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1

Transparent metal selenide alloy counter electrodes for high-efficiency bifacial dye-sensitized solar cells.  

PubMed

The exploration of cost-effective and transparent counter electrodes (CEs) is a persistent objective in the development of bifacial dye-sensitized solar cells (DSSCs). Transparent counter electrodes based on binary-alloy metal selenides (M-Se; M=Co, Ni, Cu, Fe, Ru) are now obtained by a mild, solution-based method and employed in efficient bifacial DSSCs. Owing to superior charge-transfer ability for the I(-) /I3 (-) redox couple, electrocatalytic activity toward I3 (-) reduction, and optical transparency, the bifacial DSSCs with CEs consisting of a metal selenide alloy yield front and rear efficiencies of 8.30?% and 4.63?% for Co0.85 Se, 7.85?% and 4.37?% for Ni0.85 Se, 6.43?% and 4.24?% for Cu0.50 Se, 7.64?% and 5.05?% for FeSe, and 9.22?% and 5.90?% for Ru0.33 Se in comparison with 6.18?% and 3.56?% for a cell with an electrode based on pristine platinum, respectively. Moreover, fast activity onset, high multiple start/stop capability, and relatively good stability demonstrate that these new electrodes should find applications in solar panels. PMID:25358619

Duan, Yanyan; Tang, Qunwei; Liu, Juan; He, Benlin; Yu, Liangmin

2014-12-22

2

Fully printable transparent monolithic solid-state dye-sensitized solar cell with mesoscopic indium tin oxide counter electrode.  

PubMed

We present a new transparent monolithic mesoscopic solid-state dye-sensitized solar cell based on trilamellar films of mesoscopic TiO2 nanocrystalline photoanode, a ZrO2 insulating layer and an indium tin oxide counter electrode (ITO-CE), which were screen-printed layer by layer on a single substrate. When the thickness of the ITO-CE was optimized to 2.1 ?m, this very simple and fully printable solid-state DSSC with D102 dye and spiro-OMeTAD hole transport materials presents efficiencies of 1.73% when irradiated from the front side and 1.06% when irradiated from the rear side under a standard simulated sunlight condition (AM 1.5 Global, 100 mW cm(-2)). Higher parameters could be expected with a better transparent mesoscopic counter electrode and hole conductor for the printable monolithic mesoscopic solid-state DSSC. PMID:25030303

Yang, Ying; Ri, Kwangho; Rong, Yaoguang; Liu, Linfeng; Liu, Tongfa; Hu, Min; Li, Xiong; Han, Hongwei

2014-09-01

3

Cost-effective bifacial dye-sensitized solar cells with transparent iron selenide counter electrodes. An avenue of enhancing rear-side electricity generation capability  

NASA Astrophysics Data System (ADS)

Alloy materials have established themselves as alternative electrocatalysts for electrochemical devices because of their cost-effectiveness, high conductivity, good electrocatalytic activity, and reasonable stability. Aiming at reducing fabrication cost without sacrificing power conversion efficiency of dye-sensitized solar cells (DSSCs), we report the feasibility of designing transparent and cost-effective Fe-Se alloy counter electrodes for bifacial DSSCs. Due to the rapid charge transfer ability and electrocatalytic activity, maximum front and rear efficiencies of 7.64% and 4.95% are measured for the DSSC with FeSe alloy electrode in comparison with 6.97% and 3.56% from Pt-based solar cell. The impressive results along with simple synthesis highlight the potential application of Fe-Se alloys in robust bifacial DSSCs.

Liu, Juan; Tang, Qunwei; He, Benlin; Yu, Liangmin

2015-02-01

4

An efficient and transparent copper sulfide nanosheet film counter electrode for bifacial quantum dot-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Copper sulfide (CuS) with nanosheet structure has been synthesized at a low temperature in situ on copper (Cu) film coated fluorine-doped tin oxide glass and bifacial quantum dot-sensitized solar cells (QDSSCs) were herein developed by using these CuS as counter electrodes (CEs). CuS is an environmental compatible and low toxic material. The obtained two-dimensional CuS nanosheet film presents high carrier mobility and exhibits highly catalytic performance for the polysulfide-based electrolyte. The QDSSC based on a CuS CE presents a power conversion efficiency (PCE) of 3.65% by optimizing the thickness of the Cu film under front illumination. The QDSSC based on a CuS CE prepared with a 200 nm thick Cu film shows a very close PCE under front and rear illuminations in which the values are as high as 2.70% and 2.40%, respectively. All the PCEs of the CuS CEs are much higher than that of the Pt CE (1.34%).

Ke, Weijun; Fang, Guojia; Lei, Hongwei; Qin, Pingli; Tao, Hong; Zeng, Wei; Wang, Jing; Zhao, Xingzhong

2014-02-01

5

A facile synthesis of bimetallic AuPt nanoparticles as a new transparent counter electrode for quantum-dot-sensitized solar cells  

NASA Astrophysics Data System (ADS)

This study first reports the synthesis of AuPt bimetallic nanoparticles (AuPt-BNPs) on an FTO glass substrate using dry plasma reduction (DPR) and its application as an alternative transparent counter electrode (CE) for quantum-dot-sensitized solar cells (QDSCs) operated under bi-side illumination. DPR is an economically feasible and ecologically sustainable method. The formation of ultrafine crystalline AuPt-BNPs on an FTO substrate is confirmed through TEM, HRTEM with HAADF-STEM and HAADF-STEM-EDS analyses. The mechanism for controlling the size, mono-dispersity, and areal number density of nanoparticles on the substrate surface is suggested. The CE fabricated with AuPt-BNPs exhibits a high electro-catalytic activity without losing the optical transmittance of the FTO substrate. The QDSC employing the AuPt-BNP electrode reaches efficiencies of 2.4% under front-side illumination and 2.2% under back-side illumination. Bi-side illumination yields an efficiency of 3.4%, which is comparable to an efficiency of 3.7% obtained for the QDSC with the state-of-the-art CE.

Dao, Van-Duong; Choi, Youngwoo; Yong, Kijung; Larina, Liudmila L.; Shevaleevskiy, Oleg; Choi, Ho-Suk

2015-01-01

6

Pulse-reverse electrodeposition of transparent nickel phosphide film with porous nanospheres as a cost-effective counter electrode for dye-sensitized solar cells.  

PubMed

A Ni2P nanolayer with porous nanospheres was directly coated on fluorine-doped tin oxide glass by pulse-reverse deposition as a low-cost counter electrode catalyst for dye-sensitized solar cells, and the photoelectron conversion efficiency of the cell was increased to 7.32% by using a porous nanosphere catalyst due to the significantly improved ion transport. PMID:24132176

Wu, Mao-Sung; Wu, Jia-Fang

2013-12-01

7

3?D single-walled carbon nanotube/graphene aerogels as pt-free transparent counter electrodes for high efficiency dye-sensitized solar cells.  

PubMed

3D single-walled carbon nanotube (SWCNT)/graphene aerogel (NGS) was synthesized and used as an alternative to platinized fluorine-doped tin oxide (FTO) in dye-sensitized solar cells (DSSCs). An island-like structure formed on the FTO using the spin-coating method, leading to a transmittance (49.86?% at 671?nm). The resulting NGS-based counter electrodes (CEs) exhibited excellent power conversion efficiency (PCE) (8.31?%) compared to Pt (7.56?%). Surprisingly, PCE increased to 9.64?% under assisted by a mirror; The excellent performance of DSSCs can be attributed to the high electrical conductivity and good electrocatalytic activity induced by the SWCNTs and the excellent catalytic properties of graphene, coupled with the 3D structure with a larger surface area and good surface hydrophilicity for increased electrolyte-electrode interactions and electrolyte/reactant diffusion. Hence, our results demonstrate that 3D-NGS materials have considerable potential for DSSC-related applications and merit further investigation. PMID:25351578

Ma, Jie; Li, Cheng; Yu, Fei; Chen, Junhong

2014-12-01

8

Fully solution-processed transparent conducting oxide-free counter electrodes for dye-sensitized solar cells: spray-coated single-wall carbon nanotube thin films loaded with chemically-reduced platinum nanoparticles.  

PubMed

We report fully solution-processed fabrication of transparent conducting oxide-free counter electrodes (CEs) for dye-sensitized solar cells (DSSCs) by combining spray-coating of single-wall carbon nanotubes (SWCNTs) and chemical reduction of chloroplatinic acid precursor to platinum nanoparticles (Pt NPs) with formic acid. The power conversion efficiency of a semitransparent DSSC with such SWCNT-based CE loaded with Pt NPs is comparable to that of a control device with a conventional CE. Quantification of Pt loading shows that network morphology of entangled SWCNTs is efficient in forming and retaining chemically reduced Pt NPs. Moreover, electron microscopy and electrochemical impedance spectroscopy results show that mainly Pt NPs, which are tens of nanometers in diameter and reside at the surface of SWCNT CEs, contribute to electrocatalytic activity for triiodide reduction, to which we attribute strong correlation between power conversion efficiency of DSSCs and time constant deduced from equivalent-circuit analysis of impedance spectra. PMID:25122074

Kim, Sang Yong; Kim, Yesel; Lee, Kyung Moon; Yoon, Woo Sug; Lee, Ho Seok; Lee, Jong Tae; Kim, Seung-Joo; Ahn, Yeong Hwan; Park, Ji-Yong; Lee, Tai Kyu; Lee, Soonil

2014-08-27

9

Optical impedance transformer for transparent conducting electrodes.  

PubMed

A fundamental limitation of transparent conducting electrode design is thought to be the trade-off between photonic and electronic performances. The photonic transmission property of a transparent conducting electrode, however, is not intrinsic but depends critically on the electromagnetic environment where the electrode is located. We develop the concept of optical impedance transformation, and use this concept to design nanophotonic structures that provide broadband and omnidirectional reduction of optical loss in an ultrathin transparent conducting electrode, without compromising its electrical performance. PMID:24773302

Wang, Ken Xingze; Piper, Jessica R; Fan, Shanhui

2014-05-14

10

Optical impedance transformer for transparent conducting electrodes  

NASA Astrophysics Data System (ADS)

We present a practical and robust concept to bypass the typical trade-off between optical transparency and electrical conductivity of transparent conducting electrodes. A transparent conducting electrode serves to transmit photons and conduct electrons, and the frequencies of the corresponding optical and dc electric fields differ by at least 12 orders of magnitude. Therefore, we could engineer the optical electric field to influence the optical property, which is not intrinsic, of the transparent electrode without sacrificing its electrical performance. For a given light power input, the optical impedance transformer reduces the loss in a transparent electrode by raising the refractive index of its surrounding medium. The concept of optical impedance transformer can be realized by nanocone arrays, and we use it to design nanophotonic structures that provide broadband and omnidirectional reduction of optical loss in an ultrathin graphene electrode. In addition, the concept applies to thicker or nanostructured transparent electrodes. The results are verified against first-principles full-field electromagnetic simulations.

Wang, Ken X.; Piper, Jessica R.; Fan, Shanhui

2014-09-01

11

Performance dependence of Si quantum dot-sensitized solar cells on counter electrode  

NASA Astrophysics Data System (ADS)

Au counter electrode is generally used with polysulfide electrolyte for quantum dot-sensitized solar cells (QDSCs) due to degradation of QD by iodine electrolyte and strong interaction between Pt counter electrode and S2- ions in polysulfide electrolyte. In this work, the effects of the thickness and morphology of Au counter electrode on the performance of Si QDSC were investigated. Au film thickness was linearly controlled from 5 to 500 nm by deposition time. Cyclic voltammetry and impedance analysis clarified the catalytic activity of counter electrode, surface resistance of transparent conductive oxide (TCO), and the charge transportation at the counter electrode. The increase of Au film thickness reduced the surface resistance of TCO with increased conductivity. No significant difference in the redox reaction from electrolyte to Si QDs was observed for Au film thickness from 20 to 500 nm. Catalytic reaction of counter electrode was activated with the increase of Au film thickness up to 200 nm. The impedance of charge transportation at the counter electrode was also decreased with Au deposition. Their surface resistance, catalytic activity and internal resistance were reflected in overall performance. Consequently, Si QDSC with 200-nm-thick Au counter electrode had the best performance.

Seo, Hyunwoong; Ichida, Daiki; Uchida, Giichiro; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu

2014-01-01

12

Transparent electrode for optical switch  

DOEpatents

The invention relates generally to optical switches and techniques for applying a voltage to an electro-optical crystal, and more particularly, to transparent electodes for an optical switch. System architectures for very large inertial confinement fusion (ICF) lasers require active optical elements with apertures on the order of one meter. Large aperture optical switches are needed for isolation of stages, switch-out from regenerative amplifier cavities and protection from target retroreflections.

Goldhar, J.; Henesian, M.A.

1984-10-19

13

Transparent metallic fractal electrodes for semiconductor devices.  

PubMed

Nanostructured metallic films have the potential to replace metal oxide films as transparent electrodes in optoelectronic devices. An ideal transparent electrode should possess a high, broadband, and polarization-independent transmittance. Conventional metallic gratings and grids with wavelength-scale periodicities, however, do not have all of these qualities. Furthermore, the transmission properties of a nanostructured electrode need to be assessed in the actual dielectric environment provided by a device, where a high-index semiconductor layer can reflect a substantial fraction of the incident light. Here we propose nanostructured aluminum electrodes with space-filling fractal geometries as alternatives to gratings and grids and experimentally demonstrate their superior optoelectronic performance through integration with Si photodetectors. As shown by polarization and spectrally resolved photocurrent measurements, devices with fractal electrodes exhibit both a broadband transmission and a flat polarization response that outperforms both square grids and linear gratings. Finally, we show the benefits of adding a thin silicon nitride film to the nanostructured electrodes to further reduce reflection. PMID:25140611

Afshinmanesh, Farzaneh; Curto, Alberto G; Milaninia, Kaveh M; van Hulst, Niek F; Brongersma, Mark L

2014-09-10

14

MWCNT employed counter electrode for DSSCs  

Microsoft Academic Search

In this study, we proposed and investigated the performance of DSSCs with the multi-walled carbon nanotube (MWCNT) on the counter electrode(CE). The 0.45cm2 DSSC device of glass\\/FTO\\/TiO2 blocking layer\\/TiO2(8.5um)\\/Dye(N719)\\/ electrolyte (C6DMII,GSCN)\\/MWCNT\\/FTO\\/glass was fabricated, and then the surface morphology of CEs and the energy conversion efficiency of the DSSC device were characterized by scanning electron microscope(SEM), photocurrent-voltage(I–V), cyclic voltammetry(C-V), and Impedance

Byungkwan Yu; Yunyoung Noh; Jeungjo Han; Ohsung Song

2011-01-01

15

Copper Nanowires as Fully Transparent Conductive Electrodes  

PubMed Central

In pondering of new promising transparent conductors to replace the cost rising tin-doped indium oxide (ITO), metal nanowires have been widely concerned. Herein, we demonstrate an approach for successful synthesis of long and fine Cu nanowires (NWs) through a novel catalytic scheme involving nickel ions. Such Cu NWs in high aspect ratio (diameter of 16.2 ± 2?nm and length up to 40??m) provide long distance for electron transport and, meanwhile, large space for light transmission. Transparent electrodes fabricated using the Cu NW ink achieve a low sheet resistance of 1.4?Ohm/sq at 14% transmittance and a high transparency of 93.1% at 51.5?Ohm/sq. The flexibility and stability were tested with 100-timebending by 180°and no resistance change occurred. Ohmic contact was achieved to the p- and n-GaN on blue light emitting diode chip and bright electroluminescence from the front face confirmed the excellent transparency. PMID:23900572

Guo, Huizhang; Lin, Na; Chen, Yuanzhi; Wang, Zhenwei; Xie, Qingshui; Zheng, Tongchang; Gao, Na; Li, Shuping; Kang, Junyong; Cai, Duanjun; Peng, Dong-Liang

2013-01-01

16

Innovative transparent electrode for flexible displays  

NASA Astrophysics Data System (ADS)

This paper presents a new transparent electrode (TE) for flexible displays and energy saving windows. The TE is a room temperature vacuum-deposited multi-layer thin-film system. Both highly transparent rigid materials including glass and ceramics as well as flexible polymeric materials such as polyethylene terephthalate (PET) and polypropylene can serve as substrates for the TE. The TE is deposited as a flexible coating that can be rolled around a 0.5cm diameter cylinder with little or no reduction in electrical conductivity and that can assume pre-extension states after an applied stress is relieved. The TE exhibits high visible transmittance without color. The transmission spectrum of the TE, which matches the eye sensitivity curve, allows the viewing of true background colors through the coating. The photopic transmittance of the TE is 88% and it is a UV inhibiter. The new transparent conductor has 3-5 Ohm/sq of sheet resistance. The environmental stability of the TE was evaluated in a wedeometer with the coating on a PET substrate withstanding 150 hours at 50 °C, 95% humidity, and ultraviolet (UV), without changing its original performance. The coating can be patterned using standard etching procedures.. In this paper, the properties of the TE are compared with those of common transparent conductive oxides (TCO) including ITO, ZnO: Al and SnO2:F. In addition to the technical description, the paper analyzes potential markets and applications of the TE with emphasis on the replacing current TCO coatings, specifically ITO for flexible display electrode and energy saving window applications.

Demiryont, Hulya; Shannon, Kenneth C., III

2006-05-01

17

Electrolessly deposited electrospun metal nanowire transparent electrodes.  

PubMed

Metal nanowire (MNW) transparent electrodes have been widely developed for their promising sheet resistance (R(s))-transmittance (T) performance, excellent mechanical flexibility, and facile synthesis. How to lower the junction resistance without compromising optical transmittance has become the key issue in enhancing their performance. Here we combine electrospinning and electroless deposition to synthesize interconnected, ultralong MNW networks. For both silver and copper nanowire networks, the R(s) and T values reach around 10 ?/sq and 90%, respectively. This process is scalable and takes place at ambient temperature and pressure, which opens new opportunities for flexible electronics and roll-to-roll large-scale manufacturing. PMID:25019606

Hsu, Po-Chun; Kong, Desheng; Wang, Shuang; Wang, Haotian; Welch, Alex J; Wu, Hui; Cui, Yi

2014-07-30

18

Graphene Transparent Conductive Electrodes for Next- Generation Microshutter Arrays  

NASA Technical Reports Server (NTRS)

Graphene is a single atomic layer of graphite. It is optically transparent and has high electron mobility, and thus has great potential to make transparent conductive electrodes. This invention contributes towards the development of graphene transparent conductive electrodes for next-generation microshutter arrays. The original design for the electrodes of the next generation of microshutters uses indium-tin-oxide (ITO) as the electrode material. ITO is widely used in NASA flight missions. The optical transparency of ITO is limited, and the material is brittle. Also, ITO has been getting more expensive in recent years. The objective of the invention is to develop a graphene transparent conductive electrode that will replace ITO. An exfoliation procedure was developed to make graphene out of graphite crystals. In addition, large areas of single-layer graphene were produced using low-pressure chemical vapor deposition (LPCVD) with high optical transparency. A special graphene transport procedure was developed for transferring graphene from copper substrates to arbitrary substrates. The concept is to grow large-size graphene sheets using the LPCVD system through chemical reaction, transfer the graphene film to a substrate, dope graphene to reduce the sheet resistance, and pattern the film to the dimension of the electrodes in the microshutter array. Graphene transparent conductive electrodes are expected to have a transparency of 97.7%. This covers the electromagnetic spectrum from UV to IR. In comparison, ITO electrodes currently used in microshutter arrays have 85% transparency in mid-IR, and suffer from dramatic transparency drop at a wavelength of near-IR or shorter. Thus, graphene also has potential application as transparent conductive electrodes for Schottky photodiodes in the UV region.

Li, Mary; Sultana, Mahmooda; Hess, Larry

2012-01-01

19

Solution-processed metal nanowire mesh transparent electrodes.  

PubMed

Transparent conductive electrodes are important components of thin-film solar cells, light-emitting diodes, and many display technologies. Doped metal oxides are commonly used, but their optical transparency is limited for films with a low sheet resistance. Furthermore, they are prone to cracking when deposited on flexible substrates, are costly, and require a high-temperature step for the best performance. We demonstrate solution-processed transparent electrodes consisting of random meshes of metal nanowires that exhibit an optical transparency equivalent to or better than that of metal-oxide thin films for the same sheet resistance. Organic solar cells deposited on these electrodes show a performance equivalent to that of devices based on a conventional metal-oxide transparent electrode. PMID:18189445

Lee, Jung-Yong; Connor, Stephen T; Cui, Yi; Peumans, Peter

2008-02-01

20

Failure of silver nanowire transparent electrodes under current flow  

PubMed Central

Silver nanowire transparent electrodes have received much attention as a replacement for indium tin oxide, particularly in organic solar cells. In this paper, we show that when silver nanowire electrodes conduct current at levels encountered in organic solar cells, the electrodes can fail in as little as 2?days. Electrode failure is caused by Joule heating which causes the nanowires to breakup and thus create an electrical discontinuity in the nanowire film. More heat is created, and thus failure occurs sooner, in more resistive electrodes and at higher current densities. Suggestions to improve the stability of silver nanowire electrodes are given. PMID:23680014

2013-01-01

21

Tungsten Trioxide/Liquid Electrolyte Electrochromic Devices with Amorphous Iron Tungstate Counter Electrodes— Response Characteristics and Cell Reliability  

NASA Astrophysics Data System (ADS)

Tungsten trioxide electrochromic devices using amorphous iron tungstate-graphite mixtures as counter electrodes were investigasted with the aim of attaining high reliability in such devices. The display electrode was prepared by an improved process which preserves transparent conductive layers in direct contact with the electrolyte, preventing the latter from dissolving them. Spin-on-glass-coated soda-glass substrates were used to eliminate the cell degradation caused by Na diffusion from substrate glass into WO3 films. Iron tungstate-graphite counter electrodes typically have a large capacity of 100 mC/V\\cdotcm2, with the result that the counter electrode potential change during operation was very small. Cells could be operated at a constant voltage with preferable response and long cycle lives of over 107.

