Structure-Property Relationships for Poly(alkyl thiophene)-Fullerene Derivative Thin Filmsto Optimize Performance in Photovoltaic Devices

DOE PAGES

Deb, Nabankur; Li, Bohao; Skoda, Maximilian; ...

2016-02-08

Nanoscale bulk heterojunction (BHJ) systems, consisting of fullerenes dispersed in conjugated polymers as the active component, have been actively studied over the last decades in order to produce high performance organic photovoltaics (OPVs). A significant role in device efficiency is played by the active layer morphology, but despite considerable study, a full understanding of the exact role that morphology plays and therefore a definitive method to produce and control an ideal morphology is lacking. In order to understand the BHJ phase behavior and associated morphology in these devices, we have used neutron reflection, together with grazing incidence X-ray and neutronmore » scattering and X-ray photoelectron spectroscopy (XPS) to determine the morphology of the BHJ active layer in functional devices. We have studied nine model BHJ systems based on mixtures of three poly(3-alkyl thiophenes, P3AT) (A=butyl, hexyl, octyl) blended with three different fullerene derivatives, which provides variations in crystallinity and miscibility within the BHJ composite. In studying properties of functional devices, we show a direct correlation between the observed morphology within the BHJ layer and the device performance metrics, i.e., the short-circuit current (J SC), fill factor (FF), open-circuit voltage (VOC) and overall power conversion efficiency (PCE). Using these model systems, the effect of typical thermal annealing processes on the BHJ morphology through the film thickness as a function of the polythiophene-fullerene mixtures and different electron transport layer interfaces has been determined. It is shown that fullerene enrichment occurs at both the electrode interfaces after annealing. The degree of fullerene enrichment is found to strongly correlate with J SC and to a lesser degree with FF. Finally, based on these findings we demonstrate that by deliberately adding a fullerene layer at the electron transport layer interface, J SC can be increased by up to 20%, resulting in an overall increase in PCE of 5%.« less

Update on Vaccine-Derived Polioviruses - Worldwide, January 2014-March 2015.

PubMed

Diop, Ousmane M; Burns, Cara C; Sutter, Roland W; Wassilak, Steven G; Kew, Olen M

2015-06-19

Since the World Health Assembly's 1988 resolution to eradicate poliomyelitis, one of the main tools of the World Health Organization (WHO) Global Polio Eradication Initiative (GPEI) has been the live, attenuated oral poliovirus vaccine (OPV). OPV might require several doses to induce immunity but provides long-term protection against paralytic disease. Through effective use of OPV, GPEI has brought polio to the threshold of eradication. Wild poliovirus type 2 (WPV2) was eliminated in 1999, WPV3 has not been detected since November 2012, and WPV1 circulation appears to be restricted to parts of Pakistan and Afghanistan. However, continued use of OPV carries two key risks. The first, vaccine-associated paralytic poliomyelitis (VAPP) has been recognized since the early 1960s. VAPP is a very rare event that occurs sporadically when an administered dose of OPV reverts to neurovirulence and causes paralysis in the vaccine recipient or a nonimmune contact. VAPP can occur among immunologically normal vaccine recipients and their contacts as well as among persons who have primary immunodeficiencies (PIDs) manifested by defects in antibody production; it is not associated with outbreaks. The second, the emergence of genetically divergent, neurovirulent vaccine-derived polioviruses (VDPVs) was recognized more recently. Circulating VDPVs (cVDPVs) resemble WPVs and, in areas with low OPV coverage, can cause polio outbreaks. Immunodeficiency-associated VDPVs (iVDPVs) can replicate and be excreted for years in some persons with PIDs; GPEI maintains a registry of iVDPV cases. Ambiguous VDPVs (aVDPVs) are isolates that cannot be classified definitively. This report updates previous surveillance summaries and describes VDPVs detected worldwide during January 2014-March 2015. Those include new cVDPV outbreaks in Madagascar and South Sudan, and sharply reduced type 2 cVDPV (cVDPV2) circulation in Nigeria and Pakistan during the latter half of 2014. Eight newly identified persons in six countries were found to excrete iVDPVs, and a patient in the United Kingdom was still excreting iVDPV2 in 2014 after more than 28 years. Ambiguous VDPVs were found among immunocompetent persons and environmental samples in 16 countries. Because the large majority of VDPV case-isolates are type 2, WHO has developed a plan for coordinated worldwide withdrawal of trivalent (types 1, 2, and 3) OPV (tOPV) and replacement with bivalent (types 1 and 3) OPV (bOPV) in April 2016, preceded by introduction of at least 1 dose of injectable inactivated poliovirus vaccine (IPV) into routine immunization schedules worldwide to maintain immunity to type 2 viruses.

Molecular dynamics and charge transport in organic semiconductors: a classical approach to modeling electron transfer

DOE PAGES

Pelzer, Kenley M.; Vázquez-Mayagoitia, Álvaro; Ratcliff, Laura E.; ...

2017-01-01

Organic photovoltaics (OPVs) are a promising carbon-neutral energy conversion technology, with recent improvements pushing power conversion efficiencies over 10%. A major factor limiting OPV performance is inefficiency of charge transport in organic semiconducting materials (OSCs). Due to strong coupling with lattice degrees of freedom, the charges form polarons, localized quasi-particles comprised of charges dressed with phonons. These polarons can be conceptualized as pseudo-atoms with a greater effective mass than a bare charge. Here we propose that due to this increased mass, polarons can be modeled with Langevin molecular dynamics (LMD), a classical approach with a computational cost much lower thanmore » most quantum mechanical methods. Here we present LMD simulations of charge transfer between a pair of fullerene molecules, which commonly serve as electron acceptors in OSCs. We find transfer rates consistent with experimental measurements of charge mobility, suggesting that this method may provide quantitative predictions of efficiency when used to simulate materials on the device scale. Our approach also offers information that is not captured in the overall transfer rate or mobility: in the simulation data, we observe exactly when and why intermolecular transfer events occur. In addition, we demonstrate that these simulations can shed light on the properties of polarons in OSCs. In conclusion, much remains to be learned about these quasi-particles, and there are no widely accepted methods for calculating properties such as effective mass and friction. Lastly, our model offers a promising approach to exploring mass and friction as well as providing insight into the details of polaron transport in OSCs.« less

Organic photovoltaic devices with a single layer geometry (Conference Presentation)

NASA Astrophysics Data System (ADS)

Kolesov, Vladimir A.; Fuentes-Hernandez, Canek; Aizawa, Naoya; Larrain, Felipe A.; Chou, Wen-Fang; Perrotta, Alberto; Graham, Samuel; Kippelen, Bernard

2016-09-01

Organic photovoltaics (OPV) can lead to a low cost and short energy payback time alternative to existing photovoltaic technologies. However, to fulfill this promise, power conversion efficiencies must be improved and simultaneously the architecture of the devices and their processing steps need to be further simplified. In the most efficient devices to date, the functions of photocurrent generation, and hole/electron collection are achieved in different layers adding complexity to the device fabrication. In this talk, we present a novel approach that yields devices in which all these functions are combined in a single layer. Specifically, we report on bulk heterojunction devices in which amine-containing polymers are first mixed in the solution together with the donor and acceptor materials that form the active layer. A single-layer coating yields a self-forming bottom electron-collection layer comprised of the amine-containing polymer (e.g. PEIE). Hole-collection is achieved by subsequent immersion of this single layer in a solution of a polyoxometalate (e.g. phosphomolybdic acid (PMA)) leading to an electrically p-doped region formed by the diffusion of the dopant molecules into the bulk. The depth of this doped region can be controlled with values up to tens of nm by varying the immersion time. Devices with a single 500 nm-thick active layer of P3HT:ICBA processed using this method yield power conversion efficiency (PCE) values of 4.8 ± 0.3% at 1 sun and demonstrate a performance level superior to that of benchmark three-layer devices with separate layers of PEIE/P3HT:ICBA/MoOx (4.1 ± 0.4%). Devices remain stable after shelf lifetime experiments carried-out at 60 °C over 280 h.

Mechanical properties of organic semiconductors for mechanically stable and intrinsically stretchable solar cells (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lipomi, Darren J.

2016-09-01

This presentation describes my group's efforts to understand the molecular and microstructural basis for the mechanical properties of organic semiconductors for organic photovoltaic (OPV) devices. Our work is motivated by two goals. The first goal is to mitigate mechanical forms of degradation of printed modules during roll-to-roll fabrication, installation, and environmental forces—i.e., wind, rain, snow, and thermal expansion and contraction. Mechanical stability is a prerequisite for inexpensive processing on flexible substrates: to encapsulate devices in glass is to surrender this advantage. The second goal is to enable the next generation of ultra-flexible and stretchable solar cells for collapsible, portable, and wearable applications, and as low-cost sources of energy—"solar tarps"—for disaster relief and for the developing world. It may seem that organic semiconductors, due to their carbon framework, are already sufficiently compliant for these applications. We have found, however, that the mechanical properties (stiffness and brittleness) occupy a wide range of values, and can be difficult to predict from molecular structure alone. We are developing an experimental and theoretical framework for how one can combine favorable charge-transport properties and mechanical compliance in organic semiconductor films. In particular, we have explored the roles of the backbone, alkyl side chain, microstructural order, the glass transition, molecular packing with fullerenes, plasticizing effects of additives, extent of separation of [60]PCBM and [70]PCBM, structural randomness in low-bandgap polymers, and reinforcement by encapsulation, on the mechanical compliance. We are exploring the applicability of semi-empirical "back-of-the-envelope" models, along with multi-scale molecular dynamics simulations, with the ultimate goal of designing electroactive organic materials whose mechanical properties can be dialed-in. We have used the insights we have developed to demonstrate several new applications for OPV that demand extreme compliance, including biaxial stretching and conformal bonding of whole devices to hemispheres, and devices with ultrathin encapsulation mounted on human skin that survive significant cyclic mechanical deformation in the outdoor environment.

Combinations of Quality and Frequency of Immunization Activities to Stop and Prevent Poliovirus Transmission in the High-Risk Area of Northwest Nigeria

PubMed Central

Duintjer Tebbens, Radboud J.; Pallansch, Mark A.; Wassilak, Steven G. F.; Cochi, Stephen L.; Thompson, Kimberly M.

2015-01-01

Background Frequent supplemental immunization activities (SIAs) with the oral poliovirus vaccine (OPV) represent the primary strategy to interrupt poliovirus transmission in the last endemic areas. Materials and Methods Using a differential-equation based poliovirus transmission model tailored to high-risk areas in Nigeria, we perform one-way and multi-way sensitivity analyses to demonstrate the impact of different assumptions about routine immunization (RI) and the frequency and quality of SIAs on population immunity to transmission and persistence or emergence of circulating vaccine-derived polioviruses (cVDPVs) after OPV cessation. Results More trivalent OPV use remains critical to avoid serotype 2 cVDPVs. RI schedules with or without inactivated polio vaccine (IPV) could significantly improve population immunity if coverage increases well above current levels in under-vaccinated subpopulations. Similarly, the impact of SIAs on overall population immunity and cVDPV risks depends on their ability to reach under-vaccinated groups (i.e., SIA quality). Lower SIA coverage in the under-vaccinated subpopulation results in a higher frequency of SIAs needed to maintain high enough population immunity to avoid cVDPVs after OPV cessation. Conclusions National immunization program managers in northwest Nigeria should recognize the benefits of increasing RI and SIA quality. Sufficiently improving RI coverage and improving SIA quality will reduce the frequency of SIAs required to stop and prevent future poliovirus transmission. Better information about the incremental costs to identify and reach under-vaccinated children would help determine the optimal balance between spending to increase SIA and RI quality and spending to increase SIA frequency. PMID:26068928

Combinations of Quality and Frequency of Immunization Activities to Stop and Prevent Poliovirus Transmission in the High-Risk Area of Northwest Nigeria.

PubMed

Duintjer Tebbens, Radboud J; Pallansch, Mark A; Wassilak, Steven G F; Cochi, Stephen L; Thompson, Kimberly M

2015-01-01

Frequent supplemental immunization activities (SIAs) with the oral poliovirus vaccine (OPV) represent the primary strategy to interrupt poliovirus transmission in the last endemic areas. Using a differential-equation based poliovirus transmission model tailored to high-risk areas in Nigeria, we perform one-way and multi-way sensitivity analyses to demonstrate the impact of different assumptions about routine immunization (RI) and the frequency and quality of SIAs on population immunity to transmission and persistence or emergence of circulating vaccine-derived polioviruses (cVDPVs) after OPV cessation. More trivalent OPV use remains critical to avoid serotype 2 cVDPVs. RI schedules with or without inactivated polio vaccine (IPV) could significantly improve population immunity if coverage increases well above current levels in under-vaccinated subpopulations. Similarly, the impact of SIAs on overall population immunity and cVDPV risks depends on their ability to reach under-vaccinated groups (i.e., SIA quality). Lower SIA coverage in the under-vaccinated subpopulation results in a higher frequency of SIAs needed to maintain high enough population immunity to avoid cVDPVs after OPV cessation. National immunization program managers in northwest Nigeria should recognize the benefits of increasing RI and SIA quality. Sufficiently improving RI coverage and improving SIA quality will reduce the frequency of SIAs required to stop and prevent future poliovirus transmission. Better information about the incremental costs to identify and reach under-vaccinated children would help determine the optimal balance between spending to increase SIA and RI quality and spending to increase SIA frequency.

Regulatory Aspects of Sabin Type 2 Withdrawal From Trivalent Oral Poliovirus Vaccine: Process and Lessons Learned.

PubMed

Decina, Daniela; Fournier-Caruana, Jacqueline; Takane, Marina; Ostad Ali Dehaghi, Razieh; Sutter, Roland

2017-07-01

Withdrawal of type 2 oral poliovirus vaccine (OPV) in OPV-using countries required regulatory approval for use of inactivated poliovirus vaccine and bivalent OPV in routine immunization. Worldwide, a variety of mechanisms were used by member states, with some differences in approach observed between inactivated poliovirus vaccine and bivalent OPV. These included acceptance for use of World Health Organization (WHO) prequalified vaccines, registration and licensure pathways, participation in WHO-convened joint reviews of licensing dossiers, as well as pragmatic application of alternatively available mechanisms, when appropriate. Simple but effective tools were used to monitor progress and to record, authenticate, and share information. Essential to achievement of regulatory targets was ongoing communication with key stakeholders, including switch-country national regulatory authorities, vaccine manufacturers, partner organizations, and relevant units within WHO. Understanding of the regulatory environment gained through the OPV switch can be helpful in supporting further stages of the polio end game and other time-sensitive vaccine introduction programs. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Charge carrier transport and injection across organic heterojunctions

NASA Astrophysics Data System (ADS)

Tsang, Sai Wing

The discovery of highly efficient organic light-emitting diodes (OLEDs) in the 1980s has stimulated extensive research on organic semiconductors and devices. Underlying this breakthrough is the realization of the organic heterojunction (OH). Besides OLEDs, the implementation of the OH also significantly improves the power conversion efficiency in organic photovoltaic cells (OPVs). The continued technological advancements in organic electronic devices depend on the accumulation of knowledge of the intrinsic properties of organic materials and related interfaces. Among them, charge-carrier transport and carrier injection are two key factors that govern the performance of a device. This thesis mainly focuses on the charge carrier injection and transport at organic heterojunctions. The carrier transport properties of different organic materials used in this study are characterized by time-of-flight (TOF) and admittance spectroscopy (AS). An injection model is formulated by considering the carrier distribution at both sides of the interface. Using a steady-state simulation approach, the effect of accumulated charges on energy level alignment at OH is revealed. Instead of a constant injection barrier, it is found that the barrier varies with applied voltage. Moreover, an escape probability function in the injection model is modified by taking into account the total hopping rate and available hopping sites at the interface. The model predicts that the injection current at low temperature can be dramatically modified by an extremely small density of deep trap states. More importantly, the temperature dependence of the injection current is found to decrease with increasing barrier height. This suggests that extracting the barrier height from the J vs 1/T plot, as commonly employed in the literature, is problematic. These theoretical predictions are confirmed by a series of experiments on heterojunction devices with various barrier heights. In addition, the presence of deep trap states is also consistent with carrier mobility measurements at low temperature. From the point of view of application, an interface chemical doping method is proposed to engineer the carrier injection at an organic heterojunction. It is found that the injection current can be effectively increased or suppressed by introducing a thin (2 nm) doped organic layer at the interface. This technique is further extended to study the impact of an injection barrier at the OH, in OLEDs, on device performance. It is shown that a 0.3 eV injection barrier at the OH, that is normally negligible at metal/organic interface, can reduce the device efficiency by 25%. This is explained by the carrier distribution in the density-of-states at the OH. Furthermore, the carrier transport properties in a bulk heterojunction system are investigated. The bulk heterojunction consists of an interpenetrating network of a polymeric electron donor and a molecular electron acceptor. This material system has been studied in the last few years as an attractive power conversion efficiency (5% under AM 1.5) of OPV cells has been demonstrated. It is found that the electron mobility is greatly dependent on the thermal treatment of the film. Interfacial dipole effect at the heterojunction between the donor and the acceptor is proposed to be the determining factor that alters the carrier mobility in different nanoscale structures.

Rotaxanes and Photovoltaic Materials Based on Pi-Conjugated Donors and Acceptors: Toward Energy Transduction on the Nanoscale

NASA Astrophysics Data System (ADS)

Bruns, Carson J.

The flow of energy between its various forms is central to our understanding of virtually all natural phenomena, from the origins and fate of the universe to the mechanisms that underpin Life. Therefore, a deeper fundamental understanding of how to manage energy processes at the molecular scale will open new doors in science and technology. This dissertation describes organic molecules and materials that are capable of transducing various forms of energy on the nanoscale, namely, a class of mechanically interlocked molecules known as rotaxanes for electrochemical-to-mechanical energy transduction (Part I), and a class of thin films known as organic photovoltaics (OPVs) for solar-to-electric energy transduction (Part II). These materials are all based on conjugated molecules with a capacity to donate or accept pi-electrons. A contemporary challenge in molecular nanotechnology is the development of artificial molecular machines (AMMs) that mimic the ability of motor proteins (e.g. myosin, kinesin) to perform mechanical work by leveraging a combination of energy sources and rich structural chemistry. Part I describes the synthesis, characterization, molecular dynamics, and switching properties of a series of `daisy chain' and oligorotaxane AMM prototypes. All compounds are templated by charge transfer and hydrogen bonding interactions between pi-associated 1,5-dioxynaphthlene donors appended with polyether groups and pi-acceptors of either neutral (naphthalenediimide) or charged (4,4´-bipyridinium) varieties, and are synthesized using efficient one-pot copper(I)-catalyzed azide-alkyne cycloaddition `click chemistry' protocols. The interlocked architectures of these rotaxanes enable them to express sophisticated secondary structures (i.e. foldamers) and mechanical motions in solution, which have been elucidated using dynamic 1H NMR spectroscopy. Furthermore, molecular dynamics simulations, cyclic voltammetry, and spectroelectrochemistry experiments have demonstrated that the muscle-like contractile-extensile motions of the daisy chains can be controlled by redox or thermal stimuli. It is concluded that donor-acceptor daisy chains and oligorotaxanes of unprecendented complexity can be readily prepared using click chemistry and actuated in solution. Motivated by the global demand for low-cost renewable energy, novel pi-donor molecules based on thiophene and diketopyrrolopyrrole (DPP) moieties are investigated in the context of thin-film materials for OPV technologies in Part II. Homologous families of small-molecule donors have been synthesized to investigate the effects of various molecular design principles on the morphological, optical, electronic, and photovoltaic properties of the corresponding thin-film materials. This strategy has been executed in the context of inorganic-organic hybrid OPVs and also more conventional bulk heterojunction (BHJ) OPVs. In the former case, a series of terthiophene surfactants with systematic variations in valency, geometry, and flexibility are electrodeposited on transparent electrodes from aqueous solutions to yield lamellar Zn(OH)2 materials with nanoscale periodicity, which are characterized by scanning electron miscroscopy and two-dimensional grazing incidence X-ray scattering. It is concluded that monovalent, flexible, linear surfactants yield the most dense and anisotropic nanostructures that are ideal for OPVs. For BHJ OPVs, the family of compounds under investigation are small molecule (SM) donors based on electron-rich heterocyclic acenes (benzodithiophene, benzodifuran, naphtho-dithiophene) and electron-poor thiophene-flanked DPP units. Single crystal X-ray structures of the SM donors are compared with morphological, hole mobility, photovoltaic efficiency data on their blends with a common fullerene acceptor to elucidate the optimal molecular design principles for this class of OPVs. It is concluded that the best-performing molecules have a symmetric architecture in which the central acene core comprises an extended pi-system.

Challenges to health workers and their opinions about parents' refusal of oral polio vaccination in the Khyber Pakhtoon Khawa (KPK) province, Pakistan.

PubMed

Khan, Tahir Mehmood; Sahibzada, Muhammad Umar Khayam

2016-04-19

A qualitative study design was adapted to explore the challenges faced by health workers (HWs) during the polio health campaign. In addition, HWs' opinions about the factors causing parents to refuse oral polio vaccination (OPV) were also explored. Four focus group discussions (FGDs) were held (from 1st January 2015-31st March 2015) with the HWs who participated in the OPV campaigns in the polio red zones of Khyber Pakhtoon Khawa (KPK) province of Pakistan, namely Kohat (FG 1), Domel and Bannu (FG 2), Hangoo (FG 3), and Peshawar (FG 4). A total of N=42 HWs (10-11 in each FG) agreed to participate in this study. Overall, HWs disclosed that public attitude and harsh behaviour towards the HWs and security threats are the two main challenges they face. Common issues hindering parents' willingness to vaccinate their children against OPV are: OPV is seen as haram and not permitted in Islam, it is said to contain the blood of pigs (Khinzir) and monkeys, and parents are afraid that it is done to induce sterility among their children. HWs also shared that parents have a strong belief in the conspiracies that are associated with OPV, i.e. the USA and CIA, are spying on us and our government is helping them to achieve their agenda. Furthermore, HWs revealed that frequent visits may further strengthen parents' perceptions and make them more resistant to OPV. The common side effects of OPV reported by parents were mainly gastro-intestinal problems and in some cases mild to moderate fever with some respiratory symptoms. There is a great need to improve the logistics and facilities for HWs assisting in vaccination programmes. Furthermore, it is necessary to improve education, so people understand the basic concept of revaccination and booster doses, thereby assisting in creating a basic understanding of vaccinations, which may trigger changes in attitudes and make people believe in the benefits of OPV rather than following the conspiracies that lead them to refuse it. Copyright © 2016 Elsevier Ltd. All rights reserved.

Immunogenicity of type 2 monovalent oral and inactivated poliovirus vaccines for type 2 poliovirus outbreak response: an open-label, randomised controlled trial.

PubMed

Zaman, Khalequ; Estívariz, Concepción F; Morales, Michelle; Yunus, Mohammad; Snider, Cynthia J; Gary, Howard E; Weldon, William C; Oberste, M Steven; Wassilak, Steven G; Pallansch, Mark A; Anand, Abhijeet

2018-06-01

Monovalent type 2 oral poliovirus vaccine (mOPV2) and inactivated poliovirus vaccine (IPV) are used to respond to type 2 poliovirus outbreaks. We aimed to assess the effect of two mOPV2 doses on the type 2 immune response by varying the time interval between mOPV2 doses and IPV co-administration with mOPV2. We did a randomised, controlled, parallel, open-label, non-inferiority, inequality trial at two study clinics in Dhaka, Bangladesh. Healthy infants aged 6 weeks (42-48 days) at enrolment were randomly assigned (1:1:1:1) to receive two mOPV2 doses (each dose consisting of two drops [0·1 mL in total] of about 10 5 50% cell culture infectious dose of type 2 Sabin strain) at intervals of 1 week, 2 weeks, 4 weeks (standard or control group), or 4 weeks with IPV (0·5 mL of type 1 [Mahoney, 40 D-antigen units], type 2 [MEF-1, 8 D-antigen units], and type 3 [Saukett, 32 D-antigen units]) administered intramuscularly with the first mOPV2 dose. We used block randomisation, randomly selecting blocks of sizes four, eight, 12, or 16 stratified by study sites. We concealed randomisation assignment from staff managing participants in opaque, sequentially numbered, sealed envelopes. Parents and clinic staff were unmasked to assignment after the randomisation envelope was opened. Laboratory staff analysing sera were masked to assignment, but investigators analysing data and assessing outcomes were not. The primary outcome was type 2 immune response measured 4 weeks after mOPV2 administration. The primary modified intention-to-treat analysis included participants with testable serum samples before and after vaccination. A non-inferiority margin of 10% and p=0·05 (one-tailed) was used. This trial is registered at ClinicalTrials.gov, number NCT02643368, and is closed to accrual. Between Dec 7, 2015, and Jan 5, 2016, we randomly assigned 760 infants to receive two mOPV2 doses at intervals of 1 week (n=191), 2 weeks (n=191), 4 weeks (n=188), or 4 weeks plus IPV (n=190). Immune responses after two mOPV2 doses were observed in 161 (93%) of 173 infants with testable serum samples in the 1 week group, 169 (96%) of 177 in the 2 week group, and 176 (97%) of 181 in the 4 week group. 1 week and 2 week intervals between two mOPV2 doses were non-inferior to 4 week intervals because the lower bound of the absolute differences in the percentage of immune responses were greater than -10% (-4·2% [90% CI -7·9 to -0·4] in the 1 week group and -1·8% [-5·0 to 1·5] in the 2 week group vs the 4 week group). The immune response elicited by two mOPV2 doses 4 weeks apart was not different when IPV was added to the first dose (176 [97%] of 182 infants with IPV vs 176 [97%] of 181 without IPV; p=1·0). During the trial, two serious adverse events (pneumonia; one [1%] of 186 patients in the 1 week group and one [1%] of 182 in the 4 week group) and no deaths were reported; the adverse events were not attributed to the vaccines. Administration of mOPV2 at short intervals does not interfere with its immunogenicity. The addition of IPV to the first mOPV2 dose did not improve poliovirus type 2 immune response. US Centers for Disease Control and Prevention. Copyright © 2018 Elsevier Ltd. All rights reserved.

Different secretory IgA antibody responses after immunization with inactivated and live poliovirus vaccines.

PubMed

Hanson, L A; Carlsson, B; Jalil, F; Lindblad, B S; Khan, S R; van Wezel, A L

1984-01-01

The influence on secretory IgA antibody levels in milk and saliva of vaccination with oral, live poliovirus vaccine ( OPV ) and inactivated poliovirus vaccine (IPV) was studied. IPV, especially the antigen-rich Dutch vaccine, more often induced increases in antibody titers in milk (50%) than did OPV (26%) (P less than .01). OPV more often decreased the antibody levels in milk (40%) than did IPV (10%) (P less than .01). It was striking that mainly high prevaccination titers were decreased. The increases of IgA antibody in saliva were less striking. IPV caused increases as often in milk as in saliva, whereas OPV more often induced increases in IgA antibody in saliva, but there was a poor correlation between the changes in antibody titers in milk and those in saliva.

Basic aspects for improving the energy conversion efficiency of hetero-junction organic photovoltaic cells.

PubMed

Ryuzaki, Sou; Onoe, Jun

2013-01-01

Hetero-junction organic photovoltaic (OPV) cells consisting of donor (D) and acceptor (A) layers have been regarded as next-generation PV cells, because of their fascinating advantages, such as lightweight, low fabrication cost, resource free, and flexibility, when compared to those of conventional PV cells based on silicon and semiconductor compounds. However, the power conversion efficiency (η) of the OPV cells has been still around 8%, though more than 10% efficiency has been required for their practical use. To fully optimize these OPV cells, it is necessary that the low mobility of carriers/excitons in the OPV cells and the open circuit voltage (V OC), of which origin has not been understood well, should be improved. In this review, we address an improvement of the mobility of carriers/excitons by controlling the crystal structure of a donor layer and address how to increase the V OC for zinc octaethylporphyrin [Zn(OEP)]/C60 hetero-junction OPV cells [ITO/Zn(OEP)/C60/Al]. It was found that crystallization of Zn(OEP) films increases the number of inter-molecular charge transfer (IMCT) excitons and enlarges the mobility of carriers and IMCT excitons, thus significantly improving the external quantum efficiency (EQE) under illumination of the photoabsorption band due to the IMCT excitons. Conversely, charge accumulation of photo-generated carriers in the vicinity of the donor/acceptor (D/A) interface was found to play a key role in determining the V OC for the OPV cells.

Mass media effect on vaccines uptake during silent polio outbreak.

PubMed

Sagy, Iftach; Novack, Victor; Gdalevich, Michael; Greenberg, Dan

2018-03-14

During 2013, isolation of a wild type 1 poliovirus from routine sewage sample in Israel, led to a national OPV campaign. During this period, there was a constant cover of the outbreak by the mass media. To investigate the association of media exposure and OPV and non-OPV vaccines uptake during the 2013 silent polio outbreak in Israel. We received data on daily immunization rates during the outbreak period from the Ministry of Health (MoH). We conducted a multivariable time trend analysis to assess the association between daily media exposure and vaccines uptake. Analysis was stratified by ethnicity and socio-economic status (SES). During the MoH supplemental immunization activity, 138,799 OPV vaccines were given. There was a significant association between media exposure and OPV uptake, most prominent in a lag of 3-5 days from the exposure among Jews (R.R 1.79C.I 95% 1.32-2.41) and high SES subgroups (R.R 1.71C.I 95% 1.27-2.30). These subgroups also showed increased non-OPV uptake in a lag of 3-5 days from the media exposure, in all vaccines except for MMR. Lower SES and non-Jewish subgroups did not demonstrate the same association. Our findings expand the understanding of public behaviour during outbreaks. The public response shows high variability within specific subgroups. These findings highlight the importance of tailored communication strategies for each subgroup. Copyright © 2018 Elsevier Ltd. All rights reserved.

The role of exciton ionization processes in bulk heterojunction organic photovoltaic cells

NASA Astrophysics Data System (ADS)

Zou, Yunlong; Holmes, Russell

2015-03-01

Dissociating photogenerated excitons into their constituent charges is essential for efficient photoconversion in organic semiconductors. Organic photovoltaics cells (OPV) widely adopt a heterojunction architecture where dissociation is facilitated by charge transfer at a donor-acceptor (D-A) interface. Interestingly, recent work on MoOx/C60 Schottky OPVs has demonstrated that excitons in C60 may also undergo bulk-ionization to generate photocurrent, driven by the built-in field at the MoOx/C60 interface. Here, we show that bulk-ionization processes also contribute to the photocurrent in bulk heterojunction (BHJ) OPVs with fullerene-rich compositions. The short-circuit current density (JSC) in a MoOx/C60 Schottky OPVs shows almost no dependence on temperature down to 80 K. This characteristic of bulk-ionization allows the use of temperature-dependent measurements of JSC to distinguish dissociation by bulk-ionization from charge transfer at a D-A interface. For BHJ OPVs constructed using the D-A pairing of boron subphthalocyanine chloride (SubPc)-C60, bulk-ionization is found to contribute >10% of the total photocurrent and >30% of the photocurrent from C60. We further find that fullerene-rich SubPc-C60 BHJ OPVs show a larger open-circuit voltage (VOC) than evenly mixed BHJs due to the presence of bulk-ionization. This talk will examine the dependence of JSC and VOC on the relative fraction of dissociation by charge transfer and bulk-ionization processes.

Basic aspects for improving the energy conversion efficiency of hetero-junction organic photovoltaic cells

PubMed Central

Ryuzaki, Sou; Onoe, Jun

2013-01-01

Hetero-junction organic photovoltaic (OPV) cells consisting of donor (D) and acceptor (A) layers have been regarded as next-generation PV cells, because of their fascinating advantages, such as lightweight, low fabrication cost, resource free, and flexibility, when compared to those of conventional PV cells based on silicon and semiconductor compounds. However, the power conversion efficiency (η) of the OPV cells has been still around 8%, though more than 10% efficiency has been required for their practical use. To fully optimize these OPV cells, it is necessary that the low mobility of carriers/excitons in the OPV cells and the open circuit voltage (V OC), of which origin has not been understood well, should be improved. In this review, we address an improvement of the mobility of carriers/excitons by controlling the crystal structure of a donor layer and address how to increase the V OC for zinc octaethylporphyrin [Zn(OEP)]/C60 hetero-junction OPV cells [ITO/Zn(OEP)/C60/Al]. It was found that crystallization of Zn(OEP) films increases the number of inter-molecular charge transfer (IMCT) excitons and enlarges the mobility of carriers and IMCT excitons, thus significantly improving the external quantum efficiency (EQE) under illumination of the photoabsorption band due to the IMCT excitons. Conversely, charge accumulation of photo-generated carriers in the vicinity of the donor/acceptor (D/A) interface was found to play a key role in determining the V OC for the OPV cells. PMID:23853702

Financial Support to Eligible Countries for the Switch From Trivalent to Bivalent Oral Polio Vaccine-Lessons Learned.

PubMed

Shendale, Stephanie; Farrell, Margaret; Hampton, Lee M; Harris, Jennifer B; Kachra, Tasleem; Kurji, Feyrouz; Patel, Manish; Ramirez Gonzalez, Alejandro; Zipursky, Simona

2017-07-01

The global switch from trivalent oral polio vaccine (tOPV) to bivalent oral polio vaccine (bOPV) ("the switch") presented an unprecedented challenge to countries. In order to mitigate the risks associated with country-level delays in implementing the switch, the Global Polio Eradication Initiative provided catalytic financial support to specific countries for operational costs unique to the switch. Between November 2015 and February 2016, a total of approximately US$19.4 million in financial support was provided to 67 countries. On average, country budgets allocated 20% to human resources, 23% to trainings and meetings, 8% to communications and advocacy, 9% to logistics, 15% to monitoring, and 5% to waste management. All 67 funded countries successfully switched from tOPV to bOPV during April-May 2016. This funding provided target countries with the necessary catalytic support to facilitate the execution of the switch on an accelerated timeline, and the mechanism offers a model for similar support to future global health efforts, such as the eventual global withdrawal of bOPV. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Understanding the free energy barrier and multiple timescale dynamics of charge separation in organic photovoltaic cells.

PubMed

Yan, Yaming; Song, Linze; Shi, Qiang

2018-02-28

By employing several lattice model systems, we investigate the free energy barrier and real-time dynamics of charge separation in organic photovoltaic (OPV) cells. It is found that the combined effects of the external electric field, entropy, and charge delocalization reduce the free energy barrier significantly. The dynamic disorder reduces charge carrier delocalization and results in the increased charge separation barrier, while the effect of static disorder is more complicated. Simulation of the real-time dynamics indicates that the free charge generation process involves multiple time scales, including an ultrafast component within hundreds of femtoseconds, an intermediate component related to the relaxation of the hot charge transfer (CT) state, and a slow component on the time scale of tens of picoseconds from the thermally equilibrated CT state. Effects of hot exciton dissociation as well as its dependence on the energy offset between the Frenkel exciton and the CT state are also analyzed. The current results indicate that only a small energy offset between the band gap and the lowest energy CT state is needed to achieve efficient free charge generation in OPV devices, which agrees with recent experimental findings.

On the possibility of singlet fission in crystalline quaterrylene

NASA Astrophysics Data System (ADS)

Wang, Xiaopeng; Liu, Xingyu; Cook, Cameron; Schatschneider, Bohdan; Marom, Noa

2018-05-01

Singlet fission (SF), the spontaneous down-conversion of a singlet exciton into two triplet excitons residing on neighboring molecules, is a promising route to improve organic photovoltaic (OPV) device efficiencies by harvesting two charge carriers from one photon. However, only a few materials have been discovered that exhibit intermolecular SF in the solid state, most of which are acene derivatives. Recently, there has been a growing interest in rylenes as potential SF materials. We use many-body perturbation theory in the GW approximation and the Bethe-Salpeter equation to investigate the possibility of intermolecular SF in crystalline perylene and quaterrylene. A new method is presented for determining the percent charge transfer (%CT) character of an exciton wave-function from double-Bader analysis. This enables relating exciton probability distributions to crystal packing. Based on comparison to known and predicted SF materials with respect to the energy conservation criterion (ES-2ET) and %CT, crystalline quaterrylene is a promising candidate for intermolecular SF. Furthermore, quaterrylene is attractive for OPV applications, thanks to its high stability and narrow optical gap. Perylene is not expected to exhibit SF; however, it is a promising candidate for harvesting sub-gap photons by triplet-triplet annihilation.