Yamanaka, Kazusuke

1986-07-01

22

Surface-Plasmon Enhanced Transparent Electrodes in Organic Photovoltaics  

SciTech Connect

Random silver nanohole films were created through colloidal lithography techniques and metal vapor deposition. The transparent electrodes were characterized by uv-visible spectroscopy and incorporated into an organic solar cell. The test cells were evaluated for solar power-conversion efficiency and incident photon-to-current conversion efficiency. The incident photon-to-current conversion efficiency spectra displayed evidence that a nanohole film with 92 nm diameter holes induces surface-plasmon-enhanced photoconversion. The nanohole silver films demonstrate a promising route to removing the indium tin oxide transparent electrode that is ubiquitous in organic optoelectronics.

Reilly III, T. H.; van de Lagemaat, J.; Tenent, R. C.; Morfa, A. J.; Rowlen, K. L.

2008-01-01

23

TCO/Ag/TCO transparent electrodes for solar cells application  

NASA Astrophysics Data System (ADS)

Among transparent electrodes, transparent conductive oxides (TCO)/metal/TCO structures can achieve optical and electrical performances comparable to, or better than, single TCO layers and very thin metallic films. In this work, we report on thin multilayers based on aluminum zinc oxide (AZO), indium tin oxide (ITO) and Ag deposited by RF magnetron sputtering on soda lime glass at room temperature. The TCO/Ag/TCO structures with thicknesses of about 50/10/50 nm were deposited with all combinations of AZO and ITO as top and bottom layers. While the electrical conductivity is dominated by the Ag intralayer irrespective of the TCO nature, the optical transmissions show a dependence on the nature of the top and bottom TCOs, mainly due to the change in the reflectivity of the multilayers. Structural, electrical and optical properties are studied to optimize the structure for very thin transparent electrodes suitable for photovoltaic applications.

Boscarino, S.; Crupi, I.; Mirabella, S.; Simone, F.; Terrasi, A.

2014-09-01

24

Hot-rolling nanowire transparent electrodes for surface roughness minimization  

PubMed Central

Silver nanowire transparent electrodes are a promising alternative to transparent conductive oxides. However, their surface roughness presents a problem for their integration into devices with thin layers such as organic electronic devices. In this paper, hot rollers are used to soften plastic substrates with heat and mechanically press the nanowires into the substrate surface. By doing so, the root-mean-square surface roughness is reduced to 7 nm and the maximum peak-to-valley value is 30 nm, making the electrodes suitable for typical organic devices. This simple process requires no additional materials, which results in a higher transparency, and is compatible with roll-to-roll fabrication processes. In addition, the adhesion of the nanowires to the substrate significantly increases. PMID:24994963

2014-01-01

25

Transparent electrode with a nanostructured coating.  

PubMed

Using single-walled nanotubes as an example, we fabricated transparent conductive coatings and demonstrated a new technique of centrifuge coating as a potential low-waste, solution-based batch process for the fabrication of nanostructured coatings. A theoretical model is developed to account for the sheet resistance exhibited by layered random-network coatings such as nanofilaments and graphene. The model equation is analytical and compact, and allows the correlation of very different scaling regimes reported in the literature to the underlying coating microstructure. Finally, we also show a refined experimental setup to systematically measure the curvature-dependent sheet resistance. PMID:21370898

Huang, Yan Y; Terentjev, Eugene M

2011-03-22

26

Improved thermal oxidation stability of solution-processable silver nanowire transparent electrode by reduced graphene oxide.  

PubMed

Solution-processable silver nanowire-reduced graphene oxide (AgNW-rGO) hybrid transparent electrode was prepared in order to replace conventional ITO transparent electrode. AgNW-rGO hybrid transparent electrode exhibited high optical transmittance and low sheet resistance, which is comparable to ITO transparent electrode. In addition, it was found that AgNW-rGO hybrid transparent electrode exhibited highly enhanced thermal oxidation and chemical stabilities due to excellent gas-barrier property of rGO passivation layer onto AgNW film. Furthermore, the organic solar cells with AgNW-rGO hybrid transparent electrode showed good photovoltaic behavior as much as solar cells with AgNW transparent electrode. It is expected that AgNW-rGO hybrid transparent electrode can be used as a key component in various optoelectronic application such as display panels, touch screen panels, and solar cells. PMID:23206541

Ahn, Yumi; Jeong, Youngjun; Lee, Youngu

2012-12-01

27

Carbon Nanotube Assemblies for Transparent Conducting Electrodes  

SciTech Connect

The goal of this chapter is to introduce readers to the fundamental and practical aspects of nanotube assemblies made into transparent conducting networks and discuss some practical aspects of their characterization. Transparent conducting coatings (TCC) are an essential part of electro-optical devices, from photovoltaics and light emitting devices to electromagnetic shielding and electrochromic widows. The market for organic materials (including nanomaterials and polymers) based TCCs is expected to show a growth rate of 56.9% to reach nearly 20.3billionin2015,whilethemarketfortraditionalinorganictransparentelectronicswillexperiencegrowthwithratesof6.7103 billion in 2015. Emerging flexible electronic applications have brought additional requirements of flexibility and low cost for TCC. However, the price of indium (the major component in indium tin oxide TCC) continues to increase. On the other hand, the price of nanomaterials has continued to decrease due to development of high volume, quality production processes. Additional benefits come from the low cost, nonvacuum deposition of nanomaterials based TCC, compared to traditional coatings requiring energy intensive vacuum deposition. Among the materials actively researched as alternative TCC are nanoparticles, nanowires, and nanotubes with high aspect ratio as well as their composites. The figure of merit (FOM) can be used to compare TCCs made from dissimilar materials and with different transmittance and conductivity values. In the first part of this manuscript, we will discuss the seven FOM parameters that have been proposed, including one specifically intended for flexible applications. The approach for how to measure TCE electrical properties, including frequency dependence, will also be discussed. We will relate the macroscale electrical characteristics of TCCs to the nanoscale parameters of conducting networks. The fundamental aspects of nanomaterial assemblies in conducting networks will also be addressed. We will review recent literature on TCCs composed of carbon nanotubes of different types in terms of the FOM.

Garrett, Matthew P [ORNL] [ORNL; Gerhardt, Rosario [ORNL] [ORNL

2012-01-01

28

Topological insulator nanostructures for near-infrared transparent flexible electrodes.  

PubMed

Topological insulators are an intriguing class of materials with an insulating bulk state and gapless Dirac-type edge/surface states. Recent theoretical work predicts that few-layer topological insulators are promising candidates for broadband and high-performance optoelectronic devices due to their spin-momentum-locked massless Dirac edge/surface states, which are topologically protected against all time-reversal-invariant perturbations. Here, we present the first experimental demonstration of near-infrared transparent flexible electrodes based on few-layer topological-insulator Bi(2)Se(3) nanostructures epitaxially grown on mica substrates by means of van der Waals epitaxy. The large, continuous, Bi(2)Se(3)-nanosheet transparent electrodes have single Dirac cone surface states, and exhibit sheet resistances as low as ~330 ? per square, with a transparency of more than 70% over a wide range of wavelengths. Furthermore, Bi(2)Se(3)-nanosheet transparent electrodes show high chemical and thermal stabilities as well as excellent mechanical durability, which may lead to novel optoelectronic devices with unique properties. PMID:22437712

Peng, Hailin; Dang, Wenhui; Cao, Jie; Chen, Yulin; Wu, Di; Zheng, Wenshan; Li, Hui; Shen, Zhi-Xun; Liu, Zhongfan

2012-04-01

29

Electro-deposited vanadium oxide as a counter-electrode for PProDOT-Me2 based electrochromic devices (ECDs)  

NASA Astrophysics Data System (ADS)

A preparation and characterization of thin film vanadium oxide for use as a transparent ion storage layer/counter-electrode in organic ECDs is reported. A cathodic polymer film, Poly[3,3-dimethyle-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine] (PProDOT-Me2) was used as the electrochromic material. Counter-electrodes were prepared using a sol-gel method and deposited using electrophoresis. Indium Tin oxide (I TO) glass was used as an electrically conductive and transparent substrate. This paper focuses on optimized characteristics complimentary to a PProDOT-Me2 based electrochromic thin film. Gels of vanadium oxide were created from V2O5 powder mixed with hydrogen peroxide (H2O2) and deionized water. Thin films were deposited onto a substrate submerged in the solution and subjected to cyclic voltammetry. Deposition parameters were varied and their effect on counter electrode characteristics investigated. The thin film exhibited a capacitance curve similar to the PProDOT-Me2 based EC film while maintaining a transmittance greater than 60% indicating that V2O5 is a suitable material. The ensuing 1 inch x 1 inch smart window exhibits a change in transmittance of 60% and a lifetime of over 100,000 cycles at a switching speed of 1 second. Larger sized devices of six and twelve inches were successfully prepared and switched between the dark blue and transparent states in less than 15 seconds.

Kaneko, Calen; Xu, Chunye; Liu, Lu; Ning, Dai; Taya, Minoru

2005-05-01

30

Comparison of transparent conducting electrodes on mercuric iodide photocells  

SciTech Connect

Three materials have been developed and tested which are suitable as transparent conducting electrodes on mercuric iodide; aqueous ionic contacts of NAC/ell/ and LiC/ell/, polyvinyl alcohol/phosphoric acid, and indium--tin--oxide (ITO). Polyvinyl alcohol/phosphoric acid is a conducting polymer and ITO is a wide band gap semiconductor. Photocell dimensions were in the range of 0.5 to 3.8 cm diam by about 1 mm thick. Photocells with these electrodes were evaluated for their spectral response in the range of 300 to 650 nm, response uniformity over the electrode activities area, leakage current and reliability. All units showed better than 75% quantum efficiency in the range 350 to 550 nm. Photodetector leakage currents ranged from 25 to 200 pA and have shown long term stability up to 1 year.

Cheng, A.Y.; Markakis, J.M.

1987-01-01

31

Carbon microspheres via microwave-assisted synthesis as counter electrodes of dye-sensitized solar cells.  

PubMed

Carbon microspheres (CSs) were successfully fabricated and used as counter electrodes of dye-sensitized solar cells (DSSCs). CSs were obtained through a fast microwave-assisted approach using sucrose as the precursor in a microwave system and subsequent thermal treatment at 600, 800 and 1000°C. A maximum photovoltaic conversion efficiency of 5.5% is achieved for DSSCs based on the CSs counter electrodes, which is comparable to the cell based on conventional Pt counter electrode at one sun (AM 1.5G, 100mWcm(-2)). The results suggest the CSs to be a potential candidate for counter electrodes of DSSCs. PMID:25643959

Sun, Hengchao; Chen, Taiqiang; Liu, Yong; Hou, Xian; Zhang, Li; Zhu, Guang; Sun, Zhuo; Pan, Likun

2015-05-01

32

Flexible carbon nanotube-based composite plates as efficient monolithic counter electrodes for dye solar cells.  

PubMed

We demonstrate a general approach to fabricate a novel low-cost, lightweight and flexible nanocomposite foil that can be effectively implemented as a monolithic counter-electrode in dye solar cells. The pivotal aim of this work was to replace not only the platinum catalyzer film, but even the underlying transparent conductive oxide-coated substrate, by means of a monolithic counter electrode based on carbonaceous materials. According to our approach, a proper dispersion of multiwalled carbon nanotubes (MWCNTs) has been added to a dilute polypropylene solution in toluene. The composite solution has been then adequately mixed and subsequently dried by means of a controlled solvent evaporation process; the resulting powder has been modeled by compression molding into thin plates. Four different series of plates have been realized by tuning the carbon nanotubes concentration from 5 wt % to 20 wt %. Finally, a specifically setup reactive ion etching treatment with oxygen plasma has been carried out onto the plate surface to remove the residual polymeric capping layer and allow the embedded CNTs to protrude on top of the surface. A fine-tuning of the morphological features has been made possible by adjusting the plasma etching conditions. For all the treated surfaces, the most meaningful electrochemical parameters have been quantitatively analyzed by means of both electrochemical impedance spectroscopy and cyclic voltammetry measurements. An as high as 13.8 mA/cm(2) photocurrent density, along with a solar conversion efficiency of 6.67%, has been measured for a dye solar cell mounting a counter-electrode based on a 20 wt % CNT nanocomposite. PMID:21870845

Malara, Francesco; Manca, Michele; De Marco, Luisa; Pareo, Paola; Gigli, Giuseppe

2011-09-01

33

Uniformly embedded silver nanomesh as highly bendable transparent conducting electrode  

NASA Astrophysics Data System (ADS)

Ag-nanomesh-based highly bendable conducting electrodes are developed using a combination of metal nanotransfer printing and embossing for the 6-inch wafer scale. Two Ag nanomeshes, including pitch sizes of 7.5 and 10 ?m, are used to obtain highly transparent (approximately 85% transmittance at a wavelength of 550 nm) and electrically conducting properties (below 10 ? sq?1). The Ag nanomeshes are also distinguished according to the fabrication process, which is called transferred or embedded Ag nanomesh on polyethylene terephthalate (PET) substrate, in order to compare their stability against bending stress. Then the enhancement of bending stability when the Ag nanomesh is embedded in the PET substrate is confirmed.

Choi, Hak-Jong; Choo, Soyoung; Jung, Pil-Hoon; Shin, Ju-Hyeon; Kim, Yang-Doo; Lee, Heon

2015-02-01

34

Dye-sensitized solar cell counter electrodes based on carbon nanotubes.  

PubMed

Dye-sensitized solar cells (DSSCs) have received significant attention from the scientific community since their discovery in 1991. However, the high cost and scarcity of platinum has motivated researchers to seek other suitable materials for the counter electrode of DSSCs. Owing to their exceptional properties such as high conductivity, good electrochemical activity, and low cost, carbon nanotubes (CNTs) have been considered as promising alternatives to expensive platinum (Pt) in the counter electrode of DSSCs. Herein, we provide a Minireview of the CNTs use in the counter electrode of DSSCs. A brief overview of Pt-based counter electrodes is also discussed. Particular attention is given to the recent advances of counter electrodes with CNT-based composite structures. PMID:25367083

Hwang, Seunghwa; Batmunkh, Munkhbayar; Nine, Md J; Chung, Hanshik; Jeong, Hyomin

2015-01-12

35

Design of dielectric/metal/dielectric transparent electrodes for flexible electronics  

NASA Astrophysics Data System (ADS)

A flexible transparent electrode (FTE) is one of the most essential parts for the next generation of flexible optoelectronic devices, including solar cells, displays, and solid-state lighting devices. Although a lot of candidate materials for the FTE such as metallic nanowires, carbon nanotube, and graphene have been investigated, each material has fundamental limits as FTE applications, such as low transmittance (70% to 80%), high sheet resistance (>100 ohm/sq) and rough surface morphology. Dielectric/metal/dielectric (DMD) electrode structure is a promising candidate for next-generation flexible transparent electrodes. Compared with other transparent electrodes, DMD electrodes show best performance in terms of optical transparency, sheet resistance, and mechanical flexibility. In addition, it has been also reported that the device performances can be significantly enhanced by the microcavity effects with the DMD electrodes. We review the relevant principles and discusses recent progress in DMD electrodes.

Kim, Sungjun; Lee, Jong-Lam

2012-01-01

36

Ultrasmooth, extremely deformable and shape recoverable Ag nanowire embedded transparent electrode  

PubMed Central

Transparent electrodes have been widely used in electronic devices such as solar cells, displays, and touch screens. Highly flexible transparent electrodes are especially desired for the development of next generation flexible electronic devices. Although indium tin oxide (ITO) is the most commonly used material for the fabrication of transparent electrodes, its brittleness and growing cost limit its utility for flexible electronic devices. Therefore, the need for new transparent conductive materials with superior mechanical properties is clear and urgent. Ag nanowire (AgNW) has been attracting increasing attention because of its effective combination of electrical and optical properties. However, it still suffers from several drawbacks, including large surface roughness, instability against oxidation and moisture, and poor adhesion to substrates. These issues need to be addressed before wide spread use of metallic NW as transparent electrodes can be realized. In this study, we demonstrated the fabrication of a flexible transparent electrode with superior mechanical, electrical and optical properties by embedding a AgNW film into a transparent polymer matrix. This technique can produce electrodes with an ultrasmooth and extremely deformable transparent electrode that have sheet resistance and transmittance comparable to those of an ITO electrode. PMID:24763248

Nam, Sanggil; Song, Myungkwan; Kim, Dong-Ho; Cho, Byungjin; Lee, Hye Moon; Kwon, Jung-Dae; Park, Sung-Gyu; Nam, Kee-Seok; Jeong, Yongsoo; Kwon, Se-Hun; Park, Yun Chang; Jin, Sung-Ho; Kang, Jae-Wook; Jo, Sungjin; Kim, Chang Su

2014-01-01

37

Ultrasmooth, extremely deformable and shape recoverable Ag nanowire embedded transparent electrode.  

PubMed

Transparent electrodes have been widely used in electronic devices such as solar cells, displays, and touch screens. Highly flexible transparent electrodes are especially desired for the development of next generation flexible electronic devices. Although indium tin oxide (ITO) is the most commonly used material for the fabrication of transparent electrodes, its brittleness and growing cost limit its utility for flexible electronic devices. Therefore, the need for new transparent conductive materials with superior mechanical properties is clear and urgent. Ag nanowire (AgNW) has been attracting increasing attention because of its effective combination of electrical and optical properties. However, it still suffers from several drawbacks, including large surface roughness, instability against oxidation and moisture, and poor adhesion to substrates. These issues need to be addressed before wide spread use of metallic NW as transparent electrodes can be realized. In this study, we demonstrated the fabrication of a flexible transparent electrode with superior mechanical, electrical and optical properties by embedding a AgNW film into a transparent polymer matrix. This technique can produce electrodes with an ultrasmooth and extremely deformable transparent electrode that have sheet resistance and transmittance comparable to those of an ITO electrode. PMID:24763248

Nam, Sanggil; Song, Myungkwan; Kim, Dong-Ho; Cho, Byungjin; Lee, Hye Moon; Kwon, Jung-Dae; Park, Sung-Gyu; Nam, Kee-Seok; Jeong, Yongsoo; Kwon, Se-Hun; Park, Yun Chang; Jin, Sung-Ho; Kang, Jae-Wook; Jo, Sungjin; Kim, Chang Su

2014-01-01

38

Uniformly embedded silver nanomesh as highly bendable transparent conducting electrode.  

PubMed

Ag-nanomesh-based highly bendable conducting electrodes are developed using a combination of metal nanotransfer printing and embossing for the 6-inch wafer scale. Two Ag nanomeshes, including pitch sizes of 7.5 and 10 ?m, are used to obtain highly transparent (approximately 85% transmittance at a wavelength of 550 nm) and electrically conducting properties (below 10 ? sq(-1)). The Ag nanomeshes are also distinguished according to the fabrication process, which is called transferred or embedded Ag nanomesh on polyethylene terephthalate (PET) substrate, in order to compare their stability against bending stress. Then the enhancement of bending stability when the Ag nanomesh is embedded in the PET substrate is confirmed. PMID:25590555

Choi, Hak-Jong; Choo, Soyoung; Jung, Pil-Hoon; Shin, Ju-Hyeon; Kim, Yang-Doo; Lee, Heon

2015-02-01

39

AlGaN\\/GaN HEMT With a Transparent Gate Electrode  

Microsoft Academic Search

AlGaN\\/GaN high-electron-mobility transistors (HEMTs) with indium tin oxide (ITO) transparent gate electrodes have been fabricated. The transparent gate electrodes enable the investigation of photon, electron, and phonon behaviors in active regions in HEMTs using optical characterizations such as electroluminescence, photoluminescence, and Raman spectroscopy technologies. Leakage current, on\\/off ratio, and transparency have been compared for transistors using Ni\\/Au\\/Ni, ITO, and Ni\\/ITO

Yi Pei; Kenneth J. Vampola; Zhen Chen; Rongming Chu; Steven P. DenBaars; Umesh K. Mishra

2009-01-01

40

Carbon nanotube counter electrode for high-efficient fibrous dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

High-efficient fibrous dye-sensitized solar cell with carbon nanotube (CNT) thin films as counter electrodes has been reported. The CNT films were fabricated by coating CNT paste or spraying CNT suspension solution on Ti wires. A fluorine tin oxide-coated CNT underlayer was used to improve the adherence of the CNT layer on Ti substrate for sprayed samples. The charge transfer catalytic behavior of fibrous CNT/Ti counter electrodes to the iodide/triiodide redox pair was carefully studied by electrochemical impedance and current-voltage measurement. The catalytic activity can be enhanced by increasing the amount of CNT loading on substrate. Both the efficiencies of fibrous dye-sensitized solar cells using paste coated and sprayed CNT films as counter electrodes are comparative to that using Pt wires, indicating the feasibility of CNT/Ti wires as fibrous counter electrode for superseding Pt wires.

Huang, Shuqing; Sun, Huicheng; Huang, Xiaoming; Zhang, Quanxin; Li, Dongmei; Luo, Yanhong; Meng, Qingbo

2012-04-01

41

Conducting polymers based counter electrodes for dye-sensitized solar cells  

SciTech Connect

Conducting polymer films were synthesized and employed as an alternative to expensive platinum counter electrodes for dye-sensitized solar cells. poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) thin films were spin-coated and polypyrrole films were electrochemically deposited via cyclic voltammetry method on ITO substrates. The morphology of the films were imaged by SEM and AFM. These films show good catalytic activity towards triiodide reduction as compared to Pt/FTO electrodes. Finally the photovoltaic performance of DSSC fabricated using N3 dye were compared with PT/FTO, PEDOT/ITO, and e-PPy counter electrodes.

Veerender, P., E-mail: veeru1009@gmail.com, E-mail: veeru1009@gmail.com; Saxena, Vibha, E-mail: veeru1009@gmail.com, E-mail: veeru1009@gmail.com; Gusain, Abhay, E-mail: veeru1009@gmail.com, E-mail: veeru1009@gmail.com; Jha, P., E-mail: veeru1009@gmail.com, E-mail: veeru1009@gmail.com; Koiry, S. P., E-mail: veeru1009@gmail.com, E-mail: veeru1009@gmail.com; Chauhan, A. K., E-mail: veeru1009@gmail.com, E-mail: veeru1009@gmail.com; Aswal, D. K., E-mail: veeru1009@gmail.com, E-mail: veeru1009@gmail.com; Gupta, S. K., E-mail: veeru1009@gmail.com, E-mail: veeru1009@gmail.com [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai - 400085 (India)

2014-04-24

42

Conducting polymers based counter electrodes for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Conducting polymer films were synthesized and employed as an alternative to expensive platinum counter electrodes for dye-sensitized solar cells. poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) thin films were spin-coated and polypyrrole films were electrochemically deposited via cyclic voltammetry method on ITO substrates. The morphology of the films were imaged by SEM and AFM. These films show good catalytic activity towards triiodide reduction as compared to Pt/FTO electrodes. Finally the photovoltaic performance of DSSC fabricated using N3 dye were compared with PT/FTO, PEDOT/ITO, and e-PPy counter electrodes.

Veerender, P.; Saxena, Vibha; Gusain, Abhay; Jha, P.; Koiry, S. P.; Chauhan, A. K.; Aswal, D. K.; Gupta, S. K.

2014-04-01

43

Nanostructured electrochromic films by inkjet printing on large area and flexible transparent silver electrodes  

NASA Astrophysics Data System (ADS)

Printed electrochromic flexible films were obtained by combining transparent silver grid electrodes formed by self-assembly and inkjet printed WO3 nanoparticles. Concentrated dispersions of WO3 nanoparticles were inkjet printed on transparent plastic silver grid electrodes with a high transparency of 83% in the spectral range of 400-800 nm, and a low sheet resistance in the range of 1-5 ? sq-1. These electrodes were used for electrochromic applications for the first time. The resultant patterned nanostructured electrochromic films maintained their coloring and bleaching performance after bending of the flexible films.Printed electrochromic flexible films were obtained by combining transparent silver grid electrodes formed by self-assembly and inkjet printed WO3 nanoparticles. Concentrated dispersions of WO3 nanoparticles were inkjet printed on transparent plastic silver grid electrodes with a high transparency of 83% in the spectral range of 400-800 nm, and a low sheet resistance in the range of 1-5 ? sq-1. These electrodes were used for electrochromic applications for the first time. The resultant patterned nanostructured electrochromic films maintained their coloring and bleaching performance after bending of the flexible films. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06890k

Layani, Michael; Darmawan, Peter; Foo, Wan Ling; Liu, Liang; Kamyshny, Alexander; Mandler, Daniel; Magdassi, Schlomo; Lee, Pooi See

2014-04-01

44

Electrochemical and Optical Evaluation of Noble Metal-and Carbon-ITO Hybrid Optically Transparent Electrodes  

SciTech Connect

Optically transparent hybrid electrodes were constructed by sputtering or thermally evaporating layers of varying thickness of Au, Pd, Pt, or C onto an existing conductive indium-tin oxide (ITO) layer on glass. These electrodes were characterized using UV-Vis spectroscopy and cyclic voltammetry; redox probes examined were potassium ferricyanide, tris-(2, 2'-bipyridyl)ruthenium(II) chloride, hydroquinone, and para-aminophenol (PAP). Each type of hybrid was evaluated and compared with other hybrids, as well as with bare ITO electrodes and commercially available Au, Pt, and glassy carbon disk electrodes. Our results indicated that these hybrid electrodes are reasonably robust, easy to prepare, and extend the capabilities of bare ITO surfaces with respect to the electrochemical response (especially for organic redox probes), while giving up little in the way of optical transparency. Because of these characteristics, hybrid electrodes should be especially suited to many spectroelectrochemical applications.

Zudans, Imants; Paddock, Jean R.; Kuramitz, Hideki; Maghasi, Anne T.; Wansapura, Chamika M.; Conklin, Sean D.; Kaval, Necati; Shtoyko, Tanya; Monk, David J.; Bryan, Samuel A.; Hubler, Timothy L.; Richardson, John N.; Seliskar, Carl J.; Heineman, William R.

2004-04-15

45

Electrochemically Reduced Graphene Oxide Multilayer Films as Efficient Counter Electrode for Dye-Sensitized Solar Cells  

PubMed Central

We report on a new counter electrode for dye-sensitized solar cells (DSCs), which is prepared using layer-by-layer assembly of negatively charged graphene oxide and positively charged poly (diallyldimethylammonium chloride) followed by an electrochemical reduction procedure. The DSC devises using the heteroleptic Ru complex C106TBA as sensitizer and this new counter electrode reach power conversion efficiencies of 9.5% and 7.6% in conjunction with low volatility and solvent free ionic liquid electrolytes, respectively. The new counter electrode exhibits good durability (60°C for 1000?h in a solar simulator, 100?mW cm?2) during the accelerated tests when used in combination with an ionic liquid electrolyte. This work identifies a new class of electro-catalysts with potential for low cost photovoltaic devices. PMID:23508212

Xu, Xiaobao; Huang, Dekang; Cao, Kun; Wang, Mingkui; Zakeeruddin, Shaik M.; Grätzel, Michael

2013-01-01

46

Impact of transparent electrode on photoresponse of ZnO-based phototransistor  

SciTech Connect

ZnO-based photo-thin film transistors with enhanced photoresponse were developed using transparent conductive oxide contacts. Changing the electrode from opaque Mo to transparent In-Zn-O increases the photocurrent by five orders of magnitude. By changing the opacity of each source and drain electrode, we could observe how the photoresponse is affected. We deduce that the photocurrent generation mechanism is based on an energy band change due to the photon irradiation. More importantly, we reveal that the photocurrent is determined by the energy barrier of injected electrons at the interface between the source electrode and the active layer.

Lee, Seunghyup; Ahn, Seung-Eon, E-mail: seungeon.ahn@samsung.com; Jeon, Yongwoo; Ahn, Ji-Hoon; Song, Ihun; Kim, Jungwoo; Choi, Hyung; Chung, U-in; Park, Jaechul [Advanced Device Laboratory, Samsung Advanced Institute of Technology, Samsung Electronics Corporation, Yongin-Si, Gyeonggi-Do 446-712 (Korea, Republic of)] [Advanced Device Laboratory, Samsung Advanced Institute of Technology, Samsung Electronics Corporation, Yongin-Si, Gyeonggi-Do 446-712 (Korea, Republic of); Jeon, Sanghun [Department of Display and Semiconductor Physics and Department of Applied Physics, Korea University, 2511, Sejongro, Sejong, 339–700 (Korea, Republic of)] [Department of Display and Semiconductor Physics and Department of Applied Physics, Korea University, 2511, Sejongro, Sejong, 339–700 (Korea, Republic of); Yun, Dong-Jin [Analytical Science Group, Samsung Advanced Institute of Technology, Samsung Electronics Corporation, Yongin-Si, Gyeonggi-Do 446-712 (Korea, Republic of)] [Analytical Science Group, Samsung Advanced Institute of Technology, Samsung Electronics Corporation, Yongin-Si, Gyeonggi-Do 446-712 (Korea, Republic of)

2013-12-16

47

Transparent and flexible low noise graphene electrodes for simultaneous electrophysiology and neuroimaging.  

PubMed

Calcium imaging is a versatile experimental approach capable of resolving single neurons with single-cell spatial resolution in the brain. Electrophysiological recordings provide high temporal, but limited spatial resolution, because of the geometrical inaccessibility of the brain. An approach that integrates the advantages of both techniques could provide new insights into functions of neural circuits. Here, we report a transparent, flexible neural electrode technology based on graphene, which enables simultaneous optical imaging and electrophysiological recording. We demonstrate that hippocampal slices can be imaged through transparent graphene electrodes by both confocal and two-photon microscopy without causing any light-induced artefacts in the electrical recordings. Graphene electrodes record high-frequency bursting activity and slow synaptic potentials that are hard to resolve by multicellular calcium imaging. This transparent electrode technology may pave the way for high spatio-temporal resolution electro-optic mapping of the dynamic neuronal activity. PMID:25327632

Kuzum, Duygu; Takano, Hajime; Shim, Euijae; Reed, Jason C; Juul, Halvor; Richardson, Andrew G; de Vries, Julius; Bink, Hank; Dichter, Marc A; Lucas, Timothy H; Coulter, Douglas A; Cubukcu, Ertugrul; Litt, Brian

2014-01-01

48

Increase in the DSSC efficiency when using metal-coated carbon nanowall counter electrodes  

NASA Astrophysics Data System (ADS)

This research was conducted to improve the efficiency of dye-sensitized solar cells (DSSCs) using metal-layer-coated carbon nanowalls (CNWs) as counter electrodes. The CNWs were synthesized on a fluorine-doped tin-oxide (FTO) glass substrate in a microwave plasma-enhanced chemical vapor deposition (PECVD) system using methane (CH4), and the CNWS were sputter-coated with metal films several times by using an RF magnetron sputtering system and four-inch metal targets (Cu, W and Ni, separately). Then, the metal-layer-coated CNWs were used as counter electrodes for manufacturing the DSCCs. The vertical and the surface conditions of the metal-coated CNWs used as the DSCC electrodes were characterized by their electrical variations through field-emission scanning electron microscopy (FE-SEM) and Hall measurements. Their optical characteristics were analyzed using UV-Vis equipment, and the energy conversion efficiencies of the DSSCs manufactured using the metal-layer-coated CNWs as the counter electrodes were measured. The results confirmed that the efficiency improved when the W-coated CNW was used as the counter electrode.

Lee, Sangjoon; Choi, Won Seok; Lim, Dong-Gun; Choi, Eun Chang; Hong, Byungyou

2014-08-01

49

Carbon nanotube/graphene nanocomposite as efficient counter electrodes in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

We demonstrated the replacement of the Pt catalyst normally used in the counter electrode of a dye-sensitized solar cell (DSSC) by a nanocomposite of dry spun carbon multi-walled nanotube (MWNT) sheets with graphene flakes (Gr-F). The effectiveness of this counter electrode on the reduction of the triiodide in the iodide/triiodide redox (I-/I3-) redox reaction was studied in parallel with the use of the dry spun carbon MWNT sheets alone and graphene flakes used independent of each other. This nanocomposite deposited onto fluorinated tin-oxide-coated glass showed improved catalytic behavior and power conversion efficiency (7.55%) beyond the use of the MWNTs alone (6.62%) or graphene alone (4.65%) for the triiodide reduction reaction in DSSC. We also compare the use of the carbon MWNT/Gr-F composite counter electrode with a DSSC using the standard Pt counter electrode (8.8%). The details of increased performance of graphene/MWNT composite electrodes as studied are discussed in terms of increased catalytic activity permitted by sharp atomic edges that arise from the structure of graphene flakes or the defect sites in the carbon MWNT and increased electrical conductivity between the carbon MWNT bundles by the graphene flakes.

Velten, Josef; Mozer, Attila J.; Li, Dan; Officer, David; Wallace, Gordon; Baughman, Ray; Zakhidov, Anvar

2012-03-01

50

Bifacial dye-sensitized solar cells from covalent-bonded polyaniline-multiwalled carbon nanotube complex counter electrodes  

NASA Astrophysics Data System (ADS)

Exploration of cost-effective counter electrodes (CEs) and enhancement of power conversion efficiency have been two persistent objectives for dye-sensitized solar cells (DSSCs). In the current work, polyaniline-multiwalled carbon nanotube (PANi-MWCNT) complexes are synthesized by a reflux method and employed as CE materials for bifacial DSSCs. Owing to the high optical transparency of PANi-MWCNT complex CE, the incident light from rear side can compensate for the incident light from TiO2 anode. The charge-transfer ability and electrochemical behaviors demonstrate the potential utilization of PANi-MWCNT complex CEs in robust bifacial DSSCs. The electrochemical properties as well as photovoltaic performances are optimized by adjusting MWCNT dosages. A maximum power conversion efficiency of 9.24% is recorded from the bifacial DSSC employing PANi-8 wt‰ MWCNT complex CE for both irradiation, which is better than 8.08% from pure PANi CE.

Zhang, Huihui; He, Benlin; Tang, Qunwei; Yu, Liangmin

2015-02-01

51

Improved durability of dye-sensitized solar cell with H2-reduced carbon counter electrode  

NASA Astrophysics Data System (ADS)

Carbon counter electrodes for dye-sensitized solar cells (DSSCs) have attracted strong attention due to their low material cost and practically high power conversion efficiency (PCE). However, there were issues in PCE stability observed during durability tests. In this study, H2-reduced carbon counter electrode for low cost DSSCs is introduced and demonstrated improved durability over the conventional carbon electrodes, with the absolute PCE value of 7.7%. It was found that carbon resistance decay ratio improved compared to those without H2-reduction process. These cells after the durability test were disassembled, and surface adsorptions on the carbon counter electrodes were analyzed. The adsorption of compounds originated from the dye and co-adsorbents on the H2-reduced carbon electrode was largely reduced, due to the cleaning of surface functional groups that can adsorb large molecules. These results suggest that H2-reduction process proposed in this work effectively reduces surface adsorptions on carbon electrode, and as a result improves the durability of DSSCs.

Takada, Harumi; Obana, Yoshiaki; Sasaki, Ryo; Kuribayashi, Miki; Kanno, Masato; Zhu, Cheng; Bessho, Takeru; Takagi, Yuto; Hinokuma, Koichiro; Noda, Kazuhiro

2015-01-01

52

Thermally exfoliated graphene based counter electrode for low cost dye sensitized solar cells  

SciTech Connect

Graphene obtained from thermal exfoliation of graphite oxide are highly wrinkled and have large surface area. Their wrinkled nature is expected to give them excellent catalytic activity. Herein, we demonstrate the use of thermally exfoliated graphene (TEG) as cost effective electrocatalyst for the tri-iodide reduction in dye sensitized solar cells (DSSCs). X-ray diffraction, Raman and Infra red spectroscopy and electron microscopy studies confirm the defective and wrinkled nature of TEG. BET surface area measurement show a large surface area of {approx} 470 m{sup 2}/g. The counter electrode was fabricated by drop casting a slurry of TEG dispersed in a Nafion:Ethanol solution on fluorine doped tin oxide (FTO) substrates. The use of Nafion prevented film ''peel off,'' thus ensuring a good substrate adhesion. Electrochemical impedance spectroscopy reveals that TEG had a catalytic performance comparable to that of Pt, suggesting its use as counter electrode material. As expected, the DSSC fabricated with Nafion solubilized TEG/FTO as counter electrode shows an efficiency of about 2.8%, comparable to Pt counter electrode based DSSC which has an efficiency of about 3.4%.

Kaniyoor, Adarsh; Ramaprabhu, Sundara [Alternative Energy and Nanotechnology Laboratory, Nano Functional Materials Technology Centre, Department of Physics, Indian Institute of Technology Madras, Chennai (India)

2011-06-15

53

Functionalized Graphene as a Catalytic Counter Electrode in Dye-Sensitized  

E-print Network

%).1,2 In typical DSSC architectures, the photon-induced oxida- tion of a dye occurs at a TiO2 photoanode, while but typically requires a platinum catalyst in DSSC operation.3 5 Platinum has high catalytic activity toward I3, since platinum is a precious metal, much incentive exists to develop DSSC counter electrodes using

Aksay, Ilhan A.

54

High-performance NiO/Ag/NiO transparent electrodes for flexible organic photovoltaic cells.  

PubMed

Transparent electrodes with a dielectric-metal-dielectric (DMD) structure can be implemented in a simple manufacturing process and have good optical and electrical properties. In this study, nickel oxide (NiO) is introduced into the DMD structure as a more appropriate dielectric material that has a high conduction band for electron blocking and a low valence band for efficient hole transport. The indium-free NiO/Ag/NiO (NAN) transparent electrode exhibits an adjustable high transmittance of ?82% combined with a low sheet resistance of ?7.6 ?·s·q(-1) and a work function of 5.3 eV after UVO treatment. The NAN electrode shows excellent surface morphology and good thermal, humidity, and environmental stabilities. Only a small change in sheet resistance can be found after NAN electrode is preserved in air for 1 year. The power conversion efficiencies of organic photovoltaic cells with NAN electrodes deposited on glass and polyethylene terephthalate (PET) substrates are 6.07 and 5.55%, respectively, which are competitive with those of indium tin oxide (ITO)-based devices. Good photoelectric properties, the low-cost material, and the room-temperature deposition process imply that NAN electrode is a striking candidate for low-cost and flexible transparent electrode for efficient flexible optoelectronic devices. PMID:25148532

Xue, Zhichao; Liu, Xingyuan; Zhang, Nan; Chen, Hong; Zheng, Xuanming; Wang, Haiyu; Guo, Xiaoyang

2014-09-24

55

Electrode with transparent series resistance for uniform switching of optical modulation devices  

DOEpatents

Switching uniformity of an optical modulation device for controlling the propagation of electromagnetic radiation is improved by use of an electrode comprising an electrically resistive layer that is transparent to the radiation. The resistive layer is preferably an innerlayer of a wide-bandgap oxide sandwiched between layers of indium tin oxide or another transparent conductor, and may be of uniform thickness, or may be graded so as to provide further improvement in the switching uniformity. The electrode may be used with electrochromic and reversible electrochemical mirror (REM) smart window devices, as well as display devices based on various technologies.

Tench, D. Morgan (Camarillo, CA); Cunningham, Michael A. (Thousand Oaks, CA); Kobrin, Paul H. (Newbury Park, CA)

2008-01-08

56

Ultra-Thin Optically Transparent Carbon Electrodes Produced from Layers of Adsorbed Proteins  

PubMed Central

This work describes a simple, versatile, and inexpensive procedure to prepare optically transparent carbon electrodes, using proteins as precursors. Upon adsorption, the protein-coated substrates were pyrolyzed under reductive conditions (5% H2) to form ultra-thin, conductive electrodes. Because proteins spontaneously adsorb to interfaces forming uniform layers, the proposed method does not require a precise control of the preparation conditions, specialized instrumentation, or expensive precursors. The resulting electrodes were characterized by a combination of electrochemical, optical, and spectroscopic means. As a proof-of-concept, the optically-transparent electrodes were also used as substrate for the development of an electrochemical glucose biosensor. The proposed films represent a convenient alternative to more sophisticated, and less available, carbon-based nanomaterials. Furthermore, these films could be formed on a variety of substrates, without classical limitations of size or shape. PMID:23421732

Alharthi, Sarah A.; Benavidez, Tomas E.; Garcia, Carlos D.

2013-01-01

57

ZnO:H indium-free transparent conductive electrodes for active-matrix display applications  

NASA Astrophysics Data System (ADS)

Transparent conductive electrodes based on hydrogen (H)-doped zinc oxide (ZnO) have been proposed for active-matrix (AM) display applications. When fabricated with optimal H plasma power and optimal plasma treatment time, the resulting ZnO:H films exhibit low sheet resistance of 200 ?/? and high average transmission of 85% at a film thickness of 150 nm. The demonstrated transparent conductive ZnO:H films can potentially replace indium-tin-oxide and serve as pixel electrodes for organic light-emitting diodes as well as source/drain electrodes for ZnO-based thin-film transistors. Use of the proposed ZnO:H electrodes means that two photomask stages can be removed from the fabrication process flow for ZnO-based AM backplanes.

Chen, Shuming; Wang, Sisi

2014-12-01

58

Design and characterisation of a thin-film electrode array with shared reference/counter electrodes for electrochemical detection.  

PubMed

In the current study, a novel electrode array and integrated microfluidics have been designed and characterised in order to create a sensor chip which is not only easy, rapid and cheaper to produce but also have a smaller imprint and good electrochemical sensing properties. The current study includes the assessment of the effects of an Au quasi-reference electrode and the use of shared reference/counter electrodes for the array, in order to obtain a small array that can be produced using a fine metal mask. In the study, it is found that when Au is used as the quasi-reference electrode, the arrays with shared reference and counter electrodes result in faster electron transfer kinetics and prevent the potential change with respect to scan rate, and hence is advantageous with respect to conventional electrodes. In addition, the resulting novel electrode array has been shown to result in higher current density (10.52 µA/cm(2); HRP detection assay) and measured diffusion coefficient (14.40×10(-12) cm(2)/s; calculated from the data of cyclic voltammetry with 1mM potassium ferricyanide) with respect to conventional electrodes tested in the study. Using the new electrode arrays, the detection limits obtained from horse radish peroxidase (HRP) and bisphenol A assays were 12.5 ng/ml (2.84×10(-10) M ) and 10 ng/ml (44×10(-9) M), respectively. Performing the HRP detection assay in a flow injection system using array integrated microfluidics provided 25 times lower detection limit (11.36×10(-12) M), although Ti has been used as electrode material instead of Au. In short, incorporation of this new electrode array to lab-on-a-chip or MEMs (micro-electro mechanic systems) technologies may pave the way for easy to use automated biosensing devices that could be used for a variety of applications from diagnostics to environmental monitoring, and studies will continue to move forward in this direction. PMID:24561521

Uludag, Yildiz; Olcer, Zehra; Sagiroglu, Mahmut Samil

2014-07-15

59

Low Reflectivity and High Flexibility of Tin-Doped Indium Oxide Nanofiber Transparent Electrodes  

E-print Network

), the crystal structure of the nanofibers was determined to be the cubic bixbyite In2O3 structure, and no otherLow Reflectivity and High Flexibility of Tin-Doped Indium Oxide Nanofiber Transparent Electrodes-mail: yicui@stanford.edu Abstract: Tin-doped indium oxide (ITO) has found widespread use in solar cells

Cui, Yi

60

Au@MnO2 core-shell nanomesh electrodes for transparent flexible supercapacitors.  

PubMed

A novel Au@MnO2 supercapacitor is presented. The sophisticated core-shell architecture combining an Au nanomesh core with a MnO2 shell on a flexible polymeric substrate is demonstrated as an electrode for high performance transparent flexible supercapacitors (TFSCs). Due to their unique structure, high areal/gravimetric capacitance and rate capability for TFSCs are achieved. PMID:24976434

Qiu, Tengfei; Luo, Bin; Giersig, Michael; Akinoglu, Eser Metin; Hao, Long; Wang, Xiangjun; Shi, Lin; Jin, Meihua; Zhi, Linjie

2014-10-29

61

High-performance plastic platinized counter electrode via photoplatinization technique for flexible dye-sensitized solar cells.  