Understanding the free energy barrier and multiple timescale dynamics of charge separation in organic photovoltaic cells

NASA Astrophysics Data System (ADS)

Yan, Yaming; Song, Linze; Shi, Qiang

2018-02-01

By employing several lattice model systems, we investigate the free energy barrier and real-time dynamics of charge separation in organic photovoltaic (OPV) cells. It is found that the combined effects of the external electric field, entropy, and charge delocalization reduce the free energy barrier significantly. The dynamic disorder reduces charge carrier delocalization and results in the increased charge separation barrier, while the effect of static disorder is more complicated. Simulation of the real-time dynamics indicates that the free charge generation process involves multiple time scales, including an ultrafast component within hundreds of femtoseconds, an intermediate component related to the relaxation of the hot charge transfer (CT) state, and a slow component on the time scale of tens of picoseconds from the thermally equilibrated CT state. Effects of hot exciton dissociation as well as its dependence on the energy offset between the Frenkel exciton and the CT state are also analyzed. The current results indicate that only a small energy offset between the band gap and the lowest energy CT state is needed to achieve efficient free charge generation in OPV devices, which agrees with recent experimental findings.

On the possibility of singlet fission in crystalline quaterrylene.

PubMed

Wang, Xiaopeng; Liu, Xingyu; Cook, Cameron; Schatschneider, Bohdan; Marom, Noa

2018-05-14

Singlet fission (SF), the spontaneous down-conversion of a singlet exciton into two triplet excitons residing on neighboring molecules, is a promising route to improve organic photovoltaic (OPV) device efficiencies by harvesting two charge carriers from one photon. However, only a few materials have been discovered that exhibit intermolecular SF in the solid state, most of which are acene derivatives. Recently, there has been a growing interest in rylenes as potential SF materials. We use many-body perturbation theory in the GW approximation and the Bethe-Salpeter equation to investigate the possibility of intermolecular SF in crystalline perylene and quaterrylene. A new method is presented for determining the percent charge transfer (%CT) character of an exciton wave-function from double-Bader analysis. This enables relating exciton probability distributions to crystal packing. Based on comparison to known and predicted SF materials with respect to the energy conservation criterion (E S -2E T ) and %CT, crystalline quaterrylene is a promising candidate for intermolecular SF. Furthermore, quaterrylene is attractive for OPV applications, thanks to its high stability and narrow optical gap. Perylene is not expected to exhibit SF; however, it is a promising candidate for harvesting sub-gap photons by triplet-triplet annihilation.

Probing charge transfer complex states in organic solar cells using photocurrent spectroscopy

NASA Astrophysics Data System (ADS)

Moghe, Dhanashree; Adil, Danish; Kanimozhi, Catherine; Dutta, Gitesh; Patil, Satish; Guha, Suchismita

2013-03-01

Diketopyrrolopyrrole (DPP) containing copolymers-fullerene blends have gained a lot of interest in organic optoelectronics with a great potential in organic photovoltaics (OPVs). The interfacial charge transfer complex (CTC) states formed in donor-acceptor blended OPVs play a major role in the overall efficiency of the device. We investigate the spectral photocurrent characteristics of five DPP based copolymers; two of them being benzothiadiazole and carbazole -based statistical copolymers of DPP. These systems provide a wide range of bandgap energies ranging from ~ 1.4 to 1.7 eV. We use Fourier transform photocurrent spectroscopy (FTPS) and monochromatic photocurrent (PC) to identify the CTC states in these DPP copolymer -fullerene blends. The stability of the CTC state is found to be dependent on the band gap energy difference between the donor copolymer and the acceptor. We support our inferences from theoretical results obtained using density-functional theory (DFT) and time-dependent DFT for two DPP based copolymers The theoretical calculations reveal a higher contribution of the CTC states to the lowest excited state in the phenyl-based DPP monomer, which has a larger bandgap energy compared to the thiophene-based DPP system, in the presence of a fullerene molecule.

Accessing Synthetically-Challenging Isoindole-Based Materials for Assessment in Organic Photovoltaics via Chemical and Engineering Methodologies =

NASA Astrophysics Data System (ADS)

Dang, Jeremy

Isoindoles are a broad class of compounds that comprise a very small space within the domain of established photoactive materials for organic photovoltaics (OPVs). Given this scarcity, combined with the performance appeal of presently and well known isoindole-based compounds such as the phthalocyanines, it is a worthy undertaking to develop new materials in this domain. This thesis aims to bring to light the suitability of five novel, or underexplored, classes of isoindole-based materials for OPVs. These classes are the boron subphthalocyanine (BsubPc) polymers, oxygen-bridged dimers of BsubPcs (mu-oxo-(BsubPc) 2), boron subnaphthalocyanines (BsubNcs), group XIII metal complexes of 1,3-bis(2-pyridylimino)isodinoline (BPI), and the boron tribenzosubporphyrins (BsubPys). The synthesis of these materials was proven to be challenging as evident in their low isolated yields, lengthy synthetic and purification processes, and/or batch-to-batch variations. This outcome was not surprising given their undeveloped chemical nature. The photo- and electro-physical properties were characterized and shown to be desirable for all classes other than the group XIII metal complexes of BPI for OPVs. mu-Oxo-(BsubPc)2 and BsubNcs show promise in this application while BsubPc polymers and BsubPys will be subjects of future exploration. The results from the work herein aid to develop and strengthen the fundamental understanding of the structure-property relationships of isoindole derivatives. On a broader scale, the work demonstrates their versatility as functional materials for OPVs and their possible expansion to other organic electronic technologies like organic light emitting diodes and organic field effect transistors.

Identification and control of a poliomyelitis outbreak in Xinjiang, China.

PubMed

Luo, Hui-Ming; Zhang, Yong; Wang, Xin-Qi; Yu, Wen-Zhou; Wen, Ning; Yan, Dong-Mei; Wang, Hua-Qing; Wushouer, Fuerhati; Wang, Hai-Bo; Xu, Ai-Qiang; Zheng, Jing-Shan; Li, De-Xin; Cui, Hui; Wang, Jian-Ping; Zhu, Shuang-Li; Feng, Zi-Jian; Cui, Fu-Qiang; Ning, Jing; Hao, Li-Xin; Fan, Chun-Xiang; Ning, Gui-Jun; Yu, Hong-Jie; Wang, Shi-Wen; Liu, Da-Wei; Wang, Dong-Yan; Fu, Jian-Ping; Gou, Ai-li; Zhang, Guo-Min; Huang, Guo-Hong; Chen, Yuan-Sheng; Mi, Sha-Sha; Liu, Yan-Min; Yin, Da-Peng; Zhu, Hui; Fan, Xin-Chun; Li, Xin-Lan; Ji, Yi-Xin; Li, Ke-Li; Tang, Hai-Shu; Xu, Wen-Bo; Wang, Yu; Yang, Wei-Zhong

2013-11-21

The last case of infection with wild-type poliovirus indigenous to China was reported in 1994, and China was certified as a poliomyelitis-free region in 2000. In 2011, an outbreak of infection with imported wild-type poliovirus occurred in the province of Xinjiang. We conducted an investigation to guide the response to the outbreak, performed sequence analysis of the poliovirus type 1 capsid protein VP1 to determine the source, and carried out serologic and coverage surveys to assess the risk of viral propagation. Surveillance for acute flaccid paralysis was intensified to enhance case ascertainment. Between July 3 and October 9, 2011, investigators identified 21 cases of infection with wild-type poliovirus and 23 clinically compatible cases in southern Xinjiang. Wild-type poliovirus type 1 was isolated from 14 of 673 contacts of patients with acute flaccid paralysis (2.1%) and from 13 of 491 healthy persons who were not in contact with affected persons (2.6%). Sequence analysis implicated an imported wild-type poliovirus that originated in Pakistan as the cause of the outbreak. A public health emergency was declared in Xinjiang after the outbreak was confirmed. Surveillance for acute flaccid paralysis was enhanced, with daily reporting from all public and private hospitals. Five rounds of vaccination with live, attenuated oral poliovirus vaccine (OPV) were conducted among children and adults, and 43 million doses of OPV were administered. Trivalent OPV was used in three rounds, and monovalent OPV type 1 was used in two rounds. The outbreak was stopped 1.5 months after laboratory confirmation of the index case. The 2011 outbreak in China showed that poliomyelitis-free countries remain at risk for outbreaks while the poliovirus circulates anywhere in the world. Global eradication of poliomyelitis will benefit all countries, even those that are currently free of poliomyelitis.

Inactivated polio vaccine: time to introduce it in India's national immunization schedule.

PubMed

Verma, Ramesh; Khanna, Pardeep; Chawla, Suraj

2012-07-01

Polio is a communicable disease caused by poliovirus that may attack nerve cells of the brain and spinal cord. The victims develop neurological complications, likes stiffness of the neck, muscular weakness, or paralysis of one or more limbs. In severe cases, it may be fatal due to respiratory paralysis. The world has seen tremendous gains in polio eradication over the past year. India and Nigeria saw a reduction in cases of almost 95% from 2009 to 2010, and cases of wild poliovirus type 3 (WPV3) fell by 92% globally over the same period. In fact, no case has been reported in India since February 2011, such that India may be on the verge of eradicating polio. Nevertheless, polio control experts are particularly worried about Vaccine-Derived Poliovirus (VDPV). Global surveillance efforts picked up 430 cases of VDPV from several countries between July 2009 and March 2011. In India, 7 cases of VDPV were reported during the year 2011. As long as OPV is used, virologists say that the world is at risk of VDPV causing polio in unprotected children. Achieving a polio-free world will require the "cessation of all OPV" and with it the elimination of the risk of vaccine-associated paralytic polio (VAPP) or VDPV infections. To this effect, in 2011 the Global Polio Eradication Initiative (GPEI) will produce and develop a new roadmap for VDPV Elimination. Several countries have shifted from all OPV to sequential OPV-IPV schedules and all-IPV schedules with elimination of live poliovirus. IPV will be indispensable in the post-eradication era when use of OPV has to stop but "vaccination against polio" cannot stop. IPV offers complete individual protection and has been considered as an additional tool at present for those who can afford the vaccine, and since we are nearing the eradication of polio, it is time to shift from OPV to sequential OPV-IPV schedule in India. Such a strategy will avoid inevitable problems with VAPP.

Genome of Horsepox Virus

PubMed Central

Tulman, E. R.; Delhon, G.; Afonso, C. L.; Lu, Z.; Zsak, L.; Sandybaev, N. T.; Kerembekova, U. Z.; Zaitsev, V. L.; Kutish, G. F.; Rock, D. L.

2006-01-01

Here we present the genomic sequence of horsepox virus (HSPV) isolate MNR-76, an orthopoxvirus (OPV) isolated in 1976 from diseased Mongolian horses. The 212-kbp genome contained 7.5-kbp inverted terminal repeats and lacked extensive terminal tandem repetition. HSPV contained 236 open reading frames (ORFs) with similarity to those in other OPVs, with those in the central 100-kbp region most conserved relative to other OPVs. Phylogenetic analysis of the conserved region indicated that HSPV is closely related to sequenced isolates of vaccinia virus (VACV) and rabbitpox virus, clearly grouping together these VACV-like viruses. Fifty-four HSPV ORFs likely represented fragments of 25 orthologous OPV genes, including in the central region the only known fragmented form of an OPV ribonucleotide reductase large subunit gene. In terminal genomic regions, HSPV lacked full-length homologues of genes variably fragmented in other VACV-like viruses but was unique in fragmentation of the homologue of VACV strain Copenhagen B6R, a gene intact in other known VACV-like viruses. Notably, HSPV contained in terminal genomic regions 17 kbp of OPV-like sequence absent in known VACV-like viruses, including fragments of genes intact in other OPVs and approximately 1.4 kb of sequence present only in cowpox virus (CPXV). HSPV also contained seven full-length genes fragmented or missing in other VACV-like viruses, including intact homologues of the CPXV strain GRI-90 D2L/I4R CrmB and D13L CD30-like tumor necrosis factor receptors, D3L/I3R and C1L ankyrin repeat proteins, B19R kelch-like protein, D7L BTB/POZ domain protein, and B22R variola virus B22R-like protein. These results indicated that HSPV contains unique genomic features likely contributing to a unique virulence/host range phenotype. They also indicated that while closely related to known VACV-like viruses, HSPV contains additional, potentially ancestral sequences absent in other VACV-like viruses. PMID:16940536

Clustered lot quality assurance sampling: a tool to monitor immunization coverage rapidly during a national yellow fever and polio vaccination campaign in Cameroon, May 2009.

PubMed

Pezzoli, L; Tchio, R; Dzossa, A D; Ndjomo, S; Takeu, A; Anya, B; Ticha, J; Ronveaux, O; Lewis, R F

2012-01-01

We used the clustered lot quality assurance sampling (clustered-LQAS) technique to identify districts with low immunization coverage and guide mop-up actions during the last 4 days of a combined oral polio vaccine (OPV) and yellow fever (YF) vaccination campaign conducted in Cameroon in May 2009. We monitored 17 pre-selected districts at risk for low coverage. We designed LQAS plans to reject districts with YF vaccination coverage <90% and with OPV coverage <95%. In each lot the sample size was 50 (five clusters of 10) with decision values of 3 for assessing OPV and 7 for YF coverage. We 'rejected' 10 districts for low YF coverage and 14 for low OPV coverage. Hence we recommended a 2-day extension of the campaign. Clustered-LQAS proved to be useful in guiding the campaign vaccination strategy before the completion of the operations.

Intestinal Immune Responses to Type 2 Oral Polio Vaccine (OPV) Challenge in Infants Previously Immunized With Bivalent OPV and Either High-Dose or Standard Inactivated Polio Vaccine.

PubMed

Brickley, Elizabeth B; Strauch, Carolyn B; Wieland-Alter, Wendy F; Connor, Ruth I; Lin, Shu; Weiner, Joshua A; Ackerman, Margaret E; Arita, Minetaro; Oberste, M Steven; Weldon, William C; Sáez-Llorens, Xavier; Bandyopadhyay, Ananda S; Wright, Peter F

2018-01-17

The impact of inactivated polio vaccines (IPVs) on intestinal mucosal immune responses to live poliovirus is poorly understood. In a 2014 phase 2 clinical trial, Panamanian infants were immunized at 6, 10, and 14 weeks of age with bivalent oral polio vaccine (bOPV) and randomized to receive either a novel monovalent high-dose type 2-specific IPV (mIPV2HD) or a standard trivalent IPV at 14 weeks. Infants were challenged at 18 weeks with a monovalent type 2 oral polio vaccine (mOPV2). Infants' intestinal immune responses during the 3 weeks following challenge were investigated by measuring poliovirus type-specific neutralization and immunoglobulin (Ig) A, IgA1, IgA2, IgD, IgG, and IgM antibodies in stool samples. Despite mIPV2HD's 4-fold higher type 2 polio D-antigen content and heightened serum neutralization profile, mIPV2HD-immunized infants' intestinal immune responses to mOPV2 challenge were largely indistinguishable from those receiving standard IPV. Mucosal responses were tightly linked to evidence of active infection and, in the 79% of participants who shed virus, robust type 2-specific IgA responses and stool neutralization were observed by 2 weeks after challenge. Enhancing IPV-induced serum neutralization does not substantively improve intestinal mucosal immune responses or limit viral shedding on mOPV2 challenge. NCT02111135. © The Author(s) 2018. Published by Oxford University Press for the Infectious Diseases Society of America.

Antigenic Evolution of Vaccine-Derived Polioviruses: Changes in Individual Epitopes and Relative Stability of the Overall Immunological Properties

PubMed Central

Yakovenko, Maria L.; Cherkasova, Elena A.; Rezapkin, Gennady V.; Ivanova, Olga E.; Ivanov, Alexander P.; Eremeeva, Tatyana P.; Baykova, Olga Y.; Chumakov, Konstantin M.; Agol, Vadim I.

2006-01-01

The Sabin oral poliovirus vaccine (OPV) readily undergoes changes in antigenic sites upon replication in humans. Here, a set of antigenically altered descendants of the three OPV serotypes (76 isolates) was characterized to determine the driving forces behind these changes and their biological implications. The amino acid residues of OPV derivatives that lie within or close to the known antigenic sites exhibited a marked tendency to be replaced by residues characteristic of homotypic wild polioviruses, and these changes may occur very early in OPV evolution. The specific amino acid alterations nicely correlated with serotype-specific changes in the reactivity of certain individual antigenic sites, as revealed by the recently devised monoclonal antibody-based enzyme-linked immunosorbent assay. In comparison to the original vaccine, small changes, if any, in the neutralizing capacity of human or rabbit sera were observed in highly diverged vaccine polioviruses of three serotypes, in spite of strong alterations of certain epitopes. We propose that the common antigenic alterations in evolving OPV strains largely reflect attempts to eliminate fitness-decreasing mutations acquired either during the original selection of the vaccine or already present in the parental strains. Variability of individual epitopes does not appear to be primarily caused by, or lead to, a significant immune evasion, enhancing only slightly, if at all, the capacity of OPV derivatives to overcome immunity in human populations. This study reveals some important patterns of poliovirus evolution and has obvious implications for the rational design of live viral vaccines. PMID:16501074

Intestinal Immune Responses to Type 2 Oral Polio Vaccine (OPV) Challenge in Infants Previously Immunized With Bivalent OPV and Either High-Dose or Standard Inactivated Polio Vaccine

PubMed Central

Brickley, Elizabeth B; Strauch, Carolyn B; Wieland-Alter, Wendy F; Connor, Ruth I; Lin, Shu; Weiner, Joshua A; Ackerman, Margaret E; Arita, Minetaro; Oberste, M Steven; Weldon, William C; Sáez-Llorens, Xavier; Bandyopadhyay, Ananda S; Wright, Peter F

2018-01-01

Abstract Background The impact of inactivated polio vaccines (IPVs) on intestinal mucosal immune responses to live poliovirus is poorly understood. Methods In a 2014 phase 2 clinical trial, Panamanian infants were immunized at 6, 10, and 14 weeks of age with bivalent oral polio vaccine (bOPV) and randomized to receive either a novel monovalent high-dose type 2–specific IPV (mIPV2HD) or a standard trivalent IPV at 14 weeks. Infants were challenged at 18 weeks with a monovalent type 2 oral polio vaccine (mOPV2). Infants’ intestinal immune responses during the 3 weeks following challenge were investigated by measuring poliovirus type-specific neutralization and immunoglobulin (Ig) A, IgA1, IgA2, IgD, IgG, and IgM antibodies in stool samples. Results Despite mIPV2HD’s 4-fold higher type 2 polio D–antigen content and heightened serum neutralization profile, mIPV2HD-immunized infants’ intestinal immune responses to mOPV2 challenge were largely indistinguishable from those receiving standard IPV. Mucosal responses were tightly linked to evidence of active infection and, in the 79% of participants who shed virus, robust type 2–specific IgA responses and stool neutralization were observed by 2 weeks after challenge. Conclusions Enhancing IPV-induced serum neutralization does not substantively improve intestinal mucosal immune responses or limit viral shedding on mOPV2 challenge. Clinical Trials Registration NCT02111135. PMID:29304199

Interrupting wild poliovirus transmission using oral poliovirus vaccine: environmental surveillance in high-risks area of India.

PubMed

Chowdhary, Rashmi; Dhole, T N

2008-08-01

Global eradication of poliomyelitis has reached critical stage. Sabin Oral Poliovirus Vaccine (OPV) has been successful in three major regions of the world. In India eradication of poliomyelitis from states of Uttar Pradesh (UP) and Bihar has been difficult due to high population and low-socioeconomic standards of living. Acute flaccid paralysis (AFP) surveillance and intensive OPV rounds continues with the World Health Organization (WHO) operational strategies. Yet apparent lack of progress in reducing the number of wild cases has resulted in occasional impatience and frustration, even leading to questions about ultimate feasibility of global eradication using OPV. Lucknow in UP is in geographical area endemic for poliomyelitis and is surrounded by high-risk areas yet maintains a polio-free status since 2002. Environmental surveillance study was conducted (2004-2006) to authenticate the decline in the wild poliovirus (PV) cases in Lucknow. Sewage sample analyses were compared with stools of AFP patients and healthy children from same geographical area. Study reveals useful information on OPV circulation and proves important epidemiological tool to trust WHO's OPV immunization program. Genetic sequencing had detected silent wild PV-1 circulation of RCP1PGI (EU049849), RCP2PGI (EU049850), RCP3PGI (EU049851), and RCP4PGI (EU049852) in sewage waters. Properties of isolates from sewage reflected those of viruses excreted from human. This study provides valuable information and encouragement to AFP surveillance to maintain high levels of OPV immunization campaigns in the most difficult endemic region of India to interrupt the wild PV transmission.

Molecular dynamics and charge transport in organic semiconductors: a classical approach to modeling electron transfer† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6sc04547b Click here for additional data file.

PubMed Central

Vázquez-Mayagoitia, Álvaro; Ratcliff, Laura E.; Tretiak, Sergei; Bair, Raymond A.; Gray, Stephen K.; Van Voorhis, Troy; Larsen, Ross E.; Darling, Seth B.

2017-01-01

Organic photovoltaics (OPVs) are a promising carbon-neutral energy conversion technology, with recent improvements pushing power conversion efficiencies over 10%. A major factor limiting OPV performance is inefficiency of charge transport in organic semiconducting materials (OSCs). Due to strong coupling with lattice degrees of freedom, the charges form polarons, localized quasi-particles comprised of charges dressed with phonons. These polarons can be conceptualized as pseudo-atoms with a greater effective mass than a bare charge. We propose that due to this increased mass, polarons can be modeled with Langevin molecular dynamics (LMD), a classical approach with a computational cost much lower than most quantum mechanical methods. Here we present LMD simulations of charge transfer between a pair of fullerene molecules, which commonly serve as electron acceptors in OSCs. We find transfer rates consistent with experimental measurements of charge mobility, suggesting that this method may provide quantitative predictions of efficiency when used to simulate materials on the device scale. Our approach also offers information that is not captured in the overall transfer rate or mobility: in the simulation data, we observe exactly when and why intermolecular transfer events occur. In addition, we demonstrate that these simulations can shed light on the properties of polarons in OSCs. Much remains to be learned about these quasi-particles, and there are no widely accepted methods for calculating properties such as effective mass and friction. Our model offers a promising approach to exploring mass and friction as well as providing insight into the details of polaron transport in OSCs. PMID:28553494

Performance enhancement in organic photovoltaic solar cells using iridium (Ir) ultra-thin surface modifier (USM)

NASA Astrophysics Data System (ADS)

Pandey, Rina; Lim, Ju Won; Kim, Jung Hyuk; Angadi, Basavaraj; Choi, Ji Won; Choi, Won Kook

2018-06-01

In this study, Iridium (Ir) metallic layer as an ultra-thin surface modifier (USM) was deposited on ITO coated glass substrate using radio frequency magnetron sputtering for improving the photo-conversion efficiency of organic photovoltaic cells. Ultra-thin Ir acts as a surface modifier replacing the conventional hole transport layer (HTL) PEDOT:PSS in organic photovoltaic (OPV) cells with two different active layers P3HT:PC60BM and PTB7:PC70BM. The Ir USM (1.0 nm) coated on ITO glass substrate showed transmittance of 84.1% and work function of >5.0 eV, which is higher than that of ITO (4.5-4.7 eV). The OPV cells with Ir USM (1.0 nm) exhibits increased power conversion efficiency of 3.70% (for P3HT:PC60BM active layer) and 7.28% (for PTB7:PC70BM active layer) under 100 mW/cm2 illumination (AM 1.5G) which are higher than those of 3.26% and 6.95% for the same OPV cells but with PEDOT:PSS as HTL instead of Ir USM. The results reveal that the chemically stable Ir USM layer could be used as an alternative material for PEDOT:PSS in organic photovoltaic cells.

[Inactivated poliovirus vaccines: an inevitable choice for eliminating poliomyelitis].

PubMed

Vidor, J D; Jean-Denis, Shu

2016-12-06

The inactivated poliovirus vaccine (IPV) is a very old tool in the fight against poliomyelitis. Though supplanted by oral poliovirus vaccine (OPV) in the 1960s and 1970s, the IPV has now become an inevitable choice because of the increasingly recognized risks associated with continuous use of OPVs. Following the pioneering work of Jonas Salk, who established key principles for the IPV, considerable experience has accumulated over the years. This work has led to modern Salk IPV-containing vaccines, based on the use of inactivated wildtype polioviruses, which have been deployed for routine use in many countries. Very good protection against paralysis is achieved with IPV through the presence of circulating antibodies able to neutralize virus infectivity toward motor neurons. In addition, with IPV, a variable degree of protection against mucosal infection (and therefore transmission) through mucosal antibodies and immune cells is achieved, depending on previous exposure of subjects to wildtype or vaccine polioviruses. The use of an IPV-followed-by-OPV sequential immunization schedule has the potential advantage of eliminating the vaccine-associated paralytic poliomyelitis (VAPP) risk, while limiting the risks of vaccine-derived poliovirus (VDPVs). Sabin strain-derived IPVs are new tools, only recently beginning to be deployed, and data are being generated to document their performance. IPVs will play an irreplaceable role in global eradication of polio.

Parallel bulk heterojunction photovoltaics based on all-conjugated block copolymer additives

DOE PAGES

Mok, Jorge W.; Kipp, Dylan; Hasbun, Luis R.; ...

2016-08-23

We demonstrated that the addition of block copolymers to binary donor–acceptor blends represents an effective approach to target equilibrium, co-continuous morphologies of interpenetrating donors and acceptors in our recent study. We report a study of the impact of all-conjugated poly(thieno[3,4-b]-thiophene-co-benzodithiophene)-b-polynaphthalene diimide (PTB7-b-PNDI) block copolymer additives on the electronic properties and photovoltaic performance of bulk heterojunction organic photovoltaic active layers comprised of a PTB7 donor and a phenyl-C61-butyric acid methyl ester (PCBM61) acceptor. We find that small amounts of BCP additives lead to improved performance due to a large increase in the device open-circuit voltage (VOC), and the VOC is pinnedmore » to this higher value for higher BCP additive loadings. Such results contrast prior studies of ternary blend OPVs where either a continuous change in VOC or a value of VOC pinned to the lowest value is observed. We hypothesize and provide evidence in the form of device and morphology analyses that the impact of VOC is likely due to the formation of a parallel bulk heterojunction made up of isolated PCBM and PNDI acceptor domains separated by intermediate PTB7 donor domains. Our work demonstrates that all-conjugated block copolymers can be utilized as additives to both dictate morphology and modulate the electronic properties of the active layer.« less

Parallel bulk heterojunction photovoltaics based on all-conjugated block copolymer additives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mok, Jorge W.; Kipp, Dylan; Hasbun, Luis R.

We demonstrated that the addition of block copolymers to binary donor–acceptor blends represents an effective approach to target equilibrium, co-continuous morphologies of interpenetrating donors and acceptors in our recent study. We report a study of the impact of all-conjugated poly(thieno[3,4-b]-thiophene-co-benzodithiophene)-b-polynaphthalene diimide (PTB7-b-PNDI) block copolymer additives on the electronic properties and photovoltaic performance of bulk heterojunction organic photovoltaic active layers comprised of a PTB7 donor and a phenyl-C61-butyric acid methyl ester (PCBM61) acceptor. We find that small amounts of BCP additives lead to improved performance due to a large increase in the device open-circuit voltage (VOC), and the VOC is pinnedmore » to this higher value for higher BCP additive loadings. Such results contrast prior studies of ternary blend OPVs where either a continuous change in VOC or a value of VOC pinned to the lowest value is observed. We hypothesize and provide evidence in the form of device and morphology analyses that the impact of VOC is likely due to the formation of a parallel bulk heterojunction made up of isolated PCBM and PNDI acceptor domains separated by intermediate PTB7 donor domains. Our work demonstrates that all-conjugated block copolymers can be utilized as additives to both dictate morphology and modulate the electronic properties of the active layer.« less

Managing the Planned Cessation of a Global Supply Market: Lessons Learned From the Global Cessation of the Trivalent Oral Poliovirus Vaccine Market

PubMed Central

Ottosen, Ann; Ghazieh, Andisheh; Fournier-Caruana, Jacqueline; Ntow, Abraham Kofi; Gonzalez, Alejandro Ramirez

2017-01-01

Abstract The Polio Eradication and Endgame Strategic Plan 2013-2018 calls for the phased withdrawal of OPV, beginning with the globally synchronized cessation of tOPV by mid 2016. From a global vaccine supply management perspective, the strategy provided two key challenges; (1) the planned cessation of a high volume vaccine market; and (2) the uncertainty of demand leading and timeline as total vaccine requirements were contingent on epidemiology. The withdrawal of trivalent OPV provided a number of useful lessons that could be applied for the final OPV cessation. If carefully planned for and based on a close collaboration between programme partners and manufacturers, the cessation of a supply market can be undertaken with a successful outcome for both parties. As financial risks to manufacturers increase even further with OPV cessation, early engagement from the cessation planning phase and consideration of production lead times will be critical to ensure sufficient supply throughout to achieve programmatic objectives. As the GPEI will need to rely on residual stocks including with manufacturers through to the last campaign to achieve its objectives, the GPEI should consider to decide on and communicate a suitable mechanism for co-sharing of financial risks or other financial arrangement for the outer years. PMID:28838167

Oral iodine supplementation does not reduce neutralizing antibody responses to oral poliovirus vaccine.

PubMed Central

Taffs, R. E.; Enterline, J. C.; Rusmil, K.; Muhilal; Suwardi, S. S.; Rustama, D.; Djatnika; Cobra, C.; Semba, R. D.; Cohen, N.; Asher, D. M.

1999-01-01

Iodine deficiency is a major cause of impaired mental development, goitre, and cretinism in many parts of the world. Because existing immunization programmes can be used to deliver oral iodized oil (OIO) to infants at risk, it was important to know whether OIO could adversely affect the antibody response to vaccines, such as trivalent oral poliovirus vaccine (OPV). A randomized, double-blind, placebo-controlled clinical trial was conducted in Subang, West Java, Indonesia, in which 617 eight-week-old infants received either OIO or a placebo (poppy-seed oil) during a routine visit for their first dose of OPV as part of the Expanded Programme on Immunization (EPI). The infants received two boosters of OPV at 4-week intervals after the first dose, and were followed up when 6 months old. Neutralizing antibody titres to poliovirus serotypes 1, 2, and 3 were compared in serum samples that were taken from 478 of these infants just before the first dose of OPV and at 6 months. It was found that oral iodized oil did not reduce the antibody responses to any of the three serotypes of OPV. These results indicate that oral iodine may safely be delivered to infants at the same time as oral poliovirus vaccine according to current EPI immunization schedules. PMID:10427933

Vaccine-associated paralytic poliomyelitis in India during 1999: decreased risk despite massive use of oral polio vaccine.

PubMed Central

Kohler, Kathryn A.; Banerjee, Kaushik; Gary Hlady, W.; Andrus, Jon K.; Sutter, Roland W.

2002-01-01

OBJECTIVE: Vaccine-associated paralytic poliomyelitis (VAPP) is a rare but serious consequence of the administration of oral polio vaccine (OPV). Intensified OPV administration has reduced wild poliovirus transmission in India but VAPP is becoming a matter of concern. METHODS: We analysed acute flaccid paralysis (AFP) surveillance data in order to estimate the VAPP risk in this country. VAPP was defined as occurring in AFP cases with onset of paralysis in 1999, residual weakness 60 days after onset, and isolation of vaccine-related poliovirus. Recipient VAPP cases were a subset with onset of paralysis between 4 and 40 days after receipt of OPV. FINDINGS: A total of 181 AFP cases met the case definition. The following estimates of VAPP risk were made: overall risk, 1 case per 4.1 to 4.6 million OPV doses administered; recipient risk,1 case per 12.2 million; first-dose recipient risk, 1 case per 2.8 million; and subsequent-dose recipient risk, 1 case per 13.9 million. CONCLUSION: On the basis of data from a highly sensitive surveillance system the estimated VAPP risk in India is evidently lower than that in other countries, notwithstanding the administration of multiple OPV doses to children in mass immunization campaigns. PMID:11984607

Oligo(phenylenevinylene) hybrids and self-assemblies: versatile materials for excitation energy transfer.

PubMed

Praveen, Vakayil K; Ranjith, Choorikkat; Bandini, Elisa; Ajayaghosh, Ayyappanpillai; Armaroli, Nicola

2014-06-21

Oligo(phenylenevinylene)s (OPVs) are extensively investigated π-conjugated molecules that exhibit absorption and fluorescence in the UV-Vis spectral region, which can be widely tuned by chemical functionalisation and external control (e.g. solvent, temperature, pH). Further modulation of the optoelectronic properties of OPVs is possible by supramolecular aggregation, primarily driven by hydrogen bonding or π-stacking interactions. In recent years, extensive research work has been accomplished in exploiting the unique combination of the structural and electronic properties of OPVs, most of which has been targeted at the preparation of molecules and materials featuring photoinduced energy transfer. This review intends to offer an overview of the multicomponent arrays and self-assembled materials based on OPV which have been designed to undergo energy transfer by means of a thorough choice of excitation donor-acceptor partners. We present a few selected examples of photoactive dyads and triads containing organic moieties (e.g. fullerene, phenanthroline) as well as coordination compounds (Cu(I) complexes). We then focus more extensively on self-assembled materials containing suitably functionalised OPVs that lead to hydrogen bonded aggregates, helical structures, gels, nanoparticles, vesicles, mesostructured organic-inorganic hybrid films, functionalised nanoparticles and quantum dots. In most cases, these materials exhibit luminescence whose colour and intensity is related to the efficiency and direction of the energy transfer processes.

Assessing the individual risk of fecal poliovirus shedding among vaccinated and non-vaccinated subjects following national health weeks in Mexico

PubMed Central

Ferreyra-Reyes, Leticia; Cruz-Hervert, Luis Pablo; Troy, Stephanie B.; Huang, ChunHong; Sarnquist, Clea; Delgado-Sánchez, Guadalupe; Canizales-Quintero, Sergio; Holubar, Marisa; Ferreira-Guerrero, Elizabeth; Montero-Campos, Rogelio; Rodríguez-Álvarez, Mauricio; Mongua-Rodriguez, Norma; Maldonado, Yvonne

2017-01-01

Background Mexico introduced inactivated polio vaccine (IPV) into its routine immunization (RI) schedule in 2007 but continued to give trivalent oral polio vaccine (tOPV) twice a year during national health weeks (NHW) through 2015. Objectives To evaluate individual variables associated with poliovirus (PV) shedding among children with IPV-induced immunity after vaccination with tOPV and their household contacts. Materials and methods We recruited 72 children (both genders, ≤30 months, vaccinated with at least two doses of IPV) and 144 household contacts (both genders, 2 per household, children and adults) between 08/2010 and 09/2010 in Orizaba, Veracruz. Three NHW took place (one before and two after enrollment). We collected fecal samples monthly for 12 months, and tested 2500 samples for polioviruses types 1, 2 and 3 with three serotype-specific singleplex real-time RT-PCR (rRT-PCR) assays. In order to increase the specificity for OPV virus, all positive and 112 negative samples were also processed with a two-step, OPV serotype-specific multiplex rRT-PCR. Analysis We estimated adjusted hazard ratios (HR) and 95% CI using Cox proportional hazards regression for recurrent events models accounting for individual clustering to assess the association of individual variables with the shedding of any poliovirus for all participants and stratifying according to whether the participant had received tOPV in the month of sample collection. Results 216 participants were included. Of the 2500 collected samples, using the singleplex rRT-PCR assay, PV was detected in 5.7% (n = 142); PV1 in 1.2% (n = 29), PV2 in 4.1% (n = 103), and PV3 in 1.9% (n = 48). Of the 256 samples processed by multiplex rRT-PCR, PV was detected in 106 (PV1 in 16.41% (n = 42), PV2 in 21.09% (n = 54), and PV3 in 23.05% (n = 59). Both using singleplex and multiplex assays, shedding of OPV among non-vaccinated children and subjects older than 5 years of age living in the same household was associated with shedding of PV2 by a household contact. All models were adjusted by sex, age, IPV vaccination and OPV shedding by the same individual during the previous month of sample collection. Conclusion Our results provide important evidence regarding the circulation of poliovirus in a mixed vaccination context (IPV+OPV) which mimics the “transitional phase” that occurs when countries use both vaccines simultaneously. Shedding of OPV2 by household contacts was most likely the source of infection of non-vaccinated children and subjects older than 5 years of age living in the same household. PMID:29023555

Morphology and Performance of Polymer Solar Cell Characterized by DPD Simulation and Graph Theory.