PubMed

A photoplatinization technique was proposed to deposit Pt on a thin TiO(2) layer modified indium tin oxide-coated polyethylene naphthalate (ITO/PEN) substrate at low temperature (about 50 °C after 1 h of UV irradiation) for the first time. The fabrication process includes coating and hydrolyzing the tetra-n-butyl titanate to form a TiO(2)-modified layer and the photoplatinization of the modified substrate in H(2)PtCl(6)/2-propanol precursor solution under UV irradiation. The obtained platinized electrodes were used as counter electrodes (CE) for flexible dye-sensitized solar cells (FDSCs). The well-optimized platinized electrode showed high optical transmittance, up to 76.5% between 400 and 800 nm (T(av)), and the charge transfer resistance (R(ct)) was as low as 0.66 ? cm(2). A series of characterizations also demonstrated the outstanding chemical/electrochemical durability and mechanical stability of the platinized electrode. The FDSCs with TiO(2)/Ti photoanodes and the obtained CEs achieved a power conversion efficiency (PCE) up to 8.12% under rear-side irradiation (AM 1.5 illumination, 100 mW cm(-2)). The obtained CEs were also employed in all-plastic bifacial DSCs. When irradiated from the rear side, the bifacial FDSC yielded a PCE of 6.26%, which approached 90% that of front-side irradiation (6.97%). Our study revealed that, apart from serving as a functional layer for deposition of Pt, the thin TiO(2) layer modification on ITO/PEN substrates also played an important role in improving the transparency and the mechanical properties of the CE. The effect of the thickness of the TiO(2) layer for Pt coating on the performance of the CE was also investigated. PMID:23039879

Fu, Nian-Qing; Fang, Yan-Yan; Duan, Yan-Dong; Zhou, Xiao-Wen; Xiao, Xu-Rui; Lin, Yuan

2012-11-27

62

Transparent conductive oxide electrode dependence of photocurrent characteristics in bacteriorhodopsin photocells  

NASA Astrophysics Data System (ADS)

We investigated the photocurrent characteristics in photocells using bacteriorhodopsin (bR) thin films deposited on various kinds of transparent conductive oxide (TCO) electrodes. The photocurrent depends largely on the species of TCO and partly on the surface morphology. The photocell using a bR thin film deposited on a fluorine-doped tin oxide electrode with a textured structure showed the largest photocurrent. Our results indicate that the variation of capacitance near the interface induced by the bR's light-driven proton pump function affects the transient photocurrent, while the capacitance near the interface is produced by the TCO electrode, bR thin film, and electrolyte solution.

Yamada, Toshiki; Haruyama, Yoshihiro; Kasai, Katsuyuki; Kaji, Takahiro; Tominari, Yukihiro; Tanaka, Shukichi; Otomo, Akira

2014-11-01

63

Flexible organic light-emitting devices with a smooth and transparent silver nanowire electrode  

NASA Astrophysics Data System (ADS)

We demonstrate a flexible organic light-emitting device (OLED) by using silver nanowire (AgNW) transparent electrode. A template stripping process has been employed to fabricate the AgNW electrode on a photopolymer substrate. From this approach, a random AgNW network electrode can be transferred to the flexible substrate and its roughness has been successfully decreased. As a result, the devices obtained by this method exhibit high efficiency. In addition, the flexible OLEDs keep good performance under a small bending radius.

Cui, Hai-Feng; Zhang, Yi-Fan; Li, Chuan-Nan

2014-07-01

64

Transparent Electrode Materials for Simultaneous Amperometric Detection of Exocytosis and Fluorescence Microscopy  

PubMed Central

We have developed and tested transparent microelectrode arrays capable of simultaneous amperometric measurement of oxidizable molecules and fluorescence imaging through the electrodes. Surface patterned microelectrodes were fabricated from three different conducting materials: Indium-tin-oxide (ITO), nitrogen-doped diamond-like carbon (DLC) deposited on top of ITO, or very thin (12–17 nm) gold films on glass substrates. Chromaffin cells loaded with lysotracker green or acridine orange dye were placed atop the electrodes and vesicle fluorescence imaged with total internal reflection fluorescence (TIRF) microscopy while catecholamine release from single vesicles was measured as amperometric spikes with the surface patterned electrodes. Electrodes fabricated from all three materials were capable of detecting amperometric signals with high resolution. Unexpectedly, amperometric spikes recorded with ITO electrodes had only about half the amplitude and about half as much charge as those detected with DLC or gold electrodes, indicating that the ITO electrodes are not as sensitive as gold or DLC electrodes for measurement of quantal catecholamine release. The lower sensitivity of ITO electrodes was confirmed by chronoamperometry measurements comparing the currents in the presence of different analytes with the different electrode materials. PMID:22708072

Kisler, Kassandra; Kim, Brian N.; Liu, Xin; Berberian, Khajak; Fang, Qinghua; Mathai, Cherian J.; Gangopadhyay, Shubhra; Gillis, Kevin D.; Lindau, Manfred

2012-01-01

65

Compound Ag nanocluster-graphene electrodes as transparent and current spreading electrodes for improved light output power in near-ultraviolet light emitting diodes  

NASA Astrophysics Data System (ADS)

We introduced a two-dimensional graphene network on a Ag nanocluster as a transparent and current spreading electrode (TCSE) for a near-ultraviolet light emitting diode (NUV-LED), and compared the performance with those with graphene electrodes or conventional indium tin oxide (ITO) electrodes. The current-voltage characteristics and electroluminescence (EL) data showed that compound Ag nanocluster-graphene (CA-G) electrodes operated well as TCSEs in NUV-LED devices. The forward voltage at an input current of 20 mA was 4.06 V for the NUV-LED of current spreading electrodes with CA-G electrodes, which is only slightly higher than the value 3.96 V with ITO electrodes as TCSEs. The EL intensity of NUV-LEDs with CA-G electrodes also showed a slight increase, compared to that of NUV-LEDs with planar ITO transparent conducting electrodes.

Seo, Tae Hoon; Kim, Seongjun; Jong Kim, Myung; Kim, Hyunsoo; Suh, Eun-Kyung

2014-05-01

66

High figure-of-merit ultrathin metal transparent electrodes incorporating a conductive grid  

SciTech Connect

It is known that ultrathin (<10 nm) metal films (UTMFs) can achieve high level of optical transparency at the expense of the electrical sheet resistance. In this letter, we propose a design, the incorporation of an ad hoc conductive grid, which can significantly reduce the sheet resistance of UTMF based transparent electrodes, leaving practically unchanged their transparency. The calculated highest figure-of-merit corresponds to a filling factor and a grid spacing-to-linewidth ratio of 0.025 and 39, respectively. To demonstrate the capability of the proposed method the sheet resistance of a continuous 2 nm Ni film (>950 OMEGA/square) is reduced to approx6.5 OMEGA/square when a 100 nm thick Cu grid is deposited on it. The transparency is instead maintained at values exceeding 75%. These results, which can be further improved by making thicker grids, already demonstrate the potential in applications, such as photovoltaic cells, optical detectors and displays.

Ghosh, D. S.; Chen, T. L. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, Castelldefels, Barcelona, 08860 Catalunya (Spain); Pruneri, V. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, Castelldefels, Barcelona, 08860 Catalunya (Spain); ICREA-Institucio Catalana de Recerca i Estudis Avancats, 08010 Barcelona (Spain)

2010-01-25

67

Properties of an Au/Pt bilayered counter electrode in dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

A 0.45 cm2 dye-sensitized solar cell (DSSC) device with glass/FTO/blocking layer/TiO2/dye/electrolyte/50 nm Pt/50 nm Au/glass was prepared to improve the energy conversion efficiency by applying an Au/Pt bilayer to the flat glass substrate of the counter electrode (CE). For comparison, Au and Pt CEs, 100 nm in thickness, on flat glass substrates were also prepared using the same method. The photovoltaic properties, such as the short circuit current density ( J sc ), open circuit voltage ( V oc ), fill factor ( FF) and energy conversion efficiency (ECE), were checked using a solar simulator and potentiostat. The strain of a Pt thin film was examined by x-ray diffraction. The sheet resistance and interface resistance were examined using a four point probe and impedance measurements. The measured energy conversion efficiencies of the dye-sensitized solar cell devices with Pt only and Au/Pt bilayer counter electrodes were 4.60% and 5.28%, respectively. The Au/Pt bilayer was confirmed by XRD, which also revealed a large compressive strain of -6.66 × 10-3 in the Pt layer. The interface resistance at the interface between the counter electrode and electrolyte decreased when an Au/Pt bilayered thin film was applied. The increase in efficiency at the Au/Pt bilayered counter electrode was attributed to the effect of a compressive strain field formed at the Pt layer and the low resistive Au layer used.

Noh, Yunyoung; Song, Ohsung

2014-09-01

68

DSSC with a novel Pt counter electrodes using pulsed electroplating techniques  

Microsoft Academic Search

The thin Pt electrode on transparent conductive oxide (TCO) substrate, i.e., FTO\\/glass, for the dye-sensitized solar cell was prepared by a pulsed electrodeposition method. The characteristic properties of the pulse-plated Pt film were prepared and compared with the conventional sputtered Pt film. The composition and surface morphology of the Pt thin film were examined by scanning electron microscope with energy

Chun-Chen Yang; Huan Qing Zhang; Yu Rong Zheng

2011-01-01

69

Synthesis of MWNTs using thermal chemical vapor deposition for the application of a counter electrode for DSSCs  

Microsoft Academic Search

MWNTs (Multi-wall Carbon nanotubes) were grown using thermal CVD at a low temperature of 530 °C to be fabricated as a counter electrode of dye-sensitized solar cells (DSSCs). Ammonia gas and acetylene gas were introduced as reactive gas sources with 90 sccm and 108 sccm, respectively. DSSCs using CNT and Pt counter electrodes were fabricated using conventional method to compare its efficiencies. As

Ji Young Roh; Yang Hee Kim; Caroline Sunyong Lee

2011-01-01

70

Ag nanowire percolating network embedded in indium tin oxide nanoparticles for printable transparent conducting electrodes  

SciTech Connect

Solution-based printable transparent conducting electrodes consisting of Ag nanowire (NW) and indium tin oxide (ITO) nanoparticles (NPs) were fabricated by simple brush painting at room temperature under atmospheric ambient conditions. Effectively embedding the Ag NW percolating network into the ITO NPs provided a conduction path, led to a metallic conduction behavior of the ITO NPs/Ag NW/ITO NPs multilayer and supplied electrons into the ITO NPs. The optimized ITO NPs/Ag NW/ITO NPs multilayer showed a sheet resistance of 16.57??/sq and an optical transparency of 79.50% without post annealing. Based on high resolution transmission electron microscope analysis, we investigated the microstructure and interface structure of the ITO NPs/Ag NW/ITO NPs multilayer electrodes and suggested a possible mechanism to explain the low resistivity of the multilayers.

Jeong, Jin-A; Kim, Han-Ki, E-mail: imdlhkkim@khu.ac.kr [Department of Advanced Materials Engineering for Information and Electronics, Kyung Hee University, 1 Seocheon-dong, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of)

2014-02-17

71

Highly transparent Nb-doped indium oxide electrodes for organic solar cells  

SciTech Connect

The authors investigated the characteristics of Nb-doped In{sub 2}O{sub 3} (INbO) films prepared by co-sputtering of Nb{sub 2}O{sub 5} and In{sub 2}O{sub 3} for use in transparent anodes for organic solar cells (OSCs). To optimize the Nb dopant composition in the In{sub 2}O{sub 3} matrix, the effect of the Nb doping power on the resistivity and transparency of the INbO films were examined. The electronic structure and microstructure of the INbO films were also investigated using synchrotron x-ray absorption spectroscopy and x-ray diffraction examinations in detail. At the optimized Nb co-sputtering power of 30?W, the INbO film exhibited a sheet resistance of 15??/sq, and an optical transmittance of 86.04% at 550?nm, which are highly acceptable for the use as transparent electrodes in the fabrication of OSCs. More importantly, the comparable power conversion efficiency (3.34%) of the OSC with an INbO anode with that (3.31%) of an OSC with a commercial ITO anode indicates that INbO films are promising as a transparent electrode for high performance OSCs.

Kim, Jun Ho; Seong, Tae-Yeon [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Na, Seok-In [Professional Graduate School of Flexible and Printable Electronics, Chonbuk National University, 664-14, Deokjin-dong, Jeongju-si, Jellabuk-do 561-756 (Korea, Republic of); Chung, Kwun-Bum [Department of Physics, Dankook University, Mt. 29, Anseo-Dong, Chenan 330-714 (Korea, Republic of); Lee, Hye-Min; Kim, Han-Ki, E-mail: imdlhkkim@khu.ac.kr [Department of Advanced Materials Engineering for Information and Electronics, Kyung Hee University, 1 Seocheon-dong, Yongin, Gyeonggi-do 446-701 (Korea, Republic of)

2014-03-15

72

Improvements in purification of silver nanowires by decantation and fabrication of flexible transparent electrodes. Application to capacitive touch sensors.  

PubMed

Transparent flexible electrodes made of metallic nanowires, and in particular silver nanowires (AgNWs), appear as an extremely promising alternative to transparent conductive oxides for future optoelectronic devices. Though significant progresses have been made the last few years, there is still some room for improvement regarding the synthesis of high quality silver nanowire solutions and fabrication process of high performance electrodes. We show that the commonly used purification process can be greatly simplified through decantation. Using this process it is possible to fabricate flexible electrodes by spray coating with sheet resistance lower than 25 ? sq?¹ at 90% transparency in the visible spectrum. These electrodes were used to fabricate an operative transparent flexible touch screen. To our knowledge this is the first reported AgNW based touch sensor relying on capacitive technology. PMID:23619480

Mayousse, Céline; Celle, Caroline; Moreau, Eléonore; Mainguet, Jean-François; Carella, Alexandre; Simonato, Jean-Pierre

2013-05-31

73

Two carboxyethyltin functionalized polyoxometalates for assembly on carbon nanotubes as efficient counter electrode materials in dye-sensitized solar cells.  

PubMed

Two novel open-chain carboxyethyltin decorated sandwich-type germanotungstates have been successfully synthesized. They could markedly increase the electrocatalytic activity of single-walled carbon nanotubes toward triiodide reduction when assembled into composite electrodes, which have shown a conversion efficiency of 6.32% that is comparable to that of Pt electrodes (6.29%) when used as counter electrodes in dye-sensitized solar cells. PMID:25317838

Sang, Xiao-Jing; Li, Jian-Sheng; Zhang, Lan-Cui; Zhu, Zai-Ming; Chen, Wei-Lin; Li, Yang-Guang; Su, Zhong-Min; Wang, En-Bo

2014-12-01

74

The effect of SWCNT with the functional group deposited on the counter electrode on the dye-sensitized solar cell  

Microsoft Academic Search

This study investigated the applicability of single wall carbon nanotubes (SWCNT) with the functional group deposited on the FTO-glass (Fluorine doped tin oxide, SnO2:F) substrate of the counter electrode for a dye-sensitized solar cell (DSSC). A nanocrystalline TiO2 layer was fabricated on the FTO-glass substrate of the working electrode, and then sintered in a high-temperature furnace. The working electrode with

Chuen-Shii Chou; Che-I Huang; Ru-Yuan Yang; Chun-Po Wang

2010-01-01

75

Bragg stack-functionalized counter electrode for solid-state dye-sensitized solar cells.  

PubMed

A highly reflective counter electrode is prepared through the deposition of alternating layers of organized mesoporous TiO(2) (om-TiO(2)) and colloidal SiO(2) (col-SiO(2)) nanoparticles. We present the effects of introducing this counter electrode into dye-sensitized solar cells (DSSCs) for maximizing light harvesting properties. The om-TiO(2) layers with a high refractive index are prepared by using an atomic transfer radical polymerization and a sol-gel process, in which a polyvinyl chloride-g-poly(oxyethylene) methacrylate graft copolymer is used as a structure-directing agent. The col-SiO(2) layers with a low refractive index are prepared by spin-coating commercially available silica nanoparticles. The properties of the Bragg stack (BS)-functionalized counter electrode in DSSCs are analyzed by using a variety of techniques, including spectroscopic ellipsometry, SEM, UV/Vis spectroscopy, incident photon-to-electron conversion efficiency, electrochemical impedance spectroscopy, and intensity modulated photocurrent/voltage spectroscopy measurements, to understand the critical factors contributing to the cell performance. When incorporated into DSSCs that are used in conjunction with a polymerized ionic liquid as the solid electrolyte, the energy conversion efficiency of this solid-state DSSC (ssDSSC) approaches 6.6 %, which is one of the highest of the reported N719 dye-based ssDSSCs. Detailed optical and electrochemical analyses of the device performance show that this assembly yields enhanced light harvesting without the negative effects of charge recombination or electrolyte penetration, which thus, presents new possibilities for effective light management. PMID:23576320

Park, Jung Tae; Prosser, Jacob H; Kim, Dong Jun; Kim, Jong Hak; Lee, Daeyeon

2013-05-01

76

Efficient iron sulfide counter electrode for quantum dots-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Iron sulfide is explored as the counter electrode (CE) in quantum dots-sensitized solar cells (QDSCs), which is prepared by simply immersing carbon steel in Na2S solution. The photoelectrochemical performance and the electrocatalytic property of iron sulfide are much higher than those of Pt and are very close to those of Cu2S. Since the preparation method of iron sulfide CE is simple, carbon steel substrate is stable in polysulfide electrolyte, the storage of Fe element in earth is very abundant and iron ions are environmentally friendly, iron sulfide shows much prospect as the efficient, stable, lost-cost and environmentally friendly CE of QDSCs.

Chen, Haining; Zhu, Liqun; Liu, Huicong; Li, Weiping

2014-01-01

77

An original route to immobilize an organic biocide onto a transparent tin dioxide electrode.  

PubMed

Prevention of biofilm growth on surfaces immersed in an aqueous environment could be obtained either by the release of an antifouling biocide or by the presence of such compounds on the surface. In this paper it is shown, for the first time, that an electrochemical treatment performed in the presence of chlorides and proteins allows the immobilization of an organic biocide (chloramine) on the electrode. This electrode is a stable transparent conductive tin dioxide film coated on glass. It is polarized to oxidize chloride ions into hypochlorous acid, which reacts with the organic matter (bovine serum albumin) present at the electrode/solution interface, leading on one hand to the chlorination of the proteins with in particular the chloramine formation and on the other hand to the protein aggregation on the surface. PMID:17311439

Debiemme-Chouvy, Catherine; Haskouri, Sanae; Folcher, Guy; Cachet, Hubert

2007-03-27

78

Counters  

NSDL National Science Digital Library

All About Circuits is a website that âÂÂprovides a series of online textbooks covering electricity and electronics.â Written by Tony R. Kuphaldt, the textbooks available here are wonderful resources for students, teachers, and anyone who is interested in learning more about electronics. This specific section, Counters, is the eleventh chapter in Volume IV âÂÂDigital. A few of the topics covered in this chapter include: Binary count sequence; Asynchronous counters; and Counter modulus. Diagrams and detailed descriptions of concepts are included throughout the chapter to provide users with a comprehensive lesson. Visitors to the site are also encouraged to discuss concepts and topics using the All About Circuits discussion forums (registration with the site is required to post materials).

Kuphaldt, Tony R.

2008-07-18

79

Stretchable and Transparent Electrodes using Hybrid Structures of Graphene-Metal Nanotrough Networks with High Performances and Ultimate Uniformity.  

PubMed

Transparent electrodes that can maintain their electrical and optical properties stably against large mechanical deformations are essential in numerous applications of flexible and wearable electronics. In this paper, we report a comprehensive analysis of the electrical, optical, and mechanical properties of hybrid nanostructures based on graphene and metal nanotrough networks as stretchable and transparent electrodes. Compared to the single material of graphene or the nanotrough, the formation of this hybrid can improve the uniformity of sheet resistance significantly, that is, a very low sheet resistance (1 ?/sq) with a standard deviation of less than ±0.1 ?/sq, high transparency (91% in the visible light regime), and superb stretchability (80% in tensile strain). The successful demonstration of skin-attachable, flexible, and transparent arrays of oxide semiconductor transistors fabricated using hybrid electrodes suggests substantial promise for the next generation of electronic devices. PMID:25299634

An, Byeong Wan; Hyun, Byung Gwan; Kim, So-Yun; Kim, Minji; Lee, Mi-Sun; Lee, Kyongsoo; Koo, Jae Bon; Chu, Hye Yong; Bae, Byeong-Soo; Park, Jang-Ung

2014-11-12

80

Bifacial dye-sensitized solar cells: A strategy to enhance overall efficiency based on transparent polyaniline electrode  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cell (DSSC) is a promising solution to global energy and environmental problems because of its clean, low-cost, high efficiency, good durability, and easy fabrication. However, enhancing the efficiency of the DSSC still is an important issue. Here we devise a bifacial DSSC based on a transparent polyaniline (PANI) counter electrode (CE). Owing to the sunlight irradiation simultaneously from the front and the rear sides, more dye molecules are excited and more carriers are generated, which results in the enhancement of short-circuit current density and therefore overall conversion efficiency. The photoelectric properties of PANI can be improved by modifying with 4-aminothiophenol (4-ATP). The bifacial DSSC with 4-ATP/PANI CE achieves a light-to-electric energy conversion efficiency of 8.35%, which is increased by ~24.6% compared to the DSSC irradiated from the front only. This new concept along with promising results provides a new approach for enhancing the photovoltaic performances of solar cells.

Wu, Jihuai; Li, Yan; Tang, Qunwei; Yue, Gentian; Lin, Jianming; Huang, Miaoliang; Meng, Lijian

2014-02-01

81

Mechanical integrity and environmental reliability of a single wall carbon nanotube as a flexible transparent conducting electrode  

NASA Astrophysics Data System (ADS)

We investigated a single wall carbon nanotube (SWCNT) electrode as a potential flexible transparent conducting electrode. The mechanical integrity of an SWCNT electrode spray-coated onto a polyethylene terephthalate substrate was investigated via outer/inner bending, twisting, stretching, and adhesion tests. In particular, its environmental reliability under high-temperature and high-humidity conditions was characterized. The spray-coated SWCNT electrode showed a sheet resistance of 200 ?/square and a transparency of 83%. The SWCNT electrode showed a constant resistance change (?R/R0) within an outer and inner bending radius of 2.5 mm. The bending fatigue test showed that the SWCNT electrode can withstand 10,000 bending cycles at a bending radius of 5 mm. Furthermore, the resistance change of the stretched SWCNT electrode was fairly constant up to a strain of 5%, which is quite stable compared with the resistance change of conventional amorphous indium tin oxide electrodes. The SWCNT electrode also showed good adhesion strength. The environmental storage test at a high temperature (85 °C) indicated that change in the electrical resistance of the SWCNT electrode is less than 9% after 100 h test. In the environmental reliability tests at 85% relative humidity (RH) and 60 °C/90% RH, the ?R/R0 of the SWCNT electrode was very small. These results indicate that the SWCNT electrode has good environmental stability.

Eun, Kyoungtae; Lee, Eun Kyung; Lee, Mi Kyoung; Kim, Kyunnyun; Kim, Wonhyo; Shin, Kwonwoo; Choa, Sung-Hoon

2014-01-01

82

Transparent and flexible supercapacitors with single walled carbon nanotube thin film electrodes.  

PubMed

We describe a simple process for the fabrication of transparent and flexible, solid-state supercapacitors. Symmetric electrodes made up of binder-free single walled carbon nanotube (SWCNT) thin films were deposited onto polydimethylsiloxane substrates by vacuum filtration followed by a stamping method, and solid-state supercapacitor devices were assembled using a gel electrolyte. An optical transmittance of 82% was found for 0.02 mg of SWCNTs, and a specific capacitance of 22.2 F/g was obtained. The power density can reach to 41.5 kW · kg(-1) and shows good capacity retention (94%) upon cycling over 500 times. Fabricated supercapacitors will be relevant for the realization of transparent and flexible devices with energy storage capabilities, displays and touch screens in particular. PMID:25127070

Yuksel, Recep; Sarioba, Zeynep; Cirpan, Ali; Hiralal, Pritesh; Unalan, Husnu Emrah

2014-09-10

83

Intrinsically stretchable transparent electrodes based on silver-nanowire-crosslinked-polyacrylate composites.  

PubMed

Stretchable transparent composites have been synthesized consisting of a silver nanowire (AgNW) network embedded in the surface layer of a crosslinked poly(acrylate) matrix. The interpenetrating networks of AgNWs and the crosslinked polymer matrix lead to high surface conductivity, high transparency, and rubbery elasticity. The presence of carboxylic acid groups on the polymer chains enhances the bonding between AgNWs and the polymer matrix, and further increases the stretchability of the composites. The sheet resistance of the composite electrode increases by only 2.3 times at 50% strain. Repeated stretching to 50% strain and relaxation only causes a small increase of the sheet resistance after 600 cycles. The morphology of the composites during reversible stretching and relaxation has been investigated to expound the conductivity changes. PMID:22885805

Hu, Weili; Niu, Xiaofan; Li, Lu; Yun, Sungryul; Yu, Zhibin; Pei, Qibing

2012-08-31

84

Highly flexible, hybrid-structured indium tin oxides for transparent electrodes on polymer substrates  

SciTech Connect

We developed highly flexible, hybrid-structured crystalline indium tin oxide (ITO) for use as transparent electrodes on polymer substrates by embedding Ag nanoparticles (AgNPs) into the substrate. The hybrid ITO consists of domains in one orientation grown on the AgNPs and a matrix of the other orientation. The domains are stronger than the matrix and function as barriers to crack propagation. As a result, both the critical bending radius (r{sub c}) (under which the resistivity change ({Delta}{rho}) is less than a given value) and the change in {Delta}{rho} with decreasing r significantly decreased in the hybrid ITO compared with homogenous ITO.

Triambulo, Ross E.; Kim, Jung-Hoon; Park, Jin-Woo [Department of Materials Science and Engineering, Yonsei University, Seoul (Korea, Republic of)] [Department of Materials Science and Engineering, Yonsei University, Seoul (Korea, Republic of); Na, Min-Young; Chang, Hye-Jung [Advanced Analysis Center, Korea Institute of Science and Technology (KIST), Seoul (Korea, Republic of)] [Advanced Analysis Center, Korea Institute of Science and Technology (KIST), Seoul (Korea, Republic of)

2013-06-17

85

Modelling of optical transport behavior of organic photovoltaic devices with nano-pillar transparent conducting electrodes  

NASA Astrophysics Data System (ADS)

Optical transport behavior of organic photo-voltaic devices with nano-pillar transparent electrodes is investigated in this paper in order to understand possible enhancement of their charge-collection efficiency. Modeling and simulations of optical transport due to this architecture show an interesting regime of length-scale dependent optical characteristics. An electromagnetic wave propagation model is employed with simulation objectives toward understanding the mechanism of optical scattering and waveguide effects due to the nano-pillars and effective transmission through the active layer. Partial filling of gaps between the nano-pillars due to the nano-fabrication process is taken into consideration. Observations made in this paper will facilitate appropriate design rules for nano-pillar electrodes.

Jagdish, A. K.; Ramamurthy, Praveen C.; Mahapatra, D. Roy; Hegde, Gopalkrishna

2014-08-01

86

Functionalized graphene sheets in dye-sensitized solar cell counter electrodes  

NASA Astrophysics Data System (ADS)

The use of thermally exfoliated graphite oxide, commonly referred to as functionalized graphene sheets (FGSs), was investigated as a catalytic counter electrode material in dye-sensitized solar cells to substitute for platinum nanoparticles traditionally used in devices. A catalyst's activity depends both on the material's intrinsic activity as well as on its surface area accessible for reaction. Thus, this work aimed i) to determine the intrinsic activity of FGSs with various chemical compositions and structures, and ii) to create high surface area networks of FGSs to use as catalytic electrodes in dye-sensitized solar cells. Monolayers of FGSs were fabricated and electrochemically tested to determine the intrinsic catalytic activity for a common dye-sensitized solar cell redox mediator, cobalt bipyridine. It was found that lattice defect rich, oxygen-site poor FGSs catalyze the reduction of the cobalt complex as well as platinum does, exhibiting a rate constant of ~ 6 x 10-3 cm/s. This rate is an order of magnitude faster than exhibited with oxygen-site rich graphene oxide, and over two orders of magnitude faster than found with the basal plane of graphite (as a surrogate for pristine graphene). FGSs are less catalytic towards the iodide/triiodide redox mediator, thus larger surface areas must be used for effective catalysis. In this work, conductive, high surface area networks of FGSs were produced by first tape casting surfactant-stabilized aqueous suspensions of FGSs and then thermolyzing the surfactant materials. Iodide/triiodide mediated dye-sensitized solar cells using these FGS electrodes exhibited power conversion efficiencies within 10% of devices using platinum nanoparticles. Furthermore, to interpret the catalytic activity of FGSs towards the reduction of triiodide, a new electrochemical impedance spectroscopy equivalent circuit was proposed that matches the observed spectra features to the appropriate phenomena. Lastly, improved catalytic performance was achieved through better control of electrode morphology. By using ethyl cellulose as a sacrificial binder, and partially thermolyzing it, electrodes were created which exhibited lower effective charge transfer resistance (< 1 ?·cm 2) than the traditional platinum electrodes for the iodide/triiodide, the cobalt bipyridine, and a sulfur-based redox couple. Dye-sensitized solar cells using these FGS electrodes had power conversion efficiencies equal to or greater than those using platinum nanoparticles with each of the three major redox mediators.

Roy-Mayhew, Joseph Dominic

87

Large-scale graphene-based composite films for flexible transparent electrodes fabricated by electrospray deposition  

NASA Astrophysics Data System (ADS)

Large-scale transparent conducting electrodes were fabricated using the electrospray method on a glass wafer and polyethylene terephthalate film using chemically reduced graphene oxide and poly (3,4-ethylenedioxythiophene) (PEDOT). Graphene oxide (GO) is prepared by the modified Hummers method, and reduced GO (RG) is prepared at low temperature. By varying the concentration of RG and PEDOT of the composite material on the substrate, the electrical conductivity and transmittance of the electrode was controlled. The optical transmittance values of the graphene-based electrode at a wavelength of 550 nm were between 81 and 95% and had sheet resistances from 370 to 5400 ? sq?1. After 1000 cycles of a bending test, the sheet resistances of the graphene-based composite films were unchanged. Different types of graphene and graphene-based electrodes were characterized by field-emission scanning electron microscopy, high-resolution transmission electron microscopy, high-resolution Raman spectroscopy, x-ray photoelectron spectroscopy, x-ray diffraction, transmittance, and electrical conductivity measurements.

Kim, Woo Sik; Moon, Sook Young; Kim, Hui Jin; Park, Sungjin; Koyanagi, Jun; Huh, Hoon

2014-12-01

88

Enhanced performance in dye-sensitized solar cells via carbon nanofibers-platinum composite counter electrodes  

NASA Astrophysics Data System (ADS)

A composite counter electrode (CE) made of electrospun carbon nanofibers (ECNs) and platinum (Pt) nanoparticles has been demonstrated for the first time to improve the performance of dye-sensitized solar cells (DSCs). The new ECN-Pt composite CE exhibited a more efficient electro-catalytic performance with lower charge transfer resistance (Rct), larger surface area, and faster reaction rate than those of conventional Pt. It reduced the overall series resistance (Rse), decreased dark saturation current density (J0) and increased shunt resistance (Rsh) of the DSCs, thereby leading to a higher fill factor (FF) and larger open circuit voltage (Voc). The reduced electron transport resistance (Rs) and faster charge transfer rate in the CE led to a smaller overall cell series resistance (Rse) in the ECN-Pt composite based DSCs. The DSCs based on an ECN-Pt CE achieved a ? of ~8%, which was improved over those of pure Pt or ECN based cells.

Poudel, Prashant; Zhang, Lifeng; Joshi, Prakash; Venkatesan, Swaminathan; Fong, Hao; Qiao, Qiquan

2012-07-01

89

PtRu nanofiber alloy counter electrodes for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

With an aim of enhancing the light-to-electric power conversion efficiency of dye-sensitized solar cell (DSSC), here we synthesize PtRu nanofiber alloys using a low-temperature hydrothermal technique which are employed as counter electrodes (CEs) for DSSCs. Owing to the good electrical conduction and electrocatalysis, light-to-electric power conversion efficiencies of PtRu-based DSSCs have been elevated in comparison with that of Pt CE based DSSC. The DSSC employing PtRu3 alloy CE gives a power conversion efficiency of 6.80% in comparison with 6.17% from Pt-based DSSC. The reasonable conversion efficiency, simple preparation, and scalability demonstrate the potential use of PtRu alloys in efficient DSSCs.

Cai, Hongyuan; Tang, Qunwei; He, Benlin; Li, Pinjiang

2014-07-01

90

Robust polyaniline-graphene complex counter electrodes for efficient dye-sensitized solar cells.  

PubMed

With an aim of accelerating the charge transfer between polyaniline (PANi) and graphene, polyaniline-graphene (PANi-graphene) complexes are synthesized by a reflux technique and employed as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). Because of the easy charge-transfer between PANi (N atoms) and graphene (C atoms) by a covalent bond, electrical conduction and electrocatalysis of PANi-graphene complex CEs, and therefore power conversion efficiency of their DSSCs have been elevated in comparison with that of PANi-only CE. The resultant PANi-graphene complex CEs are characterized by spectral analysis, morphology observation, and electrochemical tests. The DSSC employing PANi-8 wt ‰ graphene complex CE gives an impressive power conversion efficiency of 7.78%, which is higher than 6.24% from PANi-only and 6.52% from Pt-only CE-based DSSCs. PMID:24826943

He, Benlin; Tang, Qunwei; Wang, Min; Chen, Haiyan; Yuan, Shuangshuang

2014-06-11

91

Highly efficient and bendable organic solar cells using a three-dimensional transparent conducting electrode  

NASA Astrophysics Data System (ADS)

A three-dimensional (3D) transparent conducting electrode, consisting of a quasi-periodic array of discrete indium-tin-oxide (ITO) nanoparticles superimposed on a highly conducting oxide-metal-oxide multilayer using ITO and silver oxide (AgOx) as oxide and metal layers, respectively, is synthesized on a polymer substrate and used as an anode in highly flexible organic solar cells (OSCs). The 3D electrode is fabricated using vacuum sputtering sequences to achieve self-assembly of distinct ITO nanoparticles on a continuous ITO-AgOx-ITO multilayer at room-temperature without applying conventional high-temperature vapour-liquid-solid growth, solution-based nanoparticle coating, or complicated nanopatterning techniques. Since the 3D electrode enhances the hole-extraction rate in OSCs owing to its high surface area and low effective series resistance for hole transport, OSCs based on this 3D electrode exhibit a power conversion efficiency that is 11-22% higher than that achievable in OSCs by means of conventional planar ITO film-type electrodes. A record high efficiency of 6.74% can be achieved in a bendable OSC fabricated on a poly(ethylene terephthalate) substrate.A three-dimensional (3D) transparent conducting electrode, consisting of a quasi-periodic array of discrete indium-tin-oxide (ITO) nanoparticles superimposed on a highly conducting oxide-metal-oxide multilayer using ITO and silver oxide (AgOx) as oxide and metal layers, respectively, is synthesized on a polymer substrate and used as an anode in highly flexible organic solar cells (OSCs). The 3D electrode is fabricated using vacuum sputtering sequences to achieve self-assembly of distinct ITO nanoparticles on a continuous ITO-AgOx-ITO multilayer at room-temperature without applying conventional high-temperature vapour-liquid-solid growth, solution-based nanoparticle coating, or complicated nanopatterning techniques. Since the 3D electrode enhances the hole-extraction rate in OSCs owing to its high surface area and low effective series resistance for hole transport, OSCs based on this 3D electrode exhibit a power conversion efficiency that is 11-22% higher than that achievable in OSCs by means of conventional planar ITO film-type electrodes. A record high efficiency of 6.74% can be achieved in a bendable OSC fabricated on a poly(ethylene terephthalate) substrate. Electronic supplementary information (ESI) available: FE-SEM images of Ar plasma-treated PET surfaces, curve deconvolution of XPS Ag 3d5/2 spectra, refractive indices and extinction coefficients of the Ag and AgOx (O/Ag = 10 at%), changes in the specular reflections of the IAOI-NPA and IAI-NPA electrodes for different O/Ag atomic ratios and thicknesses of the AgOx layer, and comparisons between the Jsc values determined from simulated AM 1.5G illumination and IPCE spectra. See DOI: 10.1039/c3nr06755f

Wang, Wei; Bae, Tae-Sung; Park, Yeon Hyun; Kim, Dong Ho; Lee, Sunghun; Min, Guanghui; Lee, Gun-Hwan; Song, Myungkwan; Yun, Jungheum

2014-05-01

92

Effects of hydrazine hydrate treatment on the performance of reduced graphene oxide film as counter electrode in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

The reduced graphene oxide (RGO) counter electrodes were prepared by drop casting method and followed by heat treatment. The as-prepared RGO counter electrodes were used as substitution for Pt counter electrode in dye-sensitized solar cells (DSSCs). The effects of hydrazine hydrate in graphene oxide (GO) suspension on the performance of RGO counter electrodes were investigated. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements revealed that a moderate amount of hydrazine hydrate can enhance the catalytic activity of the RGO film toward the reduction of I3- and decrease the sheet resistance of the film. The efficiency (?) of DSSC based on the RGO counter electrodes with optimum addition of hydrazine hydrate increased from 1.826% to 2.622% under a simulated solar illumination of 100 mW cm-2 (AM 1.5).

Qiu, Leifei; Zhang, Haiyan; Wang, Wenguang; Chen, Yiming; Wang, Rong

2014-11-01

93

Rapid atmospheric pressure plasma jet processed reduced graphene oxide counter electrodes for dye-sensitized solar cells.  

PubMed

In this work, we present the use of reduced graphene oxide (rGO) as the counter electrode materials in dye-sensitized solar cells (DSSCs). rGO was first deposited on a fluorine-doped tin oxide glass substrate by screen-printing, followed by post-treatment to remove excessive organic additives. We investigated the effect of atmospheric pressure plasma jet (APPJ) treatment on the DSSC performance. A power conversion efficiency of 5.19% was reached when DSSCs with an rGO counter electrode were treated by APPJs in the ambient air for a few seconds. For comparison, it requires a conventional calcination process at 400 °C for 15 min to obtain comparable efficiency. Scanning electron micrographs show that the APPJ treatment modifies the rGO structure, which may reduce its conductivity in part but simultaneously greatly enhances its catalytic activity. Combined with the rapid removal of organic additives by the highly reactive APPJ, DSSCs with APPJ-treated rGO counter electrode show comparable efficiencies to furnace-calcined rGO counter electrodes with greatly reduced process time. This ultrashort process time renders an estimated energy consumption per unit area of 1.1 kJ/cm(2), which is only one-third of that consumed in a conventional furnace calcination process. This new methodology thus saves energy, cost, and time, which is greatly beneficial to future mass production. PMID:25127290

Liu, Hsiao-Wei; Liang, Sheng-Ping; Wu, Ting-Jui; Chang, Haoming; Kao, Peng-Kai; Hsu, Cheng-Che; Chen, Jian-Zhang; Chou, Pi-Tai; Cheng, I-Chun

2014-09-10

94

High performance ZnO-SnO?:F nanocomposite transparent electrodes for energy applications.  

PubMed

Enhancing the propagation length of light without sacrificing the electro-optical properties of transparent electrodes is of particular interest to solar cells for reaching higher efficiency. This can typically be achieved by nanostructured electrodes but all too often at the expense of complexity and cost-effectiveness. In this work, we demonstrate the simple and low-cost fabrication of a new type of ZnO-SnO2:F nanocomposite thin film by combining spin-coated ZnO nanoparticles on glass with fluorine-doped SnO2 thin films deposited by atmospheric spray pyrolysis. The resulting nanocomposites exhibit a dual surface morphology featuring rough ZnO-SnO2:F nanostructures along with the original smooth SnO2:F thin film. By readily modulating the surface morphology of ZnO-SnO2:F nanocomposite thin films with the initial ZnO NP surface coverage, the scattering efficiency of the incident light can remarkably be controlled over the 400-1100 nm solar spectrum wavelength range. High quality hazy ZnO-SnO2:F thin layers are therefore formed with an averaged haze factor ranging from 0.4 to 64.2% over the 400-1100 nm solar spectrum range while the sheet resistance is kept smaller than 15 ?/sq for an average total optical transmittance close to 80%, substrate absorption and reflection included. Eventually, optical simulations using Fourier transform techniques are performed for computing the obtained haze factors and show good agreement with experimental data in the 400-1100 nm solar spectrum wavelength range. This opens up additional opportunities for further design optimization of nanoengineered transparent electrodes. PMID:25073487

Giusti, Gaël; Consonni, Vincent; Puyoo, Etienne; Bellet, Daniel

2014-08-27

95

A novel hierarchical Pt- and FTO-free counter electrode for dye-sensitized solar cell  

PubMed Central

A novel hierarchical Pt- and FTO-free counter electrode (CE) for the dye-sensitized solar cell (DSSC) was prepared by spin coating the mixture of TiO2 nanoparticles and poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) solution onto the glass substrate. Compared with traditional Pt/FTO CE, the cost of the new CE is dramatically reduced by the application of bilayer TiO2-PEDOT:PSS/PEDOT:PSS film and the glass substrate. The sheet resistance of this composite film is 35 ? sq?1 and is low enough to be used as an electrode. The surface morphologies of TiO2-PEDOT:PSS layer and modified PEDOT:PSS layer were characterized by scanning electron microscope, which shows that the former had larger surface areas than the latter. Electrochemical impedance spectra and Tafel polarization curves prove that the catalytic activity of TiO2-PEDOT:PSS/PEDOT:PSS/glass CE is higher than that of PEDOT:PSS/FTO CE and is similar to Pt/FTO CE's. This new fabricated device with TiO2-PEDOT:PSS/PEDOT:PSS/glass CE achieves a high power conversion efficiency (PCE) of 4.67%, reaching 91.39% of DSSC with Pt/FTO CE (5.11%). PMID:24808802

2014-01-01

96

Pt-free counter electrode for dye-sensitized solar cells with high efficiency.  

PubMed

Dye-sensitized solar cells (DSSCs) have attracted widespread attention in recent years as potential cost-effective alternatives to silicon-based and thin-film solar cells. Within typical DSSCs, the counter electrode (CE) is vital to collect electrons from the external circuit and catalyze the I3- reduction in the electrolyte. Careful design of the CEs can improve the catalytic activity and chemical stability associated with the liquid redox electrolyte used in most cells. In this Progress Report, advances made by our groups in the development of CEs for DSSCs are reviewed, highlighting important contributions that promise low-cost, efficient, and robust DSSC systems. Specifically, we focus on the design of novel Pt-free CE catalytic materials, including design ideas, fabrication approaches, characterization techniques, first-principle density functional theory (DFT) calculations, ab-initio Car-Parrinello molecular dynamics (CPMD) simulations, and stability evaluations, that serve as practical alternatives to conventional noble metal Pt electrodes. We stress the merits and demerits of well-designed Pt-free CEs, such as carbon materials, conductive polymers, transition metal compounds (TMCs) and their corresponding hybrids. Also, the prospects and challenges of alternative Pt catalysts for their applications in new-type DSSCs and other catalytic fields are discussed. PMID:25080873

Yun, Sining; Hagfeldt, Anders; Ma, Tingli

2014-09-01

97

A novel hierarchical Pt- and FTO-free counter electrode for dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

A novel hierarchical Pt- and FTO-free counter electrode (CE) for the dye-sensitized solar cell (DSSC) was prepared by spin coating the mixture of TiO2 nanoparticles and poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) solution onto the glass substrate. Compared with traditional Pt/FTO CE, the cost of the new CE is dramatically reduced by the application of bilayer TiO2-PEDOT:PSS/PEDOT:PSS film and the glass substrate. The sheet resistance of this composite film is 35 ? sq-1 and is low enough to be used as an electrode. The surface morphologies of TiO2-PEDOT:PSS layer and modified PEDOT:PSS layer were characterized by scanning electron microscope, which shows that the former had larger surface areas than the latter. Electrochemical impedance spectra and Tafel polarization curves prove that the catalytic activity of TiO2-PEDOT:PSS/PEDOT:PSS/glass CE is higher than that of PEDOT:PSS/FTO CE and is similar to Pt/FTO CE's. This new fabricated device with TiO2-PEDOT:PSS/PEDOT:PSS/glass CE achieves a high power conversion efficiency (PCE) of 4.67%, reaching 91.39% of DSSC with Pt/FTO CE (5.11%).