PubMed

Du, Chunmiao; Ji, Yujin; Xue, Junwei; Hou, Tingjun; Tang, Jianxin; Lee, Shuit-Tong; Li, Youyong

2015-11-19

The morphology of active layers in the bulk heterojunction (BHJ) solar cells is critical to the performance of organic photovoltaics (OPV). Currently, there is limited information for the morphology from transmission electron microscopy (TEM) techniques. Meanwhile, there are limited approaches to predict the morphology /efficiency of OPV. Here we use Dissipative Particle Dynamics (DPD) to determine 3D morphology of BHJ solar cells and show DPD to be an efficient approach to predict the 3D morphology. Based on the 3D morphology, we estimate the performance indicator of BHJ solar cells by using graph theory. Specifically, we study poly (3-hexylthiophene)/[6, 6]-phenyl-C61butyric acid methyl ester (P3HT/PCBM) BHJ solar cells. We find that, when the volume fraction of PCBM is in the region 0.4 ∼ 0.5, P3HT/PCBM will show bi-continuous morphology and optimum performance, consistent with experimental results. Further, the optimum temperature (413 K) for the morphology and performance of P3HT/PCBM is in accord with annealing results. We find that solvent additive plays a critical role in the desolvation process of P3HT/PCBM BHJ solar cell. Our approach provides a direct method to predict dynamic 3D morphology and performance indicator for BHJ solar cells.

Characterization of ectromelia virus deficient in EVM036, the homolog of vaccinia virus F13L, and its application for rapid generation of recombinant viruses.

PubMed

Roscoe, Felicia; Xu, Ren-Huan; Sigal, Luis J

2012-12-01

The orthopoxvirus (OPV) vaccinia virus (VACV) requires an intact F13L gene to produce enveloped virions (EV) and to form plaques in cell monolayers. Simultaneous introduction of an exogenous gene and F13L into F13L-deficient VACV results in expression of the foreign gene and restoration of plaque size. This is used as a method to rapidly generate VACV recombinants without the need for drug selection. However, whether other OPVs require the orthologs of F13L to generate EV and form plaques, whether F13L orthologs and EV are important for OPV pathogenesis in natural hosts, and whether a system based on F13L ortholog deficiency can be used to generate recombinant OPVs other than VACV have not been reported. The F13L ortholog in ectromelia virus (ECTV), the agent of mousepox, is EVM036. We show that ECTV lacking EVM036 formed small plaques and was highly attenuated in vivo but still induced strong antibody responses. Reintroduction of EVM036 in tandem with the DsRed gene resulted in a virus that expressed DsRed in infected cells but was indistinguishable from wild-type ECTV in terms of plaque size and in vivo virulence. Thus, our data show that, like F13L in VACV, EVM036 is required for ECTV plaque formation and that EVM036 and EV are important for ECTV virulence. Our experiments also suggest that OPVs deficient in F13L orthologs could serve as safer anti-OPV vaccines. Further, our results demonstrate that ECTV deficient in EVM036 can be exploited for the rapid generation of fully virulent ECTV expressing foreign genes of interest.

Morphological control in polymer solar cells using low-boiling-point solvent additives

NASA Astrophysics Data System (ADS)

Mahadevapuram, Rakesh C.

In the global search for clean, renewable energy sources, organic photovoltaics (OPVs) have recently been given much attention. Popular modern-day OPVs are made from solution-processible, carbon-based polymers (e.g. the model poly(3-hexylthiophene) that are intimately blended with fullerene derivatives (e.g. [6,6]-phenyl-C71-butyric acid methyl ester) to form what is known as the dispersed bulk-heterojunction (BHJ). This BHJ architecture has produced some of the most efficient OPVs to date, with reports closing in on 10% power conversion efficiency. To push efficiencies further into double digits, many groups have identified the BHJ nanomorphology---that is, the phase separations and grain sizes within the polymer: fullerene composite---as a key aspect in need of control and improvement. As a result, many methods, including thermal annealing, slow-drying (solvent) annealing, vapor annealing, and solvent additives, have been developed and studied to promote BHJ self-organization. Processing organic photovoltaic (OPV) blend solutions with high-boiling-point solvent additives has recently been used for morphological control in BHJ OPV cells. Here we show that even low-boiling-point solvents can be effective additives. When P3HT:PCBM OPV cells were processed with a low-boiling-point solvent tetrahydrafuran as an additive in parent solvent o-dichlorobenzene, charge extraction increased leading to fill factors as high as 69.5%, without low work-function cathodes, electrode buffer layers or thermal treatment. This was attributed to PCBM demixing from P3HT domains and better vertical phase separation, as indicated by photoluminescence lifetimes, hole mobilities, and shunt leakage currents. Dependence on solvent parameters and applicability beyond P3HT system was also investigated.

Effects of humidity during formation of zinc oxide electron contact layers from a diethylzinc precursor solution

DOE PAGES

Mauger, Scott A.; Steirer, K. Xerxes; Boe, Jonas; ...

2016-01-19

Here, this work focuses on the role of humidity in the formation of ZnO thin films from a reactive diethylzinc precursor solution for use as the electron contact layer (ECL) in organic photovoltaic (OPV) devices. This method is well suited for flexible devices because the films are annealed at 120 °C, making the process compatible with polymer substrates. ZnO films were prepared by spin coating and annealing at different relative humidity (RH) levels. It is found that RH during coating and annealing affects the chemical and physical properties of the ZnO films. Using x-ray photoelectron spectroscopy it is found thatmore » increasing RH during the formation steps produces a more stoichiometric oxide and a higher Zn/O ratio. Spectroscopic ellipsometry data shows a small decrease in the optical band gap with increased humidity, consistent with a more stoichiometric oxide. Kelvin probe measurements show that increased RH during formation results in a larger work function (i.e. further from vacuum). Consistent with these data, but counter to what might be expected, when these ZnO films are used as ECLs in OPV devices those with ZnO ECLs processed in low RH (less stoichiometric) had higher power conversion efficiency than those with high-RH processed ZnO due to improved open-circuit voltage. The increase in open-circuit voltage with decreasing humidity was observed with two different donor polymers and fullerene acceptors, which shows the trend is due to changes in ZnO. The observed changes in open-circuit voltage follow the same trend as the ZnO work function indicating that the increase in open-circuit voltage with decreasing humidity is the result of improved energetics at the interface between the bulk-heterojunction and the ZnO layer due to a vacuum level shift.« less

The theoretical study of passive and active optical devices via planewave based transfer (scattering) matrix method and other approaches

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhuo, Ye

2011-01-01

In this thesis, we theoretically study the electromagnetic wave propagation in several passive and active optical components and devices including 2-D photonic crystals, straight and curved waveguides, organic light emitting diodes (OLEDs), and etc. Several optical designs are also presented like organic photovoltaic (OPV) cells and solar concentrators. The first part of the thesis focuses on theoretical investigation. First, the plane-wave-based transfer (scattering) matrix method (TMM) is briefly described with a short review of photonic crystals and other numerical methods to study them (Chapter 1 and 2). Next TMM, the numerical method itself is investigated in details and developed inmore » advance to deal with more complex optical systems. In chapter 3, TMM is extended in curvilinear coordinates to study curved nanoribbon waveguides. The problem of a curved structure is transformed into an equivalent one of a straight structure with spatially dependent tensors of dielectric constant and magnetic permeability. In chapter 4, a new set of localized basis orbitals are introduced to locally represent electromagnetic field in photonic crystals as alternative to planewave basis. The second part of the thesis focuses on the design of optical devices. First, two examples of TMM applications are given. The first example is the design of metal grating structures as replacements of ITO to enhance the optical absorption in OPV cells (chapter 6). The second one is the design of the same structure as above to enhance the light extraction of OLEDs (chapter 7). Next, two design examples by ray tracing method are given, including applying a microlens array to enhance the light extraction of OLEDs (chapter 5) and an all-angle wide-wavelength design of solar concentrator (chapter 8). In summary, this dissertation has extended TMM which makes it capable of treating complex optical systems. Several optical designs by TMM and ray tracing method are also given as a full complement of this work.« less

Polio Endgame, Information Gaps Related to Vaccines and Immunity.

PubMed

Ahmad, Mohammad; Bahl, Sunil; Kunwar, Abhishek

2016-08-07

Evidence generated through research studies has guided programmatic actions and fine-tuned strategies for the Global Polio Eradication Initiative (GPEI). However, many gaps still persist in the understanding of a risk-free implementation of the polio endgame. Immediate concerns relate to the introduction of inactivated polio vaccine (IPV) and switch from trivalent oral polio vaccine (tOPV) to bivalent oral polio vaccine (bOPV) in routine immunization schedule. A comprehensive understanding of mucosal immunity in populations and best response options against circulating vaccine derived poliovirus (cVDPV) outbreaks in post tOPV-bOPV switch is essential to mitigate the risks of wild and vaccine-derived poliovirus importations and emergence of cVDPVs in polio-free countries. A clearer picture is also needed on few operational issues, interference between polio vaccines and other EPI vaccines and products related to polio endgame. It is also extremely important to develop mechanisms to identify and manage long-term poliovirus excretors who may pose a risk of reintroduction into the population after global eradication of poliovirus.

Light Manipulation in Organic Photovoltaics

PubMed Central

Ou, Qing‐Dong

2016-01-01

Organic photovoltaics (OPVs) hold great promise for next‐generation photovoltaics in renewable energy because of the potential to realize low‐cost mass production via large‐area roll‐to‐roll printing technologies on flexible substrates. To achieve high‐efficiency OPVs, one key issue is to overcome the insufficient photon absorption in organic photoactive layers, since their low carrier mobility limits the film thickness for minimized charge recombination loss. To solve the inherent trade‐off between photon absorption and charge transport in OPVs, the optical manipulation of light with novel micro/nano‐structures has become an increasingly popular strategy to boost the light harvesting efficiency. In this Review, we make an attempt to capture the recent advances in this area. A survey of light trapping schemes implemented to various functional components and interfaces in OPVs is given and discussed from the viewpoint of plasmonic and photonic resonances, addressing the external antireflection coatings, substrate geometry‐induced trapping, the role of electrode design in optical enhancement, as well as optically modifying charge extraction and photoactive layers. PMID:27840805

Intrinsic coincident full-Stokes polarimeter using stacked organic photovoltaics.

PubMed

Yang, Ruonan; Sen, Pratik; O'Connor, B T; Kudenov, M W

2017-02-20

An intrinsic coincident full-Stokes polarimeter is demonstrated by using strain-aligned polymer-based organic photovoltaics (OPVs) that can preferentially absorb certain polarized states of incident light. The photovoltaic-based polarimeter is capable of measuring four Stokes parameters by cascading four semitransparent OPVs in series along the same optical axis. This in-line polarimeter concept potentially ensures high temporal and spatial resolution with higher radiometric efficiency as compared to the existing polarimeter architecture. Two wave plates were incorporated into the system to modulate the S₃ Stokes parameter so as to reduce the condition number of the measurement matrix and maximize the measured signal-to-noise ratio. Radiometric calibration was carried out to determine the measurement matrix. The polarimeter presented in this paper demonstrated an average RMS error of 0.84% for reconstructed Stokes vectors after normalized to S₀. A theoretical analysis of the minimum condition number of the four-cell OPV design showed that for individually optimized OPV cells, a condition number of 2.4 is possible.

Construction and photophysical properties of organic-inorganic nanonetworks based on oligo(phenylenevinylene) and functionalized gold nanoparticles.

PubMed

Yang, Jien; Liu, Xiaofeng; Huang, Changshui; Zhou, Chunjie; Li, Yuliang; Zhu, Daoben

2010-02-22

Novel organic-inorganic nanonetworks of oligo(phenylenevinylene) (OPV) and gold nanoparticles (GNPs) have been synthesized by the amine-based epoxide ring-opening reaction. The resulting OPV-GNPs nanocomposites exhibit homogeneous and well-defined interfaces between the organic ligands and the inorganic nanoparticles, thereby promoting efficient electronic interfacial interaction between the two constituents. The functionalized gold nanoparticles serve as chemical reagents for the construction of nanohybrids, while the epoxide-terminated OPV acts as linkage between gold nanoparticles. The new architecture provides a facile methodology for fabrication of novel organic-inorganic nanohybrids under relatively mild conditions, which facilitates further applications of hybrid materials.

The effect of mass immunisation campaigns and new oral poliovirus vaccines on the incidence of poliomyelitis in Pakistan and Afghanistan, 2001-11: a retrospective analysis.

PubMed

O'Reilly, Kathleen M; Durry, Elias; ul Islam, Obaid; Quddus, Arshad; Abid, Ni'ma; Mir, Tahir P; Tangermann, Rudi H; Aylward, R Bruce; Grassly, Nicholas C

2012-08-04

Pakistan and Afghanistan are two of the three remaining countries yet to interrupt wild-type poliovirus transmission. The increasing incidence of poliomyelitis in these countries during 2010-11 led the Executive Board of WHO in January, 2012, to declare polio eradication a "programmatic emergency for global public health". We aimed to establish why incidence is rising in these countries despite programme innovations including the introduction of new vaccines. We did a matched case-control analysis based on a database of 46,977 children aged 0-14 years with onset of acute flaccid paralysis between Jan 1, 2001, and Dec 31, 2011. The vaccination history of children with poliomyelitis was compared with that of children with acute flaccid paralysis due to other causes to estimate the clinical effectiveness of oral poliovirus vaccines (OPVs) in Afghanistan and Pakistan by conditional logistic regression. We estimated vaccine coverage and serotype-specific vaccine-induced population immunity in children aged 0-2 years and assessed their association with the incidence of poliomyelitis over time in seven regions of Afghanistan and Pakistan. Between Jan 1, 2001, and Dec 31, 2011, there were 883 cases of serotype 1 poliomyelitis (710 in Pakistan and 173 in Afghanistan) and 272 cases of poliomyelitis serotype 3 (216 in Pakistan and 56 in Afghanistan). The estimated clinical effectiveness of a dose of trivalent OPV against serotype 1 poliomyelitis was 12·5% (95% CI 5·6-18·8) compared with 34·5% (16·1-48·9) for monovalent OPV (p=0·007) and 23·4% (10·4-34·6) for bivalent OPV (p=0·067). Bivalent OPV was non-inferior compared with monovalent OPV (p=0·21). Vaccination coverage decreased during 2006-11 in the Federally Administered Tribal Areas (FATA), Balochistan, and Khyber Pakhtunkhwa in Pakistan and in southern Afghanistan. Although partially mitigated by the use of more effective vaccines, these decreases in coverage resulted in lower vaccine-induced population immunity to poliovirus serotype 1 in FATA and Balochistan and associated increases in the incidence of poliomyelitis. The effectiveness of bivalent OPV is comparable with monovalent OPV and can therefore be used in eradicating serotype 1 poliomyelitis whilst minimising the risks of serotype 3 outbreaks. However, decreases in vaccination coverage in parts of Pakistan and southern Afghanistan have severely limited the effect of this vaccine. Poliovirus Research subcommittee of WHO, Royal Society, and Medical Research Council. Copyright © 2012 Elsevier Ltd. All rights reserved.

Managing the Planned Cessation of a Global Supply Market: Lessons Learned From the Global Cessation of the Trivalent Oral Poliovirus Vaccine Market.

PubMed

Rubin, Jennifer; Ottosen, Ann; Ghazieh, Andisheh; Fournier-Caruana, Jacqueline; Ntow, Abraham Kofi; Gonzalez, Alejandro Ramirez

2017-07-01

The Polio Eradication and Endgame Strategic Plan 2013-2018 calls for the phased withdrawal of OPV, beginning with the globally synchronized cessation of tOPV by mid 2016. From a global vaccine supply management perspective, the strategy provided two key challenges; (1) the planned cessation of a high volume vaccine market; and (2) the uncertainty of demand leading and timeline as total vaccine requirements were contingent on epidemiology. The withdrawal of trivalent OPV provided a number of useful lessons that could be applied for the final OPV cessation. If carefully planned for and based on a close collaboration between programme partners and manufacturers, the cessation of a supply market can be undertaken with a successful outcome for both parties. As financial risks to manufacturers increase even further with OPV cessation, early engagement from the cessation planning phase and consideration of production lead times will be critical to ensure sufficient supply throughout to achieve programmatic objectives. As the GPEI will need to rely on residual stocks including with manufacturers through to the last campaign to achieve its objectives, the GPEI should consider to decide on and communicate a suitable mechanism for co-sharing of financial risks or other financial arrangement for the outer years. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Progress Toward Containment of Poliovirus Type 2 - Worldwide, 2017.

PubMed

Previsani, Nicoletta; Singh, Harpal; St Pierre, Jeanette; Boualam, Liliane; Fournier-Caruana, Jacqueline; Sutter, Roland W; Zaffran, Michel

2017-06-23

The Global Polio Eradication Initiative (GPEI) continues to make progress toward the eradication target. Only one of the three serotypes, wild poliovirus (WPV) type 1 (WPV1), is still circulating, and the numbers of cases and countries with endemic transmission are at record lows. With the certification of wild poliovirus type 2 (WPV2) eradication in 2015 and the global replacement of trivalent oral poliovirus vaccine (tOPV) containing Sabin poliovirus types 1, 2, and 3 with bivalent OPV containing only Sabin poliovirus types 1 and 3 during April-May 2016, poliovirus type 2 (PV2) is now an eradicated pathogen. However, in eight countries (Cameroon, Chad, Democratic Republic of Congo, Mozambique, Niger, Nigeria, Pakistan, and Syria), monovalent type 2 OPV (mOPV2) was authorized for large-scale outbreak control after tOPV withdrawal (1). Poliovirus containment, an evolving area of work that affects every country, aims to ensure that all PV2 specimens are safely contained to minimize the risk for reintroducing the virus into communities. This report summarizes the current status of poliovirus containment and progress since the last report (2), and outlines remaining challenges. Within 30 countries, 86 facilities have been designated by the relevant national authorities (usually the Ministry of Health) to become poliovirus-essential facilities for the continued storage or handling of PV2 materials; each country is responsible for ensuring that these facilities meet all biorisk management requirements.

Effect of buffer on the immune response to trivalent oral poliovirus vaccine in Bangladesh: a community based randomized controlled trial.

PubMed

Chandir, Subhash; Ahamed, Kabir U; Baqui, Abdullah H; Sutter, Roland W; Okayasu, Hiromasa; Pallansch, Mark A; Oberste, Mark S; Moulton, Lawrence H; Halsey, Neal A

2014-11-01

Polio eradication efforts have been hampered by low responses to trivalent oral poliovirus vaccine (tOPV) in some developing countries. Since stomach acidity may neutralize vaccine viruses, we assessed whether administration of a buffer solution could improve the immunogenicity of tOPV. Healthy infants 4-6 weeks old in Sylhet, Bangladesh, were randomized to receive tOPV with or without a sodium bicarbonate and sodium citrate buffer at age 6, 10, and 14 weeks. Levels of serum neutralizing antibodies for poliovirus types 1, 2, and 3 were measured before and after vaccination, at 6 and 18 weeks of age, respectively. Serologic response rates following 3 doses of tOPV for buffer recipients and control infants were 95% and 88% (P=.065), respectively, for type 1 poliovirus; 95% and 97% (P=.543), respectively, for type 2 poliovirus; and 90% and 89% (P=.79), respectively, for type 3 poliovirus. Administration of a buffer solution prior to vaccination was not associated with statistically significant increases in the immune response to tOPV; however, a marginal 7% increase (P=.065) in serologic response to poliovirus type 1 was observed. NCT01579825. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Wild and vaccine-derived poliovirus circulation, and implications for polio eradication.

PubMed

Lopalco, P L

2017-02-01

Polio cases due to wild virus are reported by only three countries in the world. Poliovirus type 2 has been globally eradicated and the last detection of poliovirus type 3 dates to November 2012. Poliovirus type 1 remains the only circulating wild strain; between January and September 2016 it caused 26 cases (nine in Afghanistan, 14 in Pakistan, three in Nigeria). The use of oral polio vaccine (OPV) has been the key to success in the eradication effort. However, paradoxically, moving towards global polio eradication, the burden caused by vaccine-derived polioviruses (VDPVs) becomes increasingly important. In this paper circulation of both wild virus and VDPVs is reviewed and implications for the polio eradication endgame are discussed. Between April and May 2016 OPV2 cessation has been implemented globally, in a coordinated switch from trivalent OPV to bivalent OPV. In order to decrease the risk for cVDPV2 re-emergence inactivated polio vaccine (IPV) has been introduced in the routine vaccine schedule of all countries. The likelihood of re-emergence of cVDPVs should markedly decrease with time after OPV cessation, but silent circulation of polioviruses cannot be ruled out even a long time after cessation. For this reason, immunity levels against polioviruses should be kept as high as possible in the population by the use of IPV, and both clinical and environmental surveillance should be maintained at a high level.

Development of a multiplex RT-PCR assay for the identification of recombination types at different genomic regions of vaccine-derived polioviruses.

PubMed

Dimitriou, T G; Kyriakopoulou, Z; Tsakogiannis, D; Fikatas, A; Gartzonika, C; Levidiotou-Stefanou, S; Markoulatos, P

2016-08-01

Polioviruses (PVs) are the causal agents of acute paralytic poliomyelitis. Since the 1960s, poliomyelitis has been effectively controlled by the use of two vaccines containing all three serotypes of PVs, the inactivated poliovirus vaccine and the live attenuated oral poliovirus vaccine (OPV). Despite the success of OPV in polio eradication programme, a significant disadvantage was revealed: the emergence of vaccine-associated paralytic poliomyelitis (VAPP). VAPP is the result of accumulated mutations and putative recombination events located at the genome of attenuated vaccine Sabin strains. In the present study, ten Sabin isolates derived from OPV vaccinees and environmental samples were studied in order to identify recombination types located from VP1 to 3D genomic regions of virus genome. The experimental procedure that was followed was virus RNA extraction, reverse transcription to convert the virus genome into cDNA, PCR and multiplex-PCR using specific designed primers able to localize and identify each recombination following agarose gel electrophoresis. This multiplex RT-PCR assay allows for the immediate detection and identification of multiple recombination types located at the viral genome of OPV derivatives. After the eradication of wild PVs, the remaining sources of poliovirus infection worldwide would be the OPV derivatives. As a consequence, the immediate detection and molecular characterization of recombinant derivatives are important to avoid epidemics due to the circulation of neurovirulent viral strains.

Toward Cost-Effective Fingerprinting Methodology to Distinguish Maize Open-Pollinated Varieties

USDA-ARS?s Scientific Manuscript database

In Africa, many smallholder farmers grow open pollinated maize varieties (OPVs), as they allow seed recycling and out-yield traditional farmer’s (unimproved) landraces. One popular OPV, ZM521 released by the International Maize and Wheat Improvement Center (CIMMYT), has been provided to farmers, o...

Optical, Electrical and Magnetic Studies of Pi-Conjugated Organic Semiconductor Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vardeny, Zeev Valentine

Over the duration of this grant our group has studied the transient and cw optical response of various π-conjugated polymers, oligomers, single crystals, fullerene molecules and blends of organic donor-acceptor molecules. We have been also involved in complementary experiments such as magneto-optical studies and spin-physics. We have advanced the field of photophysics of these materials by providing information on their excited state energies and primodal and long-lived photoexcitations such as singlet excitons, triplet excitons, polaron-pairs, excimers and exciplexes. We also fabricated various organic optoelectronic devices such as organic light emitting diodes (OLED), electrochemical cells, organic diodes, organic spin-valves (OSV), andmore » organic photovoltaic (OPV) solar cells. These devices benefited the society in terms of cheap and energy saving illumination, as well as harnessing the solar energy.« less

Carrier mobility in mesoscale heterogeneous organic materials: Effects of crystallinity and anisotropy on efficient charge transport

NASA Astrophysics Data System (ADS)

Kobayashi, Hajime; Shirasawa, Raku; Nakamoto, Mitsunori; Hattori, Shinnosuke; Tomiya, Shigetaka

2017-07-01

Charge transport in the mesoscale bulk heterojunctions (BHJs) of organic photovoltaic devices (OPVs) is studied using multiscale simulations in combination with molecular dynamics, the density functional theory, the molecular-level kinetic Monte Carlo (kMC) method, and the coarse-grained kMC method, which was developed to estimate mesoscale carrier mobility. The effects of the degree of crystallinity and the anisotropy of the conductivity of donors on hole mobility are studied for BHJ structures that consist of crystalline and amorphous pentacene grains that act as donors and amorphous C60 grains that act as acceptors. We find that the hole mobility varies dramatically with the degree of crystallinity of pentacene because it is largely restricted by a low-mobility amorphous region that occurs in the hole transport network. It was also found that the percolation threshold of crystalline pentacene is relatively high at approximately 0.6. This high percolation threshold is attributed to the 2D-like conductivity of crystalline pentacene, and the threshold is greatly improved to a value of approximately 0.3 using 3D-like conductive donors. We propose essential guidelines to show that it is critical to increase the degree of crystallinity and develop 3D conductive donors for efficient hole transport through percolative networks in the BHJs of OPVs.

Acetylene-Based Materials in Organic Photovoltaics

PubMed Central

Silvestri, Fabio; Marrocchi, Assunta

2010-01-01

Fossil fuel alternatives, such as solar energy, are moving to the forefront in a variety of research fields. Organic photovoltaic systems hold the promise of a lightweight, flexible, cost-effective solar energy conversion platform, which could benefit from simple solution-processing of the active layer. The discovery of semiconductive polyacetylene by Heeger et al. in the late 1970s was a milestone towards the use of organic materials in electronics; the development of efficient protocols for the palladium catalyzed alkynylation reactions and the new conception of steric and conformational advantages of acetylenes have been recently focused the attention on conjugated triple-bond containing systems as a promising class of semiconductors for OPVs applications. We review here the most important and representative (poly)arylacetylenes that have been used in the field. A general introduction to (poly)arylacetylenes, and the most common synthetic approaches directed toward making these materials will be firstly given. After a brief discussion on working principles and critical parameters of OPVs, we will focus on molecular arylacetylenes, (co)polymers containing triple bonds, and metallopolyyne polymers as p-type semiconductor materials. The last section will deal with hybrids in which oligomeric/polymeric structures incorporating acetylenic linkages such as phenylene ethynylenes have been attached onto C60, and their use as the active materials in photovoltaic devices. PMID:20480031

Intrinsic coincident full-Stokes polarimeter using stacked organic photovoltaics and architectural comparison of polarimeter techniques

NASA Astrophysics Data System (ADS)

Yang, Ruonan; Sen, Pratik; O'Connor, B. T.; Kudenov, M. W.

2017-08-01

An intrinsic coincident full-Stokes polarimeter is demonstrated by using stain-aligned polymer-based organic photovoltaics (OPVs) which can preferentially absorb certain polarized states of incident light. The photovoltaic-based polarimeter is capable of measuring four stokes parameters by cascading four semitransparent OPVs in series along the same optical axis. Two wave plates were incorporated into the system to modulate the S3 stokes parameter so as to reduce the condition number of the measurement matrix. The model for the full-Stokes polarimeter was established and validated, demonstrating an average RMS error of 0.84%. The optimization, based on minimizing the condition number of the 4-cell OPV design, showed that a condition number of 2.4 is possible. Performance of this in-line polarimeter concept was compared to other polarimeter architectures, including Division of Time (DoT), Division of Amplitude (DoAm), Division of Focal Plane (DoFP), and Division of Aperture (DoA) from signal-to-noise ratio (SNR) perspective. This in-line polarimeter concept has the potential to enable both high temporal (as compared with a DoT polarimeter) and high spatial resolution (as compared with DoFP and DoA polarimeters). We conclude that the intrinsic design has the same √2 SNR advantage as the DoAm polarimeter, but with greater compactness.

Decreased performance of live attenuated, oral rotavirus vaccines in low-income settings: causes and contributing factors.

PubMed

Velasquez, Daniel E; Parashar, Umesh; Jiang, Baoming

2018-02-01

Numerous studies have shown that the oral rotavirus vaccines are less effective in infants born in low income countries compared to those born in developed countries. Identifying the specific factors in developing countries that decrease and/or compromise the protection that rotavirus vaccines offer, could lead to a path for designing new strategies for the vaccines' improvement. Areas covered: We accessed PubMed to identify rotavirus vaccine performance studies (i.e., efficacy, effectiveness and immunogenicity) and correlated performance with several risk factors. Here, we review the factors that might contribute to the low vaccine efficacy, including passive transfer of maternal rotavirus antibodies, rotavirus seasonality, oral polio vaccine (OPV) administered concurrently, microbiome composition and concomitant enteric pathogens, malnutrition, environmental enteropathy, HIV, and histo blood group antigens. Expert commentary: We highlight two major factors that compromise rotavirus vaccines' efficacy: the passive transfer of rotavirus IgG antibodies to infants and the  co-administration of rotavirus vaccines with OPV. We also identify other potential risk factors that require further research because the data about their interference with the efficacy of rotavirus vaccines are inconclusive and at times conflicting.

Are hot charge transfer states the primary cause of efficient free-charge generation in polymer:fullerene organic photovoltaic devices? A kinetic Monte Carlo study.

PubMed

Jones, Matthew L; Dyer, Reesha; Clarke, Nigel; Groves, Chris

2014-10-14

Kinetic Monte Carlo simulations are used to examine the effect of high-energy, 'hot' delocalised charge transfer (HCT) states for donor:acceptor and mixed:aggregate blends, the latter relating to polymer:fullerene photovoltaic devices. Increased fullerene aggregation is shown to enhance charge generation and short-circuit device current - largely due to the increased production of HCT states at the aggregate interface. However, the instances where HCT states are predicted to give internal quantum efficiencies in the region of 50% do not correspond to HCT delocalisation or electron mobility measured in experiments. These data therefore suggest that HCT states are not the primary cause of high quantum efficiencies in some polymer:fullerene OPVs. Instead it is argued that HCT states are responsible for the fast charge generation seen in spectroscopy, but that regional variation in energy levels are the cause of long-term, efficient free-charge generation.

Simultaneously Enhancing the Cohesion and Electrical Conductivity of PEDOT:PSS Conductive Polymer Films using DMSO Additives.

PubMed

Lee, Inhwa; Kim, Gun Woo; Yang, Minyang; Kim, Taek-Soo

2016-01-13

Conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) ( PSS) has attracted significant attention as a hole transport and electrode layer that substitutes metal electrodes in flexible organic devices. However, its weak cohesion critically limits the reliable integration of PSS in flexible electronics, which highlights the importance of further investigation of the cohesion of PSS. Furthermore, the electrical conductivity of PSS is insufficient for high current-carrying devices such as organic photovoltaics (OPVs) and organic light emitting diodes (OLEDs). In this study, we improve the cohesion and electrical conductivity through adding dimethyl sulfoxide (DMSO), and we demonstrate the significant changes in the properties that are dependent on the wt % of DMSO. In particular, with the addition of 3 wt % DMSO, the maximum enhancements for cohesion and electrical conductivity are observed where the values increase by 470% and 6050%, respectively, due to the inter-PEDOT bridging mechanism. Furthermore, when OLED devices using the PSS films are fabricated using the 3 wt % DMSO, the display exhibits 18% increased current efficiency.

Poly(sodium 4-styrenseulfonate)-modified monolayer graphene for anode applications of organic photovoltaic cells

NASA Astrophysics Data System (ADS)

Zhou, Yongfang; Wang, Min; Wang, Liang; Liu, Shuli; Chen, Shufen; Cao, Kun; Shang, Wenjuan; Mai, Jiangquan; Zhao, Baomin; Feng, Jing; Lu, Xinhui; Huang, Wei

2017-09-01

An insulated poly(sodium 4-styrenseulfonate) (PSS) was used to modify monolayer graphene for anode applications of organic photovoltaics (OPVs). With this PSS interfacial modification layer, the OPVs showed a significant increase of 56.4% in efficiency due to an improved work function and hydrophilic feature of graphene and an enlarged recombination resistance of carriers/excitons. Doping a highly contorted 1,2,5-thiadiazole-fused 12-ring polyaromatic hydrocarbon into the active layer to form ternary blended OPVs further enlarged the recombination resistance of carriers/excitons and improved light absorption of the active layer, with which a high power conversion efficiency of 6.29% was acquired.

Influence of a MoOx interlayer on the open-circuit voltage in organic photovoltaic cells

NASA Astrophysics Data System (ADS)

Zou, Yunlong; Holmes, Russell J.

2013-07-01

Metal-oxides have been used as interlayers at the anode-organic interface in organic photovoltaic cells (OPVs) to increase the open-circuit voltage (VOC). We examine the role of MoOx in determining the maximum VOC in a planar heterojunction OPV and find that the interlayer strongly affects the temperature dependence of VOC. Boron subphthalocyanine chloride (SubPc)-C60 OPVs that contain no interlayer show a maximum VOC of 1.2 V at low temperature, while those with MoOx show no saturation, reaching VOC > 1.4 V. We propose that the MoOx-SubPc interface forms a Schottky junction that provides an additional contribution to VOC at low temperature.

Can we agree on a prescription? A view from the perspective of the developing countries.

PubMed

Stoeckel, P

There are serious obstacles, particularly on the African Continent, to the application of the official strategy for eradication of poliomyelitis. Outbreaks in countries where a potent OPV was used keep raising the question of its efficacy in routine programs. Based on the South American strategy, 200 million doses of OPV are needed for the 11 million children born each year. Such quantities of vaccine can hardly be procured for the rest of the world. Organization of vaccination campaigns will be competing with other public health programs. Studies in Africa and in the Middle East have shown the good performance of one or two doses of eIPV combined with DTP. At the current price of the quadruple vaccine DTP-eIPV, its cost effectiveness not only in money, but in practical terms, especially for the inventory, the cold chain, and the delivery, would be extremely attractive.

Interface Energetics and Chemical Doping of Organic Electronic Materials

NASA Astrophysics Data System (ADS)

Kahn, Antoine

2014-03-01

The energetics of organic semiconductors and their interfaces are central to the performance of organic thin film devices. The relative positions of charge transport states across the many interfaces of multi-layer OLEDs, OPV cells and OFETs determine in great part the efficiency and lifetime of these devices. New experiments are presented here, that look in detail at the position of these transport states and associated gap states and electronic traps that tail into the energy gap of organic molecular (e.g. pentacene) or polymer (P3HT, PBDTTT-C) semiconductors, and which directly affect carrier mobility in these materials. Disorder, sometime caused by simple exposure to an inert gas, impurities and defects are at the origin of these electronic gap states. Recent efforts in chemical doping in organic semiconductors aimed at mitigating the impact of electronic gap states are described. An overview of the reducing or oxidizing power of several n- and p-type dopants for vacuum- or solution-processed films, and their effect on the electronic structure and conductivity of both vacuum- and solution-processed organic semiconductor films is given. Finally, the filling (compensation) of active gap states via doping is investigated on the electron-transport materials C60 and P(NDI2OD-T2) , and the hole-transport polymer PBDTTT-C.

Environmental Surveillance of Poliovirus in Sewage Water around the Introduction Period for Inactivated Polio Vaccine in Japan

PubMed Central

Nakamura, Tomofumi; Hamasaki, Mitsuhiro; Yoshitomi, Hideaki; Ishibashi, Tetsuya; Yoshiyama, Chiharu; Maeda, Eriko; Yoshida, Hiromu

2015-01-01

Environmental virus surveillance was conducted at two independent sewage plants from urban and rural areas in the northern prefecture of the Kyushu district, Japan, to trace polioviruses (PVs) within communities. Consequently, 83 PVs were isolated over a 34-month period from April 2010 to January 2013. The frequency of PV isolation at the urban plant was 1.5 times higher than that at the rural plant. Molecular sequence analysis of the viral VP1 gene identified all three serotypes among the PV isolates, with the most prevalent serotype being type 2 (46%). Nearly all poliovirus isolates exhibited more than one nucleotide mutation from the Sabin vaccine strains. During this study, inactivated poliovirus vaccine (IPV) was introduced for routine immunization on 1 September 2012, replacing the live oral poliovirus vaccine (OPV). Interestingly, the frequency of PV isolation from sewage waters declined before OPV cessation at both sites. Our study highlights the importance of environmental surveillance for the detection of the excretion of PVs from an OPV-immunized population in a highly sensitive manner, during the OPV-to-IPV transition period. PMID:25556189

Recommendations of 2nd National Consultative Meeting of Indian Academy of Pediatrics (IAP) on polio eradication and improvement of routine immunization.

PubMed

Vashishtha, Vipin M; Kalra, Ajay; John, T Jacob; Thacker, Naveen; Agarwal, R K

2008-05-01

Persistence of intense wild poliovirus (WPV) transmission, particularly type 3 in northern India necessitated the Indian Academy of Pediatrics (IAP) to convene a National Consultative Meeting to review its earlier recommendations on polio eradication and improvement of routine immunization. More than thirty experts were invited and intense deliberations were held over two days to draw consensus statements on various issues related with polio eradication. To review the ongoing strategy, identify the existing challenges, and suggest modifications to the current strategy for eradication of poliomyelitis in India. IAP reiterates its support to ongoing efforts on polio eradication but demand some flexibility in the strategy. The immediate challenges identified include persistent WPV type 1 transmission in Uttar Pradesh (UP) and Bihar, intense type 3 transmission also in UP and Bihar, and maintaining polio-free status of all other states. Circulating vaccine derived poliovirus (cVDPV), particularly type 2, was identified as a great future threat. Neglect of routine immunization (RI), poor efficacy of oral polio vaccine (OPV), operational issues, and inadequate uptake of OPV in the 2 endemic states are the main reasons of failure to interrupt transmission of WPV 1 and 3. However, for the first time in history the intensity of WPV 1 circulation is very low in western UP. IAP suggests that high-quality, uniform and consistent performance of supplementary immunization activities (SIAs) in all districts of western UP, particularly using mOPV1(monovalent OPV1) should be maintained to avoid reestablishment of circulation of type 1 poliovirus. A judicious mix of mOPV1 and mOPV3, given sequentially or even simultaneously (after validating the efficacies) will be necessary to address the upsurge of WPV3. Re-establishing routine immunization should be the foremost priority. IAP strongly recommends to Government of India (GOI) to take urgent measures to attain coverage of a minimum of 90% against all UIP antigens in all the states by the end of 2008. In view of the need to simultaneously raise immunity levels to protect against WPVs 1, 3 and cVDPV2, IPV may be given immediate consideration as an additional tool. IPV will be essential in the postWPVeradication phase; it can play a useful role even in the current WPV eradication phase. IAP urges the GOI to urgently sort out various issues associated with implementation of the proposal to use IPV. More transparency is needed on cases of vaccine associated paralytic poliomyelitis (VAPP). Further improvement in stool collection rates is also warranted to minimize the tally of compatible cases. IAP urges the social mobilization network to address the issues of waning interest and shifting focus and negative media coverage. Alternate tactics like reduced numbers of SIAs applied in the low transmission season, along with IPVDTP combination vaccine in RI can also be considered. IAP believes it will be risky to stop vaccination against poliomyelitis in postWPV eradication phase. The best option is to gradually introduce IPV starting now, so that a switch to IPV following high-performance national immunization days (NIDs) can be made to ensure sustained high immunity against all polioviruses, wild and vaccine derived. IAP requests the global polio eradication initiative (GPEI) to continue relevant research to inform on various aspects related to polio eradication, defined as zero incidence of any poliovirus infection. IAP also urges GOI to take immediate measures for improvement of environmental sanitation.

Polio immunization policy in Mexico: economic assessment of current practice and future alternatives.

PubMed

Mascareñas, A; Salinas, J; Tasset-Tisseau, A; Mascareñas, C; Khan, M M

2005-06-01

The World Health Organization recommends that all children aged less than 5 years should be vaccinated against polio through intensive immunization programmes as well as routine immunization. A national immunization week (NIW) was held in February 2002 in the Monterrey district of Mexico. A prospective micro-costing study was conducted to measure the total cost to the state of the NIW, the cost profile, and the ratio of cost per immunization contact to cost per dose of oral polio vaccine (OPV), and to compare OPV and inactive polio vaccine (IPV) in economic terms. Two scenarios were used as the basis for calculation. The cost of volunteers was excluded from the "lower-cost scenario" and included in the "upper-cost scenario". The total cost of the NIW was USD 100,454 for the lower-cost scenario and USD 156,614 for the upper-cost scenario. The major part of the costs was personnel costs (67.30 and 77.53% of the total costs in the lower- and upper-cost scenario, respectively). The ratio of cost per immunization contact to cost per dose of OPV was 6.45 for the lower-cost scenario and 10.05 for the upper-cost scenario. Changing from the current OPV-based intensive and routine schedule to a sequential IPV-OPV routine schedule would save USD 14.52 per vaccinated child, and changing to a full IPV routine schedule would save USD 9.41 per vaccinated child.

Phase II and III Clinical Studies of Diphtheria-Tetanus-Acellular Pertussis Vaccine Containing Inactivated Polio Vaccine Derived from Sabin Strains (DTaP-sIPV).

PubMed

Okada, Kenji; Miyazaki, Chiaki; Kino, Yoichiro; Ozaki, Takao; Hirose, Mizuo; Ueda, Kohji

2013-07-15

Phase II and III clinical studies were conducted to evaluate immunogenicity and safety of a novel DTaP-IPV vaccine consisting of Sabin inactivated poliovirus vaccine (sIPV) and diphtheria-tetanus-acellular pertussis vaccine (DTaP). A Phase II study was conducted in 104 healthy infants using Formulation H of the DTaP-sIPV vaccine containing high-dose sIPV (3, 100, and 100 D-antigen units for types 1, 2, and 3, respectively), and Formulations M and L, containing half and one-fourth of the sIPV in Formulation H, respectively. Each formulation was administered 3 times for primary immunization and once for booster immunization. A Phase III study was conducted in 342 healthy infants who received either Formulation M + oral polio vaccine (OPV) placebo or DTaP + OPV. The OPV or OPV placebo was orally administered twice between primary and booster immunizations. Formulation M was selected as the optimum dose. In the Phase III study, the seropositive rate was 100% for all Sabin strains after primary immunization, and the neutralizing antibody titer after booster immunization was higher than in the control group (DTaP + OPV). All adverse reactions were clinically acceptable. DTaP-sIPV was shown to be a safe and immunogenic vaccine. JapicCTI-121902 for Phase II study, JapicCTI-101075 for Phase III study (http://www.clinicaltrials.jp/user/cte_main.jsp).

Vaccine-associated paralytic poliomyelitis: a review of the epidemiology and estimation of the global burden.

PubMed

Platt, Lauren R; Estívariz, Concepción F; Sutter, Roland W

2014-11-01

Vaccine-associated paralytic poliomyelitis (VAPP) is a rare adverse event associated with oral poliovirus vaccine (OPV). This review summarizes the epidemiology and provides a global burden estimate. A literature review was conducted to abstract the epidemiology and calculate the risk of VAPP. A bootstrap method was applied to calculate global VAPP burden estimates. Trends in VAPP epidemiology varied by country income level. In the low-income country, the majority of cases occurred in individuals who had received >3 doses of OPV (63%), whereas in middle and high-income countries, most cases occurred in recipients after their first OPV dose or unvaccinated contacts (81%). Using all risk estimates, VAPP risk was 4.7 cases per million births (range, 2.4-9.7), leading to a global annual burden estimate of 498 cases (range, 255-1018). If the analysis is limited to estimates from countries that currently use OPV, the VAPP risk is 3.8 cases per million births (range, 2.9-4.7) and a burden of 399 cases (range, 306-490). Because many high-income countries have replaced OPV with inactivated poliovirus vaccine, the VAPP burden is concentrated in lower-income countries. The planned universal introduction of inactivated poliovirus vaccine is likely to substantially decrease the global VAPP burden by 80%-90%. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

SU-E-CAMPUS-I-01: Nanometric Organic Photovoltaic Thin Film X-Ray Detectors for Clinical KVp Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elshahat, Bassem; Gill, Hardeep; Kumar, Jayant

2014-06-15

Purpose: To fabricate and test nanometric organic photovoltaic (OPV) cells made of various active-layer/electrode thicknesses and sizes; to determine the optimal material combinations and geometries suitable for dose measurements in clinical kilovoltage x-ray beams. Methods: The OPV consisted of P3HT:PCBM photoactive materials sandwiched between aluminum and Indium Tin Oxide (ITO) electrodes. Direct conversion of xrays in the active layer composed of donor and acceptor semiconducting organic materials generated signal in photovoltaic mode (without external voltage bias). OPV cells were fabricated with different active layer thicknesses (150, 270, 370 nm) and electrode areas (0.4, 0.7, 0.9, 1.4, 2.6 cm{sup 2}). Amore » series of experiments were preformed in the energy range of 60–150 kVp. The net current per unit area (nA/cm{sup 2}) was measured using 200 mAs time-integrated beam current. Results: The net OPV current as function of beam energy (kVp) was proportional to ∼E{sup 0,4} {sup 5} when adjusted for beam output. The best combination of parameters for these cells was 270 nm active layer thicknesses for 0.7 cm{sup 2} electrode area. The measured current ranged from 0.69 to 2.43 nA/cm{sup 2} as a function of x-ray energy between 60 and 150 kVp, corresponding to 0.09 – 0.06 nA/cm{sup 2}/mGy, respectively, when adjusted for the beam output. Conclusion: The experiments indicate that OPV detectors possessing 270 nm active layer and 0.7 cm{sup 2} Al electrode areas have sensitivity by a factor of 2.5 greater than commercial aSi thin film PV. Because OPV can be made flexible and they do not require highvoltage bias supply, they open the possibility for using as in-vivo detectors in radiation safety in x-ray imaging beams.« less

Patterns of orthopox virus wild rodent hosts in South Germany.

PubMed

Essbauer, Sandra; Hartnack, Sonja; Misztela, Krystian; Kiessling-Tsalos, Judith; Bäumler, Walter; Pfeffer, Martin

2009-06-01

Although cowpox virus (CPXV) infections in a variety of dead-end hosts have been investigated in Germany for more than 50 years, data on species and geographical distribution of CPXV in reservoir hosts are sparse. Here we present the first comprehensive study of 825 rodents that have been collected in Bavaria, Southern Germany. In summary, six different rodent species (Apodemus flavicollis, Myodes glareolus, Microtus arvalis, Apodemus sylvaticus, Microtus agrestis, and Arvicola amphibius) were trapped at three main trapping sites and investigated using a serum neutralization test (SNT). Prevalence of orthopox virus (OPV)-neutralizing antibodies was (with exception of one trapping site) highest in bank voles, ranging from 24.5% to 42.4%; often with SNT titers > or =96. Two up to 25% of yellow-necked mice were OPV sero-positive, but wood mice only at one site with 5.5%. Up to 7.7% of common voles were found to be OPV seroreactive, while M. agrestis and A. amphibius only sporadically showed seroreactivity. Further analyses of a subset of 450 bank voles and yellow-necked mice trapped at one site over a 18-month period revealed that male yellow-necked mice and female gravid yellow-necked mice had significantly more OPV-neutralizing antibodies. Mean body weight and OPV-seroreactivity were significantly negatively associated in male A. flavicollis. This was not due to shorter body length or smaller body mass index, but previously OPV-infected male A. flavicollis had dramatically reduced mean kidney weights. Seroreactivity in female bank voles was positively related to lung weights. We also found that both male yellow-necked mice and male bank voles with positive SNT titers had higher infestation rates with ectoparasites. We here show for the first time that A. flavicollis beside M. glareolus is a hypothetic host for CPXV, and that there are big geographical and spatial variations concerning the seroprevalence in rodent populations in South Germany.

Vaccination against poliomyelitis in economically underdeveloped countries

PubMed Central

Sabin, Albert B.

1980-01-01

Poliomyelitis lameness surveys in children of school age recently reported from Burma, Egypt, Ghana, and the Philippines have indicated an estimated, average annual endemic incidence of paralytic poliomyelitis similar to or higher than the overall average annual rate in the USA during the peak years in the prevaccine era. Contrary to oft-expressed dogma, high rates of paralytic poliomyelitis are occurring annually in regions with high infant mortality rates, continuing undernutrition, and absence of basic sanitary facilities. Recent data indicate that prolonged breast feeding does not impede the effectiveness of oral poliovirus vaccine (OPV). A high prevalence of nonpoliovirus enteric infections can modify, delay, and lower the frequency of seroconversion after OPV, but these effects are overcome by multiple doses. The problem of eliminating paralytic poliomyelitis from economically underdeveloped countries depends on administrative rather than immunological or epidemiological factors, although a specially concentrated effort is needed in countries where most of the cases occur during the first two years of life and where paralytic polioviruses are propagating throughout the year in a large proportion of the infant population. Under such circumstances, expanded routine infant immunization programmes, which include OPV but reach at best only 20-40% of the total infant population, who receive only one or a few doses of vaccines requiring multiple doses, cannot be expected to eliminate paralytic poliomyelitis as an important public health problem. Injections of multiple doses of quadruple vaccine (DPT + inactivated poliomyelitis vaccine) would not only greatly increase the cost of routine immunizations but would not achieve more or as much as feeding OPV at the time of the DPT injections. Mass administration of OPV each year on 2 days of the year 2 months apart, to all children under 2, 3, or 4 years of age (depending on the epidemiological situation), without reference to the number of OPV doses they may have had before, can be expected to yield optimum results in countries with small numbers of professional health personnel and many other year-round problems. PMID:6966544

Neonatal vitamin A supplementation associated with a cluster of deaths and poor early growth in a randomised trial among low-birth-weight boys of vitamin A versus oral polio vaccine at birth

PubMed Central

2014-01-01

Background The effect of oral polio vaccine administered already at birth (OPV0) on child survival was not examined before being recommended in 1985. Observational data suggested that OPV0 was harmful for boys, and trials have shown that neonatal vitamin A supplementation (NVAS) at birth may be beneficial for boys. We set out to test this research question in a randomised trial. Methods The trial was carried out at the Bandim Health Project, Guinea-Bissau. We planned to enrol 900 low-birth weight (LBW) boys in a randomised trial to investigate whether NVAS instead of OPV0 could lower infant mortality for LBW boys. At birth, the children were randomised to OPV (usual treatment) or VAS (intervention treatment) and followed for 6 months for growth and 12 months for survival. Hazard Ratios (HR) for mortality were calculated using Cox regression. We compared the individual anthropometry measurements to the 2006 WHO growth reference. We compared differences in z-scores by linear regression. Relative risks (RR) of being stunted or underweight were calculated in Poisson regression models with robust standard errors. Results In the rainy season we detected a cluster of deaths in the VAS group and the trial was halted immediately with 232 boys enrolled. The VAS group had significantly higher mortality than the OPV0 group in the rainy season (HR: 9.91 (1.23 – 80)). All deaths had had contact with the neonatal nursery; of seven VAS boys enrolled during one week in September, six died within two months of age, whereas only one died among the six boys receiving OPV (p = 0.05). Growth (weight and arm-circumference) in the VAS group was significantly worse until age 3 months. Conclusion VAS at birth instead of OPV was not beneficial for the LBW boys in this study. With the premature closure of the trial it was not possible to answer the research question. However, the results of this study call for extra caution when testing the effect of NVAS in the future. Trial registration http://www.clinicaltrials.gov NCT00625482. Registered 18 February 2008. PMID:25163399

The effect of mass immunisation campaigns and new oral poliovirus vaccines on the incidence of poliomyelitis in Pakistan and Afghanistan, 2001–11: a retrospective analysis

PubMed Central

O'Reilly, Kathleen M; Durry, Elias; ul Islam, Obaid; Quddus, Arshad; Abid, Ni'ma; Mir, Tahir P; Tangermann, Rudi H; Aylward, R Bruce; Grassly, Nicholas C

2012-01-01

Summary Background Pakistan and Afghanistan are two of the three remaining countries yet to interrupt wild-type poliovirus transmission. The increasing incidence of poliomyelitis in these countries during 2010–11 led the Executive Board of WHO in January, 2012, to declare polio eradication a “programmatic emergency for global public health”. We aimed to establish why incidence is rising in these countries despite programme innovations including the introduction of new vaccines. Methods We did a matched case-control analysis based on a database of 46 977 children aged 0–14 years with onset of acute flaccid paralysis between Jan 1, 2001, and Dec 31, 2011. The vaccination history of children with poliomyelitis was compared with that of children with acute flaccid paralysis due to other causes to estimate the clinical effectiveness of oral poliovirus vaccines (OPVs) in Afghanistan and Pakistan by conditional logistic regression. We estimated vaccine coverage and serotype-specific vaccine-induced population immunity in children aged 0–2 years and assessed their association with the incidence of poliomyelitis over time in seven regions of Afghanistan and Pakistan. Findings Between Jan 1, 2001, and Dec 31, 2011, there were 883 cases of serotype 1 poliomyelitis (710 in Pakistan and 173 in Afghanistan) and 272 cases of poliomyelitis serotype 3 (216 in Pakistan and 56 in Afghanistan). The estimated clinical effectiveness of a dose of trivalent OPV against serotype 1 poliomyelitis was 12·5% (95% CI 5·6–18·8) compared with 34·5% (16·1–48·9) for monovalent OPV (p=0·007) and 23·4% (10·4–34·6) for bivalent OPV (p=0·067). Bivalent OPV was non-inferior compared with monovalent OPV (p=0·21). Vaccination coverage decreased during 2006–11 in the Federally Administered Tribal Areas (FATA), Balochistan, and Khyber Pakhtunkhwa in Pakistan and in southern Afghanistan. Although partially mitigated by the use of more effective vaccines, these decreases in coverage resulted in lower vaccine-induced population immunity to poliovirus serotype 1 in FATA and Balochistan and associated increases in the incidence of poliomyelitis. Interpretation The effectiveness of bivalent OPV is comparable with monovalent OPV and can therefore be used in eradicating serotype 1 poliomyelitis whilst minimising the risks of serotype 3 outbreaks. However, decreases in vaccination coverage in parts of Pakistan and southern Afghanistan have severely limited the effect of this vaccine. Funding Poliovirus Research subcommittee of WHO, Royal Society, and Medical Research Council. PMID:22766207

Hybrid Organic/Inorganic Materials Depth Profiling Using Low Energy Cesium Ions

NASA Astrophysics Data System (ADS)

Noël, Céline; Houssiau, Laurent

2016-05-01

The structures developed in organic electronics, such as organic light emitting diodes (OLEDs) or organic photovoltaics (OPVs) devices always involve hybrid interfaces, joining metal or oxide layers with organic layers. No satisfactory method to probe these hybrid interfaces physical chemistry currently exists. One promising way to analyze such interfaces is to use in situ ion beam etching, but this requires ion beams able to depth profile both inorganic and organic layers. Mono- or diatomic ion beams commonly used to depth profile inorganic materials usually perform badly on organics, while cluster ion beams perform excellently on organics but yield poor results when organics and inorganics are mixed. Conversely, low energy Cs+ beams (<500 eV) allow organic and inorganic materials depth profiling with comparable erosion rates. This paper shows a successful depth profiling of a model hybrid system made of metallic (Au, Cr) and organic (tyrosine) layers, sputtered with 500 eV Cs+ ions. Tyrosine layers capped with metallic overlayers are depth profiled easily, with high intensities for the characteristic molecular ions and other specific fragments. Metallic Au or Cr atoms are recoiled into the organic layer where they cause some damage near the hybrid interface as well as changes in the erosion rate. However, these recoil implanted metallic atoms do not appear to severely degrade the depth profile overall quality. This first successful hybrid depth profiling report opens new possibilities for the study of OLEDs, organic solar cells, or other hybrid devices.

Spiers memorial lecture. Organic electronics: an organic materials perspective.

PubMed

Wudl, Fred

2014-01-01

This Introductory Lecture is intended to provide a background to Faraday Discussion 174: "Organic Photonics and Electronics" and will consist of a chronological, subjective review of organic electronics. Starting with "ancient history" (1888) and history (1950-present), the article will take us to the present. The principal developments involved the processes of charge carrier generation and charge transport in molecular solids, starting with insulators (photoconductors) and moving to metals, to semiconductors and ending with the most popular semiconductor devices, such as organic light-emitting diodes (OLEDs), organic field effect transistors (OFETs) and organic photovoltaics (OPVs). The presentation will be from an organic chemistry/materials point of view.

Substituent Effects In a Series of 1,7-C60(RF)2 Compounds (RF = CF3, C2F5, n-C3F7, i-C3F7, n-C4F9, s-C4F9, n-C8F17): Electron Affinities, Reduction Potentials, and E(LUMO) Values Are Not Always Correlated

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuvychko, Igor V.; Whitaker, James B.; Larson, Bryon W.

Substituent effects are of paramount importance in virtually all fields of fundamental and applied chemistry. Classical and modern examples can be found in organic chemistry (Hammett parameters and Charton steric parameters), inorganic chemistry (trans effect and trans influence), organometallic chemistry (phosphine cone angles), physical chemistry (linear free energy relationships and DFT), biochemistry (protein tertiary structure), medicinal chemistry (SAR maps and BioMAP analysis), polymer chemistry (nonlinear optical and permeation properties and glass transition temperatures), and materials chemistry (stability and luminescent properties of electroluminescent devices and light-to-power conversion efficiencies of fullerene-derivative-based OPV devices).

Combined use of inactivated and oral poliovirus vaccines in refugee camps and surrounding communities - Kenya, December 2013.

PubMed

Sheikh, Mohamed A; Makokha, Frederick; Hussein, Abdullahi M; Mohamed, Gedi; Mach, Ondrej; Humayun, Kabir; Okiror, Samuel; Abrar, Leila; Nasibov, Orkhan; Burton, John; Unshur, Ahmed; Wannemuehler, Kathleen; Estivariz, Concepcion F

2014-03-21

Since the launch of the Global Polio Eradication Initiative (GPEI) in 1988, circulation of indigenous wild poliovirus (WPV) has continued without interruption in only three countries: Afghanistan, Nigeria, and Pakistan. During April-December 2013, a polio outbreak caused by WPV type 1 (WPV1) of Nigerian origin resulted in 217 cases in or near the Horn of Africa, including 194 cases in Somalia, 14 cases in Kenya, and nine cases in Ethiopia (all cases were reported as of March 10, 2014). During December 14-18, 2013, Kenya conducted the first-ever campaign providing inactivated poliovirus vaccine (IPV) together with oral poliovirus vaccine (OPV) as part of its outbreak response. The campaign targeted 126,000 children aged ≤59 months who resided in Somali refugee camps and surrounding communities near the Kenya-Somalia border, where most WPV1 cases had been reported, with the aim of increasing population immunity levels to ensure interruption of any residual WPV transmission and prevent spread from potential new importations. A campaign evaluation and vaccination coverage survey demonstrated that combined administration of IPV and OPV in a mass campaign is feasible and can achieve coverage >90%, although combined IPV and OPV campaigns come at a higher cost than OPV-only campaigns and require particular attention to vaccinator training and supervision. Future operational studies could assess the impact on population immunity and the cost-effectiveness of combined IPV and OPV campaigns to accelerate interruption of poliovirus transmission during polio outbreaks and in certain areas in which WPV circulation is endemic.

Circulating vaccine-derived polioviruses: current state of knowledge.

PubMed Central

Kew, Olen M.; Wright, Peter F.; Agol, Vadim I.; Delpeyroux, Francis; Shimizu, Hiroyuki; Nathanson, Neal; Pallansch, Mark A.

2004-01-01

Within the past 4 years, poliomyelitis outbreaks associated with circulating vaccine-derived polioviruses (cVDPVs) have occurred in Hispaniola (2000-01), the Philippines (2001), and Madagascar (2001-02). Retrospective studies have also detected the circulation of endemic cVDPV in Egypt (1988-93) and the likely localized spread of oral poliovirus vaccine (OPV)-derived virus in Belarus (1965-66). Gaps in OPV coverage and the previous eradication of the corresponding serotype of indigenous wild poliovirus were the critical risk factors for all cVDPV outbreaks. The cVDPV outbreaks were stopped by mass immunization campaigns using OPV. To increase sensitivity for detecting vaccine-derived polioviruses (VDPVs), in 2001 the Global Polio Laboratory Network implemented additional testing requirements for all poliovirus isolates under investigation. This approach quickly led to the recognition of the Philippines and Madagascar cVDPV outbreaks, but of no other current outbreaks. The potential risk of cVDPV emergence has increased dramatically in recent years as wild poliovirus circulation has ceased in most of the world. The risk appears highest for the type 2 OPV strain because of its greater tendency to spread to contacts. The emergence of cVDPVs underscores the critical importance of eliminating the last pockets of wild poliovirus circulation, maintaining universally high levels of polio vaccine coverage, stopping OPV use as soon as it is safely possible to do so, and continuing sensitive poliovirus surveillance into the foreseeable future. Particular attention must be given to areas where the risks for wild poliovirus circulation have been highest, and where the highest rates of polio vaccine coverage must be maintained to suppress cVDPV emergence. PMID:15106296

World Health Organization Guidelines for Containment of Poliovirus Following Type-Specific Polio Eradication - Worldwide, 2015.

PubMed

Previsani, Nicoletta; Tangermann, Rudolph H; Tallis, Graham; Jafari, Hamid S

2015-08-28

In 1988, the World Health Assembly of the World Health Organization (WHO) resolved to eradicate polio worldwide. Among the three wild poliovirus (WPV) types (type 1, type 2, and type 3), WPV type 2 (WPV2) has been eliminated in the wild since 1999, and WPV type 3 (WPV3) has not been reported since 2012. In 2015, only Afghanistan and Pakistan have reported WPV transmission. On May 25, 2015, all WHO Member States endorsed World Health Assembly resolution 68.3 on full implementation of the Polio Eradication and Endgame Strategic Plan 2013-2018 (the Endgame Plan), and with it, the third Global Action Plan to minimize poliovirus facility-associated risk (GAPIII). All WHO Member States have committed to implementing appropriate containment of WPV2 in essential laboratory and vaccine production facilities* by the end of 2015 and of type 2 oral poliovirus vaccine (OPV2) within 3 months of global withdrawal of OPV2, which is planned for April 2016. This report summarizes critical steps for essential laboratory and vaccine production facilities that intend to retain materials confirmed to contain or potentially containing type-specific WPV, vaccine-derived poliovirus (VDPV), or OPV/Sabin viruses, and steps for nonessential facilities† that process specimens that contain or might contain polioviruses. National authorities will need to certify that the essential facilities they host meet the containment requirements described in GAPIII. After certification of WPV eradication, the use of all OPV will cease; final containment of all polioviruses after polio eradication and OPV cessation will minimize the risk for reintroduction of poliovirus into a polio-free world.

Progress toward poliomyelitis eradication--India, January 2007-May 2009.

PubMed

2009-07-10

India is the most populous of the four remaining countries (including Afghanistan, Nigeria, and Pakistan) where transmission of wild poliovirus (WPV) has never been interrupted. The last cases of WPV type 2 worldwide were reported in October 1999 in India. However, transmission of WPV type 1 (WPV1) and WPV type 3 (WPV3) persists in India in the northern states of Uttar Pradesh and Bihar. Transmission of indigenous WPV in all of India's other states was successfully interrupted in 2002, and all WPV cases reported since then in the country have resulted from WPV circulating in Uttar Pradesh and Bihar. This report updates previous reports and summarizes India's progress toward polio eradication since January 2007, as of May 29, 2009. In 2005, the government of India introduced the use of monovalent oral polio vaccine type 1 (mOPV1), which has higher efficacy against WPV1 than does trivalent oral polio vaccine (tOPV), in supplementary immunization activities. After a multistate WPV1 outbreak in 2006, preferential use of mOPV1 was accelerated and WPV1 cases decreased from 83 in 2007 to 18 during January-May 2009. A resurgence of WPV3 cases in Uttar Pradesh in 2007 led to an outbreak in Bihar. SIAs using monovalent type 3 OPV (mOPV3) were expanded in 2007, and the number of WPV3 cases declined from 794 in 2007 to 41 during January-May 2009. Simultaneously interrupting transmission in high-risk areas of western Uttar Pradesh and Bihar is the key to successful interruption of all WPV transmission in India.

Mothers and vaccination: knowledge, attitudes, and behaviour in Italy.

PubMed

Angelillo, I F; Ricciardi, G; Rossi, P; Pantisano, P; Langiano, E; Pavia, M

1999-01-01

The study evaluates knowledge, attitudes, and behaviour of mothers regarding the immunization of 841 infants who attended public kindergarten in Cassino and Crotone, Italy. Overall, 57.8% of mothers were aware about all four mandatory vaccinations for infants (poliomyelitis, tetanus, diphtheria, hepatitis B). The results of a multiple logistic regression analysis showed that this knowledge was significantly greater among mothers with a higher education level and among those who were older at the time of the child's birth. Respondents' attitudes towards the utility of vaccinations for preventing infectious diseases were very favourable. Almost all children (94.4%) were vaccinated with all three doses of diphtheria-tetanus (DT), oral poliovirus vaccine (OPV), and hepatitis B. The proportion of children vaccinated who received all three doses of OPV, DT or diphtheria-tetanus-pertussis (DTP), and hepatitis B vaccines within 1 month of becoming age-eligible ranged from 56.6% for the third dose of hepatitis B to 95.7% for the first dose of OPV. Results of the regression analysis performed on the responses of mothers who had adhered to the schedule for all mandatory vaccinations indicated that birth order significantly predicted vaccination nonadherence, since children who had at least one older sibling in the household were significantly less likely to be age-appropriately vaccinated. The coverage for the optional vaccines was only 22.5% and 31% for measles-mumps-rubella and for all three doses against pertussis, respectively. Education programmes promoting paediatric immunization, accessibility, and follow-up should be targeted to the entire population.

Implementing Guidance for Deployment Health Surveillance

DTIC Science & Technology

2000-09-01

Poliovirus Vaccine) 1 dose, 0.5 ml SC None IPV only to personnel in close household or intimate contact with immunocompromised individuals...OPV (Live Poliovirus Vaccine) 1 dose, 0.5 ml orally None Do not give to adults who did not complete the OPV series as a child Haemophilus... reproductive system. Includes: Complications of Pregnancy (bleeding, miscarriage, ectopic), Menstrual Abnormalities, Vaginitis, Pelvic Inflammatory

A naturally occurring cowpox virus with an ectromelia virus A-type inclusion protein gene displays atypical A-type inclusions.

PubMed

Okeke, Malachy Ifeanyi; Hansen, Hilde; Traavik, Terje

2012-01-01

Human orthopoxvirus (OPV) infections in Europe are usually caused by cowpox virus (CPXV). The genetic heterogeneity of CPXVs may in part be due to recombination with other OPV species. We describe the characterization of an atypical CPXV (CPXV-No-H2) isolated from a human patient in Norway. CPXV-No-H2 was characterized on the basis of A-type inclusion (ATI) phenotype as well as the DNA region containing the p4c and atip open reading frames. CPXV-No-H2 produced atypical V(+/) ATI, in which virions are on the surface of ATI but not within the ATI matrix. Phylogenetic analysis showed that the atip gene of CPXV-No-H2 clustered closely with that of ectromelia virus (ECTV) with a bootstrap support of 100% whereas its p4c gene is diverged compared to homologues in other OPV species. By recombination analysis we identified a putative crossover event at nucleotide 147, downstream the start of the atip gene. Our results suggest that CPXV-No-H2 originated from a recombination between CPXV and ECTV. Our findings are relevant to the evolution of OPVs. Copyright © 2011 Elsevier B.V. All rights reserved.

The mature virion of ectromelia virus, a pathogenic poxvirus, is capable of intrahepatic spread and can serve as a target for delayed therapy.

PubMed

Ma, Xueying; Xu, Ren-Huan; Roscoe, Felicia; Whitbeck, J Charles; Eisenberg, Roselyn J; Cohen, Gary H; Sigal, Luis J

2013-06-01

Orthopoxviruses (OPVs), which include the agent of smallpox (variola virus), the zoonotic monkeypox virus, the vaccine and zoonotic species vaccinia virus, and the mouse pathogen ectromelia virus (ECTV), form two types of infectious viral particles: the mature virus (MV), which is cytosolic, and the enveloped virus (EV), which is extracellular. It is believed that MVs are required for viral entry into the host, while EVs are responsible for spread within the host. Following footpad infection of susceptible mice, ECTV spreads lymphohematogenously, entering the liver at 3 to 4 days postinfection (dpi). Afterwards, ECTV spreads intrahepatically, killing the host. We found that antibodies to an MV protein were highly effective at curing mice from ECTV infection when administered after the virus reached the liver. Moreover, a mutant ECTV that does not make EV was able to spread intrahepatically and kill immunodeficient mice. Together, these findings indicate that MVs are sufficient for the spread of ECTV within the liver and could have implications regarding the pathogenesis of other OPVs, the treatment of emerging OPV infections, as well as strategies for preparedness in case of accidental or intentional release of pathogenic OPVs.

Mass immunization with inactivated polio vaccine in conflict zones--Experience from Borno and Yobe States, North-Eastern Nigeria.

PubMed

Shuaibu, Faisal M; Birukila, Gerida; Usman, Samuel; Mohammed, Ado; Galway, Michael; Corkum, Melissa; Damisa, Eunice; Mkanda, Pascal; Mahoney, Frank; Wa Nganda, Gatei; Vertefeuille, John; Chavez, Anna; Meleh, Sule; Banda, Richard; Some, Almai; Mshelia, Hyelni; Umar, Al-Umra; Enemaku, Ogu; Etsano, Andrew

2016-02-01

The use of Inactivated Polio Vaccine (IPV) in routine immunization to replace Oral Polio Vaccine (OPV) is crucial in eradicating polio. In June 2014, Nigeria launched an IPV campaign in the conflict-affected states of Borno and Yobe, the largest ever implemented in Africa. We present the initiatives and lessons learned. The 8-day event involved two parallel campaigns. OPV target age was 0-59 months, while IPV targeted all children aged 14 weeks to 59 months. The Borno state primary health care agency set up temporary health camps for the exercise and treated minor ailments for all. The target population for the OPV campaign was 685,674 children in Borno and 113,774 in Yobe. The IPV target population for Borno was 608,964 and for Yobe 111,570. OPV coverage was 105.1 per cent for Borno and 103.3 per cent for Yobe. IPV coverage was 102.9 per cent for Borno and 99.1 per cent for Yobe. (Where we describe coverage as greater than 100 per cent, this reflects original underestimates of the target populations.) A successful campaign and IPV immunization is viable in conflict areas.

Environmental surveillance of poliovirus in sewage water around the introduction period for inactivated polio vaccine in Japan.

PubMed

Nakamura, Tomofumi; Hamasaki, Mitsuhiro; Yoshitomi, Hideaki; Ishibashi, Tetsuya; Yoshiyama, Chiharu; Maeda, Eriko; Sera, Nobuyuki; Yoshida, Hiromu

2015-03-01

Environmental virus surveillance was conducted at two independent sewage plants from urban and rural areas in the northern prefecture of the Kyushu district, Japan, to trace polioviruses (PVs) within communities. Consequently, 83 PVs were isolated over a 34-month period from April 2010 to January 2013. The frequency of PV isolation at the urban plant was 1.5 times higher than that at the rural plant. Molecular sequence analysis of the viral VP1 gene identified all three serotypes among the PV isolates, with the most prevalent serotype being type 2 (46%). Nearly all poliovirus isolates exhibited more than one nucleotide mutation from the Sabin vaccine strains. During this study, inactivated poliovirus vaccine (IPV) was introduced for routine immunization on 1 September 2012, replacing the live oral poliovirus vaccine (OPV). Interestingly, the frequency of PV isolation from sewage waters declined before OPV cessation at both sites. Our study highlights the importance of environmental surveillance for the detection of the excretion of PVs from an OPV-immunized population in a highly sensitive manner, during the OPV-to-IPV transition period. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Molecular characterization of poliovirus isolates from children who contracted vaccine-associated paralytic poliomyelitis (VAPP) following administration of monovalent type 3 oral poliovirus vaccine in the 1960s in Hungary.