Zhao, Xing; Li, Meicheng; Song, Dandan; Cui, Peng; Zhang, Zhirong; Zhao, Yan; Shen, Chao; Zhang, Zhaohuang

2014-05-01

98

Low-temperature self-assembled vertically aligned carbon nanofibers as counter-electrode material for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Low-temperature AC-DC PECVD is employed for direct growth of vertically aligned carbon nanofibers (VACNFs) on ordinary transparent conductive glass as counter-electrode material for dye-sensitized solar cells (DSSCs). To the best of our knowledge, this is the first report on utilization of VACNFs grown directly on ordinary FTO-coated glass as a cost-effective catalyst material in DSSCs. According to the FESEM images, the as-grown arrays are well aligned and dense, and offer uniform coverage on the surface of the substrate. In-plane and out-of-plane conductivity measurements reveal their good electrical conductivity, and Raman spectroscopy suggests a high number of electrocatalytic active sites, favoring charge transport at the electrolyte/electrode interface. Hybrid VACNF/Pt electrodes are also fabricated for performance comparison with Pt and VACNF electrodes. X-ray diffraction results verify the crystallization of Pt in hybrid electrodes and further confirm the vertical alignment of carbon nanofibers. Electrochemical characterization indicates that VACNFs provide both high catalytic and good charge transfer capability, which can be attributed to their high surface area, defect-rich and one-dimensional structure, vertical alignment and low contact resistance. As a result, VACNF cells can achieve a comparable performance (˜5.6%) to that of the reference Pt cells (˜6.5%). Moreover, by combination of the excellent charge transport and catalytic ability of VACNFs and the high conductivity of Pt nanoparticles, hybrid VACNF/Pt cells can deliver a performance superior to that of the Pt cells (˜7.2%), despite having a much smaller amount of Pt loading, which raises hopes for low-cost large-scale production of DSSCs in the future.

Mahpeykar, S. M.; Tabatabaei, M. K.; Ghafoori-fard, H.; Habibiyan, H.; Koohsorkhi, J.

2013-11-01

99

Spectroscopic and Electrochemical Characterization of Nanostructured Optically-Transparent Carbon Electrodes  

PubMed Central

The present paper describes the results related to the optical and electrochemical characterization of thin carbon films fabricated by spin coating and pyrolysis of AZ P4330-RS photoresist. The goal of this paper is to provide comprehensive information allowing for the rational the selection of the conditions to fabricate optically-transparent carbon electrodes (OTCE) with specific electro-optical properties. According to our results, these electrodes could be appropriate choices as electrochemical transducers to monitor electrophoretic separations. At the core of this manuscript is the development and critical evaluation of a new optical model to calculate the thickness of the OTCE by variable angle spectroscopic ellipsometry (VASE). Such data was complemented with topography and roughness (obtained by AFM), electrochemical properties (obtained by cyclic voltammetry), electrical properties (obtained by electrochemical impedance spectroscopy), and structural composition (obtained by Raman spectroscopy). Although the described OTCE were used as substrates to investigate the effect of electrode potential on the real-time adsorption of proteins by ellipsometry, these results could enable the development of other biosensors that can be then integrated into various CE platforms. PMID:23595607

Benavidez, Tomas E.; Garcia, Carlos D.

2013-01-01

100

Multiscale transparent electrode architecture for efficient light management and carrier collection in solar cells.  

PubMed

The challenge for all photovoltaic technologies is to maximize light absorption, to convert photons with minimal losses into electric charges, and to efficiently extract them to the electrical circuit. For thin-film solar cells, all these tasks rely heavily on the transparent front electrode. Here we present a multiscale electrode architecture that allows us to achieve efficiencies as high as 14.1% with a thin-film silicon tandem solar cell employing only 3 ?m of silicon. Our approach combines the versatility of nanoimprint lithography, the unusually high carrier mobility of hydrogenated indium oxide (over 100 cm(2)/V/s), and the unequaled light-scattering properties of self-textured zinc oxide. A multiscale texture provides light trapping over a broad wavelength range while ensuring an optimum morphology for the growth of high-quality silicon layers. A conductive bilayer stack guarantees carrier extraction while minimizing parasitic absorption losses. The tunability accessible through such multiscale electrode architecture offers unprecedented possibilities to address the trade-off between cell optical and electrical performance. PMID:22332666

Boccard, Mathieu; Battaglia, Corsin; Hänni, Simon; Söderström, Karin; Escarré, Jordi; Nicolay, Sylvain; Meillaud, Fanny; Despeisse, Matthieu; Ballif, Christophe

2012-03-14

101

A dye-sensitized solar cell based on platinum nanotube counter electrode with efficiency of 9.05%  

NASA Astrophysics Data System (ADS)

Platinum nanotubes (PNTs) are directly grown on fluorine-doped tin oxide substrates by a facile polycarbonate template method. Morphology observation and electrochemical measurements indicate that the PNTs show a one-dimensional structure, lower charge-transfer resistance, larger exchange current density and higher electrocatalytic activity for iodide/triiodide redox reaction. Using the PNT as counter electrode and MgO as block layer on TiO2 film, the fabricated dye-sensitized solar cell achieves a light-to-electric energy conversion efficiency of 9.05% under a simulated solar light irradiation of 100 mW cm-2, the efficiency is increased by 25.5% compared to that of DSSC based on conventional Pt counter electrode. Higher efficiency for the PNT electrode is due its one-dimensional nanostructure, large surface area and good electrochemical activity to iodide/triiodide couple.

Wu, Jihuai; Tang, Ziying; Huang, Yunfang; Huang, Miaoliang; Yu, Haijun; Lin, Jianming

2014-07-01

102

A study of TiO2/carbon black composition as counter electrode materials for dye-sensitized solar cells  

PubMed Central

This study describes a systematic approach of TiO2/carbon black nanoparticles with respect to the loading amount in order to optimize the catalytic ability of triiodide reduction for dye-sensitized solar cells. In particular, the cell using an optimized TiO2 and carbon black electrode presents an energy conversion efficiency of 7.4% with a 5:1 ratio of a 40-nm TiO2 to carbon black. Based on the electrochemical analysis, the charge-transfer resistance of the carbon counter electrode changed based on the carbon black powder content. Electrochemical impedance spectroscopy and cyclic voltammetry study show lower resistance compared to the Pt counter electrode. The obtained nanostructures and photo electrochemical study were characterized. PMID:23672498

2013-01-01

103

An organic surface modifier to produce a high work function transparent electrode for high performance polymer solar cells.  

PubMed

Modification of an ITO electrode with small-molecule organic surface modifier, 4-chloro-benzoic acid (CBA), via a simple spin-coating method produces a high-work-function electrode with high transparency and a hydrophobic surface. As an alternative to PEDOT:PSS, CBA modification achieves efficiency enhancement up to 8.5%, which is attributed to enhanced light absorption within the active layer and smooth hole transport from the active layer to the anode. PMID:25515353

Choi, Hyosung; Kim, Hak-Beom; Ko, Seo-Jin; Kim, Jin Young; Heeger, Alan J

2015-02-01

104

Counter-ion dependent, longitudinal unzipping of multi-walled carbon nanotubes to highly conductive and transparent graphene nanoribbons.  

PubMed

Here we report for the first time, a simple hydrothermal approach for the bulk production of highly conductive and transparent graphene nanoribbons (GNRs) using several counter ions from K2SO4, KNO3, KOH and H2SO4 in aqueous media, where, selective intercalation followed by exfoliation gives highly conducting GNRs with over 80% yield. In these experiments, sulfate and nitrate ions act as a co-intercalant along with potassium ions resulting into exfoliation of multi-walled carbon nanotubes (MWCNTs) in an effective manner. The striking similarity of experimental results in KOH and H2SO4 that demonstrates partially damaged MWCNTs, implies that no individual K(+), SO4(2-) ion plays a key role in unwrapping of MWCNTs, rather this process is largely effective in the presence of both cations and anions working in a cooperative manner. The GNRs can be used for preparing conductive 16?k?sq(-1), transparent (82%) and flexible thin films using low cost fabrication method. PMID:24621526

Shinde, Dhanraj B; Majumder, Mainak; Pillai, Vijayamohanan K

2014-01-01

105

Counter-ion Dependent, Longitudinal Unzipping of Multi-Walled Carbon Nanotubes to Highly Conductive and Transparent Graphene Nanoribbons  

NASA Astrophysics Data System (ADS)

Here we report for the first time, a simple hydrothermal approach for the bulk production of highly conductive and transparent graphene nanoribbons (GNRs) using several counter ions from K2SO4, KNO3, KOH and H2SO4 in aqueous media, where, selective intercalation followed by exfoliation gives highly conducting GNRs with over 80% yield. In these experiments, sulfate and nitrate ions act as a co-intercalant along with potassium ions resulting into exfoliation of multi-walled carbon nanotubes (MWCNTs) in an effective manner. The striking similarity of experimental results in KOH and H2SO4 that demonstrates partially damaged MWCNTs, implies that no individual K+, SO42- ion plays a key role in unwrapping of MWCNTs, rather this process is largely effective in the presence of both cations and anions working in a cooperative manner. The GNRs can be used for preparing conductive 16 k?sq-1, transparent (82%) and flexible thin films using low cost fabrication method.

Shinde, Dhanraj B.; Majumder, Mainak; Pillai, Vijayamohanan K.

2014-03-01

106

Counter-ion Dependent, Longitudinal Unzipping of Multi-Walled Carbon Nanotubes to Highly Conductive and Transparent Graphene Nanoribbons  

PubMed Central

Here we report for the first time, a simple hydrothermal approach for the bulk production of highly conductive and transparent graphene nanoribbons (GNRs) using several counter ions from K2SO4, KNO3, KOH and H2SO4 in aqueous media, where, selective intercalation followed by exfoliation gives highly conducting GNRs with over 80% yield. In these experiments, sulfate and nitrate ions act as a co-intercalant along with potassium ions resulting into exfoliation of multi-walled carbon nanotubes (MWCNTs) in an effective manner. The striking similarity of experimental results in KOH and H2SO4 that demonstrates partially damaged MWCNTs, implies that no individual K+, SO42? ion plays a key role in unwrapping of MWCNTs, rather this process is largely effective in the presence of both cations and anions working in a cooperative manner. The GNRs can be used for preparing conductive 16?k?sq?1, transparent (82%) and flexible thin films using low cost fabrication method. PMID:24621526

Shinde, Dhanraj B.; Majumder, Mainak; Pillai, Vijayamohanan K.

2014-01-01

107

Metal wire network based transparent conducting electrodes fabricated using interconnected crackled layer as template  

NASA Astrophysics Data System (ADS)

A metal (Au) wire network, nearly invisible to the naked eye, has been realized on common substrates such as glass, to serve as a transparent conducting electrode (TCE). The process involves coating a TiO2 nanoparticle dispersion to a film thickness of ˜10 ?m, which following solvent evaporation, spontaneously forms a crackle network; the film is then used as a sacrificial template for metal deposition. The TCE thus formed exhibited visible transmittance of ˜82% and sheet resistance of 3-6 ?/square for a metal fill factor of 7.5%. With polyethylene terephthalate substrate, flexible and robust TCE could be produced and with quartz, the spectral range could be widened to cover UV and IR regions.

Kiruthika, S.; Rao, K. D. M.; Kumar, Ankush; Gupta, Ritu; Kulkarni, G. U.

2014-04-01

108

Transparent Conducting Electrodes based on 1D and 2D Ag Nanogratings for Organic Photovoltaics  

E-print Network

The optical and electrical properties of optically-thin one-dimensional (1D) Ag nanogratings and two-dimensional (2D) Ag nanogrids are studied, and their use as transparent electrodes in organic photovoltaics are explored. A large broadband and polarization-insensitive optical absorption enhancement in the organic light-harvesting layers is theoretically and numerically demonstrated using either single-layer 2D Ag nanogrids or two perpendicular 1D Ag nanogratings, and is attributed to the excitation of surface plasmon resonances and plasmonic cavity modes. Total photon absorption enhancements of 150% and 200% are achieved for the optimized single-layer 2D Ag nanogrids and double (top and bottom) perpendicular 1D Ag nanogratings, respectively.

Zeng, Beibei; Bartoli, Filbert J

2014-01-01

109

Ag@Ni core-shell nanowire network for robust transparent electrodes against oxidation and sulfurization.  

PubMed

Silver nanowire (Ag NW) based transparent electrodes are inherently unstable to moist and chemically reactive environment. A remarkable stability improvement of the Ag NW network film against oxidizing and sulfurizing environment by local electrodeposition of Ni along Ag NWs is reported. The optical transmittance and electrical resistance of the Ni deposited Ag NW network film can be easily controlled by adjusting the morphology and thickness of the Ni shell layer. The electrical conductivity of the Ag NW network film is increased by the Ni coating via welding between Ag NWs as well as additional conductive area for the electron transport by electrodeposited Ni layer. Moreover, the chemical resistance of Ag NWs against oxidation and sulfurization can be dramatically enhanced by the Ni shell layer electrodeposited along the Ag NWs, which provides the physical barrier against chemical reaction and diffusion as well as the cathodic protection from galvanic corrosion. PMID:24961495

Eom, Hyeonjin; Lee, Jaemin; Pichitpajongkit, Aekachan; Amjadi, Morteza; Jeong, Jun-Ho; Lee, Eungsug; Lee, Jung-Yong; Park, Inkyu

2014-10-29

110

Fully-sprayed and flexible organic photodiodes with transparent carbon nanotube electrodes.  

PubMed

In this study, we demonstrate the feasibility of TCO-free, fully sprayed organic photodiodes on flexible polyethylene terephthalate (PET) substrates. Transparent conducting films of single-wall carbon nanotubes are spray deposited from aqueous solutions. Low roughness is achieved, and films with sheet resistance values of 160 ?/sq at 84% in transmittance are fabricated. Process issues related to the wetting of CNTs are then examined and solved, enabling successive spray depositions of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layer and a blend of regioregular poly(3-hexylthiophene-2,5-diyl) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM). The active layer is then optimized, achieving a process yield above 90% and dark currents as low as 10(-4) mA/cm(2). An external quantum efficiency of 65% and high reproducibility in the performance of the devices are obtained. Finally, the impact of the characteristics of the transparent electrode (transmittance and sheet resistance) on the performances of the device are investigated and validated through a theoretical model and experimental data. PMID:24914700

Falco, Aniello; Cinà, Lucio; Scarpa, Giuseppe; Lugli, Paolo; Abdellah, Alaa

2014-07-01

111

Electrospray deposition of carbon nanotube thin films for flexible transparent electrodes.  

PubMed

Flexible transparent carbon nanotube (CNT) electrodes were fabricated by electrospray deposition, a large-area scalable and cost-effective process. The carbon nanotubes were dispersed in N,N-dimethylformamide (DMF) and deposited on polyethylene terephthalate (PET) substrates by electrospray deposition process at room temperature and atmospheric pressure. Major process variables were characterized and optimized for the electrospray process development such as electric field between nozzle and substrates, CNT solution flowrate, gap between nozzle and substrates, solution concentration, solvent properties and surface temperature. The sheet resistance of the electrospray deposited CNT films were reduced by HNO3 doping process. 169 Omega/sq sheet resistance and 86% optical transmittance was achieved with low surface roughness of 1.2 nm. The films showed high flexibility and transparency, making them potential replacements of ITO or ZnO in such as solid state lighting, touch panels, and solar cells. Electrospray process is a scalable process and we believe that this process can be applied for large area carbon nanotube film formation. PMID:24205613

Meng, Yinan; Xin, Guoqing; Nam, Jaewook; Cho, Sung Min; Chae, Heeyeop

2013-09-01

112

High-performance flexible organic light-emitting diodes using embedded silver network transparent electrodes.  

PubMed

Because of their mechanical flexibility, organic light-emitting diodes (OLEDs) hold great promise as a leading technology for display and lighting applications in wearable electronics. The development of flexible OLEDs requires high-quality transparent conductive electrodes with superior bendability and roll-to-roll manufacturing compatibility to replace indium tin oxide (ITO) anodes. Here, we present a flexible transparent conductor on plastic with embedded silver networks which is used to achieve flexible, highly power-efficient large-area green and white OLEDs. By combining an improved outcoupling structure for simultaneously extracting light in waveguide and substrate modes and reducing the surface plasmonic losses, flexible white OLEDs exhibit a power efficiency of 106 lm W(-1) at 1000 cd m(-2) with angular color stability, which is significantly higher than all other reports of flexible white OLEDs. These results represent an exciting step toward the realization of ITO-free, high-efficiency OLEDs for use in a wide variety of high-performance flexible applications. PMID:25470615

Zhou, Lei; Xiang, Heng-Yang; Shen, Su; Li, Yan-Qing; Chen, Jing-De; Xie, Hao-Jun; Goldthorpe, Irene A; Chen, Lin-Sen; Lee, Shuit-Tong; Tang, Jian-Xin

2014-12-23

113

Morphological and opto-electrical properties of a solution deposited platinum counter electrode for low cost dye sensitized solar cells.  

PubMed

Although platinum (Pt) is a rare and very expensive material, Pt counter electrodes are still very commonly used for reaching high efficiencies in dye-sensitized solar cells (DSCs). The use of alternative cheaper catalyst materials did not yet yield equivalent efficiencies. In this work, we tried to understand how to reduce the amount of deposited Pt-material and simultaneously deliver higher DSC performances. We systematically compared the properties of Pt-counter electrodes prepared by simple solution deposition methods such as spray-coating, dip-coating, brushing with reference to the Pt-electrodes prepared by sputtering onto fluorine doped-tin oxides (FTOs). The morphological and structural characterizations of the deposited Pt-layers were performed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The composition of Pt-material was quantified using SEM electron dispersive X-ray (EDX) mapping measurements which were further compared with optical transmission measurements. Also contact angle and sheet resistance measurements were performed. By taking Pt-layers composition, morphology and structural factors into account, 9.16% efficient N3 dye based DSCs were assembled. The DSCs were subjected to various opto-electrical characterization techniques like current-voltage (I-V), external quantum efficiency (EQE), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and transient photo voltage (TPV) measurements. The obtained experimental data suggest that the Pt counter electrodes prepared by solution deposition methods can also reach high DSC device performances with a consumption of very little amount of Pt material as compared with sputtered Pt-layers. This process also proves that higher DSC performances are not limited to the usage of sputtered Pt-layer as counter electrode. PMID:24146075

Thalluri, Gopala Krishna V V; Décultot, Marc; Henrist, Catherine; Dewalque, Jennifer; Colson, Pierre; Habraken, Serge; Spoltore, Donato; Manca, Jean; Cloots, Rudi

2013-12-01

114

A cracked polymer templated metal network as a transparent conducting electrode for ITO-free organic solar cells.  

PubMed

We report a highly transparent, low resistance Ag metal network templated by a cracked polymer thin film and its incorporation in an organic solar cell. The performance of this scalable metallic network is comparable to that of conventional ITO electrodes. This is a general approach to replace ITO in diverse thin film devices. PMID:24958552

Rao, K D M; Hunger, Christoph; Gupta, Ritu; Kulkarni, Giridhar U; Thelakkat, Mukundan

2014-08-01

115

Transparency  

ERIC Educational Resources Information Center

Citizens now expect access to information, particularly from public institutions like local school districts. They demand input and accountability. Cultural and technological changes, such as the Internet, make it possible for districts to comply. Yet transparency--the easily seen and understood actions of a school district and the thinking behind…

LaFee, Scott

2009-01-01

116

Potential-Assisted Adsorption of Bovine Serum Albumin onto Optically-Transparent Carbon Electrodes  

PubMed Central

This manuscript describes the effect of the applied potential on the adsorption of bovine serum albumin (BSA) to optically transparent carbon electrodes (OTCE). To decouple the effect of the applied potential from the high affinity of the protein for the bare surface, the surface of the OTCE was initially saturated with a layer of BSA. Experiments described in the manuscript show that potential values higher than +500 mV induced a secondary adsorption process (not observed at open-circuit potentials), yielding significant changes in the thickness (and adsorbed amount) of the BSA layer obtained. Although the process showed a significant dependence on the experimental conditions selected, the application of higher potentials, selection of pH values around the isoelectric point (IEP) of the protein, high concentrations of protein, and low ionic strengths yielded faster kinetics and the accumulation of larger amounts of protein on the substrate. These experiments, obtained around the IEP of the protein, contrast with the traditional hypothesis that enhanced electrostatic interactions between the polarized substrate and the (oppositely charged) protein are solely responsible for the enhanced adsorption. These results suggest that the potential applied to the electrode is able to polarize the adsorbed layer and induce dipole-dipole interactions between the adsorbed and the incoming protein. This mechanism could be responsible for the potential-dependent oversaturation of the surface and could bolster to the development of surfaces with enhanced catalytic activity and implants with improved biocompatibility. PMID:24156567

Benavidez, Tomás E.; Garcia, Carlos D.

2013-01-01

117

Graphene as Transparent Electrode for Direct Observation of Hole Photoemission from Silicon to Oxide  

E-print Network

The outstanding electrical and optical properties of graphene make it an excellent alternative as a transparent electrode. Here we demonstrate the application of graphene as collector material in internal photoemission (IPE) spectroscopy; enabling the direct observation of both electron and hole injections at a Si/Al2O3 interface and successfully overcoming the long-standing difficulty of detecting holes injected from a semiconductor emitter in IPE measurements. The observed electron and hole barrier heights are 3.5 eV and 4.1 eV, respectively. Thus the bandgap of Al2O3 can be further deduced to be 6.5 eV, in close agreement with the valued obtained by vacuum ultraviolet spectroscopic ellipsometry analysis. The detailed optical modeling of a graphene/Al2O3/Si stack reveals that by using graphene in IPE measurements the carrier injection from the emitter is significantly enhanced and the contribution of carrier injection from the collector electrode is minimal. The method can be readily extended to various IPE...