PubMed

Kapusinszky, Beatrix; Molnár, Zsuzsanna; Szomor, Katalin N; Berencsi, György

2010-03-01

Hungarian children were immunized with monovalent oral poliovaccine (mOPV) delivered at 6-week intervals in the order Sabin 1, Sabin 3, Sabin 2, from 1959 until 1992. During that period, 90 cases of vaccine-associated paralytic poliomyelitis (VAPP) were reported, 52 of which were associated with Sabin 3-related virus (76% of VAPP cases with virologic data). Because of renewed interest in type 3 mOPV (mOPV3), molecular methods were used to reanalyze 18 of the Sabin 3-related isolates from 15 VAPP patients, confirming the original identification. All isolates had the U472C 5'-untranslated region (5'-UTR) substitution associated with reversion to neurovirulence, and from zero to seven nucleotide substitutions in the virus protein 1 (VP1) region. No evidence was found for prolonged mOPV3 replication in the VAPP patients or for spread of Sabin 3-related viruses beyond close vaccinee contacts. The VAPP diseases were prevented by a single dose of inactivated poliovirus vaccine from 1992 to 2006 in Hungary, as proved by continuous surveillance of acute flaccid paralysis.

Using oral polio vaccine beyond the cold chain: a feasibility study conducted during the national immunization campaign in Mali.

PubMed

Halm, Ariane; Yalcouyé, Idrissa; Kamissoko, Mady; Keïta, Tenemakan; Modjirom, Ndoutabé; Zipursky, Simona; Kartoglu, Umit; Ronveaux, Olivier

2010-04-26

We conducted the first systematic documentation of using oral polio vaccine (OPV) out of the cold chain during national immunization day (NID) campaigns in Mali. Using a crossover intervention design, vaccinators compared the transport of OPV in vaccine carriers with or without ice packs. Vaccine integrity was assured through monitoring vaccine vial monitor (VVM) status. Despite ambient temperatures up to 40 degrees C, none of the VVMs on any of the vials used (n=956) reached their discard point. Over 90% of vaccinators and supervisors preferred conducting NIDs without ice packs. In addition, using OPV out of the cold chain reduced vaccine wastage resulting from melting ice packs causing labels to detach from the vial. Copyright 2010 Elsevier Ltd. All rights reserved.

Acute immune thrombocytopenic purpura as adverse reaction to oral polio vaccine (OPV).

PubMed

Jin, Cheng-qiang; Dong, Hai-xin; Sun, Zhuo-xiang; Zhou, Jian-wei; Dou, Cui-yun; Lu, Shu-hua; Yang, Rui-rui

2013-08-01

A case of acute immune thrombocytopenic purpura following oral polio vaccine (OPV) is reported. An 82-d-old infant developed purpura at the same day after the second dose of oral polio vaccine. Until the time of hospital admission, the male infant had been in good health and had not received any drugs, and the possible causes of this condition were excluded. His platelet count was 13×10(9)/L. Platelet-associated IgG was elevated, but the amount of megakaryocytes in bone marrow aspirates was within the normal range, suggesting immune mechanism-associated thrombocytopenia. The infant recovered with the proper treatment within 30 d. Attention should be paid to OPV-associated thrombocytopenia, though it seems to be less frequent than after natural infections.

Photoinduced charge separation at polymer-fullerene interfaces of BHJ solar cells (Conference Presentation)

NASA Astrophysics Data System (ADS)

Poluektov, Oleg G.; Niklas, Jens; Mardis, Kristy

2016-09-01

While photovoltaic cells are highly promising man-made devices for direct solar energy utilization, a number of fundamental questions about how the organic bulk heterojunction cell enables efficient long-lived and long-range charge separation remain unanswered. These questions were address by employing an advanced suite of EPR spectroscopy in combination with DFT calculations to study mechanism of charge separation at the polymer-fullerene interfaces of photo-active BHJ. Observed charge delocalization in BHJ upon photoinduced ET is analogous to that in organic donor-acceptor material. This is an efficient mechanism of charge stabilization in photosynthetic assemblies. Time-resolved EPR spectra show a strong polarization pattern for all polymer-fullerene blends under study, which is caused by non-Boltzmann population of the electron spin energy levels in the radical pairs. The first observation of this phenomenon was reported in natural and artificial photosynthetic assemblies, and comparison with these systems allows us to better understand charge separation processes in OPVs. The spectral analysis presented here, in combination with DFT calculations, shows that CS processes in OPV materials are similar to that in organic photosynthetic systems. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences, under Contract DE-AC02-06CH11357 at Argonne National Laboratory.

Reduced Poliovirus vaccine neutralising-antibody titres in infants with maternal HIV-exposure.

PubMed

Sanz-Ramos, Marta; Manno, Daniela; Kapambwe, Mirriam; Ndumba, Ida; Musonda, Kunda G; Bates, Matthew; Chibumbya, Julia; Siame, Joshua; Monze, Mwaka; Filteau, Suzanne; Gompels, Ursula A

2013-04-12

Maternally HIV-exposed (mHIV-EU) infants have poor health even without HIV-1 infection. The responses to vaccination are less well defined. Immunity to oral Poliovirus vaccine (OPV) was studied in Zambian infants participating in a randomised controlled trial of micronutrient fortification to improve child health. Maternally HIV-unexposed and mHIV-EU infants were recruited at 6 months age and randomised to basal or enriched micronutrient-fortified diets for 12 months. HIV-exposed mother-infant pairs had received perinatal nevirapine to prevent mother-to-child-transmission. In the cohort of 597 infants, neutralising-antibody titres to OPV were analysed at 18 months with respect to micronutrient fortification, maternal or infant HIV-1 infection, and human cytomegalovirus (HCMV) infection detected by antibodies and viraemia (serum DNA). Vaccine protection was defined as log2 titre>3. Compared to uninfected children, HIV-1-infected children had reduced neutralising antibody titres to OPV, irrespective of diet: log2 titre difference (95% confidence interval) -3.44 (-2.41; -4.46), P<0.01. OPV antibody titres were lower in HIV-infected children with HCMV viraemia compared to those without viraemia at 18 months, but did not reach significance: difference -2.55 (-6.10; 1.01), P=0.14. Breast-feeding duration was independently associated with increasing OPV titre (P-value<0.01). In mHIV-EU children there were reduced neutralising antibody titres to Poliovirus compared with maternally HIV-unexposed, irrespective of diet, maternal education and socioeconomic status: log2 titre difference (95% confidence interval) -0.56 (-0.98; -0.15), P<0.01. This difference was noticeably decreased after adjusting for breast-feeding duration, suggesting that in our study population less breast-feeding by HIV-positive mothers could explain the reduced OPV titres in mHIV-EU infants. The mHIV-EU infants had reduced polio vaccine antibody titres which were associated with reduced breast-feeding duration. This has important implications for polio eradication and control of vaccine-preventable diseases, in countries where childhood HIV-1 infection and maternal exposure are public health threats. Copyright © 2013. Published by Elsevier Ltd.

25th anniversary article: Rise to power--OPV-based solar parks.

PubMed

Krebs, Frederik C; Espinosa, Nieves; Hösel, Markus; Søndergaard, Roar R; Jørgensen, Mikkel

2014-01-08

A solar park based on polymer solar cells is described and analyzed with respect to performance, practicality, installation speed, and energy payback time. It is found that a high voltage installation where solar cells are all printed in series enables an installation rate in Watts installed per minute that far exceed any other PV technology in existence. The energy payback time for the practical installation of polymer solar cell foil on a wooden 250 square meter platform in its present form is 277 days when operated in Denmark and 180 days when operated in southern Spain. The installation and de-installation rate is above 100 m min⁻¹, which, with the present performance and web width, implies installation of >200 W min⁻¹. In comparison, this also exceeds the overall manufacturing speed of the polymer solar cell foil with a width of 305 mm which is currently 1 m min⁻¹ for complete encapsulated and tested foil. It is also significant that simultaneous installation and de-installation which enables efficient schemes for decommissioning and recycling is possible. It is highlighted where research efforts should most rationally be invested in order to make grid electricity from OPV a reality (and it is within reach).

Porphyrin Based Near Infrared-Absorbing Materials for Organic Photovoltaics

NASA Astrophysics Data System (ADS)

Zhong, Qiwen

The conservation and transformation of energy is essential to the survival of mankind, and thus concerns every modern society. Solar energy, as an everlasting source of energy, holds one of the key solutions to some of the most urgent problems the world now faces, such as global warming and the oil crisis. Advances in technologies utilizing clean, abundant solar energy, could be the steering wheel of our societies. Solar cells, one of the major advances in converting solar energy into electricity, are now capturing people's interest all over the globe. While solar cells have been commercially available for many years, the manufacturing of solar cells is quite expensive, limiting their broad based implementation. The cost of solar cell based electricity is 15-50 cents per kilowatt hour (¢/kwh), depending on the type of solar cell, compared to 0.7 ¢/kwh for fossil fuel based electricity. Clearly, decreasing the cost of electricity from solar cells is critical for their wide spread deployment. This will require a decrease in the cost of light absorbing materials and material processing used in fabricating the cells. Organic photovoltaics (OPVs) utilize organic materials such as polymers and small molecules. These devices have the advantage of being flexible and lower cost than conventional solar cells built from inorganic semiconductors (e.g. silicon). The low cost of OPVs is tied to lower materials and fabrication costs of organic cells. However, the current power conversion efficiencies of OPVs are still below 15%, while convention crystalline Si cells have efficiencies of 20-25%. A key limitation in OPVs today is their inability to utilize the near infrared (NIR) portion of the solar spectrum. This part of the spectrum comprises nearly half of the energy in sunlight that could be used to make electricity. The first and foremost step in conversion solar energy conversion is the absorption of light, which nature has provided us optimal model of, which is photosynthesis. Photosynthesis uses light from the sun to drive a series of chemical reactions. Most natural photosynthetic systems utilize chlorophylls to absorb light energy and carry out photochemical charge separation that stores energy in the form of chemical bonds. The sun produces a broad spectrum of light output that ranges from gamma rays to radio waves. The entire visible range of light (400-700 nm) and some wavelengths in the NIR (700-1000 nm), are highly active in driving photosynthesis. Although the most familiar chlorophyll-containing organisms, such as plants, algae and cyanobacteria, cannot use light longer than 700 nm, anoxygenic bacterium containing bacteriochlorophylls can use the NIR part of the solar spectrum. No organism is known to utilize light of wavelength longer than about 1000 nm for photosynthesis. NIR light has a very low-energy content in each photon, so that large numbers of these low-energy photons would have to be used to drive the chemical reactions of photosynthesis. This is thermodynamically possible but would require a fundamentally different molecular mechanism that is more akin to a heat engine than to photochemistry. Early work on developing light absorbing materials for OPVs was inspired by photosynthesis in which light is absorbed by chlorophyll. Structurally related to chlorophyll is the porphyrin family, which has accordingly drawn much interest as the potential light absorbing component in OPV applications. In this dissertation, the design and detail studies of several porphyrin-based NIR absorbing materials, including pi--extended perylenyl porphryins and pyrazole-containing carbaporphyrins, as well as porphyrin modified single-walled carbon nanotube hybrids, will be presented, dedicating efforts to develop novel and application-oriented materials for efficient utilization of sustainable solar energy.

Next generation solar cells using flexible transparent electrodes based on silver nanowires and grapheme

NASA Astrophysics Data System (ADS)

Alomairy, Sultan

Organic photovoltaic (OPV) devices have been developed extensively and optimised due to the use of nanomaterials in their construction. More recently, the demand for such devices to be flexible and mechanically robust has been a major area of research. Presently, Indium Tin Oxide (ITO) is the material that is used almost exclusively for transparent electrode. However, it has several drawbacks such as brittleness, high refractive index and high processing temperature. Furthermore, the price of ITO has been highly volatile due to scarcity of indium resources and the increased consumption of the material. Therefore, cheap, flexible and solution-processed transparent conductors are required for emerging optoelectronic devices with flexible construction which can be promising for wearable or environmentally adaptable devices purposes such as flexible solar cells and displays. Therefore, over the past decade an alternative material has been sought intensively, particularly in the need for producing large area flexible transparent electrodes. Many materials have been investigated but most investigations have focused on carbon nanotube (CNT), graphene flakes and metallic nanowires. Silver nanowires (Ag NWs) networks have been proven to show a high electrical conductivity with high optical transmittance. This special characteristic is desirable in transparent conductive electrodes in optoelectronic applications such as solar cells, light emitting diodes, and touch screen. On the other hand, Polymeric substrates that act as a non-brittle scaffold as well as protective packaging of the OPV are an essential element for such an “All-plastic” device. However, for such applications where the coating should be relatively hard a bottleneck to fabricating large area homogeneous films is associated with the formation of cracks as a result of local mismatches in mechanical properties during film formation. In this work, the fabrication and characterization of flexible transparent electrodes of Ag NWs on flexible substrates by spray deposition technique have been described. Furthermore, a way to enhance the electrical and mechanical properties of the Ag NWs transparent electrodes by incorporating a low density ensemble of graphene on top of the metal electrode networks using the Langmuir-Schafer has been achieved. Interestingly, the electrical conductivity in these hybrid electrodes is stable over relatively large strains during mechanical agitation indicating that such electrodes may have important application in future applications. Finally, producing crack-free monolayer latex over large area has been fabricated and characterised. Therefore, the polymer latex thin film has promising applications as purposes of hard coatings.

Neurovirulence of Type 1 Polioviruses Isolated from Sewage in Japan

PubMed Central

Horie, Hitoshi; Yoshida, Hiromu; Matsuura, Kumiko; Miyazawa, Miwako; Ota, Yoshihiro; Nakayama, Takashi; Doi, Yutaka; Hashizume, So

2002-01-01

Sixteen type 1 poliovirus strains were isolated from a sewage disposal plant located downstream of the Oyabe River in Japan between October 1993 and September 1995. The isolates were intratypically differentiated as vaccine-derived strains. Neutralizing antigenicity analysis with monoclonal antibodies and estimation of neurovirulence by mutant analysis by PCR and restriction enzyme cleavage (MAPREC) were performed for 13 type 1 strains of these isolates. The isolates were classified into three groups. Group I (five strains) had a variant type of antigenicity and neurovirulent phenotype. Group II (four strains) had the vaccine type of antigenicity and neurovirulent phenotype. Group III (four strains) had the vaccine type of antigenicity and an attenuated phenotype. Furthermore, it was demonstrated that the virulent isolates were neutralized by human sera obtained after oral poliomyelitis vaccine (OPV) administration, and the sera of rats immunized with inactivated poliovirus vaccine. Although vaccination was effective against virulent polioviruses, virulent viruses will continue to exist in the environment as long as OPV is in use. PMID:11772619

Correlation between the Open-Circuit Voltage and Charge Transfer State Energy in Organic Photovoltaic Cells.

PubMed

Zou, Yunlong; Holmes, Russell J

2015-08-26

In order to further improve the performance of organic photovoltaic cells (OPVs), it is essential to better understand the factors that limit the open-circuit voltage (VOC). Previous work has sought to correlate the value of VOC in donor-acceptor (D-A) OPVs to the interface energy level offset (EDA). In this work, measurements of electroluminescence are used to extract the charge transfer (CT) state energy for multiple small molecule D-A pairings. The CT state as measured from electroluminescence is found to show better correlation to the maximum VOC than EDA. The difference between EDA and the CT state energy is attributed to the Coulombic binding energy of the CT state. This correlation is demonstrated explicitly by inserting an insulating spacer layer between the donor and acceptor materials, reducing the binding energy of the CT state and increasing the measured VOC. These results demonstrate a direct correlation between maximum VOC and CT state energy.

A Planar, Chip-Based, Dual-Beam Refractometer Using an Integrated Organic Light Emitting Diode (OLED) Light Source and Organic Photovoltaic (OPV) Detectors

PubMed Central

Ratcliff, Erin L.; Veneman, P. Alex; Simmonds, Adam; Zacher, Brian; Huebner, Daniel

2010-01-01

We present a simple chip-based refractometer with a central organic light emitting diode (OLED) light source and two opposed organic photovoltaic (OPV) detectors on an internal reflection element (IRE) substrate, creating a true dual-beam sensor platform. For first-generation platforms, we demonstrate the use of a single heterojunction OLED based on electroluminescence emission from an Alq3/TPD heterojunction (tris-(8-hydroxyquinoline)aluminum/N,N′-Bis(3-methylphenyl)-N,N′-diphenylbenzidine) and light detection with planar heterojunction pentacene/C60 OPVs. The sensor utilizes the considerable fraction of emitted light from conventional thin film OLEDs that is coupled into guided modes in the IRE instead of into the forward (display) direction. A ray-optics description is used to describe light throughput and efficiency-limiting factors for light coupling from the OLED into the substrate modes, light traversing through the IRE substrate, and light coupling into the OPV detectors. The arrangement of the OLED at the center of the chip provides for two sensing regions, a “sample” and “reference” channel, with detection of light by independent OPV detectors. This configuration allows for normalization of the sensor response against fluctuations in OLED light output, stability, and local fluctuations (temperature) which might influence sensor response. The dual beam configuration permits significantly enhanced sensitivity to refractive index changes relative to single-beam protocols, and is easily integrated into a field-portable instrumentation package. Changes in refractive index (ΔR.I.) between 10−2 and 10−3 R.I. units could be detected for single channel operation, with sensitivity increased to ΔR.I. ≈ 10−4 units when the dual beam configuration is employed. PMID:20218580

Understanding threats to polio vaccine commitment among caregivers in high-priority areas of Afghanistan: a polling study.

PubMed

SteelFisher, Gillian K; Blendon, Robert J; Guirguis, Sherine; Lodge, William; Caporello, Hannah; Petit, Vincent; Coleman, Michael; Williams, Matthew R; Parwiz, Sardar Mohammad; Corkum, Melissa; Gardner, Scott; Ben-Porath, Eran N

2017-11-01

Eradication of poliovirus from endemic countries relies on vaccination of children with oral polio vaccine (OPV) many times a year until the age of 5 years. We aimed to determine caregivers' commitment to OPV in districts of Afghanistan at high risk for polio transmission and to examine what knowledge, attitudes, or experiences could threaten commitment. We designed and analysed a poll using face-to-face interviews among caregivers of children under 5 years of age. The sample was drawn via a stratified multistage cluster design with random route household selection. We calculated the percentage of committed and uncommitted caregivers. All percentages were weighted. We then compared percentages of uncommitted caregivers among those with varying knowledge, attitudes, and experiences, using logistic regression to control for possible demographic confounders. Between Dec 19, 2014, and Jan 5, 2015, we interviewed 1980 caregivers, 21% of whom were "uncommitted" to accepting OPV. Multiple measures of knowledge, attitudes, and experiences are associated with lack of commitment. For example, compared with their relevant counterparts, caregivers are more likely to be uncommitted if they did not trust vaccinators "a great deal" (54% vs 9%), if they do not know that polio spreads through contaminated water (41% vs 14%), or if they believe rumours that OPV is not halal (50% vs 21%). To enhance OPV commitment, it might be useful to consider a multifactorial approach that highlights building trust in vaccinators, providing facts about transmission, sharing positive messages to overcome key rumours, and strengthening community support for vaccination. Harvard T H Chan School of Public Health and UNICEF. Copyright © 2017 Elsevier Ltd. All rights reserved.

Supplementary polio immunization activities and prior use of routine immunization services in non-polio-endemic sub-Saharan Africa.

PubMed

Helleringer, Stephane; Frimpong, Jemima A; Abdelwahab, Jalaa; Asuming, Patrick; Touré, Hamadassalia; Awoonor-Williams, John Koku; Abachie, Thomas; Guidetti, Flavia

2012-07-01

To determine participation in polio supplementary immunization activities (SIAs) in sub-Saharan Africa among users and non-users of routine immunization services and among users who were compliant or non-compliant with the routine oral poliovirus vaccine (OPV) immunization schedule. Data were obtained from household-based surveys in non-polio-endemic sub-Saharan African countries. Routine immunization service users were children (aged < 5 years) who had ever had a health card containing their vaccination history; non-users were children who had never had a health card. Users were considered compliant with the OPV routine immunization schedule if, by the SIA date, their health card reflected receipt of required OPV doses. Logistic regression measured associations between SIA participation and use of both routine immunization services and compliance with routine OPV among users. Data from 21 SIAs conducted between 1999 and 2010 in 15 different countries met inclusion criteria. Overall SIA participation ranged from 70.2% to 96.1%. It was consistently lower among infants than among children aged 1-4 years. In adjusted analyses, participation among routine immunization services users was > 85% in 12 SIAs but non-user participation was >85% in only 5 SIAs. In 18 SIAs, participation was greater among users (P < 0.01 in 16, 0.05 in 1 and < 0.10 in 1) than non-users. In 14 SIAs, adjusted analyses revealed lower participation among non-compliant users than among compliant users (P < 0.01 in 10, < 0.05 in 2 and < 0.10 in 2). Large percentages of children participated in SIAs. Prior use of routine immunization services and compliance with the routine OPV schedule showed a strong positive association with SIA participation.

Influences of CdSe NCs on the photovoltaic parameters of BHJ organic solar cells

NASA Astrophysics Data System (ADS)

Ongul, Fatih; Yuksel, Sureyya Aydin; Allahverdi, Cagdas; Bozar, Sinem; Kazici, Mehmet; Gunes, Serap

2018-04-01

In this study, the high quality CdSe nanocrystals (NCs) capped with stearic acid were synthesized in a solvent and then purified four times by using the precipitation and redissolution process. The average size of the synthesized CdSe NCs was determined 3.0 nm via transmission electron microscopy (TEM) measurement and their corresponding optical band edge energy was also calculated as 2.1 eV using ultraviolet-visible (UV-Vis) absorption spectroscopy. The bulk heterojunction (BHJ) hybrid solar cells based on a ternary system including P3HT, PCBM and CdSe NCs at different weight concentrations (0 wt%, 0.1 wt%, 0.5 wt%, 1 wt% and 2 wt%) were fabricated by spin-casting process. The effect of the concentration of CdSe NCs on the photovoltaic parameters of these BHJ organic solar cells was investigated. The surface morphology of the photoactive layer modified by the incorporation of CdSe NCs into P3HT:PCBM matrix was observed with scanning electron microscopy (SEM). It was shown that when the concentration of CdSe NCs increases above 0.1 wt% in this ternary system, the photovoltaic performance of the devices significantly decreases. The power conversion efficiency of the organic photovoltaic (OPV) device was enhanced 20% by incorporating CdSe NCs with 0.1 wt% with respect to those without CdSe NCs.

Influences of CdSe NCs on the photovoltaic parameters of BHJ organic solar cells.

PubMed

Ongul, Fatih; Yuksel, Sureyya Aydin; Allahverdi, Cagdas; Bozar, Sinem; Kazici, Mehmet; Gunes, Serap

2018-04-05

In this study, the high quality CdSe nanocrystals (NCs) capped with stearic acid were synthesized in a solvent and then purified four times by using the precipitation and redissolution process. The average size of the synthesized CdSe NCs was determined ~3.0nm via transmission electron microscopy (TEM) measurement and their corresponding optical band edge energy was also calculated as ~2.1eV using ultraviolet-visible (UV-Vis) absorption spectroscopy. The bulk heterojunction (BHJ) hybrid solar cells based on a ternary system including P3HT, PCBM and CdSe NCs at different weight concentrations (0wt%, 0.1wt%, 0.5wt%, 1wt% and 2wt%) were fabricated by spin-casting process. The effect of the concentration of CdSe NCs on the photovoltaic parameters of these BHJ organic solar cells was investigated. The surface morphology of the photoactive layer modified by the incorporation of CdSe NCs into P3HT:PCBM matrix was observed with scanning electron microscopy (SEM). It was shown that when the concentration of CdSe NCs increases above 0.1wt% in this ternary system, the photovoltaic performance of the devices significantly decreases. The power conversion efficiency of the organic photovoltaic (OPV) device was enhanced ~20% by incorporating CdSe NCs with 0.1wt% with respect to those without CdSe NCs. Copyright © 2017 Elsevier B.V. All rights reserved.

Photoexcitation and Photochemical Stability of Organic Photovoltaic Materials from First Principles

NASA Astrophysics Data System (ADS)

Sai, Na; Leung, Kevin

2013-03-01

The development of high efficiency organic photovoltaics (OPV) has recently become enabled by the synthesis of new conjugated polymers with low band gap that allow light absorption over a broader range of the spectrum. Stability of these new polymers, a key requirement for commercialization, has not yet received sufficient attention. Here, we report first-principles theoretical modeling of photo-induced degradation of OPV polymers carried out using ab-initio density functional theory (DFT). We report photooxidation routes and reaction products for reactive species including superoxide oxygen anions and hydroxyl groups interacting with the standard workhorse OPV polymer, poly(3-hexyl-thiophene) (P3HT). We discuss theoretical issues and challenges affecting the modeling such reactions in OPV polymers. We also discuss the application of theoretical methods to low-band-gap polymers, and in particular, the effect of the chemical substitution on the photoexcitation properties of these new polymers. Sandia National Laboratories is a multiprogram laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Deparment of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. This work is supported by the Energy Frontier Research Center funded by the U.S. DOE Office of Basic Energy Sciences under Award number DE-SC0001091.

The sequence of camelpox virus shows it is most closely related to variola virus, the cause of smallpox.

PubMed

Gubser, Caroline; Smith, Geoffrey L

2002-04-01

Camelpox virus (CMPV) and variola virus (VAR) are orthopoxviruses (OPVs) that share several biological features and cause high mortality and morbidity in their single host species. The sequence of a virulent CMPV strain was determined; it is 202182 bp long, with inverted terminal repeats (ITRs) of 6045 bp and has 206 predicted open reading frames (ORFs). As for other poxviruses, the genes are tightly packed with little non-coding sequence. Most genes within 25 kb of each terminus are transcribed outwards towards the terminus, whereas genes within the centre of the genome are transcribed from either DNA strand. The central region of the genome contains genes that are highly conserved in other OPVs and 87 of these are conserved in all sequenced chordopoxviruses. In contrast, genes towards either terminus are more variable and encode proteins involved in host range, virulence or immunomodulation. In some cases, these are broken versions of genes found in other OPVs. The relationship of CMPV to other OPVs was analysed by comparisons of DNA and predicted protein sequences, repeats within the ITRs and arrangement of ORFs within the terminal regions. Each comparison gave the same conclusion: CMPV is the closest known virus to variola virus, the cause of smallpox.

Vaccine-associated paralytic poliomyelitis in an infant with perianal abscesses.

PubMed

Higashigawa, Masamune; Maegawa, Kayoka; Honma, Hitoshi; Yoshino, Ayako; Onozato, Kaori; Nashida, Yuji; Fujiwara, Takashi; Inoue, Masakazu

2010-10-01

We describe a case of vaccine-associated paralytic poliomyelitis (VAPP) in a 7-month-old infant with perianal abscesses. The infant had suffered from perianal abscesses from 3 weeks after birth. The abscesses repeatedly developed and spontaneously drained through the orifice. Twenty-seven days before admission, a live attenuated oral poliovirus vaccine (OPV) was given to the infant for the first time for routine immunization. His body temperature rose to 38°C 19 days after receiving the OPV and fell 4 days later. Flaccid paralysis of the right leg appeared 26 days after receipt of the OPV. A Sabin type 3 poliovirus was isolated from a stool obtained at admission. The DNA sequences of the VP1 region of the isolated virus were more than 99% identical with those of the vaccine strain. Mild muscle atrophy with moderate motor impairment in the right leg persisted at 18 months of age. One VAPP case provoked by a perianal abscess has been reported from the United Kingdom. Database search revealed that one of nine VAPP cases reported during 2003-2008 in Japan had a perianal abscess. Taken together, these reports and our case imply that we should give OPV with caution to infants with a perianal abscess.

Enhanced performance of P3HT/(PCBM:ZnO:TiO{sub 2}) blend based hybrid organic solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ikram, M., E-mail: mianraj.1981@gmail.com; Murray, R.; Imran, M.

Highlights: • We fabricated hybrid bulk heterojunction organic solar cells. • TiO{sub 2} and ZnO nanoparticles replace PCBM with fixed amount of P3HT in active layer • PCE was significantly improved by the introduction of TiO{sub 2} and ZnO. • A possible route toward low-cost OPV. • To the best of my knowledge, this work is the first time going to report. - Abstract: Quaternary blend hybrid organic solar cells enjoy both an increased light absorption range and an easy method to fabricate because of the simple structure. In this study effects of mixing inorganic metal oxides (ZnO and TiO{submore » 2}) nanoparticles to the active layer of organic photovoltaics devices were investigated. The active layer primarily consists of various ratios of electron donor poly (3-hexylthiophene) (P3HT) and an electron acceptor [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) together with nanostructured ZnO and TiO{sub 2} dispersed in chlorobenzene (CB) and 1,2-dichlorobenzene (DCB). The ratio of PCBM to nanoparticles was varied keeping the ratio of P3HT to acceptor material constant. Mixing of nanoparticle plays a significant role in the resulting power conversion efficiency (PCE) of the devices. An increased PCE for ZnO/TiO{sub 2} doped devices can be attributed to increased absorption in the visible region and enhanced charge collection due to the percolation networks formed by metal oxides nanoparticles.« less

Local Imaging of Optoelectronic Properties and Film Degradation in Polymer/Fullerene Solar Cells with Electrostatic Force Microscopy

NASA Astrophysics Data System (ADS)

Cox, Phillip Alexander

With power conversion efficiencies on the rise, organic photovoltaics (OPVs) hold promise as a next-generation thin-film solar technology. However, both device performance and stability are inextricably linked to local film structure. Methods capable of probing nanoscale electronic properties as a function of film structure are thus a crucial component of the rational design of efficient and robust devices. This dissertation describes the use of three scanning probe methods for studying local charge generation and photodegradation in polymer/fullerene solar cells. First, we show that time-resolved electrostatic force microscopy (trEFM) is capable of resolving local photocurrent from sub-bandgap excitation down to attoampere level currents, a result unattainable by traditional contact-mode methods. We find that the local charging rates measured with trEFM are proportional to external quantum efficiency (EQE) measurements made on completed devices, making trEFM images equivalent to local EQE maps across the entire solar spectrum. For both phase-segregated and well-mixed MDMO-PPV:PCBM film morphologies, we show that the local distribution of photocurrent is invariant to excitation wavelength, providing local evidence for the controversial result that the probability of generating separated charge carriers does not depend on whether excitons are formed at the singlet state or charge transfer state. Next, we describe how local dissipation imaging can be performed with commercially-available frequency-modulated electrostatic force microscopy (FM-EFM) and show that dissipation maps are highly sensitive to photo-oxidative effects in organic semiconductors. We show that photo-oxidation induced changes in cantilever energy dissipation are proportional to device performance losses. We further develop dissipation imaging by implementing ringdown imaging, which directly measures the quality factor of the cantilever, enabling quantitative dissipation mapping. Using organic photovoltaic materials as a testbed, we study macroscopic device degradation as a function of photooxidation for three different film morphologies. According to EQE measurements, we find that the stability of the macroscopic devices is very sensitive to processing conditions, with films processed with the solvent additive 1,8-diiodooctane being the most stable. At the microscopic level, we compare the evolution of cantilever power dissipation as a function of photochemical degradation for three different polymer/fullerene blend morphologies, and show that the evolution of local power dissipation correlates with device stability. Lastly, we show that cantilever power dissipation increases more rapidly over large fullerene aggregates than in well-mixed polymer/fullerene regions, suggesting that local photochemistry on the fullerene contributes strongly to the dissipation signal.

Comparison of camelpox viruses isolated in Dubai.

PubMed

Pfeffer, M; Meyer, H; Wernery, U; Kaaden, O R

1996-03-01

Between October 1993 and March 1994, outbreaks of pox-like exanthemas were observed in several camel raising farms in Dubai. Scabs from twenty camels with either local or generalized lesions were examined, seven of them had previously been vaccinated with a modified live camelpox virus vaccine. Inspection of scabs by electron microscopy confirmed an infection with orthopox viruses (OPV) in 10 animals and with parapox virus in one camel. Investigation of the scabs by polymerase chain reaction and dot blot assay revealed the presence of OPV in 15 or 13 samples, respectively. OPV could be isolated in cell culture in 14 cases. Restriction enzyme profiles characterized all isolates as camelpox virus. Their DNA patterns were virtually identical displaying only slight variations in the terminal fragments. In contrast, the vaccine strain showed a distinct restriction enzyme profile, indicating that it was not involved in the infections.

Computer-Aided Screening of Conjugated Polymers for Organic Solar Cell: Classification by Random Forest.

PubMed

Nagasawa, Shinji; Al-Naamani, Eman; Saeki, Akinori

2018-05-17

Owing to the diverse chemical structures, organic photovoltaic (OPV) applications with a bulk heterojunction framework have greatly evolved over the last two decades, which has produced numerous organic semiconductors exhibiting improved power conversion efficiencies (PCEs). Despite the recent fast progress in materials informatics and data science, data-driven molecular design of OPV materials remains challenging. We report a screening of conjugated molecules for polymer-fullerene OPV applications by supervised learning methods (artificial neural network (ANN) and random forest (RF)). Approximately 1000 experimental parameters including PCE, molecular weight, and electronic properties are manually collected from the literature and subjected to machine learning with digitized chemical structures. Contrary to the low correlation coefficient in ANN, RF yields an acceptable accuracy, which is twice that of random classification. We demonstrate the application of RF screening for the design, synthesis, and characterization of a conjugated polymer, which facilitates a rapid development of optoelectronic materials.

Adjuvants and Inactivated Polio Vaccine: A Systematic Review

PubMed Central

Hawken, Jennifer; Troy, Stephanie B.

2012-01-01

Poliomyelitis is nearing universal eradication; in 2011, there were 650 cases reported globally. When wild polio is eradicated, global oral polio vaccine (OPV) cessation followed by universal use of inactivated polio vaccine (IPV) is believed to be the safest vaccination strategy as IPV does not mutate or run the risk of vaccine derived outbreaks that OPV does. However, IPV is significantly more expensive than OPV. One strategy to make IPV more affordable is to reduce the dose by adding adjuvants, compounds that augment the immune response to the vaccine. No adjuvants are currently utilized in stand-alone IPV; however, several have been explored over the past six decades. From aluminum, used in many licensed vaccines, to newer and more experimental adjuvants such as synthetic DNA, a diverse group of compounds has been assessed with varying strengths and weaknesses. This review summarizes the studies to date evaluating the efficacy and safety of adjuvants used with IPV. PMID:23041122

Needle-free jet injector intradermal delivery of fractional dose inactivated poliovirus vaccine: Association between injection quality and immunogenicity.

PubMed

Resik, Sonia; Tejeda, Alina; Mach, Ondrej; Sein, Carolyn; Molodecky, Natalie; Jarrahian, Courtney; Saganic, Laura; Zehrung, Darin; Fonseca, Magile; Diaz, Manuel; Alemany, Nilda; Garcia, Gloria; Hung, Lai Heng; Martinez, Yenisleydis; Sutter, Roland W

2015-10-26

The World Health Organization recommends that as part of the polio end-game strategy a dose of inactivated poliovirus vaccine (IPV) be introduced by the end of 2015 in all countries currently using only oral poliovirus vaccine (OPV). Administration of fractional dose (1/5 of full dose) IPV (fIPV) by intradermal (ID) injection may reduce costs, but its conventional administration is with Bacillus Calmette-Guerin (BCG) needle and syringe (NS), which is time consuming and technically challenging. We compared injection quality achieved with BCG NS and three needle-free jet injectors and assessed ergonomic features of the injectors. Children between 12 and 20 months of age who had previously received OPV were enrolled in the Camaguey, Cuba study. Subjects received a single fIPV dose administered intradermally with BCG NS or one of three needle-free injector devices: Bioject Biojector 2000® (B2000), Bioject ID Pen® (ID Pen), or PharmaJet Tropis® (Tropis). We measured bleb diameter and vaccine loss as indicators of ID injection quality, with desirable injection quality defined as bleb diameter ≥5mm and vaccine loss <10%. We surveyed vaccinators to evaluate ergonomic features of the injectors. We further assessed the injection quality indicators as predictors of immune response, measured by increase in poliovirus neutralizing antibodies in blood between day 0 (pre-IPV) and 21 (post-vaccination). Delivery by BCG NS and Tropis resulted in the highest proportion of subjects with desirable injection quality; health workers ranked Biojector2000 and Tropis highest for ergonomic features. We observed that vaccine loss and desirable injection quality were associated with an immune response for poliovirus type 2 (P=0.02, P=0.01, respectively). Our study demonstrated the feasibility of fIPV delivery using needle-free injector devices with high acceptability among health workers. We did not observe the indicators of injection quality to be uniformly associated with immune response. Copyright © 2015. Published by Elsevier Ltd.

Towards fully spray coated organic light emitting devices

NASA Astrophysics Data System (ADS)

Gilissen, Koen; Stryckers, Jeroen; Manca, Jean; Deferme, Wim

2014-10-01

Pi-conjugated polymer light emitting devices have the potential to be the next generation of solid state lighting. In order to achieve this goal, a low cost, efficient and large area production process is essential. Polymer based light emitting devices are generally deposited using techniques based on solution processing e.g.: spin coating, ink jet printing. These techniques are not well suited for cost-effective, high throughput, large area mass production of these organic devices. Ultrasonic spray deposition however, is a deposition technique that is fast, efficient and roll to roll compatible which can be easily scaled up for the production of large area polymer light emitting devices (PLEDs). This deposition technique has already successfully been employed to produce organic photovoltaic devices (OPV)1. Recently the electron blocking layer PEDOT:PSS2 and metal top contact3 have been successfully spray coated as part of the organic photovoltaic device stack. In this study, the effects of ultrasonic spray deposition of polymer light emitting devices are investigated. For the first time - to our knowledge -, spray coating of the active layer in PLED is demonstrated. Different solvents are tested to achieve the best possible spray-able dispersion. The active layer morphology is characterized and optimized to produce uniform films with optimal thickness. Furthermore these ultrasonic spray coated films are incorporated in the polymer light emitting device stack to investigate the device characteristics and efficiency. Our results show that after careful optimization of the active layer, ultrasonic spray coating is prime candidate as deposition technique for mass production of PLEDs.

EDITORIAL: Flexible OLEDs and organic electronics Flexible OLEDs and organic electronics

NASA Astrophysics Data System (ADS)

Kim, Jang-Joo; Han, Min-Koo; Noh, Yong-Young

2011-03-01

Following the great discovery of the electrically conducting polymer, doped polyacetylene, which was honorably recognized in 2000 with the Nobel Prize in chemistry, conjugated molecules, i.e. organic semiconductors, have become an attractive class of active elements for various electronic or opto-electronic applications. Significant effort has been made in both academia and industry to investigate π-conjugated molecules for their unique electrical or opto-electrical properties over the last three decades. The discovery of electroluminescence in conjugated small molecules in 1982 and in polymers in 1989 was a major breakthrough, bringing those molecules to commercial applications within reach for the first time in (opto-)electronic devices, such as organic light-emitting diodes (OLEDs), photovoltaic cells (OPVs), and field-effect transistors (OFETs). Nowadays, we use OLED displays in everyday life in mobile devices. The potential of these devices, which have been fabricated with conjugated molecules, lies in the possibility to combine the advantages of solution processability, chemical tunability and material strength of polymers with the typical properties of plastics, to realize low-cost, large-area electronic devices on flexible substrates by solution deposition and direct-write graphic art printing techniques. The articles in the flexible OLEDs and organic electronics special issue in Semiconductor Science and Technology deal with a diversity of topics and effectively reflect the current status of research from all over the world on various organic electronic devices, including OLEDs, OPVs, and OFETs. Firstly, S Park et al describe the recent progress in thin-film encapsulation techniques for flexible AM-OLED and large-area OLED lightings, and their applications are discussed by J-W Park et al. Flexible active-matrix OLEDs on plastics require stable and flexible thin-film transistors processed at low temperature. Metal oxide thin-film transistors are proposed as one of the best candidates for the purpose, and J K Jeong discusses their status and perspectives. Next, several excellent research articles on OFETs follow. In particular, Y-Y Noh et al introduce an interesting method to control charge injection in top-gated OFETs by insertion of various self-assembled monolayers in their paper entitled 'Controlling contact resistance in top-gate polythiophene-based field-effect transistors by molecular engineering'. We would like to thank all the authors for their contributions, which combine new results and profound overviews of the state of the art in flexible OLEDs and organic electronics areas; it is this combination that most often adds to the value of topical issues. Special thanks also go to the staff of IOP Publishing, particularly Ms Alice Malhador, for contributing to the success of this effort. In this special issue, many wonderful reviews and research articles provide a detailed overview of recent progress in OLEDs, OPVs and OFETs as well as a scientific understanding of the device physics with these materials. We sincerely believe this special issue is a timely publication and will give productive information to a broad range of readers. Flexible OLEDs and organic electronics Contents Thin film encapsulation for flexible AM-OLED: a review Jin-Seong Park, Heeyeop Chae, Ho Kyoon Chung and Sang In Lee Large-area OLED lightings and their applications J W Park, D C Shin and S H Park Controlling contact resistance in top-gate polythiophene-based field-effect transistors by molecular engineering Yong-Young Noh, Xiaoyang Cheng, Marta Tello, Mi-Jung Lee and Henning Sirringhaus Branched polythiophene as a new amorphous semiconducting polymer for an organic field-effect transistor Makoto Karakawa, Yutaka Ie and Yoshio Aso Influence of mechanical strain on the electrical properties of flexible organic thin-film transistors Fang-Chung Chen, Tzung-Da Chen, Bing-Ruei Zeng and Ya-Wei Chung Frequency operation of low-voltage, solution-processed organic field-effect transistors M Caironi, Y-Y Noh and H Sirringhaus Nonvolatile memory thin-film transistors using an organic ferroelectric gate insulator and an oxide semiconducting channel Sung-Min Yoon, Shinhyuk Yang, Chun-Won Byun, Soon-Won Jung, Min-Ki Ryu, Sang-Hee Ko Park, ByeongHoon Kim, Himchan Oh, Chi-Sun Hwang and Byoung-Gon Yu The status and perspectives of metal oxide thin-film transistors for active matrix flexible displays Jae Kyeong Jeong Vertical phase segregation of hybrid poly(3-hexylthiophene) and fullerene derivative composites controlled via velocity of solvent drying Tao Song, Zhongwei Wu, Yingfen Tu, Yizheng Jin and Baoquan Sun Variations of cell performance in ITO-free organic solar cells with increasing cell areas Jun-Seok Yeo, Jin-Mun Yun, Seok-Soon Kim, Dong-Yu Kim, Junkyung Kim and Seok-In Na

Demand Creation for Polio Vaccine in Persistently Poor-Performing Communities of Northern Nigeria: 2013-2014.

PubMed

Warigon, Charity; Mkanda, Pascal; Muhammed, Ado; Etsano, Andrew; Korir, Charles; Bawa, Samuel; Gali, Emmanuel; Nsubuga, Peter; Erbeto, Tesfaya B; Gerlong, George; Banda, Richard; Yehualashet, Yared G; Vaz, Rui G

2016-05-01

Poliomyelitis remains a global threat despite availability of oral polio vaccine (OPV), proven to reduce the burden of the paralyzing disease. In Nigeria, children continue to miss the opportunity to be fully vaccinated, owing to factors such as unmet health needs and low uptake in security-compromised and underserved communities. We describe the implementation and evaluation of several activities to create demand for polio vaccination in persistently poor-performing local government areas (LGAs). We assessed the impact of various polio-related interventions, to measure the contribution of demand creation activities in 77 LGAs at very high risk for polio, located across 10 states in northern Nigeria. Interventions included provision of commodities along with the polio vaccine. There was an increasing trend in the number of children reached by different demand creation interventions. A total of 4 819 847 children were vaccinated at health camps alone. There was a reduction in the number of wards in which >10% of children were missed by supplementary immunization activities due to noncompliance with vaccination recommendations, a rise in the proportion of children who received ≥4 OPV doses, and a decrease in the proportion of children who were underimmunized or unimmunized. Demand creation interventions increased the uptake of polio vaccines in persistently poor-performing high-risk communities in northern Nigeria during September 2013-November 2014. © 2016 World Health Organization; licensee Oxford Journals.

Morphology-defined interaction of copper phthalocyanine with O2/H2O

NASA Astrophysics Data System (ADS)

Muckley, Eric S.; Miller, Nicholas; Jacobs, Christopher B.; Gredig, Thomas; Ivanov, Ilia N.

2016-10-01

Copper phthalocyanine (CuPc) is an important hole transport layer for organic photovoltaics (OPVs), but interaction with ambient gas/vapor may lead to changes in its electronic properties and limit OPV device lifetimes. CuPc films of thickness 25 and 100 nm were grown by thermal sublimation at 25°C, 150°C, and 250°C in order to vary morphology. We measured electrical resistance and film mass in situ during exposure to controlled pulses of O2 and H2O vapor. CuPc films deposited at 250°C showed a factor of 5 higher uptake of O2 as detected by a quartz crystal microbalance (QCM), possibly due to the formation of β-CuPc at T>200°C which allows higher O2 mobility between stacked molecules. While weight-based measurements stabilize after ˜10 min of gas exposure, resistance response stabilizes over times >1 h, suggesting that mass change occurs by rapid adsorption at active surface sites whereas resistive response is dominated by slow diffusion of adsorbates into the bulk film. The 25 nm films exhibit higher resistive response than 100 nm films after an hour of O2/H2O exposure due to fast analyte diffusion down to the film/electrode interface. We found evidence of decoupling of CuPc from the gold-coated QCM crystal due to preferential adsorption of O2/H2O molecules on gold.

Structural and Electrical Functionality of NiO Interfacial Films in Bulk Heterojunction Organic Solar Cells

DTIC Science & Technology

2011-04-01

glass /ITO electrodes. These NiO layers are found to be advantageous in BHJ OPV applications due to favorable energy band levels, interface passivation, p...NiO films grown on glass /ITO electrodes. These NiO layers are found to be advantageous in BHJ OPV applications due to favorable energy band levels...carrier transport characteristics. II. EXPERIMENTAL SECTION Substrate Preparation. ITO-coated glass (11 Ω/0) was pur- chased from Delta Technologies

Impact of Thermal Annealing on Organic Photovoltaic Cells Using Regioisomeric Donor-Acceptor-Acceptor Molecules.

PubMed

Zhang, Tao; Han, Han; Zou, Yunlong; Lee, Ying-Chi; Oshima, Hiroya; Wong, Ken-Tsung; Holmes, Russell J

2017-08-02

We report a promising set of donor-acceptor-acceptor (D-A-A) electron-donor materials based on coplanar thieno[3,2-b]/[2,3-b]indole, benzo[c][1,2,5]thiadiazole, and dicyanovinylene, which are found to show broadband absorption with high extinction coefficients. The role of the regioisomeric electron-donating thienoindole moiety on the physical and structural properties is examined. Bulk heterojunction (BHJ) organic photovoltaic cells (OPVs) based on the thieno[2,3-b]indole-based electron donor NTU-2, using C 70 as an electron acceptor, show a champion power conversion efficiency of 5.2% under AM 1.5G solar simulated illumination. This efficiency is limited by a low fill factor (FF), as has previously been the case in D-A-A systems. In order to identify the origin of the limited FF, further insight into donor layer charge-transport behavior is realized by examining planar heterojunction OPVs, with emphasis on the evolution of film morphology with thermal annealing. Compared to as-deposited OPVs that exhibit insufficient donor crystallinity, crystalline OPVs based on annealed thin films show an increase in the short-circuit current density, FF, and power conversion efficiency. These results suggest that that the crystallization of D-A-A molecules might not be realized spontaneously at room temperature and that further processing is needed to realize efficient charge transport in these materials.

Human rotavirus vaccine is highly efficacious when coadministered with routine expanded program of immunization vaccines including oral poliovirus vaccine in Latin America.

PubMed

Tregnaghi, Miguel W; Abate, Héctor J; Valencia, Alejandra; Lopez, Pio; Da Silveira, Themis Reverbel; Rivera, Luis; Rivera Medina, Doris Maribel; Saez-Llorens, Xavier; Gonzalez Ayala, Silvia Elena; De León, Tirza; Van Doorn, Leen-Jan; Pilar Rubio, Maria Del; Suryakiran, Pemmaraju Venkata; Casellas, Javier M; Ortega-Barria, Eduardo; Smolenov, Igor V; Han, Htay-Htay

2011-06-01

The efficacy of a rotavirus vaccine against severe rotavirus gastroenteritis when coadministered with routine Expanded Program on Immunization (EPI) vaccines including oral polio vaccine (OPV) was evaluated in this study. Double-blind, randomized (2:1), placebo-controlled study conducted across 6 Latin American countries. Healthy infants (N = 6568) 6 to 12 weeks of age received 2 doses of RIX4414 vaccine or placebo following a 0, 1- to 2-month schedule. Routine vaccines including OPV were coadministered according to local EPI schedule. Vaccine efficacy (VE) against severe rotavirus gastroenteritis caused by circulating wild-type rotavirus from 2 weeks post-Dose 2 until 1 year of age was calculated with 95% confidence interval [CI]. Safety was assessed during the entire study period. Immunogenicity of RIX4414 and OPV was also assessed. During the efficacy follow-up period (mean duration = 7.4 months), 7 and 19 cases of severe rotavirus gastroenteritis were reported in the vaccine and placebo groups, respectively, with a VE of 81.6% (95% CI: 54.4-93.5). VE against severe rotavirus gastroenteritis caused by G1 type was 100% (95% CI: <0-100) and 80.6% (95% CI: 51.4-93.2) against the pooled non-G1 rotavirus types, respectively. There was no difference (P = 0.514) in the incidence of serious adverse events reported in the 2 groups. Antirotavirus IgA seropositivity rate at 1 to 2 months post-Dose 2 was 61.4% (95% CI: 53.7-68.6) in the RIX4414 group; similar seroprotection rates (≥96.0%) against the 3 antipoliovirus types was observed 1 month post-Dose 3 of OPV in both groups. RIX4414 was highly efficacious against severe rotavirus gastroenteritis caused by the circulating wild-type rotavirus (G1 and non-G1) when coadministered with routine EPI vaccines including OPV.

Communications, Immunization, and Polio Vaccines: Lessons From a Global Perspective on Generating Political Will, Informing Decision-Making and Planning, and Engaging Local Support.

PubMed

Menning, Lisa; Garg, Gaurav; Pokharel, Deepa; Thrush, Elizabeth; Farrell, Margaret; Kodio, Frederic Kunjbe; Veira, Chantal Laroche; Wanyoike, Sarah; Malik, Suleman; Patel, Manish; Rosenbauer, Oliver

2017-07-01

The requirements under objective 2 of the Polio Eradication and Endgame Strategic Plan 2013-2018-to introduce at least 1 dose of inactivated poliomyelitis vaccine (IPV); withdraw oral poliomyelitis vaccine (OPV), starting with the type 2 component; and strengthen routine immunization programs-set an ambitious series of targets for countries. Effective implementation of IPV introduction and the switch from trivalent OPV (containing types 1, 2, and 3 poliovirus) to bivalent OPV (containing types 1 and 3 poliovirus) called for intense global communications and coordination on an unprecedented scale from 2014 to 2016, involving global public health technical agencies and donors, vaccine manufacturers, World Health Organization and United Nations Children's Fund regional offices, and national governments. At the outset, the new program requirements were perceived as challenging to communicate, difficult to understand, unrealistic in terms of timelines, and potentially infeasible for logistical implementation. In this context, a number of core areas of work for communications were established: (1) generating awareness and political commitment via global communications and advocacy; (2) informing national decision-making, planning, and implementation; and (3) in-country program communications and capacity building, to ensure acceptance of IPV and continued uptake of OPV. Central to the communications function in driving progress for objective 2 was its ability to generate a meaningful policy dialogue about polio vaccines and routine immunization at multiple levels. This included efforts to facilitate stakeholder engagement and ownership, strengthen coordination at all levels, and ensure an iterative process of feedback and learning. This article provides an overview of the global efforts and challenges in successfully implementing the communications activities to support objective 2. Lessons from the achievements by countries and partners will likely be drawn upon when all OPVs are completely withdrawn after polio eradication, but also may offer a useful model for other global health initiatives. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Supplementary polio immunization activities and prior use of routine immunization services in non-polio-endemic sub-Saharan Africa

PubMed Central

Frimpong, Jemima A; Abdelwahab, Jalaa; Asuming, Patrick; Touré, Hamadassalia; Awoonor-Williams, John Koku; Abachie, Thomas; Guidetti, Flavia

2012-01-01

Abstract Objective To determine participation in polio supplementary immunization activities (SIAs) in sub-Saharan Africa among users and non-users of routine immunization services and among users who were compliant or non-compliant with the routine oral poliovirus vaccine (OPV) immunization schedule. Methods Data were obtained from household-based surveys in non-polio-endemic sub-Saharan African countries. Routine immunization service users were children (aged < 5 years) who had ever had a health card containing their vaccination history; non-users were children who had never had a health card. Users were considered compliant with the OPV routine immunization schedule if, by the SIA date, their health card reflected receipt of required OPV doses. Logistic regression measured associations between SIA participation and use of both routine immunization services and compliance with routine OPV among users. Findings Data from 21 SIAs conducted between 1999 and 2010 in 15 different countries met inclusion criteria. Overall SIA participation ranged from 70.2% to 96.1%. It was consistently lower among infants than among children aged 1–4 years. In adjusted analyses, participation among routine immunization services users was > 85% in 12 SIAs but non-user participation was > 85% in only 5 SIAs. In 18 SIAs, participation was greater among users (P < 0.01 in 16, 0.05 in 1 and < 0.10 in 1) than non-users. In 14 SIAs, adjusted analyses revealed lower participation among non-compliant users than among compliant users (P < 0.01 in 10, < 0.05 in 2 and < 0.10 in 2). Conclusion Large percentages of children participated in SIAs. Prior use of routine immunization services and compliance with the routine OPV schedule showed a strong positive association with SIA participation. PMID:22807595

Achieving high performance polymer tandem solar cells via novel materials design

NASA Astrophysics Data System (ADS)

Dou, Letian

Organic photovoltaic (OPV) devices show great promise in low-cost, flexible, lightweight, and large-area energy-generation applications. Nonetheless, most of the materials designed today always suffer from the inherent disadvantage of not having a broad absorption range, and relatively low mobility, which limit the utilization of the full solar spectrum. Tandem solar cells provide an effective way to harvest a broader spectrum of solar radiation by combining two or more solar cells with different absorption bands. However, for polymer solar cells, the performance of tandem devices lags behind single-layer solar cells mainly due to the lack of suitable low-bandgap polymers (near-IR absorbing polymers). In this dissertation, in order to achieve high performance, we focus on design and synthesis of novel low bandgap polymers specifically for tandem solar cells. In Chapter 3, I demonstrate highly efficient single junction and tandem polymer solar cells featuring a spectrally matched low-bandgap conjugated polymer (PBDTT-DPP: bandgap, ˜1.44 eV). The polymer has a backbone based on alternating benzodithiophene and diketopyrrolopyrrole units. A single-layer device based on the polymer provides a power conversion efficiency of ˜6%. When the polymer is applied to tandem solar cells, a power conversion efficiency of 8.62% is achieved, which was the highest certified efficiency for a polymer solar cell. To further improve this material system, in Chapter 4, I show that the reduction of the bandgap and the enhancement of the charge transport properties of the low bandgap polymer PBDTT-DPP can be accomplished simultaneously by substituting the sulfur atoms on the DPP unit with selenium atoms. The newly designed polymer PBDTT-SeDPP (Eg = 1.38 eV) shows excellent photovoltaic performance in single junction devices with PCEs over 7% and photo-response up to 900 nm. Tandem polymer solar cells based on PBDTT-SeDPP are also demonstrated with a 9.5% PCE, which are more than 10% enhancement over those based on PBDTT-DPP. Finally, in Chapter 5, I demonstrate a new polymer system based on alternating dithienopyran and benzothiadiazole units with a bandgap of 1.38 eV, high mobility, deep highest occupied molecular orbital. As a result, a single-junction device shows high external quantum efficiency of >60% and spectral response that extends to 900 nm, with a power conversion efficiency of 7.9%. The polymer enables a solution processed tandem solar cell with certified 10.6% power conversion efficiency under standard reporting conditions, which is the first certified polymer solar cell efficiency over 10%.

Field study of fecal excretion as a decision support tool in response to silent reintroduction of wild-type poliovirus 1 into Israel.

PubMed

Moran-Gilad, Jacob; Mendelson, Ella; Burns, Cara C; Bassal, Ravit; Gdalevich, Michael; Sofer, Danit; Oberste, M Steven; Shulman, Lester M; Kaliner, Ehud; Hindiyeh, Musa; Hindiye, Musa; Mor, Orna; Shahar, Liora; Iber, Jane; Yishay, Ruth; Manor, Joseph; Lev, Boaz; Gamzu, Ronni; Grotto, Itamar

2015-05-01

Israel has used an inactivated polio vaccine (IPV)-only schedule since 2005 (95% coverage). Silent reintroduction of wild type poliovirus 1 (WPV1) into Israel in early 2013 was detected in Southern Israel via routine environmental surveillance without clinical cases. To estimate the rate of WPV1 excretion by age and residence and inform decision-making regarding supplemental immunization with OPV. A convenience sample of Bedouin and Jewish residential areas in the epicenter of the incident, focusing on under 8 year-olds who not previously given OPV. Fecal samples were directly tested for WPV1 RNA using a novel qRT-PCR assay. Positive samples were confirmed by gold standard cell culture and subject to genotyping. Overall, 2196 non-duplicate fecal samples were collected and analyzed. WPV1 was detected in 61 samples (2.8%), 55 of which (90.2%) were from Bedouins. WPV1 excretion rates were 5.4% among Bedouins and 0.6% among Jewish individuals. Respective age-specific rates among Bedouin and Jewish children were 4.9% and 0.2% for 0-2 years and 7.2% and 1.7% for 2-8 years. Molecular testing had 89.5% sensitivity (higher than culture) and 100% specificity. The rapid performance of a field study to evaluate WPV1 excretion unequivocally demonstrated substantial WPV1 infection rates among children under 8 years in Southern Israel, thus informing the decision to vaccinate this age group with bOPV and risk communication to both healthcare personnel and the public. Rapid development and implementation of molecular screening can thus underpin risk assessment and management in complex epidemiological situations. Copyright © 2015 Elsevier B.V. All rights reserved.

Laser processing of organic photovoltaic cells with a roll-to-roll manufacturing process

NASA Astrophysics Data System (ADS)

Petsch, Tino; Haenel, Jens; Clair, Maurice; Keiper, Bernd; Scholz, Christian

2011-03-01

Flexible large area organic photovoltaic (OPV) is currently one of the fastest developing areas of organic electronics. New light absorbing polymer blends combined with new transparent conductive materials provide higher power conversion efficiencies while new and improved production methods are developed to achieve higher throughput at reduced cost. A typical OPV is formed by TCO layers as the transparent front contact and polymers as active layer as well as interface layer between active layer and front contact. The several materials have to be patterned in order to allow for a row connection of the solar cell. 3D-Micromac used ultra-short pulsed lasers to evaluate the applicability of various wavelengths for the selective ablation of the indium tin oxide (ITO) layer and the selective ablation of the bulk hetero junction (BHJ) consisting of poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) on top of a Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) without damaging the ITO. These lasers in combination with high performance galvanometer scanning systems achieve superior scribing quality without damaging the substrate. With scribing speeds of 10 m/s and up it is possible to integrate this technology into a roll-to-roll manufacturing tool. The functionality of an OPV usually also requires an annealing step, especially when using a BHJ for the active layer consisting of P3HT:PCBM, to optimize the layers structure and therewith the efficiency of the solar cell (typically by thermal treatment, e.g. oven). The process of laser annealing was investigated using a short-pulsed laser with a wavelength close to the absorption maximum of the BHJ.

Rapid synthesis of ultra-long silver nanowires for tailor-made transparent conductive electrodes: proof of concept in organic solar cells.

PubMed

José Andrés, Luis; Fe Menéndez, María; Gómez, David; Luisa Martínez, Ana; Bristow, Noel; Paul Kettle, Jeffrey; Menéndez, Armando; Ruiz, Bernardino

2015-07-03

Rapid synthesis of ultralong silver nanowires (AgNWs) has been obtained using a one-pot polyol-mediated synthetic procedure. The AgNWs have been prepared from the base materials in less than one hour with nanowire lengths reaching 195 μm, which represents the quickest synthesis and one of the highest reported aspect ratios to date. These results have been achieved through a joint analysis of all reaction parameters, which represents a clear progress beyond the state of the art. Dispersions of the AgNWs have been used to prepare thin, flexible, transparent and conducting films using spray coating. Due to the higher aspect ratio, an improved electrical percolation network is observed. This allows a low sheet resistance (RS = 20.2 Ω/sq), whilst maintaining high optical film transparency (T = 94.7%), driving to the highest reported figure-of-merit (FoM = 338). Owing to the light-scattering influence of the AgNWs, the density of the AgNW network can also be varied to enable controllability of the optical haze through the sample. Based on the identification of the optimal haze value, organic photovoltaics (OPVs) have been fabricated using the AgNWs as the transparent electrode and have been benchmarked against indium tin oxide (ITO) electrodes. Overall, the performance of OPVs made using AgNWs sees a small decrease in power conversion efficiency (PCE), primarily due to a fall in open-circuit voltage (50 mV). This work indicates that AgNWs can provide a low cost, rapid and roll-to-roll compatible alternative to ITO in OPVs, with only a small compromise in PCE needed.

Rapid synthesis of ultra-long silver nanowires for tailor-made transparent conductive electrodes: proof of concept in organic solar cells

NASA Astrophysics Data System (ADS)

José Andrés, Luis; Menéndez, María Fe; Gómez, David; Martínez, Ana Luisa; Bristow, Noel; Kettle, Jeffrey Paul; Menéndez, Armando; Ruiz, Bernardino

2015-07-01

Rapid synthesis of ultralong silver nanowires (AgNWs) has been obtained using a one-pot polyol-mediated synthetic procedure. The AgNWs have been prepared from the base materials in less than one hour with nanowire lengths reaching 195 μm, which represents the quickest synthesis and one of the highest reported aspect ratios to date. These results have been achieved through a joint analysis of all reaction parameters, which represents a clear progress beyond the state of the art. Dispersions of the AgNWs have been used to prepare thin, flexible, transparent and conducting films using spray coating. Due to the higher aspect ratio, an improved electrical percolation network is observed. This allows a low sheet resistance (RS = 20.2 Ω/sq), whilst maintaining high optical film transparency (T = 94.7%), driving to the highest reported figure-of-merit (FoM = 338). Owing to the light-scattering influence of the AgNWs, the density of the AgNW network can also be varied to enable controllability of the optical haze through the sample. Based on the identification of the optimal haze value, organic photovoltaics (OPVs) have been fabricated using the AgNWs as the transparent electrode and have been benchmarked against indium tin oxide (ITO) electrodes. Overall, the performance of OPVs made using AgNWs sees a small decrease in power conversion efficiency (PCE), primarily due to a fall in open-circuit voltage (50 mV). This work indicates that AgNWs can provide a low cost, rapid and roll-to-roll compatible alternative to ITO in OPVs, with only a small compromise in PCE needed.

Mucosal immune response to poliovirus vaccines in childhood.

PubMed

Ogra, P L

1984-01-01

Comparative evaluation of the systemic and secretory antibody response to live attenuated (oral) poliovirus vaccine ( OPV ) or inactivated poliovirus vaccine (IPV) has suggested that both vaccines are highly effective in inducing seroconversion and in preventing paralytic poliomyelitis. However, parenteral immunization with IPV does not appear to be highly effective in inducing secretory antibody response in the nasopharynx or alimentary tract during primary immunization. Reimmunization with IPV in subjects previously primed with parenterally administered IPV appears to result in a mild booster effect on the development of secretory antibody response. More significantly, rechallenge by the oral route with OPV in IPV-primed subjects resulted in a marked enhancement of secretory antibody response. In general, no suppression of systemic or secretory response to poliovirus was observed with either form ( OPV vs. IPV) or with route of immunization. These observations are discussed in relation to the immune response observed with other mucosally or parenterally administered antigens. Their implications in the development of oral tolerance are briefly reviewed.

Introduction of Sequential Inactivated Polio Vaccine–Oral Polio Vaccine Schedule for Routine Infant Immunization in Brazil’s National Immunization Program

PubMed Central

Domingues, Carla Magda Allan S.; de Fátima Pereira, Sirlene; Marreiros, Ana Carolina Cunha; Menezes, Nair; Flannery, Brendan

2015-01-01

In August 2012, the Brazilian Ministry of Health introduced inactivated polio vaccine (IPV) as part of sequential polio vaccination schedule for all infants beginning their primary vaccination series. The revised childhood immunization schedule included 2 doses of IPV at 2 and 4 months of age followed by 2 doses of oral polio vaccine (OPV) at 6 and 15 months of age. One annual national polio immunization day was maintained to provide OPV to all children aged 6 to 59 months. The decision to introduce IPV was based on preventing rare cases of vaccine-associated paralytic polio, financially sustaining IPV introduction, ensuring equitable access to IPV, and preparing for future OPV cessation following global eradication. Introducing IPV during a national multivaccination campaign led to rapid uptake, despite challenges with local vaccine supply due to high wastage rates. Continuous monitoring is required to achieve high coverage with the sequential polio vaccine schedule. PMID:25316829

Adjuvants and inactivated polio vaccine: a systematic review.

PubMed

Hawken, Jennifer; Troy, Stephanie B

2012-11-19

Poliomyelitis is nearing universal eradication; in 2011, there were 650 cases reported globally. When wild polio is eradicated, global oral polio vaccine (OPV) cessation followed by use of universal inactivated polio vaccine (IPV) is believed to be the safest vaccination strategy as IPV does not mutate or run the risk of vaccine derived outbreaks that OPV does. However, IPV is significantly more expensive than OPV. One strategy to make IPV more affordable is to reduce the dose by adding adjuvants, compounds that augment the immune response to the vaccine. No adjuvants are currently utilized in stand-alone IPV; however, several have been explored over the past six decades. From aluminum, used in many licensed vaccines, to newer and more experimental adjuvants such as synthetic DNA, a diverse group of compounds has been assessed with varying strengths and weaknesses. This review summarizes the studies to date evaluating the efficacy and safety of adjuvants used with IPV. Copyright © 2012 Elsevier Ltd. All rights reserved.

[Enteroviruses in the XX and XXI centuries].

PubMed

Seĭbil', V B; Malyshkina, L P

2005-01-01

The modern view of the role of enteroviruses in the eradication of poliomyelitis is presented. Enteroviruses were discovered in the XX century. In the 1950s they caused great epidemics of poliomyelitis and serous meningitis in many countries of the world. The introduction of oral poliomyelitis vaccine (OPV) into medical practice made it possible to eliminate the epidemics of poliomyelitis in a short time. Poliomyelitis morbidity was reduced to sporadic cases and in a number of regions disappeared. OPV produced non-specific influence also on the epidemics of serous meningitis, as well as on a case incidence. The eradication of poliomyelitis viruses and the cessation of immunization with OPV will not result in eradication of paralytic diseases. Paralytogenic viruses of 20 serotypes circulate in nature, and some of these viruses are capable of causing the outbreaks of severe paralytic diseases. The authors propose either to retain immunization with OVP as tour immunizations with monovaccine of type 2, or to create new live enterovirus vaccines on the basis of avirulent enterovirus strains.

An assessment of the reasons for oral poliovirus vaccine refusals in northern Nigeria.

PubMed

Michael, Charles A; Ogbuanu, Ikechukwu U; Storms, Aaron D; Ohuabunwo, Chima J; Corkum, Melissa; Ashenafi, Samra; Achari, Panchanan; Biya, Oladayo; Nguku, Patrick; Mahoney, Frank

2014-11-01

Accumulation of susceptible children whose caregivers refuse to accept oral poliovirus vaccine (OPV) contributes to the spread of poliovirus in Nigeria. During and immediately following the OPV campaign in October 2012, polio eradication partners conducted a study among households in which the vaccine was refused, using semistructured questionnaires. The selected study districts had a history of persistent OPV refusals in previous campaigns. Polio risk perception was low among study participants. The majority (59%) of participants believed that vaccination was either not necessary or would not be helpful, and 30% thought it might be harmful. Religious beliefs were an important driver in the way people understood disease. Fifty-two percent of 48 respondents reported that illnesses were due to God's will and/or destiny and that only God could protect them against illnesses. Only a minority (14%) of respondents indicated that polio was a significant problem in their community. Caregivers refuse OPV largely because of poor polio risk perception and religious beliefs. Communication strategies should, therefore, aim to increase awareness of polio as a real health threat and educate communities about the safety of the vaccine. In addition, polio eradication partners should collaborate with other agencies and ministries to improve total primary healthcare packages to address identified unmet health and social needs. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

General method for simultaneous optimization of light trapping and carrier collection in an ultra-thin film organic photovoltaic cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsai, Cheng-Chia, E-mail: ct2443@columbia.edu; Grote, Richard R.; Beck, Jonathan H.

2014-07-14

We describe a general method for maximizing the short-circuit current in thin planar organic photovoltaic (OPV) heterojunction cells by simultaneous optimization of light absorption and carrier collection. Based on the experimentally obtained complex refractive indices of the OPV materials and the thickness-dependence of the internal quantum efficiency of the OPV active layer, we analyze the potential benefits of light trapping strategies for maximizing the overall power conversion efficiency of the cell. This approach provides a general strategy for optimizing the power conversion efficiency of a wide range of OPV structures. In particular, as an experimental trial system, the approach ismore » applied here to a ultra-thin film solar cell with a SubPc/C{sub 60} photovoltaic structure. Using a patterned indium tin oxide (ITO) top contact, the numerically optimized designs achieve short-circuit currents of 0.790 and 0.980 mA/cm{sup 2} for 30 nm and 45 nm SubPc/C{sub 60} heterojunction layer thicknesses, respectively. These values correspond to a power conversion efficiency enhancement of 78% for the 30 nm thick cell, but only of 32% for a 45 nm thick cell, for which the overall photocurrent is actually higher. Applied to other material systems, the general optimization method can elucidate if light trapping strategies can improve a given cell architecture.« less

Ecotoxicological assessment of solar cell leachates: Copper indium gallium selenide (CIGS) cells show higher activity than organic photovoltaic (OPV) cells.

PubMed

Brun, Nadja Rebecca; Wehrli, Bernhard; Fent, Karl

2016-02-01

Despite the increasing use of photovoltaics their potential environmental risks are poorly understood. Here, we compared ecotoxicological effects of two thin-film photovoltaics: established copper indium gallium selenide (CIGS) and organic photovoltaic (OPV) cells. Leachates were produced by exposing photovoltaics to UV light, physical damage, and exposure to environmentally relevant model waters, representing mesotrophic lake water, acidic rain, and seawater. CIGS cell leachates contained 583 μg L(-1) molybdenum at lake water, whereas at acidic rain and seawater conditions, iron, copper, zinc, molybdenum, cadmium, silver, and tin were present up to 7219 μg L(-1). From OPV, copper (14 μg L(-1)), zinc (87 μg L(-1)) and silver (78 μg L(-1)) leached. Zebrafish embryos were exposed until 120 h post-fertilization to these extracts. CIGS leachates produced under acidic rain, as well as CIGS and OPV leachates produced under seawater conditions resulted in a marked hatching delay and increase in heart edema. Depending on model water and solar cell, transcriptional alterations occurred in genes involved in oxidative stress (cat), hormonal activity (vtg1, ar), metallothionein (mt2), ER stress (bip, chop), and apoptosis (casp9). The effects were dependent on the concentrations of cationic metals in leachates. Addition of ethylenediaminetetraacetic acid protected zebrafish embryos from morphological and molecular effects. Our study suggests that metals leaching from damaged CIGS cells, may pose a potential environmental risk. Copyright © 2015 Elsevier B.V. All rights reserved.

Expert review on poliovirus immunity and transmission.