Yan, Rusen; Kirillov, Oleg A; Li, Wei; Basham, James; Boosalis, Alex; Liang, Xuelei; Jena, Debdeep; Richter, Curt A; Seabaugh, Alan; Gundlach, David J; Xing, Huili G; Nguyen, N V

2012-01-01

118

Two-dimensional acoustic particle focusing enables sheathless chip Coulter counter with planar electrode configuration.  

PubMed

The field of cytometry has grown in scope and importance ever since the early 20th century with leaps in technology introducing the Coulter counter and the flow cytometer. Cytometry methods have brought about a revolution for the medical and biotechnology industry by providing fast and accurate analysis of cell and particle suspensions. Recent developments in the field aim at improving current cytometers and to provide miniaturized low-cost cytometry systems for point-of-care clinical diagnostics or research. In an attempt to address the need for particle positioning which is important for both impedance and optically based cytometers we present a microfluidic system which precisely positions cells and particles, using acoustic forces and subsequently performs measurements using an integrated and simple planar electrode Coulter-type impedance cytometer without the need for sheath flows. Data is presented to show how the acoustic method improves the accuracy of the impedance cytometer when prefocusing is employed to particles and cells (diluted whole blood). Confocal imaging and simulations support the findings and provide the basis for further improvements. The acoustophoretic prefocusing technique opens a path towards small, low cost cytometers while also providing an easy way to improve current systems. PMID:25300357

Grenvall, Carl; Antfolk, Christian; Bisgaard, Christer Zoffmann; Laurell, Thomas

2014-12-21

119

Characterization of indium oxide for the use as a counter-electrode in an electrochromic device  

SciTech Connect

Thin films of indium oxide, In{sub 2}O{sub 3} (4000 {Angstrom}), deposited on commercially available In{sub 2}O{sub 3}: Sn (ITO)/glass by rf sputtering, have been examined for potential application as a counter-electrode material in an electrochromic device, based on their chemical, structural, and optical properties. Cyclic voltammetry experiments showed that mobile lithium ions can be inserted (chemical reduction) and removed (chemical oxidation) from the host structure of indium oxide. Coulometric titrations showed that the films exhibited a hysteresis behavior for the injection and removal of lithium ions in Li{sub x}In{sub 2}O{sub 3} (x=0-0.23). Structural investigations of the indium oxide films, utilizing electron diffraction techniques, indicated that they were crystalline with a crystallite size of 175 {Angstrom}, in agreement with x-ray diffraction results. Differences in optical transmission between the lithiated and delithiated thin films were no more than 5% in the visible/near-infrared regions of the spectrum. 6 refs., 5 figs., 1 tab.

Yu, P.C.; Haas, T.E. (Tufts Univ., Medford, MA (USA). Dept. of Chemistry); Goldner, R.B. (Tufts Univ., Medford, MA (USA). Electro-Optics Technology Center); Cogan, S.F. (EIC Labs., Inc., Norwood, MA (USA))

1991-01-01

120

Co-Electrophoretic Deposition Multiwall Carbon Nanotubes/Pt Counter Electrodes for Dye-Sensitized Solar Cell  

NASA Astrophysics Data System (ADS)

Multiwall carbon nanotubes (MWCNTs) and platinum (Pt) were coated on fluorine doped tin oxide (FTO) coated glass by a direct current electrophoretic method, and were used as dye-sensitized solar cell counter electrodes. Scanning electron microscopy (SEM) detected the deposition of carbon nanotubes on FTO-glass. The deposition of Pt nanoparticles on carbon nanotube surfaces was confirmed by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Cell efficiencies of MWCNTs, Pt and MWCNTs/Pt dye-sensitized solar cells (DSSCs) were ?1.41, ?8.13, and ?8.90%, respectively. The improvement of the composited MWCNTs/Pt cell efficiency is due to the presence of both catalysts (MWCNTs and Pt) enhancing counter electrode catalytic activity as observed by cyclic voltammetry (CV) and reducing charge-transfer resistance as observed by electrochemical impedance spectroscopy (EIS).

Maiaugree, Wasan; Pimanpang, Samuk; Towannang, Madsakorn; Rutphonsan, Phikun; Laupa, Seksan; Jarernboon, Wirat; Amornkitbamrung, Vittaya

2012-10-01

121

Complexation of polyaniline and graphene for efficient counter electrodes in dye-sensitized solar cells: Enhanced charge transfer ability  

NASA Astrophysics Data System (ADS)

With an aim of significantly enhancing charge-transfer ability of counter electrodes and therefore photovoltaic performances of dye-sensitized solar cells (DSSCs), here we pioneerly report the complexation of polyaniline (PANi) and graphene as well as their employment as counter electrodes (CEs) in efficient DSSCs. Owing to the covalent bond between PANi (N atoms) and graphene (C atoms), charge transfer kinetics is dramatically elevated, which can be confirmed by the enhancement on electrocatalytic activity toward triiodides and a decrease in charge-transfer resistance. A power conversion efficiency of 7.70% is determined from DSSC using PANi-8 wt‰ graphene complex CE in comparison with 6.40% from pure PANi CE-based DSSC. The high conversion efficiency, facile charge-transfer in combination with simple preparation, relatively low cost, and scalability demonstrates the potential use of PANi-graphene complexes in robust DSSCs.

He, Benlin; Tang, Qunwei; Wang, Min; Ma, Chunqing; Yuan, Shuangshuang

2014-06-01

122

Wurtzite copper-zinc-tin sulfide as a superior counter electrode material for dye-sensitized solar cells  

PubMed Central

Wurtzite and kesterite Cu2ZnSnS4 (CZTS) nanocrystals were employed as counter electrode (CE) materials for dye-sensitized solar cells (DSSCs). Compared to kesterite CZTS, the wurtzite CZTS exhibited higher electrocatalytic activity for catalyzing reduction of iodide electrolyte and better conductivity. Accordingly, the DSSC with wurtzite CZTS CE generated higher power conversion efficiency (6.89%) than that of Pt (6.23%) and kesterite CZTS (4.89%) CEs. PMID:24191954

2013-01-01

123

Preparation and characterization of polyaniline film on stainless steel by electrochemical polymerization as a counter electrode of DSSC  

Microsoft Academic Search

Polyaniline (PANI) films were electrodeposited on stainless steel 304 (SS) from 0.5M H2SO4 solution containing 0.3M aniline by potentiostatic techniques to prepare a low cost and non-fragile counter electrode in dye-sensitized solar cell (DSSC). The compact layer, micro-particles, nanorods and fibrils were observed on the top of PANI films with different applied potentials (Eappl) by SEM. Then the conductivity and

Qi Qin; Jie Tao; Yan Yang

2010-01-01

124

Preparation of flexible organic solar cells with highly conductive and transparent metal-oxide multilayer electrodes based on silver oxide.  

PubMed

We report that significantly more transparent yet comparably conductive AgOx films, when compared to Ag films, are synthesized by the inclusion of a remarkably small amount of oxygen (i.e., 2 or 3 atom %) in thin Ag films. An 8 nm thick AgOx (O/Ag=2.4 atom %) film embedded between 30 nm thick ITO films (ITO/AgOx/ITO) achieves a transmittance improvement of 30% when compared to a conventional ITO/Ag/ITO electrode with the same configuration by retaining the sheet resistance in the range of 10-20 ? sq(-1). The high transmittance provides an excellent opportunity to improve the power-conversion efficiency of organic solar cells (OSCs) by successfully matching the transmittance spectral range of the electrode to the optimal absorption region of low band gap photoactive polymers, which is highly limited in OSCs utilizing conventional ITO/Ag/ITO electrodes. An improvement of the power-conversion efficiency from 4.72 to 5.88% is achieved from highly flexible organic solar cells (OSCs) fabricated on poly(ethylene terephthalate) polymer substrates by replacing the conventional ITO/Ag/ITO electrode with the ITO/AgOx/ITO electrode. This novel transparent electrode can facilitate a cost-effective, high-throughput, room-temperature fabrication solution for producing large-area flexible OSCs on heat-sensitive polymer substrates with excellent power-conversion efficiencies. PMID:24060352

Yun, Jungheum; Wang, Wei; Bae, Tae Sung; Park, Yeon Hyun; Kang, Yong-Cheol; Kim, Dong-Ho; Lee, Sunghun; Lee, Gun-Hwan; Song, Myungkwan; Kang, Jae-Wook

2013-10-23

125

Impedance analysis of nanocarbon DSSC electrodes  

Microsoft Academic Search

Carbon nanoparticles and multiwall carbon nanotubes were deposited on an Optically Transparent Electrode (OTE) for application in Dye Sensitised Solar Cells (DSSCs) as counter electrode materials. Electrochemical Impedance Spectroscopy (EIS) was used to evaluate the behaviour in a I3?\\/I? electrolyte solution. Results were compared to commercial Pt catalysed OTE and polycrystalline graphite. Multiwalled carbon nanotubes show low series resistance and

S. Gagliardi; L. Giorgi; R. Giorgi; N. Lisi; Th. Dikonimos Makris; E. Salernitano; A. Rufoloni

2009-01-01

126

A new architecture as transparent electrodes for solar and IR applications based on photonic structures via soft lithography  

SciTech Connect

Transparent conducting electrodes with the combination of high optical transmission and good electrical conductivity are essential for solar energy harvesting and electric lighting devices. Currently, indium tin oxide (ITO) is used because ITO offers relatively high transparency (>80%) to visible light and low sheet resistance (R{sub s} = 10 ohms/square ({Omega}#2;/?)) for electrical conduction. However, ITO is costly due to limited indium reserves, and it is brittle. These disadvantages have motivated the search for other conducting electrodes with similar or better properties. There has been research on a variety of electrode structures involving carbon nanotube networks, graphene films, nanowire and nanopatterned meshes and grids. Due to their novel characteristics in light manipulation and collection, photonic crystal structures show promise for further improvement. Here, we report on a new architecture consisting of nanoscale high aspect ratio metallic photonic structures as transparent electrodes fabricated via a combination of processes. For (Au) and silver (Ag) structures, the visible light transmission can reach as high as 80%, and the sheet resistance of the structure can be as low as 3.2{Omega}#2;/?. The optical transparency of the high aspect ratio metal structures at visible wavelength range is comparable to that of ITO glass, while their sheet resistance is more than 3 times lower, which indicates a much higher electrical conductivity of the metal structures. Furthermore, the high aspect ratio metal structures have very high infrared (IR) reflection (90%) for the transverse magnetic (TM) mode, which can lead to the development of fabrication of metallic structures as IR filters for heat control applications. Investigations of interdigitated structures based on the high aspect ratio metal electrodes are ongoing to study the feasibility in smart window applications in light transmission modulation.

Kuang, Ping

2011-05-15

127

High-performance dye-sensitized solar cells with gel-coated binder-free carbon nanotube films as counter electrode  

NASA Astrophysics Data System (ADS)

High-performance dye-sensitized solar cells (DSCs) with binder-free films of carbon nanotubes (CNTs), including single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs), as the counter electrode are reported. The CNT films were fabricated by coating gels, which were prepared by dispersing CNTs in low-molecular-weight poly(ethylene glycol) (PEG) through mechanical grinding and subsequent ultrasonication, on fluorine tin oxide (FTO) glass. PEG was removed from the CNT films through heating. These binder-free CNT films were rough and exhibited good adhesion to substrates. They were used as the counter electrode of DSCs. The DSCs with SWCNT or MWCNT counter electrodes exhibited a light-to-electricity conversion efficiency comparable with that with the conventional platinum (Pt) counter electrode, when the devices were tested immediately after device fabrication. The DSCs with an SWCNT counter electrode exhibited good stability in photovoltaic performance. The efficiency did not decrease after four weeks. On the other hand, DSCs with the MWCNT or Pt counter electrode exhibited a remarkable decrease in the photovoltaic efficiency after four weeks. The high photovoltaic performance of these DSCs is related to the excellent electrochemical catalysis of CNTs on the redox of the iodide/triiodide pair, as revealed by the cyclic voltammetry and ac impedance spectroscopy.

Mei, Xiaoguang; Cho, Swee Jen; Fan, Benhu; Ouyang, Jianyong

2010-10-01

128

Post-plasma treatment of a carbon nanowall for use as a counter electrode in a dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

This research investigates plasma-treated carbon nanowalls (CNW) for use as counter electrodes in dye-sensitized solar cells (DSSCs). The CNWs were synthesized on a fluorine-tin-oxide (FTO) glass substrate via microwave plasma-enhanced chemical vapor-deposition (PECVD) using CH4 gas. Then, post-plasma treatments were performed on the CNWs in different plasma environments (using O2, H2 and N2 gas) under the same conditions, after which DSSCs were fabricated using the plasma-treated CNWs as counter electrodes. Scanning electron microscopy (SEM) was performed to obtain cross-sectional and planar images of the CNWs, and Raman spectroscopy was used to analyze the structural characteristics of the post-plasma-treated synthesized CNWs. The energy conversion efficiency was then used to analyze the effect of using the plasma-treated CNWs as counter electrodes in the DSSCs. The DSSC for which the as-deposited CNW was used as a counter electrode showed an energy conversion efficiency of 1.64%, and the DSSC with the H2 postplasma-treated CNW counter electrode showed an energy conversion efficiency of 2.23%. Thus, the DSSC with the H2-treated electrode presented a 36% higher efficiency than the DSSC with the as-deposited CNW electrode.

Jung, Yong Ho; Choi, Won Seok; Hong, Byungyou

2014-08-01

129

Invisible metal-grid transparent electrode prepared by electrohydrodynamic (EHD) jet printing  

NASA Astrophysics Data System (ADS)

Invisible Ag-grid transparent electrodes (TEs) were prepared by electrohydrodynamic (EHD) jet printing using Ag nano-particle inks. Ag-grid width less than 10 µm was achieved by the EHD jet printing, which was invisible to the naked eye. The Ag-grid line-to-line distance (pitch) was modulated in order to investigate the electrical and optical properties of the EHD jet-printed Ag-grid TEs. The decrease in the sheet resistance at the expense of the transmittance was observed as the Ag-grid pitch decreased. The figure of merit of Ag-grid TEs with various Ag-grid pitches was investigated in order to determine the optimum pitch condition for both electrical and optical properties. With the 150 µm Ag-grid pitch, the EHD jet-printed Ag-grid TE has the sheet resistance of 4.87 ? sq-1 and the transmittance of 81.75% after annealing at 200 °C under near-infrared. Ag filling factor (FF) was defined to predict the electrical and optical properties of Ag-grid TEs. It was found that the measured electrical and optical properties were well simulated by the theoretical equations incorporating FF. The EHD jet-printed invisible Ag-grid TE with good electrical and optical properties implies its promising application to the printed optoelectronic devices.

Jang, Yonghee; Kim, Jihoon; Byun, Doyoung

2013-04-01

130

Electro-optic modulator with exceptional power-size performance enabled by transparent conducting electrodes.  

PubMed

An EO phase modulator having transparent conducting oxide electrodes and an inverted rib waveguide structure is demonstrated. This new modulator geometry employs an EO polymer having an in-device r33 = 60pm/V. The measured half-wave voltage Vpi of these devices ranges from 5.3V to 11.2V for 3.8 and 1.5 mm long devices, respectively. The lowest VpiL figure-of-merit corresponds to 0.6V-cm (7.2mW-cm(2) of power length product) in a dual-drive configuration. The trade-off between Vpi, insertion loss and modulation bandwidth is systematically analyzed. An optimized high-speed structure is proposed, with numerical simulation showing that this new structure and an in-device r33 = 150pm/V, can achieve Vpi = 0.5V in a 5mm long active length with dual drive operation. The insertion loss is targeted at 6dB, and a 3dB optical modulation bandwidth can reach > 40GHz. PMID:20389698

Yi, Fei; Ou, Fang; Liu, Boyang; Huang, Yingyan; Ho, Seng-Tiong; Wang, Yiliang; Liu, Jun; Marks, Tobin J; Huang, Su; Luo, Jingdong; Jen, Alex K-Y; Dinu, Raluca; Jin, Dan

2010-03-29

131

Highly reliable ag nanowire flexible transparent electrode with mechanically welded junctions.  

PubMed

Deformation behavior of the Ag nanowire flexible transparent electrode under bending strain is studied and results in a novel approach for highly reliable Ag nanowire network with mechanically welded junctions. Bending fatigue tests up to 500,000 cycles are used to evaluate the in situ resistance change while imposing fixed, uniform bending strain. In the initial stages of bending cycles, the thermally annealed Ag nanowire networks show a reduction in fractional resistance followed by a transient and steady-state increase at later stages of cycling. SEM analysis reveals that the initial reduction in resistance is caused by mechanical welding as a result of applied bending strain, and the increase in resistance at later stages of cycling is determined to be due to the failure at the thermally locked-in junctions. Based on the observations from this study, a new methodology for highly reliable Ag nanowire network is proposed: formation of Ag nanowire networks with no prior thermal annealing but localized junction formation through simple application of mechanical bending strain. The non-annealed, mechanically welded Ag nanowire network shows significantly enhanced cyclic reliability with essentially 0% increase in resistance due to effective formation of localized wire-to-wire contact. PMID:24789010

Hwang, Byungil; Shin, Hae-A-Seul; Kim, Taegeon; Joo, Young-Chang; Han, Seung Min

2014-08-27

132

Application of Single Wall Carbon Nanotubes as Transparent Electrodes in Cu(In,Ga)Se2-Based Solar Cells: Preprint  

SciTech Connect

We present a new thin-film solar cell structure in which the traditional transparent conductive oxide electrode (ZnO) is replaced by a transparent conductive coating consisting of a network of bundled single-wall carbon nanotubes. Optical transmission properties of these coatings are presented in relation to their electrical properties (sheet resistance), along with preliminary solar cell results from devices made using CuIn1-xGaxSe2 thin-film absorber materials. Achieving an energy conversion efficiency of >12% and a quantum efficiency of {approx}80% demonstrate the feasibility of the concept. A discussion of the device structures will be presented considering the physical properties of the new electrodes comparing current-voltage results from the new solar cell structure and those from standard ZnO/CdS/Cu(In,Ga)Se2/Mo solar cells.

Contreras, M.; Barnes, T.; van de Lagemaat, J.; Rumbles, G.; Coutts, T. J.; Weeks, C.; Glatkowski, P.; Levitsky, I.; Peltola, J.

2006-05-01

133

Optimization of transparent and reflecting electrodes for amorphous silicon solar cells. Annual subcontract report, April 1, 1994--March 31, 1995  

SciTech Connect

Transparent and reflecting electrodes are important parts of the structure of amorphous silicon solar cells. We report improved methods for depositing zinc oxide, deposition of tin nitride as a potential reflection-enhancing diffusion barrier between the a-Si and back metal electrodes. Highly conductive and transparent fluorine-doped zinc oxide was successfully produced on small areas by atmospheric pressure CVD from a less hazardous zinc precursor, zinc acetylacetonate. The optical properties measured for tin nitride showed that the back-reflection would be decreased if tin nitride were used instead of zinc oxide as a barrier layer over silver on aluminum. Niobium-doped titanium dioxide was produced with high enough electrical conductivity so that normal voltages and fill factors were obtained for a-Si cells made on it.

Gordon, R.G. [Harvard Univ., Cambridge, MA (United States)

1995-10-01

134

Optically transparent thin-film transistors based on 2D multilayer MoS2 and indium zinc oxide electrodes  

NASA Astrophysics Data System (ADS)

We report on optically transparent thin film transistors (TFTs) fabricated using multilayered molybdenum disulfide (MoS2) as the active channel, indium tin oxide (ITO) for the back-gated electrode and indium zinc oxide (IZO) for the source/drain electrodes, respectively, which showed more than 81% transmittance in the visible wavelength. In spite of a relatively large Schottky barrier between MoS2 and IZO, the n-type behavior with a field-effect mobility (?eff) of 1.4 cm2 V?1 s?1 was observed in as-fabricated transparent MoS2 TFT. In order to enhance the performances of transparent MoS2 TFTs, a picosecond pulsed laser was selectively irradiated onto the contact region of the IZO electrodes. Following laser annealing, ?eff increased to 4.5 cm2 V?1 s?1, and the on-off current ratio (Ion/Ioff) increased to 104, which were attributed to the reduction of the contact resistance between MoS2 and IZO.

Kwon, Junyeon; Hong, Young Ki; Kwon, Hyuk-Jun; Park, Yu Jin; Yoo, Byungwook; Kim, Jiwan; Grigoropoulos, Costas P.; Oh, Min Suk; Kim, Sunkook

2015-01-01

135

Optically transparent thin-film transistors based on 2D multilayer MoS2 and indium zinc oxide electrodes.  

PubMed

We report on optically transparent thin film transistors (TFTs) fabricated using multilayered molybdenum disulfide (MoS2) as the active channel, indium tin oxide (ITO) for the back-gated electrode and indium zinc oxide (IZO) for the source/drain electrodes, respectively, which showed more than 81% transmittance in the visible wavelength. In spite of a relatively large Schottky barrier between MoS2 and IZO, the n-type behavior with a field-effect mobility (?eff) of 1.4 cm(2) V(-1) s(-1) was observed in as-fabricated transparent MoS2 TFT. In order to enhance the performances of transparent MoS2 TFTs, a picosecond pulsed laser was selectively irradiated onto the contact region of the IZO electrodes. Following laser annealing, ?eff increased to 4.5 cm(2) V(-1) s(-1), and the on-off current ratio (Ion/Ioff) increased to 10(4), which were attributed to the reduction of the contact resistance between MoS2 and IZO. PMID:25548952

Kwon, Junyeon; Ki Hong, Young; Kwon, Hyuk-Jun; Jin Park, Yu; Yoo, Byungwook; Kim, Jiwan; Grigoropoulos, Costas P; Suk Oh, Min; Kim, Sunkook

2015-01-21

136

A new in-situ preparation method to FeS counter electrode for quantum dots-sensitized solar cells  

NASA Astrophysics Data System (ADS)

FeS counter electrode (CE) with the structure of three-dimensional nanospheres for quantum dots-sensitized solar cells (QDSCs) is first fabricated by alternating current (AC) etching the A3 carbon steel and characterized with scanning electron microscope (SEM), Transmission electron microscope (TEM), current-voltage and impedance spectroscopy. The device applying FeS CE achieves a power conversion efficiency of 3.34%, which are much higher than that of using Pt (1.01%) and conventional Cu2S (1.54%). These results indicated that AC provides an efficient, simple and cost-effective method to fabricate CE for QDSCs.