PubMed

Duintjer Tebbens, Radboud J; Pallansch, Mark A; Chumakov, Konstantin M; Halsey, Neal A; Hovi, Tapani; Minor, Philip D; Modlin, John F; Patriarca, Peter A; Sutter, Roland W; Wright, Peter F; Wassilak, Steven G F; Cochi, Stephen L; Kim, Jong-Hoon; Thompson, Kimberly M

2013-04-01

Successfully managing risks to achieve wild polioviruses (WPVs) eradication and address the complexities of oral poliovirus vaccine (OPV) cessation to stop all cases of paralytic poliomyelitis depends strongly on our collective understanding of poliovirus immunity and transmission. With increased shifting from OPV to inactivated poliovirus vaccine (IPV), numerous risk management choices motivate the need to understand the tradeoffs and uncertainties and to develop models to help inform decisions. The U.S. Centers for Disease Control and Prevention hosted a meeting of international experts in April 2010 to review the available literature relevant to poliovirus immunity and transmission. This expert review evaluates 66 OPV challenge studies and other evidence to support the development of quantitative models of poliovirus transmission and potential outbreaks. This review focuses on characterization of immunity as a function of exposure history in terms of susceptibility to excretion, duration of excretion, and concentration of excreted virus. We also discuss the evidence of waning of host immunity to poliovirus transmission, the relationship between the concentration of poliovirus excreted and infectiousness, the importance of different transmission routes, and the differences in transmissibility between OPV and WPV. We discuss the limitations of the available evidence for use in polio risk models, and conclude that despite the relatively large number of studies on immunity, very limited data exist to directly support quantification of model inputs related to transmission. Given the limitations in the evidence, we identify the need for expert input to derive quantitative model inputs from the existing data. © 2012 Society for Risk Analysis.

Modeling options to manage type 1 wild poliovirus imported into Israel in 2013.

PubMed

Kalkowska, Dominika A; Duintjer Tebbens, Radboud J; Grotto, Itamar; Shulman, Lester M; Anis, Emilia; Wassilak, Steven G F; Pallansch, Mark A; Thompson, Kimberly M

2015-06-01

After 25 years without poliomyelitis cases caused by circulating wild poliovirus (WPV) in Israel, sewage sampling detected WPV type 1 (WPV1) in April 2013, despite high vaccination coverage with only inactivated poliovirus vaccine (IPV) since 2005. We used a differential equation-based model to simulate the dynamics of poliovirus transmission and population immunity in Israel due to past exposure to WPV and use of oral poliovirus vaccine (OPV) in addition to IPV. We explored the influences of various immunization options to stop imported WPV1 circulation in Israel. We successfully modeled the potential for WPVs to circulate without detected cases in Israel. Maintaining a sequential IPV/OPV schedule instead of switching to an IPV-only schedule in 2005 would have kept population immunity high enough in Israel to prevent WPV1 circulation. The Israeli response to WPV1 detection prevented paralytic cases; a more rapid response might have interrupted transmission more quickly. IPV-based protection alone might not provide sufficient population immunity to prevent poliovirus transmission after an importation. As countries transition to IPV in immunization schedules, they may need to actively manage population immunity and consider continued use of OPV, to avoid the potential circulation of imported live polioviruses before globally coordinated cessation of OPV use. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Plaque and growth characteristics of different polioviruses isolated from acute flaccid paralysis in Northern Nigeria.

PubMed

Sule, W F; Oyedele, O I; Osei-Kwasi, M; Odoom, J K; Adu, F D

2008-03-01

To determine some virulent trait-related properties of poliovirus isolates from children with acute flaccid paralysis following vaccination with oral polio vaccine (OPV). Six polioviruses earlier characterised into wild, vaccine-derived and OPV-like were studied using the plaque morphology and growth kinetics at supra-optimal temperature. Department of Virology, University of Ibadan, Nigeria. Polio isolates from six children who developed acute flaccid paralysis following vaccinations with various doses of OPV were used. All the children were located in the Northern part of the country where poliovirus is still circulating. The two vaccine-derived polioviruses acquired wild type characteristics. All the six poliovirus isolates developed different forms of plaques ranging from tiny, small and large. The plaque formed could however not be used to identify the different isolates. Growth of the different isolates at supra-optimal temperature showed that the three wild polioviruses grew to a higher titre when compared with the Sabin 2 control. The two vaccine derived isolates behaved like the wild poliovirus while the OPV-like virus acquired an intermediate characteristics between wild and sabin. The wild polioviruses represented in this study are among the last vestiges of the circulating polioviruses found in the world. It is possible that the observed biological properties of wild types 1 and 3 described in the study are typical of the West African polioviruses. These properties will provide useful previews to the final identification of some important clinical isolates especially type 1 which may grow rapidly in cell culture.

Population Immunity against Serotype-2 Poliomyelitis Leading up to the Global Withdrawal of the Oral Poliovirus Vaccine: Spatio-temporal Modelling of Surveillance Data.

PubMed

Pons-Salort, Margarita; Molodecky, Natalie A; O'Reilly, Kathleen M; Wadood, Mufti Zubair; Safdar, Rana M; Etsano, Andrew; Vaz, Rui Gama; Jafari, Hamid; Grassly, Nicholas C; Blake, Isobel M

2016-10-01

Global withdrawal of serotype-2 oral poliovirus vaccine (OPV2) took place in April 2016. This marked a milestone in global polio eradication and was a public health intervention of unprecedented scale, affecting 155 countries. Achieving high levels of serotype-2 population immunity before OPV2 withdrawal was critical to avoid subsequent outbreaks of serotype-2 vaccine-derived polioviruses (VDPV2s). In August 2015, we estimated vaccine-induced population immunity against serotype-2 poliomyelitis for 1 January 2004-30 June 2015 and produced forecasts for April 2016 by district in Nigeria and Pakistan. Population immunity was estimated from the vaccination histories of children <36 mo old identified with non-polio acute flaccid paralysis (AFP) reported through polio surveillance, information on immunisation activities with different oral poliovirus vaccine (OPV) formulations, and serotype-specific estimates of the efficacy of these OPVs against poliomyelitis. District immunity estimates were spatio-temporally smoothed using a Bayesian hierarchical framework. Coverage estimates for immunisation activities were also obtained, allowing for heterogeneity within and among districts. Forward projections of immunity, based on these estimates and planned immunisation activities, were produced through to April 2016 using a cohort model. Estimated population immunity was negatively correlated with the probability of VDPV2 poliomyelitis being reported in a district. In Nigeria and Pakistan, declines in immunity during 2008-2009 and 2012-2013, respectively, were associated with outbreaks of VDPV2. Immunity has since improved in both countries as a result of increased use of trivalent OPV, and projections generally indicated sustained or improved immunity in April 2016, such that the majority of districts (99% [95% uncertainty interval 97%-100%] in Nigeria and 84% [95% uncertainty interval 77%-91%] in Pakistan) had >70% population immunity among children <36 mo old. Districts with lower immunity were clustered in northeastern Nigeria and northwestern Pakistan. The accuracy of immunity estimates was limited by the small numbers of non-polio AFP cases in some districts, which was reflected by large uncertainty intervals. Forecasted improvements in immunity for April 2016 were robust to the uncertainty in estimates of baseline immunity (January-June 2015), vaccine coverage, and vaccine efficacy. Immunity against serotype-2 poliomyelitis was forecasted to improve in April 2016 compared to the first half of 2015 in Nigeria and Pakistan. These analyses informed the endorsement of OPV2 withdrawal in April 2016 by the WHO Strategic Advisory Group of Experts on Immunization.

Population Immunity against Serotype-2 Poliomyelitis Leading up to the Global Withdrawal of the Oral Poliovirus Vaccine: Spatio-temporal Modelling of Surveillance Data

PubMed Central

O’Reilly, Kathleen M.; Etsano, Andrew; Vaz, Rui Gama; Jafari, Hamid; Grassly, Nicholas C.; Blake, Isobel M.

2016-01-01

Background Global withdrawal of serotype-2 oral poliovirus vaccine (OPV2) took place in April 2016. This marked a milestone in global polio eradication and was a public health intervention of unprecedented scale, affecting 155 countries. Achieving high levels of serotype-2 population immunity before OPV2 withdrawal was critical to avoid subsequent outbreaks of serotype-2 vaccine-derived polioviruses (VDPV2s). Methods and Findings In August 2015, we estimated vaccine-induced population immunity against serotype-2 poliomyelitis for 1 January 2004–30 June 2015 and produced forecasts for April 2016 by district in Nigeria and Pakistan. Population immunity was estimated from the vaccination histories of children <36 mo old identified with non-polio acute flaccid paralysis (AFP) reported through polio surveillance, information on immunisation activities with different oral poliovirus vaccine (OPV) formulations, and serotype-specific estimates of the efficacy of these OPVs against poliomyelitis. District immunity estimates were spatio-temporally smoothed using a Bayesian hierarchical framework. Coverage estimates for immunisation activities were also obtained, allowing for heterogeneity within and among districts. Forward projections of immunity, based on these estimates and planned immunisation activities, were produced through to April 2016 using a cohort model. Estimated population immunity was negatively correlated with the probability of VDPV2 poliomyelitis being reported in a district. In Nigeria and Pakistan, declines in immunity during 2008–2009 and 2012–2013, respectively, were associated with outbreaks of VDPV2. Immunity has since improved in both countries as a result of increased use of trivalent OPV, and projections generally indicated sustained or improved immunity in April 2016, such that the majority of districts (99% [95% uncertainty interval 97%–100%] in Nigeria and 84% [95% uncertainty interval 77%–91%] in Pakistan) had >70% population immunity among children <36 mo old. Districts with lower immunity were clustered in northeastern Nigeria and northwestern Pakistan. The accuracy of immunity estimates was limited by the small numbers of non-polio AFP cases in some districts, which was reflected by large uncertainty intervals. Forecasted improvements in immunity for April 2016 were robust to the uncertainty in estimates of baseline immunity (January–June 2015), vaccine coverage, and vaccine efficacy. Conclusions Immunity against serotype-2 poliomyelitis was forecasted to improve in April 2016 compared to the first half of 2015 in Nigeria and Pakistan. These analyses informed the endorsement of OPV2 withdrawal in April 2016 by the WHO Strategic Advisory Group of Experts on Immunization. PMID:27701425

[VACCINE-ASSOCIATED PARALYTIC POLIOMYELITIS IN RUSSIAN FEDERATION DURING THE PERIOD OF CHANGES IN VACCINATION SCHEDULE (2006-2013 yy.)].

PubMed

Ivanova, O E; Eremeeva, T P; Morozova, N S; Shakaryan, A K; Gmyl, A P; Yakovenko, M L; Korotkova, E A; Chernjavskaja, O P; Baykova, O Yu; Silenova, O V; Krasota, A Yu; Krasnoproshina, L I; Mustafina, A N; Kozlovskaja, L I

2016-01-01

The results of virologic testing of clinical materials and epidemiological analysis of vaccine-associated paralytic poliomyelitis (VAPP) cases obtained in 2006-2013 during AFP surveillance are presented. Among the 2976 cases of AFP 30 cases were VAPP. 15 cases were observed in OPV recipients, whereas 15 cases were observed in non-vaccinated contacts. The age of the patients varied from 4 months to 5.5 years (13.6 ± 12.4 months old). Children younger than 1 year constituted 63.3% of the group; boys were dominant (73.3%); 53.3% of children were vaccinated with OPV; the time period between receipt of OPV and onset of palsy was from 2 to 32 days (18.7 ± 8.2). Lower paraparesis was documented in 48.3% of patients; lower monoparesis in 37.9%; upper monoparesis, in 6.9%; tetraparesis with bulbar syndrome, in 6%. The majority of the patients (85.7%) had an unfavorable premorbid status. The violations of the humoral immunity were found in 73.9% cases: CVID (52.9%), hypogammaglobulinemia (41.2%); selective lgA deflciency (5.9%). In 70.6% cases damage to humoral immunity was combined with poor premorbid status. The most frequently observed (76%, p < 0.05) represented the single type of poliovirus--type 2 (44%) and type 3 (32%). All strains were of the vaccine origin, the divergence from the homotypic Sabin strains fell within the region of the gene encoding VPI protein, which did not exceed 0.5% of nucleotide substitutions except vaccine derived poliovirus type 2--multiple recombinant (type 2/type 3/ type 2/type 1) with the degree of the divergence of 1.44% isolated from 6-month old unvaccinated child (RUS08063034001). The frequency of the VAPP cases was a total of 1 case per 3.4 million doses of distributed OPV in 2006-2013; 2.2 cases per 1 million of newborns were observed. This frequency decreased after the introduction of the sequential scheme of vaccination (IPV, OPV) in 2008-2013 as compared with the period of exclusive use of OPV in 2006-2007: 1 case per 4.9 million doses, 1.4 cases per million newborns and 1 case per 1.9 million doses, 4.9 cases per 1 million newborns, respectively. The study has been financed from Russian Federation budget within the framework of the Program for eradication of poliomyelitis in the Russian Federation, WHO Polio eradication initiative, WHO's European Regional Bureau, Russian Foundation for Basic Research (project No. 15-15-00147).

Human Circulating Antibody-Producing B Cell as a Predictive Measure of Mucosal Immunity to Poliovirus

PubMed Central

Verma, Harish; Sharma, Prashant; Yang, Jae Seung; Saletti, Giulietta; Ahmad, Mohammad; Bahl, Sunil K.; Wierzba, Thomas F.; Nandy, Ranjan K.; Deshpande, Jagadish M.; Sutter, Roland W.; Czerkinsky, Cecil

2016-01-01

Background The “gold standard” for assessing mucosal immunity after vaccination with poliovirus vaccines consists in measuring virus excretion in stool after challenge with oral poliovirus vaccine (OPV). This testing is time and resource intensive, and development of alternative methods is a priority for accelerating polio eradication. We therefore evaluated circulating antibody-secreting cells (ASCs) as a potential means to evaluate mucosal immunity to poliovirus vaccine. Methods 199 subjects, aged 10 years, and previously immunized repeatedly with OPV, were selected. Subjects were assigned to receive either a booster dose of inactivated poliovirus vaccine (IPV), bivalent OPV (bOPV), or no vaccine. Using a micro-modified whole blood-based ELISPOT assay designed for field setting, circulating poliovirus type-specific IgA- and IgG-ASCs, including gut homing α4β7+ ASCs, were enumerated on days 0 and 7 after booster immunization. In addition, serum samples collected on days 0, 28 and 56 were tested for neutralizing antibody titers against poliovirus types 1, 2, and 3. Stool specimens were collected on day 28 (day of bOPV challenge), and on days 31, 35 and 42 and processed for poliovirus isolation. Results An IPV dose elicited blood IgA- and IgG-ASC responses in 84.8 to 94.9% of subjects, respectively. In comparison, a bOPV dose evoked corresponding blood ASC responses in 20.0 to 48.6% of subjects. A significant association was found between IgA- and IgG-ASC responses and serum neutralizing antibody titers for poliovirus type 1, 2, 3 (p<0.001). In the IPV group, α4β7+ ASCs accounted for a substantial proportion of IgA-ASCs and the proportion of subjects with a positive α4β7+ IgA-ASC response to poliovirus types 1, 2 and 3 was 62.7%, 89.8% and 45.8%, respectively. A significant association was observed between virus excretion and α4β7+ IgA- and/or IgG-ASC responses to poliovirus type 3 among immunized children; however, only a weak association was found for type 1 poliovirus. Discussion Our results suggest that virus-specific blood ASCs, especially for type 3 poliovirus, can serve as surrogate of mucosal immunity after vaccination. Further studies are needed to evaluate the duration of such memory responses and to assess the programmatic utility of this whole blood-based mucosal ASC testing for the polio eradication program. PMID:26730586

Human Circulating Antibody-Producing B Cell as a Predictive Measure of Mucosal Immunity to Poliovirus.

PubMed

Dey, Ayan; Molodecky, Natalie A; Verma, Harish; Sharma, Prashant; Yang, Jae Seung; Saletti, Giulietta; Ahmad, Mohammad; Bahl, Sunil K; Wierzba, Thomas F; Nandy, Ranjan K; Deshpande, Jagadish M; Sutter, Roland W; Czerkinsky, Cecil

2016-01-01

The "gold standard" for assessing mucosal immunity after vaccination with poliovirus vaccines consists in measuring virus excretion in stool after challenge with oral poliovirus vaccine (OPV). This testing is time and resource intensive, and development of alternative methods is a priority for accelerating polio eradication. We therefore evaluated circulating antibody-secreting cells (ASCs) as a potential means to evaluate mucosal immunity to poliovirus vaccine. 199 subjects, aged 10 years, and previously immunized repeatedly with OPV, were selected. Subjects were assigned to receive either a booster dose of inactivated poliovirus vaccine (IPV), bivalent OPV (bOPV), or no vaccine. Using a micro-modified whole blood-based ELISPOT assay designed for field setting, circulating poliovirus type-specific IgA- and IgG-ASCs, including gut homing α4β7+ ASCs, were enumerated on days 0 and 7 after booster immunization. In addition, serum samples collected on days 0, 28 and 56 were tested for neutralizing antibody titers against poliovirus types 1, 2, and 3. Stool specimens were collected on day 28 (day of bOPV challenge), and on days 31, 35 and 42 and processed for poliovirus isolation. An IPV dose elicited blood IgA- and IgG-ASC responses in 84.8 to 94.9% of subjects, respectively. In comparison, a bOPV dose evoked corresponding blood ASC responses in 20.0 to 48.6% of subjects. A significant association was found between IgA- and IgG-ASC responses and serum neutralizing antibody titers for poliovirus type 1, 2, 3 (p<0.001). In the IPV group, α4β7+ ASCs accounted for a substantial proportion of IgA-ASCs and the proportion of subjects with a positive α4β7+ IgA-ASC response to poliovirus types 1, 2 and 3 was 62.7%, 89.8% and 45.8%, respectively. A significant association was observed between virus excretion and α4β7+ IgA- and/or IgG-ASC responses to poliovirus type 3 among immunized children; however, only a weak association was found for type 1 poliovirus. Our results suggest that virus-specific blood ASCs, especially for type 3 poliovirus, can serve as surrogate of mucosal immunity after vaccination. Further studies are needed to evaluate the duration of such memory responses and to assess the programmatic utility of this whole blood-based mucosal ASC testing for the polio eradication program.

NID: ceasefire for the future.

PubMed

Tugbo, L P

1993-01-01

The goals of National Immunization Day (NID), which is held twice a year in the Philippines, include polio vaccination of all children less than 5 years of age, measles vaccination of all children aged 9 to 24 months, tetanus immunization of women aged 15 to 44 years, and vitamin A supplementation for all children under 5 years of age. This is in response to a World Declaration of the Survival, Protection, and Development of Children and a Plan of Action for the 1990s that were issued by the World Summit for Children (New York; September, 1990). The Plan has 7 major and 26 supporting goals. 3 of the goals, which are to be achieved by the end of the century, relate to micronutrient malnutrition and are as follows: 1) elimination of vitamin A deficiency disorders, 2) elimination of iodine deficiency disorders, and 3) reduction of iron deficiency anemia by 1/3. Another conference, "Ending Hidden Hunger", (Montreal, Canada; October, 1991) focused on the means and resources necessary to overcome micronutrient malnutrition. Health Secretary Juan Flavier utilized the mass media for the 1993 campaign. The messages emphasized in the campaign included 1) polio kills or cripples children for life; 2) vaccination with oral polio vaccine (OPV) is easily performed and prevents the disease without pain or injection; 3) NIDs will be held on every 3rd Wednesday of April and May from 1993 to 1995; 4) all children 0-59 months and all women 15 to 44 years are required to attend, even if previously immunized; 5) OPV given to a fully immunized child will boost immunity; 6) the Philippines will be free from polio by 1995 if all children ages 0-59 months are vaccinated on the NIDs; and 7) the participation of all filipinos is necessary to eradicate polio. Information, education, and communication (IEC) materials were distributed 2 weeks before the NID. Posters were placed in strategic government facilities, leaflets were distributed to mothers, and streamers were installed on the exterior of facilities. Immunization posts were established at all government health facilities (hospitals, lying-in centers, and barangay health stations), as well as at temporary sites at market places, shopping areas, schools, sports areas, bus and train stations, airports, and light rail transit stations. There were 2 types of posts; OPV, and EPI for measles vaccine and tetanus toxoid. The latter were staffed by trained health personnel. OPV and vitamin A were administered by nonhealth personnel, who were also part of mobile vaccination teams. Government agencies, nongovernmental organizations, international organizations, and the communities worked together. The Nutrition Center of the Philippines (NCP) staffed immunization posts in areas with NCP projects. Earlier, they had prepared lists of children, conducted orientation meetings, provided information on vitamin A, and arranged for site logistics. They provided vitamin A capsules and OPV to 1392 children.

Demand Creation for Polio Vaccine in Persistently Poor-Performing Communities of Northern Nigeria: 2013–2014

PubMed Central

Warigon, Charity; Mkanda, Pascal; Muhammed, Ado; Etsano, Andrew; Korir, Charles; Bawa, Samuel; Gali, Emmanuel; Nsubuga, Peter; Erbeto, Tesfaya B.; Gerlong, George; Banda, Richard; Yehualashet, Yared G.; Vaz, Rui G.

2016-01-01

Introduction. Poliomyelitis remains a global threat despite availability of oral polio vaccine (OPV), proven to reduce the burden of the paralyzing disease. In Nigeria, children continue to miss the opportunity to be fully vaccinated, owing to factors such as unmet health needs and low uptake in security-compromised and underserved communities. We describe the implementation and evaluation of several activities to create demand for polio vaccination in persistently poor-performing local government areas (LGAs). Methods. We assessed the impact of various polio-related interventions, to measure the contribution of demand creation activities in 77 LGAs at very high risk for polio, located across 10 states in northern Nigeria. Interventions included provision of commodities along with the polio vaccine. Results. There was an increasing trend in the number of children reached by different demand creation interventions. A total of 4 819 847 children were vaccinated at health camps alone. There was a reduction in the number of wards in which >10% of children were missed by supplementary immunization activities due to noncompliance with vaccination recommendations, a rise in the proportion of children who received ≥4 OPV doses, and a decrease in the proportion of children who were underimmunized or unimmunized. Conclusions. Demand creation interventions increased the uptake of polio vaccines in persistently poor-performing high-risk communities in northern Nigeria during September 2013–November 2014. PMID:26908717

Electronic Structure of Fullerene Acceptors in Organic Bulk-Heterojunctions. A Combined EPR and DFT Study

DOE PAGES

Mardis, Kristy L.; Webb, J.; Holloway, Tarita; ...

2015-12-03

Organic photovoltaic (OPV) devices are a promising alternative energy source. Attempts to improve their performance have focused on the optimization of electron-donating polymers, while electron-accepting fullerenes have received less attention. Here, we report an electronic structure study of the widely used soluble fullerene derivatives PC61BM and PC71BM in their singly reduced state, that are generated in the polymer:fullerene blends upon light-induced charge separation. Density functional theory (DFT) calculations characterize the electronic structures of the fullerene radical anions through spin density distributions and magnetic resonance parameters. The good agreement of the calculated magnetic resonance parameters with those determined experimentally by advancedmore » electron paramagnetic resonance (EPR) allows the validation of the DFT calculations. Thus, for the first time, the complete set of magnetic resonance parameters including directions of the principal g-tensor axes were determined. For both molecules, no spin density is present on the PCBM side chain, and the axis of the largest g-value lies along the PCBM molecular axis. While the spin density distribution is largely uniform for PC61BM, it is not evenly distributed for PC71BM.« less

Understanding and Controlling Nanoscale Morphology in Self-Assembled Semiconducting Materials

NASA Astrophysics Data System (ADS)

Kang, Hyeyeon

Self-assembled semiconducting materials have been rapidly developed for a range of applications. This work aims to control the morphology of nanostructured semiconductors to understand how their functions arise from the structural properties. The first part of this dissertation focuses on the formation of a bulk-heterojunction (BHJ) in the active layer of organic photovoltaics (OPV). A BHJ is a bicontinuous interpenetrating network of organic components. The phase separation of the electron donor and the acceptor is required to achieve a BHJ structure in the nanostructured morphology, which promotes an efficient charge transportation. The use of solvent additive is one of the strategies to control the spontaneous phase separation during the film formation. Low vapor pressure solvent additives are introduced to a polymer casting solution in a sequentially processed OPV system, to study the swelling effect on the phase separation. In particular, the change in crystallinity and vertical mixing will be intensively studied upon polymer swelling. As another strategy, we introduce a molecular structure change to fullerene derivatives. A small structural variation leads to a large enough contrast of their surface energy, which is attributed to different vertical phase separation in the active layer. It eventually allows us to examine photovoltaic performance and device physics. In the second part, mesoporous inorganic films are investigated by preparation from a nanocrystal solution or sol-gel precursors for solar energy applications. Mesoporous nanocrystal-based titania is synthesized for inorganic/organic hybrid solar cells. The effect of surface modification is examined by anchoring a fullerene derivative on to titania surface. 3D interconnected mesoporous tantalum nitride films are prepared via sol-gel method as photoanodes in solar water splitting. The simple synthetic method using polymer template enables us to successfully prepare nitride films with excellent pore periodicity. The porous tantalum nitride film is examined with photoelectrochemical measurement to investigate the correlation between nanostructuring and photocatalytic activity. For the final part of this dissertation, porous cobalt ferrite and cadmium sulfide films are studied using ellipsometric porosimetry. Understanding the nature of their pores allows us to tune the intrinsic properties of the materials or prove the newly designed synthetic method.

Materials, properties, and applications of nitrogen-doped organic semiconductors

NASA Astrophysics Data System (ADS)

Chan, Calvin Kar-Fai

As organic semiconducting materials draw increasing attention for many promising applications, including efficient organic light-emitting diodes (OLEDs), large-area organic photovoltaic (OPV) cells, and flexible organic thin-film transistors (OTFTs), chemical doping of organic materials is emerging as an important technique for overcoming performance deficiencies and material limitations of intrinsic organic films. Although p-doping has been amply demonstrated, molecular n-type doping has been difficult to study because of the inherent instability of easily oxidized n-dopants. In this work, the facile use of two low ionization energy (IE) small molecules that are suitable for n-doping a wide range of organic electronic materials is demonstrated. Cobaltocene (CoCp2) and its derivative, decamethylcobaltocene ( CoCp*2 ), were found to have fairly low IEs for organic compounds. Co-deposition of the n-dopants with different host molecules results in pronounced shifts of the Fermi-level towards unoccupied molecular states, indicating a significant increase in electron concentration. The Fermi-level shifts, measured with ultra-violet photoemission spectroscopy (UPS), are correlated with excess carrier densities using a model based on Fermi-Dirac (F-D) statistics and a Gaussian distributed density of states. The calculated electron densities suggest full dopant ionization at low concentrations, and diminished efficiency at high donor concentrations. The concentration of incorporated dopants is examined by chemical composition analysis of doped films using X-ray photoemission spectroscopy (XPS). Atomic concentration depth profiling determined by Rutherford backscattering (RBS) suggests that the incorporation of CoCp2 and CoCp*2 is well-controlled and the dopants are minimally diffusive. Organic films n-doped using CoCp2 and CoCp*2 show several orders of magnitude increase in current density resulting from both enhanced electron injection and increased electron conductivity in the bulk. Increases in the bulk conductivity suggest both improved electron mobility and higher electron concentrations. These findings are applied with previous work on p-doping to fabricate organic p-i-n homojunction devices that exhibit strong rectification and large built-in potentials. Heterojunction OPVs using undoped CuPc and n-doped C60 display significant increases in open-circuit voltage (Voc), short-circuit current (Isc), fill-factor (FF), and efficiency.

Growth and characterization of V2 O5 thin film on conductive electrode.

PubMed

Mola, Genene T; Arbab, Elhadi A A; Taleatu, Bidini A; Kaviyarasu, K; Ahmad, Ishaq; Maaza, M

2017-02-01

Vanadium pentoxide V 2 O 5 thin films were grown at room temperature on ITO coated glass substrates by electrochemical deposition. The resulting films were annealed at 300, 400 and 500°C for 1 h in ambient environment. The effect of heat treatment on the films properties such as surface morphology, crystal structure, optical absorption and photoluminescence were investigated. The x-ray diffraction study showed that the films are well crystallized with temperatures. Strong reflection from plane (400) indicated the film's preferred growth orientation. The V 2 O 5 films are found to be highly transparent across the visible spectrum and the measured photoluminescence quenching suggested the film's potential application in OPV device fabrication. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

Neutron Reflectivity Measurement for Polymer Dynamics near Graphene Oxide Monolayers

NASA Astrophysics Data System (ADS)

Koo, Jaseung

We investigated the diffusion dynamics of polymer chains confined between graphene oxide layers using neutron reflectivity (NR). The bilayers of polymethylmetacrylate (PMMA)/ deuterated PMMA (d-PMMA) films and polystyrene (PS)/d-PS films with various film thickness sandwiched between Langmuir-Blodgett (LB) monolayers of graphene oxide (GO) were prepared. From the NR results, we found that PMMA diffusion dynamics was reduced near the GO surface while the PS diffusion was not significantly changed. This is due to the different strength of GO-polymer interaction. In this talk, these diffusion results will be compared with dewetting dynamics of polymer thin films on the GO monolayers. This has given us the basis for development of graphene-based nanoelectronics with high efficiency, such as heterojunction devices for polymer photovoltaic (OPV) applications.

Budget impact of polio immunization strategy for India: introduction of one dose of inactivated poliomyelitis vaccine and reductions in supplemental polio immunization.

PubMed

Khan, M M; Sharma, S; Tripathi, B; Alvarez, F P

2017-01-01

To conduct a budget impact analysis (BIA) of introducing the immunization recommendations of India Expert Advisory Group (IEAG) for the years 2015-2017. The recommendations include introduction of one inactivated poliomyelitis vaccine (IPV) dose in the regular child immunization programme along with reductions in oral polio vaccine (OPV) doses in supplemental programmes. This is a national level analysis of budget impact of new polio immunization recommendations. Since the states of India vary widely in terms of size, vaccine coverage and supplemental vaccine needs, the study estimated the budget impact for each of the states of India separately to derive the national level budget impact. Based on the recommendations of IEAG, the BIA assumes that all children in India will get an IPV dose at 14 weeks of age in addition to the OPV and DPT (or Pentavalent-3) doses. Cost of introducing the IPV dose was estimated by considering vaccine price and vaccine delivery and administration costs. The cost savings associated with the reduction in number of doses of OPV in supplemental immunization were also estimated. The analysis used India-specific or international cost parameters to estimate the budget impact. Introduction of one IPV dose will increase the cost of vaccines in the regular immunization programme from $20 million to $47 million. Since IEAG recommends lower intensity of supplemental OPV vaccination, polio vaccine cost of supplemental programme is expected to decline from $72 million to $53 million. Cost of administering polio vaccines will also decline from $124 million to $105 million mainly due to the significantly lower intensity of supplemental polio vaccination. The net effect of adopting IEAG's recommendations on polio immunization turns out to be cost saving for India, reducing total polio immunization cost by $6 million. Additional savings could be achieved if India adopts the new policy regarding the handling of multi-dose vials after opening. Introduction of three doses of IPV with the existing polio immunization schedule will increase the budget requirement by $102 million but replacing OPV doses with IPV will increase the budget by about $59 million. Discontinuation of supplemental OPV immunization with replacement of OPV by IPV will reduce the Government of India's (GOI) polio immunization budget by $99 million. Although the overall cost of polio programme will decline with the adoption of IEAG's recommendations, state-level costs will vary widely. In states like Kerala, Karnataka, Uttar Pradesh and Andhra Pradesh, cost of polio immunization will increase while in Punjab and Jharkhand the costs will remain more or less constant. Significant cost reductions will happen in states with high intensity of supplemental polio immunizations (Bihar, Haryana and Delhi). The cost of procuring polio vaccines will more than double from $20 million to about $47 million requiring allocation of additional foreign exchanges. In some states (like Bihar), the decline in polio-related employment will be very high requiring reallocation of personnel from polio to other programmes. Copyright © 2016 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Update on Vaccine-Derived Polioviruses - Worldwide, January 2016-June 2017.

PubMed

Jorba, Jaume; Diop, Ousmane M; Iber, Jane; Henderson, Elizabeth; Sutter, Roland W; Wassilak, Steven G F; Burns, Cara C

2017-11-03

In 1988, the World Health Assembly launched the Global Polio Eradication Initiative (GPEI) (1). Among the three wild poliovirus (WPV) serotypes, only type 1 (WPV1) has been detected since 2012. Since 2014, detection of WPV1 has been limited to three countries, with 37 cases in 2016 and 11 cases in 2017 as of September 27. The >99.99% decline worldwide in polio cases since the launch of the GPEI is attributable to the extensive use of the live, attenuated oral poliovirus vaccine (OPV) in mass vaccination campaigns and comprehensive national routine immunization programs. Despite its well-established safety record, OPV use can be associated with rare emergence of genetically divergent vaccine-derived polioviruses (VDPVs) whose genetic drift from the parental OPV strains indicates prolonged replication or circulation (2). VDPVs can also emerge among persons with primary immunodeficiencies (PIDs). Immunodeficiency-associated VDPVs (iVDPVs) can replicate for years in some persons with PIDs. In addition, circulating vaccine-derived polioviruses (cVDPVs) can emerge very rarely among immunologically normal vaccine recipients and their contacts in areas with inadequate OPV coverage and can cause outbreaks of paralytic polio. This report updates previous summaries regarding VDPVs (3). During January 2016-June 2017, new cVDPV outbreaks were identified, including two in the Democratic Republic of the Congo (DRC) (eight cases), and another in Syria (35 cases), whereas the circulation of cVDPV type 2 (cVDPV2) in Nigeria resulted in cVDPV2 detection linked to a previous emergence. The last confirmed case from the 2015-2016 cVDPV type 1 (cVDPV1) outbreak in Laos occurred in January 2016. Fourteen newly identified persons in 10 countries were found to excrete iVDPVs, and three previously reported patients in the United Kingdom and Iran (3) were still excreting type 2 iVDPV (iVDPV2) during the reporting period. Ambiguous VDPVs (aVDPVs), isolates that cannot be classified definitively, were found among immunocompetent persons and environmental samples in 10 countries. Cessation of all OPV use after certification of polio eradication will eliminate the risk for new VDPV infections.

Examining geographic and socio-economic differences in outpatient and inpatient consumer expenditures for treating HIV/AIDS in Nigeria

PubMed Central

Onwujekwe, Obinna E; Ibe, Ogochukwu; Torpey, Kwasi; Dada, Stephanie; Uzochukwu, Benjamin; Sanwo, Olusola

2016-01-01

Introduction The expenditures on treatment of HIV/AIDS to households were examined to quantify the magnitude of the economic burden of HIV/AIDS to different population groups in Nigeria. The information will also provide a basis for increased action towards a reduction of the economic burden on many households when accessing antiretroviral therapy (ART). Methods A household survey was administered in three states, Adamawa, Akwa Ibom and Anambra, from the South-East, North-East and South-South zones of Nigeria, respectively. A pretested interviewer-administered questionnaire was used to collect data from a minimum sample of 1200 people living with HIV/AIDS (PLHIV). Data were collected on the medical and non-medical expenditures that patients incurred to treat HIV/AIDS for their last treatment episode within three months of the interview date. The expenditures were for outpatient visits (OPV) and inpatient stays (IPS). The incidence of catastrophic health expenditure (CHE) on ART treatment services was computed for OPV and IPS. Data were disaggregated by socio-economic status (SES) and geographic location of the households. Results The average OPV expenditures incurred by patients per OPV for HIV/AIDS treatment was US$6.1 with variations across SES and urban-rural residence. More than 95% of the surveyed households spent money on transportation to a treatment facility and over 70% spent money on food for OPV. For medical expenditures, the urbanites paid more than rural dwellers. Many patients incurred CHE during outpatient and inpatient visits. Compared to urban dwellers, rural dwellers incurred more CHE for outpatient (p=0.02) and inpatient visits (p=0.002). Conclusions Treatment expenditures were quite high, inequitable and catastrophic in some instances, hence further jeopardizing the welfare of the households and the PLHIV. Strategically locating fully functional treatment centres to make them more accessible to PLHIV will largely reduce expenditures for travel and the need for food during visits. Additionally, financial risk-protection mechanisms such as treatment vouchers, reimbursement and health insurance that will significantly reduce the expenditures borne by PLHIV and their households in seeking ART should be implemented. PMID:26838093

Polio eradication in India: progress, but environmental surveillance and vigilance still needed.

PubMed

Chatterjee, Animesh; Vidyant, Sanjukta; Dhole, Tapan N

2013-02-18

Poliomyelitis has appeared in epidemic form, become endemic on a global scale, and has been reduced to near elimination, all within the span of documented medical history. Nevertheless, effective vaccinations, global surveillance network, development of accurate viral diagnosis prompted the historical challenge, global polio eradication initiative (GPEI). Environmental surveillance of poliovirus means monitoring of wild polio virus (WPV) and vaccine derived polio virus (cVDPV) circulation in human populations by examining environmental specimens supposedly contaminated by human feces. The rationale for surveillance is based on the fact that PV-infected individuals, whether presenting with disease symptoms or not, shed large amounts of PV in the feces for several weeks. As the morbidity: infection ratio of PV infection is very low, and therefore this fact contributes to the sensitivity of poliovirus surveillance, which under optimal conditions can be better than that of the standard acute flaccid paralysis (AFP) surveillance. The World Health Organization (WHO) has included environmental surveillance of poliovirus in the new Strategic Plan of the Global Polio Eradication Initiative for years 2010-2012 to be increasingly used in PV surveillance, supplementing AFP surveillance and the strategic advisory group of experts on immunization (SAGE) recommended a switch from tOPV-bOPV to remove the threat of cVDPV2 and to accelerate the elimination of WPV type 1 and 3 as bOPV is a more immunogenic vaccine and to introduce one dose of IPV in their vaccination schedule prior to OPV cessation. Copyright © 2012 Elsevier Ltd. All rights reserved.

Circulation of Endemic Type 2 Vaccine-Derived Poliovirus in Egypt from 1983 to 1993

PubMed Central

Yang, Chen-Fu; Naguib, Tary; Yang, Su-Ju; Nasr, Eman; Jorba, Jaume; Ahmed, Nahed; Campagnoli, Ray; van der Avoort, Harrie; Shimizu, Hiroyuki; Yoneyama, Tetsuo; Miyamura, Tatsuo; Pallansch, Mark; Kew, Olen

2003-01-01

From 1988 to 1993, 30 cases of poliomyelitis associated with poliovirus type 2 were found in seven governorates of Egypt. Because many of the cases were geographically and temporally clustered and because the case isolates differed antigenically from the vaccine strain, it was initially assumed that the cases signaled the continued circulation of wild type 2 poliovirus. However, comparison of sequences encoding the major capsid protein, VP1 (903 nucleotides), revealed that the isolates were related (93 to 97% nucleotide sequence identity) to the Sabin type 2 oral poliovirus vaccine (OPV) strain and unrelated (<82% nucleotide sequence identity) to the wild type 2 polioviruses previously indigenous to Egypt (last known isolate: 1979) or to any contemporary wild type 2 polioviruses found elsewhere. The rate and pattern of VP1 divergence among the circulating vaccine-derived poliovirus (cVDPV) isolates suggested that all lineages were derived from a single OPV infection that occurred around 1983 and that progeny from the initiating infection circulated for approximately a decade within Egypt along several independent chains of transmission. Complete genomic sequences of an early (1988) and a late (1993) cVDPV isolate revealed that their 5′ untranslated region (5′ UTR) and noncapsid- 3′ UTR sequences were derived from other species C enteroviruses. Circulation of type 2 cVDPVs occurred at a time of low OPV coverage in the affected communities and ceased when OPV coverage rates increased. The potential for cVDPVs to circulate in populations with low immunity to poliovirus has important implications for current and future strategies to eradicate polio worldwide. PMID:12857906

Detection and discrimination of orthopoxviruses using microarrays of immobilized oligonucleotides.

PubMed

Laassri, Majid; Chizhikov, Vladimir; Mikheev, Maxim; Shchelkunov, Sergei; Chumakov, Konstantin

2003-09-01

Variola virus (VARV), causing smallpox, is a potential biological weapon. Methods to detect VARV rapidly and to differentiate it from other viruses causing similar clinical syndromes are needed urgently. We have developed a new microarray-based method that detects simultaneously and discriminates four orthopoxvirus (OPV) species pathogenic for humans (variola, monkeypox, cowpox, and vaccinia viruses) and distinguishes them from chickenpox virus (varicella-zoster virus or VZV). The OPV gene C23L/B29R, encoding the CC-chemokine binding protein, was sequenced for 41 strains of seven species of orthopox viruses obtained from different geographical regions. Those C23L/B29R sequences and the ORF 62 sequences from 13 strains of VZV (selected from GenBank) were used to design oligonucleotide probes that were immobilized on an aldehyde-coated glass surface (a total of 57 probes). The microchip contained several unique 13-21 bases long oligonucleotide probes specific to each virus species to ensure redundancy and robustness of the assay. A region approximately 1100 bases long was amplified from samples of viral DNA and fluorescently labeled with Cy5-modified dNTPs, and single-stranded DNA was prepared by strand separation. Hybridization was carried out under plastic coverslips, resulting in a fluorescent pattern that was quantified using a confocal laser scanner. 49 known and blinded samples of OPV DNA, representing different OPV species, and two VZV strains were tested. The oligonucleotide microarray hybridization technique identified reliably and correctly all samples. This new procedure takes only 3 h, and it can be used for parallel testing of multiple samples.

Circulation of endemic type 2 vaccine-derived poliovirus in Egypt from 1983 to 1993.

PubMed

Yang, Chen-Fu; Naguib, Tary; Yang, Su-Ju; Nasr, Eman; Jorba, Jaume; Ahmed, Nahed; Campagnoli, Ray; van der Avoort, Harrie; Shimizu, Hiroyuki; Yoneyama, Tetsuo; Miyamura, Tatsuo; Pallansch, Mark; Kew, Olen

2003-08-01

From 1988 to 1993, 30 cases of poliomyelitis associated with poliovirus type 2 were found in seven governorates of Egypt. Because many of the cases were geographically and temporally clustered and because the case isolates differed antigenically from the vaccine strain, it was initially assumed that the cases signaled the continued circulation of wild type 2 poliovirus. However, comparison of sequences encoding the major capsid protein, VP1 (903 nucleotides), revealed that the isolates were related (93 to 97% nucleotide sequence identity) to the Sabin type 2 oral poliovirus vaccine (OPV) strain and unrelated (<82% nucleotide sequence identity) to the wild type 2 polioviruses previously indigenous to Egypt (last known isolate: 1979) or to any contemporary wild type 2 polioviruses found elsewhere. The rate and pattern of VP1 divergence among the circulating vaccine-derived poliovirus (cVDPV) isolates suggested that all lineages were derived from a single OPV infection that occurred around 1983 and that progeny from the initiating infection circulated for approximately a decade within Egypt along several independent chains of transmission. Complete genomic sequences of an early (1988) and a late (1993) cVDPV isolate revealed that their 5' untranslated region (5' UTR) and noncapsid- 3' UTR sequences were derived from other species C enteroviruses. Circulation of type 2 cVDPVs occurred at a time of low OPV coverage in the affected communities and ceased when OPV coverage rates increased. The potential for cVDPVs to circulate in populations with low immunity to poliovirus has important implications for current and future strategies to eradicate polio worldwide.

DC Magnetron Sputtered IZTO Thin Films for Organic Photovoltaic Application.

PubMed

Lee, Hye Ji; Noviyana, Imas; Putri, Maryane; Koo, Chang Young; Lee, Jung-A; Kim, Jeong-Joo; Jeong, Youngjun; Lee, Youngu; Lee, Hee Young

2018-02-01

IZTO20 (In0.6Zn0.2Sn0.2O1.5) ceramic target was prepared from oxide mixture of In2O3, ZnO, and SnO2 powders. IZTO20 thin films were then deposited onto glass substrate at 400 °C by DC magnetron sputtering. The average optical transmittance determined by ultraviolet-visible spectroscopy was higher than 85% for all films. The minimum resistivity of the annealed IZTO20 thin film was approximately 6.1×10-4 Ω·cm, which tended to increase with decreasing indium content. Substrate heating and annealing were found to be important parameters affecting the electrical and optical properties. An organic photovoltaic (OPV) cell was fabricated using the IZTO20 film deposited under the optimized condition as an anode electrode and the efficiency of up to 80% compared to that of a similar OPV cell using ITO film was observed. Reduction of surface roughness and electrical resistivity through annealing treatment was found to contribute to the improved efficiency of the OPV cell.

Towards maximizing the haze effect of electrodes for high efficiency hybrid tandem solar cell

NASA Astrophysics Data System (ADS)

Vincent, Premkumar; Song, Dong-Seok; Kwon, Hyeok Bin; Kim, Do-Kyung; Jung, Ji-Hoon; Kwon, Jin-Hyuk; Choe, Eunji; Kim, Young-Rae; Kim, Hyeok; Bae, Jin-Hyuk

2018-02-01

In this study, we executed optical simulations to compute the optimum power conversion efficiency (PCE) of a-Si:H/organic photovoltaic (OPV) hybrid tandem solar cell. The maximum ideal short circuit current density (Jsc,max) of the tandem solar cell is initially obtained by optimizing the thickness of the active layer of the OPV subcell for varying thickness of the a-Si:H bottom subcell. To investigate the effect of Haze parameter on the ideal short-circuit current density (Jsc,ideal) of the solar cells, we have varied the haze ratio for the TCO electrode of the a-Si:H subcell in the tandem structure. The haze ratio was obtained for various root mean square (RMS) roughness of the TCO of the front cell. The effect of haze ratio on the Jsc,ideal on the tandem structured solar cell was studied, and the highest Jsc,ideal was obtained at a haze of 55.5% when the thickness of the OPV subcell was 150 nm and that of the a-Si:H subcell was 500 nm.

Outbreak of Type 2 Vaccine-Derived Poliovirus in Nigeria: Emergence and Widespread Circulation in an Underimmunized Population

PubMed Central

Pate, Muhammad Ali; Wannemuehler, Kathleen; Jenks, Julie; Burns, Cara; Chenoweth, Paul; Abanida, Emmanuel Ade; Adu, Festus; Baba, Marycelin; Gasasira, Alex; Iber, Jane; Mkanda, Pascal; Williams, A. J.; Shaw, Jing; Pallansch, Mark; Kew, Olen

2011-01-01

Wild poliovirus has remained endemic in northern Nigeria because of low coverage achieved in the routine immunization program and in supplementary immunization activities (SIAs). An outbreak of infection involving 315 cases of type 2 circulating vaccine-derived poliovirus (cVDPV2; >1% divergent from Sabin 2) occurred during July 2005–June 2010, a period when 23 of 34 SIAs used monovalent or bivalent oral poliovirus vaccine (OPV) lacking Sabin 2. In addition, 21 “pre-VDPV2” (0.5%–1.0% divergent) cases occurred during this period. Both cVDPV and pre-VDPV cases were clinically indistinguishable from cases due to wild poliovirus. The monthly incidence of cases increased sharply in early 2009, as more children aged without trivalent OPV SIAs. Cumulative state incidence of pre-VDPV2/cVDPV2 was correlated with low childhood immunization against poliovirus type 2 assessed by various means. Strengthened routine immunization programs in countries with suboptimal coverage and balanced use of OPV formulations in SIAs are necessary to minimize risks of VDPV emergence and circulation. PMID:21402542

Evaluation of the new control methods for oral poliomyelitis vaccine.

PubMed

Grachev, V P; Karganova, G G; Rumyantsev, A A; Ivanova, O E; Eremeeva, T P; Drozdov, S G

2001-01-01

In the draft recommendations for production and control of OPV the WHO proposed new control methods: (i) mutant analysis with PCR and restriction enzyme cleavage (MAPREC) assay that allows evaluation of poliovirus population heterogeneity at the molecular level; (ii) neurovirulence (NV) test using transgenic mice susceptible to polioviruses and (iii) control of the seed lots for the presence of the simian virus 40 (SV40) DNA sequence. This paper is focused on our experience in the practical implementation of the new methods at the Institute of Poliomyelitis and Viral Encephalitides (IPVE). Using methods based on PCR we have demonstrated that working seed viruses used by IPVE for OPV production are free from SV40 DNA sequences. Our experience on the conduction of the OPV type 3 control using TgPVR21 mice NV test (seven vaccine lots) and the MAPREC assay (more than 150 samples of single harvests and monovalent bulks) showed that these methods may be used instead of the monkey NV test, because they could not pass the vaccine failed monkey NV test. The necessity for single harvests control is discussed.

A naphthodithiophene-diketopyrrolopyrrole donor molecule for efficient solution-processed solar cells.

PubMed

Loser, Stephen; Bruns, Carson J; Miyauchi, Hiroyuki; Ortiz, Rocío Ponce; Facchetti, Antonio; Stupp, Samuel I; Marks, Tobin J

2011-06-01

We report the synthesis, characterization, and first implementation of a naphtho[2,3-b:6,7-b']dithiophene (NDT)-based donor molecule in highly efficient organic photovoltaics (OPVs). When NDT(TDPP)(2) (TDPP = thiophene-capped diketopyrrolopyrrole) is combined with the electron acceptor PC(61)BM, a power conversion efficiency (PCE) of 4.06 ± 0.06% is achieved-a record for a PC(61)BM-based small-molecule OPV. The substantial PCE is attributed to the broad, high oscillator strength visible absorption, the ordered molecular packing, and an exceptional hole mobility of NDT(TDPP)(2). © 2011 American Chemical Society

Metal substrates with nanometer scale surface roughness for flexible electronics

NASA Astrophysics Data System (ADS)

Lee, Jong-Lam; Kim, Kisoo

2012-09-01

In this work, we present a novel way in fabricating a metal substrate with nanometer scale in surface roughness (Ra < 1 nm) using a surface roughness transfer method without any polishing or planarization process. Ag film (8 inch, Ra = 0.57 nm) and an INVAR (Invariable alloy) one (20 cm × 20 cm, Ra = 1.40 nm) were demonstrated. The INVAR film was used as a substrate for fabricating organic light emitting diodes (OLED) and organic photovoltaic (OPV). The optical and electrical characteristics of OLEDs and OPVs using the INVAR were comparable to those using a conventional ITO glass substrate.

[Identification of human pathogenic variola and monkeypox viruses by real-time polymerase chain reaction].

PubMed

Kostina, E V; Gavrilova, E V; Riabinin, V A; Shchelkunov, S N; Siniakov, A N

2009-01-01

A kit of specific oligonucleotide primers and hybridization probes has been proposed to detect orthopoxviruses (OPV) and to discriminate human pathogenic viruses, such as variola virus and monkey virus by real-time polymerase chain reaction (PCR). For real-time PCR, the following pairs of fluorophore and a fluorescence quencher were used: TAMRA-BHQ2 for genus-specific probes and FAM-BHQ1 for species-specific ones (variola virus, monkeypox virus, ectomelia virus). The specificity of this assay was tested on 38 strains of 6 OPV species and it was 100%.

Delocalisation of photoexcited triplet states probed by transient EPR and hyperfine spectroscopy

NASA Astrophysics Data System (ADS)

Richert, Sabine; Tait, Claudia E.; Timmel, Christiane R.

2017-07-01

Photoexcited triplet states play a crucial role in photochemical mechanisms: long known to be of paramount importance in the study of photosynthetic reaction centres, they have more recently also been shown to play a major role in a number of applications in the field of molecular electronics. Their characterisation is crucial for an improved understanding of these processes with a particular focus on the determination of the spatial distribution of the triplet state wavefunction providing information on charge and energy transfer efficiencies. Currently, active research in this field is mostly focussed on the investigation of materials for organic photovoltaics (OPVs) and organic light emitting diodes (OLEDs). As the properties of triplet states and their spatial extent are known to have a major impact on device performance, a detailed understanding of the factors governing triplet state delocalisation is at the basis of the further development and improvement of these devices. Electron Paramagnetic Resonance (EPR) has proven a valuable tool in the study of triplet state properties and both experimental methods as well as data analysis and interpretation techniques have continuously improved over the last few decades. In this review, we discuss the theoretical and practical aspects of the investigation of triplet states and triplet state delocalisation by transient continuous wave and pulse EPR and highlight the advantages and limitations of the presently available techniques and the current trends in the field. Application of EPR in the study of triplet state delocalisation is illustrated on the example of linear multi-porphyrin chains designed as molecular wires.

Properties of thin film radiation detectors and their application to dosimetry and quality assurance in x-ray imaging

NASA Astrophysics Data System (ADS)

Elshahat, Bassem

The characteristics of two different types of thin-film radiation detectors are experimentally investigated: organic photovoltaic cells (OPV) and a new self-powered detector that operates based on high-energy secondary electrons (HEC). Although their working principles are substantially different, they both can be used for radiation detection and image formation in medical applications. OPVs with different active layer material thicknesses and aluminum electrode areas were fabricated. The OPV cell consisted of P3HT: PCBM photoactive materials, composed of donor and acceptor semiconducting organic materials, sandwiched between an aluminum electrode as anode and an indium tin oxide (ITO) electrode as a cathode. The detectors were exposed to 60150 kVp x rays, which generated photocurrent in the active layer. The electric charge production in the OPV cells was measured. The net current as function of beam energy (kVp) was proportional to ~1/kVp0.45 when adjusted for x-ray beam output. The best combination of parameters for these cells was 270-nm active layer thicknesses for 0.7cm-2 electrode area. The measured current ranged from about 0.7 to 2.4 nA/cm2 for 60-150 kVp, corresponding to about 0.09 -- 0.06 nA/cm2/mGy, respectively, when adjusted for the output x-ray source flux. The HEC detection concept was recently proposed and experimentally demonstrated by a UML/HMS research group. HEC detection employs direct conversion of high-energy electron current to detector signal without external power and amplification. The potential of using HEC detectors for diagnostic imaging application was investigated by using a heterogeneous phantom consisting of a water cylinder with Al and wax rod inserts.

Genome-Wide Comparison of Cowpox Viruses Reveals a New Clade Related to Variola Virus

PubMed Central

Kurth, Andreas; Nitsche, Andreas

2013-01-01

Zoonotic infections caused by several orthopoxviruses (OPV) like monkeypox virus or vaccinia virus have a significant impact on human health. In Europe, the number of diagnosed infections with cowpox viruses (CPXV) is increasing in animals as well as in humans. CPXV used to be enzootic in cattle; however, such infections were not being diagnosed over the last decades. Instead, individual cases of cowpox are being found in cats or exotic zoo animals that transmit the infection to humans. Both animals and humans reveal local exanthema on arms and legs or on the face. Although cowpox is generally regarded as a self-limiting disease, immunosuppressed patients can develop a lethal systemic disease resembling smallpox. To date, only limited information on the complex and, compared to other OPV, sparsely conserved CPXV genomes is available. Since CPXV displays the widest host range of all OPV known, it seems important to comprehend the genetic repertoire of CPXV which in turn may help elucidate specific mechanisms of CPXV pathogenesis and origin. Therefore, 22 genomes of independent CPXV strains from clinical cases, involving ten humans, four rats, two cats, two jaguarundis, one beaver, one elephant, one marah and one mongoose, were sequenced by using massive parallel pyrosequencing. The extensive phylogenetic analysis showed that the CPXV strains sequenced clearly cluster into several distinct clades, some of which are closely related to Vaccinia viruses while others represent different clades in a CPXV cluster. Particularly one CPXV clade is more closely related to Camelpox virus, Taterapox virus and Variola virus than to any other known OPV. These results support and extend recent data from other groups who postulate that CPXV does not form a monophyletic clade and should be divided into multiple lineages. PMID:24312452

Are childhood immunization programmes in Australia at risk? Investigation of the cold chain in the Northern Territory.

PubMed

Miller, N C; Harris, M F

1994-01-01

Since vaccines may lose their potency if transported or stored outside the recommended temperature range (2-8 degrees C), we carried out a study in the Darwin area of the Northern Territory of Australia to determine the links in the cold chain, including the extent of vaccine monitoring, and whether the vaccines were being exposed to unsafe temperatures. Sabin oral poliomyelitis vaccine (OPV) and recombinant hepatitis-B (HB) vaccine were selected for special monitoring. A total of 127 vials of OPV and 144 vials of HB vaccine were dispatched during October, November and December 1990 to the government, independent health services and general practitioner surgeries which routinely administer these vaccines. We distributed the two vaccines with MonitorMark time/temperature and Coldside indicator tags attached to cards for recording the date, location and temperature exposures each time the vaccines were moved or used. A total of 65% of the OPV and 41% of the HB vaccine monitor cards were returned for analysis. The vaccines were transported and stored at one to four locations prior to being administered. Some 23% of tagged OPV was exposed for 48 hours or more to a temperature > 10 degrees C; 47.5% of tagged HB vaccines were exposed to -3 degrees C or less, the majority of them during storage in health facilities or clinics. Exposures were independent of distance from the distribution centre, mode of transport, or type of facility. Our results show that the vaccines were often exposed to temperatures outside the recommended range during transport and storage, putting them at risk of loss of potency.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunogenicity study to investigate the interchangeability among three different types of polio vaccine: A cohort study in Japan.

PubMed

Ohfuji, Satoko; Ito, Kazuya; Ishibashi, Motoki; Shindo, Shizuo; Takasaki, Yoshio; Yokoyama, Takashi; Yokoyama, Takato; Yamashita, Yuji; Shibao, Keigo; Nakano, Takashi; Tsuru, Tomomi; Irie, Shin; Hirota, Yoshio

2017-06-01

In Japan, the routine immunization program with oral polio vaccine (OPV) has been suspended since September 2012, when a program with 4 doses of inactivated monovalent polio vaccine (IPV) or quadrivalent vaccine against diphtheria, pertussis, and tetanus with IPV (DTaP-IPV) was introduced. The aim of this study was to examine the interchangeability among these 3 types of polio vaccines.We conducted a prospective cohort study at 5 pediatric clinics in Japan. A total of 153 infants were assigned to 1 of the 4 groups by considering the vaccination history of OPV and trivalent vaccine against DTaP. Eleven infants with a history of OPV received 3 doses of DTaP-IPV; 49 infants with a history of OPV and DTaP received 3 doses of IPV; 50 polio vaccine-naïve infants received 2 doses of IPV followed by 2 doses of DTaP-IPV; and 43 polio vaccine-naive infants received 2 doses of DTaP-IPV followed by IPV. The immunogenicity after polio vaccination was evaluated among these 4 groups.After 2 doses of polio vaccination, more than 80% of the infants exhibited a neutralization antibody titer ≥1:8 for all Sabin strains and wild strains in all groups. After the third dose, the seroprotection proportion (i.e., a neutralization antibody titer ≥1:8) reached about 100%. After the fourth dose, a neutralization antibody titer exceeded the required protective levels (i.e., a neutralization antibody titer ≥1:8) considerably in all groups.Four doses of polio vaccines induced a sufficient level of immunity in Japanese infants, irrespective of vaccine combinations or order.

Genome-wide comparison of cowpox viruses reveals a new clade related to Variola virus.

PubMed

Dabrowski, Piotr Wojtek; Radonić, Aleksandar; Kurth, Andreas; Nitsche, Andreas

2013-01-01

Zoonotic infections caused by several orthopoxviruses (OPV) like monkeypox virus or vaccinia virus have a significant impact on human health. In Europe, the number of diagnosed infections with cowpox viruses (CPXV) is increasing in animals as well as in humans. CPXV used to be enzootic in cattle; however, such infections were not being diagnosed over the last decades. Instead, individual cases of cowpox are being found in cats or exotic zoo animals that transmit the infection to humans. Both animals and humans reveal local exanthema on arms and legs or on the face. Although cowpox is generally regarded as a self-limiting disease, immunosuppressed patients can develop a lethal systemic disease resembling smallpox. To date, only limited information on the complex and, compared to other OPV, sparsely conserved CPXV genomes is available. Since CPXV displays the widest host range of all OPV known, it seems important to comprehend the genetic repertoire of CPXV which in turn may help elucidate specific mechanisms of CPXV pathogenesis and origin. Therefore, 22 genomes of independent CPXV strains from clinical cases, involving ten humans, four rats, two cats, two jaguarundis, one beaver, one elephant, one marah and one mongoose, were sequenced by using massive parallel pyrosequencing. The extensive phylogenetic analysis showed that the CPXV strains sequenced clearly cluster into several distinct clades, some of which are closely related to Vaccinia viruses while others represent different clades in a CPXV cluster. Particularly one CPXV clade is more closely related to Camelpox virus, Taterapox virus and Variola virus than to any other known OPV. These results support and extend recent data from other groups who postulate that CPXV does not form a monophyletic clade and should be divided into multiple lineages.

Factors determining anti-poliovirus type 3 antibodies among orally immunised Indian infants.

PubMed

Kaliappan, Saravanakumar Puthupalayam; Venugopal, Srinivasan; Giri, Sidhartha; Praharaj, Ira; Karthikeyan, Arun S; Babji, Sudhir; John, Jacob; Muliyil, Jayaprakash; Grassly, Nicholas; Kang, Gagandeep

2016-09-22

Among the three poliovirus serotypes, the lowest responses after vaccination with trivalent oral polio vaccine (tOPV) are to serotype 3. Although improvements in routine immunisation and supplementary immunisation activities have greatly increased vaccine coverage, there are limited data on antibody prevalence in Indian infants. Children aged 5-11months with a history of not having received inactivated polio vaccine were screened for serum antibodies to poliovirus serotype 3 (PV3) by a micro-neutralisation assay according to a modified World Health Organization (WHO) protocol. Limited demographic information was collected to assess risk-factors for a lack of protective antibodies. Student's t-test, logistic regression and multilevel logistic regression (MLR) model were used to estimate model parameters. Of 8454 children screened at a mean age of 8.3 (standard deviation [SD]-1.8) months, 88.1% (95% confidence interval (CI): 87.4-88.8) had protective antibodies to PV3. The number of tOPV doses received was the main determinant of seroprevalence; the maximum likelihood estimate yields a 37.7% (95% CI: 36.2-38.3) increase in seroprevalence per dose of tOPV. In multivariable logistic regression analysis increasing age, male sex, and urban residence were also independently associated with seropositivity (Odds Ratios (OR): 1.17 (95% CI: 1.12-1.23) per month of age, 1.27 (1.11-1.46) and 1.24 (1.05-1.45) respectively). Seroprevalence of antibodies to PV3 is associated with age, gender and place of residence, in addition to the number of tOPV doses received. Ensuring high coverage and monitoring of response are essential as long as oral vaccines are used in polio eradication. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

World Witnesses a Tumultuous Year while India Reports an Eventful Decade in the Long Story of Polio Eradication.

PubMed

Chaturvedi, Sanjay

2014-04-01

With recent outbreaks in Syria and Horn of Africa, silent circulation of wild poliovirus type 1 (WPV1) in Israel, West Bank, and Gaza, and fresh spate of violence against vaccinators and their security personnel in Pakistan, the world is facing a turbulent final ascent to the summit of polio eradication. On the positive side, we may also be witnessing the end of wild poliovirus type 3 (WPV3) and defused programmatic crisis caused by funding gaps, while India registers third consecutive polio-free year. Having a cogent endgame plan 2013-2018, informed by some cardinal lessons learned from an eventful decade in India, is also a very significant development. Now, there is a parallel pursuit against WPV and vaccine-derived poliovirus (VDPV). Endgame would also involve integration of at least one dose of affordable inactivated polio vaccine (IPV) to up-scaled routine immunization (RI), switch from trivalent oral polio vaccine (tOPV) to bivalent oral polio vaccine (bOPV) in 144 countries before 2018, stockpiling of mOPV, and simultaneous global cessation of bOPV before 2020. Role of antivirals in post-eradication era is still unclear. Some specific threats emerging at this stage are as follows: Global buildup of new birth cohorts in non-endemic countries with weak RI and downscaled supplementary immunization activities (SIAs), tremendous pressure on peripheral health workers, and fatigued systems. Cultural resistance to transnational programs is taking a violent shape in some areas. Differential interpretations of 'right to say no', on both sides of the divide, are damaging a global cause. Amidst all these concerns, let us not forget to underline the sacrifice made by frontline vaccinators working in some of the most challenging circumstances.

Introduction of Inactivated Poliovirus Vaccine and Impact on Vaccine-Associated Paralytic Poliomyelitis - Beijing, China, 2014-2016.

PubMed

Zhao, Dan; Ma, Rui; Zhou, Tao; Yang, Fan; Wu, Jin; Sun, Hao; Liu, Fang; Lu, Li; Li, Xiaomei; Zuo, Shuyan; Yao, Wei; Yin, Jian

2017-12-15

When included in a sequential polio vaccination schedule, inactivated polio vaccine (IPV) reduces the risk for vaccine-associated paralytic poliomyelitis (VAPP), a rare adverse event associated with receipt of oral poliovirus vaccine (OPV). During January 2014, the World Health Organization (WHO) recommended introduction of at least 1 IPV dose into routine immunization schedules in OPV-using countries (1). The Polio Eradication and Endgame Strategic Plan 2013-2018 recommended completion of IPV introduction in 2015 and globally synchronized withdrawal of OPV type 2 in 2016 (2). Introduction of 1 dose of IPV into Beijing's Expanded Program on Immunization (EPI) on December 5, 2014 represented China's first province-wide IPV introduction. Coverage with the first dose of polio vaccine was maintained from 96.2% to 96.9%, similar to coverage with the first dose of diphtheria and tetanus toxoids and pertussis vaccine (DTP) (96.5%-97.2%); the polio vaccine dropout rate (the percentage of children who received the first dose of polio vaccine but failed to complete the series) was 1.0% in 2015 and 0.4% in 2016. The use of 3 doses of private-sector IPV per child decreased from 18.1% in 2014, to 17.4% in 2015, and to 14.8% in 2016. No cases of VAPP were identified during 2014-2016. Successful introduction of IPV into the public sector EPI program was attributed to comprehensive planning, preparation, implementation, robust surveillance for adverse events after immunization (AEFI), and monitoring of vaccination coverage. This evaluation provided information that helped contribute to the expansion of IPV use in China and in other OPV-using countries.

Interpersonal Violence and Health in Female University Students in Spain.

PubMed

Martín-Baena, David; Talavera, Marta; Montero-Piñar, Isabel

2016-11-01

Most studies address the health impact of violence by an intimate partner; therefore, violence exerted by someone other than a partner in university students and its health effects are less known. This study aims to analyze the effect of different forms of interpersonal violence on female university students' health. Women 18 to 25 years of age enrolled at two schools of the University of Valencia in the academic year 2013-2014 (N = 540) were selected, with a participation rate of 82%. Students were grouped as follows: no lifetime violence, violence by an intimate partner (IPV), other personal violence (OPV), and by both (IPV and OPV). Adjusted logistical regression analysis was performed to assess the effects of the different forms of violence on students' health. As many as 92 students (20.6%) experienced violence at least once in their lives: 46 (10.3%) by an intimate partner, 24 (5.4%) by someone other than a partner, and 22 (4.9%) by both. Abused students are more likely to suffer psychological distress and poor health perception, and more regularly used psychoactive drugs than nonabused students, although the use of medication is higher for those abused by a partner and others. Women who experienced only IPV are more likely to suffer psychological distress (adjusted odds ratio [aOR] = 1.78, p < .05, 95% confidence interval [CI; 1.10-2.86]), while those who experienced only OPV are more than twice as likely to perceive their health as poor (aOR = 2.68, p < .05, 95% CI [1.38-5.22]). The high prevalence of violence and its consistent association with a wide range of female university students' health problems suggest that violence seriously compromises women's health. Prevention programs that promote harmonious social relationships among university students should be implemented. © 2016 Sigma Theta Tau International.

Influence of the intestinal microbiota on the immunogenicity of oral rotavirus vaccine given to infants in south India.

PubMed

Parker, Edward P K; Praharaj, Ira; Zekavati, Anna; Lazarus, Robin P; Giri, Sidhartha; Operario, Darwin J; Liu, Jie; Houpt, Eric; Iturriza-Gómara, Miren; Kampmann, Beate; John, Jacob; Kang, Gagandeep; Grassly, Nicholas C

2018-01-04

Oral rotavirus vaccines have consistently proven to be less immunogenic among infants in developing countries. Discrepancies in the intestinal microbiota, including a greater burden of enteropathogens and an altered commensal community composition, may contribute to this trend by inhibiting the replication of vaccine viruses. To test this possibility, we performed a nested case-control study in Vellore, India, in which we compared the intestinal microbiota of infants who responded serologically or not after two doses of Rotarix delivered at 6 and 10 weeks of age as part of a clinical trial (CTRI/2012/05/002677). The prevalence of 40 bacterial, viral, and eukaryotic pathogen targets was assessed in pre-vaccination stool samples from 325 infants using singleplex real-time PCR on a Taqman array card (TAC). In a subset of 170 infants, we assessed bacterial microbiota composition by sequencing the 16S rRNA gene V4 region. Contrary to expectations, responders were more likely than non-responders to harbor ≥1 bacterial enteropathogen at dose 1 (26% [40/156] vs 13% [21/157] of infants with TAC results who completed the study per protocol; χ 2 , P = .006), although this was not apparent at dose 2 (24% [38/158] vs 23% [36/158]; P = .790). Rotavirus shedding after dose 1 was negatively correlated with the replication of co-administered oral poliovirus vaccine (OPV). We observed no consistent differences in composition or diversity of the 16S bacterial microbiota according to serological response, although rotavirus shedding was associated with slightly more bacterial taxa pre-vaccination. Overall, our findings demonstrate an inhibitory effect of co-administered OPV on the first dose of Rotarix, consistent with previous studies, but in the context of OPV co-administration we did not find a strong association between other components of the intestinal microbiota at the time of vaccination and Rotarix immunogenicity. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Morphology-defined interaction of copper phthalocyanine with O 2/H 2O

DOE PAGES

Muckley, Eric S.; Miller, Nicholas; Jacobs, Christopher B.; ...

2016-11-01

Copper phthalocyanine (CuPc) is an important hole transport layer for organic photovoltaics (OPVs), but its interaction with ambient gas/vapor may lead to changes in electronic properties of the material which subsequently limits the lifetime of OPV devices. CuPc films of thickness 25 nm and 100 nm were grown by thermal sublimation at 25°C, 150°C, and 250°C in order to vary morphology. Using a source-measure unit and a quartz crystal microbalance (QCM), we measured changes in electrical resistance and film mass in situ during exposure to controlled pulses of O 2 and H 2O vapor. Mass loading by O 2 wasmore » enhanced by a factor of 5 in films deposited at 250 C, possibly due to the ~200° C CuPc -> transition which allows higher O 2 mobility between stacked molecules. While gas/vapor sorption occurred over timescales of < 10 minutes, resistance change occurred over timescales > 1 hour, suggesting that mass change occurs by rapid adsorption at active surface sites, whereas resistive response is dominated by slow diffusion of adsorbates into the film bulk. Resistive response generally increases with film deposition temperature due to increased porosity associated with larger crystalline domains. The 25 nm thick films exhibit higher resistive response than 100 nm thick films after an hour of O 2/H 2O exposure due to the smaller analyte diffusion length required for reaching the film/electrode interface. We found evidence of decoupling of CuPc from the gold-coated QCM crystal due to preferential adsorption of O 2/H 2O molecules on gold, which is consistent with findings of other studies.« less

Vaccine-associated paralytic poliomyelitis caused by contact infection.

PubMed

Okuda, Bungo; Uetani, Eri; Okamoto, Kensho

2006-01-01

We encountered an adult patient with acute anterior poliomyelitis (AAP), whose monoparesis developed 28 days after his son's immunization with oral poliovirus vaccine (OPV). Neurological and electrophysiological examinations suggested that his muscular wasting of the left lower limb was due to a lower motor neuron disorder, and magnetic resonance imaging revealed the responsible lesion in the left anterior horn at the thoracolumbar junction. His stool was found to include poliovirus type 3, mainly originating from Sabin 3 by neutrization antibody and PCR-restriction fragment length polymorphism method. This indicated that the AAP resulted from contact with his son. This patient raises the question about OPV in polio-free countries.