Quan, Linlin; Li, Weiping; Zhu, Liqun; Geng, Huifang; Chang, Xiaowen; Liu, Huicong

2014-12-01

137

Enhanced efficiency of the dye-sensitized solar cells by excimer laser irradiated carbon nanotube network counter electrode  

SciTech Connect

The carbon nanotube network decorated with Pt nanoparticles (PtCNT) irradiated by excimer laser as counter electrode (CE) of dye-sensitized solar cells (DSSCs) has been systematically demonstrated. The conversion efficiency would be improved from 7.12% to 9.28% with respect to conventional Pt-film one. It was attributed to the enhanced catalytic surface from Pt nanoparticles and the improved conductivity due to the adjoining phenomenon of PtCNTs irradiated by laser. Moreover, the laser annealing could also promote the interface contact between CE and conductive glass. Therefore, such a simple laser-irradiated PtCNT network is promising for the future flexible DSSCs applications.

Chien, Yun-San, E-mail: u930347@oz.nthu.edu.tw; Fu, Wei-En [Center for Measurement Standards, Industrial Technology Research Institute, Hsinchu, Taiwan (China); Yang, Po-Yu [Taiwan Semiconductor Manufacturing Company, Hsinchu, Taiwan (China); Lee, I-Che; Chu, Chih-Chieh; Chou, Chia-Hsin; Cheng, Huang-Chung [Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, Hsinchu, Taiwan (China)

2014-02-03

138

Enhanced performance of supported HfO2 counter electrodes for redox couples used in dye-sensitized solar cells.  

PubMed

Mesoporous-graphitic-carbon-supported HfO2 (HfO2 -MGC) nanohybrids were synthesized by using a soft-template route. Characterization and a systematic investigation of the catalytic properties, stability, and catalytic mechanism were performed for HfO2 -MGC counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). The new HfO2 -MGC as a CE in DSSCs showed a surprisingly high efficiency of 7.75 % for the triiodide/iodide redox couple and 3.69 % for the disulfide/thiolate redox couple, greater than the Pt electrode in the corresponding electrolyte system, which opens up a possibility for its practical application. PMID:24399514

Yun, Sining; Pu, Haihui; Chen, Junhong; Hagfeldt, Anders; Ma, Tingli

2014-02-01

139

Ruthenium based nanostructures driven by morphological controls as efficient counter electrodes for dye-sensitized solar cells.  

PubMed

We introduce a facile approach to use ruthenium dioxide (RuO2) and ruthenium (Ru) nanostructures as effective counter electrodes instead of using platinum (Pt) for dye-sensitized solar cells (DSSCs). RuO2 and Ru nanostructure layers on the FTO glass can be readily prepared by a simple annealing process followed by the spin coating process of the mixture solution containing amorphous RuO2·xH2O precursor and poly(ethylene oxide) (PEO) as a dispersion matrix at low temperature in air. The Ru metal nanostructure layer prepared by the reduction of RuO2 with H2 shows the highest efficiency of 6.77% in DSSC operation, which is comparable to the efficiency of the Pt electrode (7.87%). PMID:25558852

Seok, Jeesoo; Ryu, Ka Yeon; Lee, Jin Ah; Jeong, Inyoung; Lee, Nam-Suk; Baik, Jeong Min; Kim, Joo Gon; Ko, Min Jae; Kim, Kyungkon; Kim, Myung Hwa

2015-01-21

140

In-situ electrochemically deposited polypyrrole nanoparticles incorporated reduced graphene oxide as an efficient counter electrode for platinum-free dye-sensitized solar cells  

PubMed Central

This paper reports a rapid and in-situ electrochemical polymerization method for the fabrication of polypyrrole nanoparticles incorporated reduced graphene oxide (rGO@PPy) nanocomposites on a ITO conducting glass and its application as a counter electrode for platinum-free dye-sensitized solar cell (DSSC). The scanning electron microscopic images show the uniform distribution of PPy nanoparticles with diameter ranges between 20 and 30?nm on the rGO sheets. The electrochemical studies reveal that the rGO@PPy has smaller charge transfer resistance and similar electrocatalytic activity as that of the standard Pt counter electrode for the I3?/I? redox reaction. The overall solar to electrical energy conversion efficiency of the DSSC with the rGO@PPy counter electrode is 2.21%, which is merely equal to the efficiency of DSSC with sputtered Pt counter electrode (2.19%). The excellent photovoltaic performance, rapid and simple fabrication method and low-cost of the rGO@PPy can be potentially exploited as a alternative counter electrode to the expensive Pt in DSSCs. PMID:24930387

Lim, Su Pei; Pandikumar, Alagarsamy; Lim, Yee Seng; Huang, Nay Ming; Lim, Hong Ngee

2014-01-01

141

In-situ electrochemically deposited polypyrrole nanoparticles incorporated reduced graphene oxide as an efficient counter electrode for platinum-free dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

This paper reports a rapid and in-situ electrochemical polymerization method for the fabrication of polypyrrole nanoparticles incorporated reduced graphene oxide (rGO@PPy) nanocomposites on a ITO conducting glass and its application as a counter electrode for platinum-free dye-sensitized solar cell (DSSC). The scanning electron microscopic images show the uniform distribution of PPy nanoparticles with diameter ranges between 20 and 30 nm on the rGO sheets. The electrochemical studies reveal that the rGO@PPy has smaller charge transfer resistance and similar electrocatalytic activity as that of the standard Pt counter electrode for the I3-/I- redox reaction. The overall solar to electrical energy conversion efficiency of the DSSC with the rGO@PPy counter electrode is 2.21%, which is merely equal to the efficiency of DSSC with sputtered Pt counter electrode (2.19%). The excellent photovoltaic performance, rapid and simple fabrication method and low-cost of the rGO@PPy can be potentially exploited as a alternative counter electrode to the expensive Pt in DSSCs.

Lim, Su Pei; Pandikumar, Alagarsamy; Lim, Yee Seng; Huang, Nay Ming; Lim, Hong Ngee

2014-06-01

142

In-situ electrochemically deposited polypyrrole nanoparticles incorporated reduced graphene oxide as an efficient counter electrode for platinum-free dye-sensitized solar cells.  

PubMed

This paper reports a rapid and in-situ electrochemical polymerization method for the fabrication of polypyrrole nanoparticles incorporated reduced graphene oxide (rGO@PPy) nanocomposites on a ITO conducting glass and its application as a counter electrode for platinum-free dye-sensitized solar cell (DSSC). The scanning electron microscopic images show the uniform distribution of PPy nanoparticles with diameter ranges between 20 and 30 nm on the rGO sheets. The electrochemical studies reveal that the rGO@PPy has smaller charge transfer resistance and similar electrocatalytic activity as that of the standard Pt counter electrode for the I?(-)/I(-) redox reaction. The overall solar to electrical energy conversion efficiency of the DSSC with the rGO@PPy counter electrode is 2.21%, which is merely equal to the efficiency of DSSC with sputtered Pt counter electrode (2.19%). The excellent photovoltaic performance, rapid and simple fabrication method and low-cost of the rGO@PPy can be potentially exploited as a alternative counter electrode to the expensive Pt in DSSCs. PMID:24930387

Lim, Su Pei; Pandikumar, Alagarsamy; Lim, Yee Seng; Huang, Nay Ming; Lim, Hong Ngee

2014-01-01

143

p-Type mesoscopic NiO as an active interfacial layer for carbon counter electrode based perovskite solar cells.  

PubMed

Replacement of the ZrO2 insulator layer in the state-of-the-art TiO2/ZrO2/carbon structure by mesoscopic p-type NiO particles led to 39% increase of energy conversion efficiency of hole-conductor-free organometallic perovskite heterojunction solar cells with carbon counter electrodes. In these cells, the light absorber, CH3NH3PbI3, formed instantly inside the pores of the entire TiO2/NiO/carbon layer upon sequential deposition of PbI2 and CH3NH3I. Photoluminescence, impedance spectroscopy and transient photovoltage decay measurements have revealed that introduction of NiO extended the electron lifetime and augmented the hole extraction of the counter electrode. As a result, the photocurrent and open-circuit voltage both increased, resulting in a cell with impressive energy conversion efficiency of 11.4% under AM1.5G conditions. PMID:25406840

Liu, Zonghao; Zhang, Meng; Xu, Xiaobao; Bu, Lingling; Zhang, Wenjun; Li, Wenhui; Zhao, Zhixin; Wang, Mingkui; Cheng, Yi-Bing; He, Hongshan

2014-11-19

144

CoS acicular nanorod arrays for the counter electrode of an efficient dye-sensitized solar cell.  

PubMed

One-dimensional cobalt sulfide (CoS) acicular nanorod arrays (ANRAs) were obtained on a fluorine-doped tin oxide (FTO) substrate by a two-step approach. First, Co(3)O(4) ANRAs were synthesized, and then they were converted to CoS ANRAs for various periods. The compositions of the films obtained after various conversion periods were verified by X-ray diffraction, UV-visible spectrophotometry, and X-ray photoelectron spectroscopy; their morphologies were examined at different periods by scanning electron microscopic and transmission electron microscopic images. Electrocatalytic abilities of the films toward I(-)/I(3)(-) were verified through cyclic voltammetry (CV) and Tafel polarization curves. Long-term stability of the films in I(-)/I(3)(-) electrolyte was studied by CV. The FTO substrates with CoS ANRAs were used as the counter electrodes for dye-sensitized solar cells; a maximum power conversion efficiency of 7.67% was achieved for a cell with CoS ANRAs, under 100 mW/cm(2), which is nearly the same as that of a cell with a sputtered Pt counter electrode (7.70%). Electrochemical impedance spectroscopy was used to substantiate the photovoltaic parameters. PMID:22747428

Kung, Chung-Wei; Chen, Hsin-Wei; Lin, Chia-Yu; Huang, Kuan-Chieh; Vittal, R; Ho, Kuo-Chuan

2012-08-28

145

Understanding interfacial charge transfer between metallic PEDOT counter electrodes and a cobalt redox shuttle in dye-sensitized solar cells.  

PubMed

Conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with iron(III) tris-p-toluenesulfonate (PEDOT:Tos) having metallic conductivity was coated onto fluorine-doped tin oxide (FTO) glass and plain glass substrates and used as a counter electrode (CE) in a dye-sensitized solar cell (DSC) with a [Co(bpy)3](3+/2+) complex redox shuttle. DSCs with PEDOT:Tos/glass CE yielded power conversion efficiencies (PCE) of 6.3%, similar to that of DSCs with platinized FTO glass CE (6.1%). The PEDOT:Tos-based counter electrodes had 5 to 10 times lower charge-transfer resistance than the Pt/FTO CE in DSCs, as analyzed by impedance spectroscopy. More detailed studies in symmetrical CE-CE cells showed that the PEDOT:Tos layers are nanoporous. Not all internal area can be used catalytically under solar cell conditions and effective charge-transfer resistance was similar to that of Pt/FTO. PMID:24410094

Park, Byung-wook; Pazoki, Meysam; Aitola, Kerttu; Jeong, Seunghee; Johansson, Erik M J; Hagfeldt, Anders; Boschloo, Gerrit

2014-02-12

146

Transparent Conductive Oxide Layer-Less Three Dimensional Dye Sensitized Solar Cells: Fabrication of Ionic Path in Three Dimensional Ti Electrode  

NASA Astrophysics Data System (ADS)

A transparent conductive oxide-less dye-sensitized solar cell (TCO-less DSC) consisting of a thick and porous Ti electrode is reported. The Ti electrode was contacted with the back of a stained porous titania layer. A thick Ti electrode prepared by conventional sputtering prevented ionic diffusions through the Ti electrode and decreased photovoltaic performance. Tetrapod-shaped ZnO crystals were used to prepare straight and continuous nanopores in the Ti electrode to maintain the ionic diffusion. 8% efficiency of the TCO-less DSC is also reported.

Beppu, Takayuki; Kashiwa, Yohei; Hayase, Shuzi; Kono, Mitsuru; Yamaguchi, Yoshihiro

2009-06-01

147

Conductive upconversion Er,Yb-FTO nanoparticle coating to replace Pt as a low-cost and high-performance counter electrode for dye-sensitized solar cells.  

PubMed

F-doped SnO2 (FTO) nanocrystals modified by Er and Yb with upconversion capability and excellent catalytic properties have been designed and fabricated as an economic replacement for Pt for use as the counter electrode (CE) in dye-sensitized solar cells. The cost of the UC-FTO counter electrode is only ?(1)/20th of that for Pt. The upconverted luminescence-mediated energy transfer and the superior catalytic property for I3(-)/I(-) circulation overpowered the slight degradation caused by increased CE/electrolyte interface resistance. A 23.9% enhancement in photocurrent was achieved with little degradation in photovoltage, resulting in a 9.12% increase in solar-to-electric power conversion efficiency. Near-infrared (NIR) light-to-electricity has been directly observed by SPS and IPCE characterizations, showing the effect of the upconversion counter electrode. PMID:24810204

Li, Liang; Yang, Yulin; Fan, Ruiqing; Chen, Shuo; Wang, Ping; Yang, Bin; Cao, Wenwu

2014-06-11

148

Semi-transparent pentacene thin film transistors with NiO x electrode operating at low voltages  

Microsoft Academic Search

We demonstrate the fabrication of semi-transparent pentacene-based thin-film transistors (TFTs) with thin poly-4-vinylphenol (PVP)\\/high-k yttrium oxide (YOx) double gate dielectric layers and also with thermally-evaporated NiOx source\\/drain (S\\/D) electrodes which show a transmittance of ?30–40% and sheet resistance range of 100–200 ?\\/? (controlled by deposition rate). Our pentacene TFTs with PVP (45 nm)\\/YOx (100 nm) layers operated at less than ?5 V, exhibiting a

D. K. Hwang; Jeong-M. Choi; Kimoon Lee; Ji Hoon Park; Eugene Kim; Seongil Im

2008-01-01

149

Synthesis of Cu2ZnSnS4 nanoparticles by solution based solid state reaction process and its application in dye sensitized solar cell as counter electrode  

NASA Astrophysics Data System (ADS)

Cu2ZnSnS4 (CZTS) nanoparticles were synthesized by using solution based solid state reaction process and films were coated on FTO (Fluorine doped tin oxide) substrate using doctor blade technique. Phase identification, crystallinity of the synthesized nanoparticles was confirmed by XRD and Raman spectroscopy. Dye sensitized solar cells (DSSC) fabricated with CZTS as counter electrode showed photo conversion efficiency 2.57 % compared to Pt based counter electrode 3.17 % efficiency. The charge transport at CZTS/ electrolyte interface was studied by using electrochemical impedance spectroscopy.

Mokurala, Krishnaiah; Bhargava, Parag; Mallick, Sudhanshu

2014-04-01

150

Room temperature flexible and transparent ITO/Ag/ITO electrode grown on flexile PES substrate by continuous roll-to-roll sputtering for flexible organic photovoltaics  

NASA Astrophysics Data System (ADS)

We prepared a flexible and transparent indium tin oxide (ITO)/Ag/ITO electrode on a polyethersulfone (PES) substrate using a specially designed roll-to-roll sputtering system at room temperature for use in flexible organic solar cells (OSCs). By the continuous roll-to-roll sputtering of the ITO and Ag targets, we fabricated a flexible ITO/Ag/ITO electrode with a sheet resistance (Rsh) of 4.28 ?/square, optical transmittance (T) of 89.28% and figure of merit value of 75.03 × 10-3 ?-1 at the optimized Ag thickness of 12 nm (dc power of 200 W) without breaking the vacuum, even though it was deposited at room temperature. The bending test results demonstrated that the ITO/Ag/ITO electrode has superior flexibility to the single ITO electrode, due to the high failure strain of the ductile Ag layer. Moreover, the flexible OSC fabricated on the optimized flexible ITO/Ag/ITO electrode showed an identical efficiency of 3.73% to the OSC fabricated on the commercial crystalline ITO electrode, due to its low sheet resistance and high transparency, which are well matched with the organic active layer. This indicates that the flexible ITO/Ag/ITO multilayer electrode grown by the continuous roll-to-roll sputtering technique is a promising flexible and transparent electrode for use in cost-efficient flexible OSCs.

Park, Yong-Seok; Choi, Kwang-Hyuk; Kim, Han-Ki

2009-12-01

151

Effect of purity on the electro-optical properties of single wall nanotube-based transparent conductive electrodes  

SciTech Connect

We present a detailed assessment of centrifugation technique for purification of single wall carbon nanotubes (SWCNTs) for application as transparent conductive electrodes. As- grown and highly-purified SWCNTs were dispersed in surfactants by ultrasonication, and then centrifuged to selectively remove carbonaceous and metal impurities. The centrifuged supernatant suspensions were made into thin films by transferring filtrated nanotube coat- ings onto glass slides. The absorbance and resistance of nanotube coatings were measured, and their optical purity level estimated from a comparison of the area of the near-infrared S22 SWCNT optical absorption band relative to the area of the background. The single-step centrifugation process is shown to purify laser-vaporization grown SWCNTs from an initial optical purity of 0.10 to an averaged purity of 0.23, with an 8.8% yield, which is comparable to other purification techniques. The quality of transparent conductive electrodes esti- mated as a ratio of visible-spectrum absorbance to sheet conductivity is improved by a fac- tor of 12 upon purification.

Garrett, Matthew P [ORNL; Ivanov, Ilia N [ORNL; Geohegan, David B [ORNL; Hu, Bin [ORNL

2013-01-01

152

Platinum-free binary Co-Ni alloy counter electrodes for efficient dye-sensitized solar cells.  

PubMed

Dye-sensitized solar cells (DSSCs) have attracted growing interest because of their application in renewable energy technologies in developing modern low-carbon economies. However, the commercial application of DSSCs has been hindered by the high expenses of platinum (Pt) counter electrodes (CEs). Here we use Pt-free binary Co-Ni alloys synthesized by a mild hydrothermal strategy as CE materials in efficient DSSCs. As a result of the rapid charge transfer, good electrical conduction, and reasonable electrocatalysis, the power conversion efficiencies of Co-Ni-based DSSCs are higher than those of Pt-only CEs, and the fabrication expense is markedly reduced. The DSSCs based on a CoNi0.25 alloy CE displays an impressive power conversion efficiency of 8.39%, fast start-up, multiple start/stop cycling, and good stability under extended irradiation. PMID:25146894

Chen, Xiaoxu; Tang, Qunwei; He, Benlin; Lin, Lin; Yu, Liangmin

2014-09-26

153

Ordered mesoporous carbon/graphene nano-sheets composites as counter electrodes in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

The composites of ordered mesoporous carbon (OMC) and graphene nano-sheets (GNS) are prepared by mixing OMC with different weight ratios of GNS, and utilized as counter electrode (CE) materials for dye-sensitized solar cells (DSSCs). Electrochemical impedance spectroscopy, Tafel polarization, and cyclic voltammetry measurements demonstrate that the OMC/GNS CEs display the enhanced electron transport property and fast reduction rate of 3-in comparison with those of the individual OMC and GNS CEs, due to the combination of superior electrical conductivity of GNS and good catalytic activity of OMC. Under AM 1.5 irradiation (100 mW cm-2), the DSSCs based on the OMC/GNS CEs show a maximum power conversion efficiency of 6.82%, which is comparable to 7.08% of the cell with the conventional Pt CE at the same experimental conditions, suggesting that the OMC/GNS composites are one of advanced CE materials for low-cost DSSCs.

Shao, Leng-Leng; Chen, Ming; Ren, Tie-Zhen; Yuan, Zhong-Yong

2015-01-01

154

Preparation of polypyrrole thin film counter electrode with pre-stored iodine and resultant influence on its performance  

NASA Astrophysics Data System (ADS)

The performance of DSSCs can be improved if iodine species can be pre-stored in the polymer counter electrodes (CEs) since the I-/I3- redox couple is usually used as the mediator in electrolyte for DSSCs. In this work, such porous polypyrrole (PPy) CEs have been successfully synthesized by electrochemical method. Detailed mechanism about the electro-polymerization and film growth has been investigated both experimentally and theoretically. The influence of iodine species pre-stored in the film during polymerization on the properties of resultant PPy CEs (such as porous structure, doping state, and electrocatalytic activity) and, thereby, the device performance has been studied thoroughly. We envision that the results may help to facilitate the research and development of the polymer-based CEs used in DSSCs.

Lu, Shan; Zhang, Xuehua; Feng, Ting; Han, Ruobing; Liu, Dongsheng; He, Tao

2015-01-01

155

Optimization of transparent and reflecting electrodes for amorphous-silicon solar cells  

NASA Astrophysics Data System (ADS)

Fluorine-doped zinc oxide was shown to have the lowest absorption loss of any of the known transparent conductors. An apparatus was constructed to deposit textured, transparent, conductive, fluorine-doped zinc oxide layers with uniform thickness over a 10 cm by 10 cm area, using inexpensive, high-productivity atmospheric pressure chemical vapor deposition. Amorphous silicon solar cells grown on these textured films show very high peak quantum efficiencies (over 90 percent). However, a significant contact resistance develops at the interface between the amorphous silicon and the zinc oxide. Transparent, conductive gallium-doped zinc oxide films were grown by APCVD at a low enough temperature (260 C) to be deposited on amorphous silicon as a final conductive back contact to solar cells. A quantum-mechanical theory of bonding was developed and applied to some metal oxides; it forms a basis for understanding TCO structures and the stability of their interfaces with silicon.

Gordon, R. G.; Hu, J.; Lacks, D.; Musher, J.; Thornton, J.; Liang, H.

1994-07-01

156

Time resolved optical emission images of an atmospheric pressure plasma jet with transparent electrodes  

SciTech Connect

We study development of plasma packages in atmospheric pressure plasma jet from their formation as a discharge close to the instantaneous cathode, following their motion between and inside the electrodes up to their emergence at the edge of the glass tube and formation of a plasma bullet. Inside both electrodes, plasma is concentrated close to the walls and is bright, while outside it is located at the axis. This paper opens issues of the geometry of electrodes, fields, and atomic processes, allowing some predictions to be made about pertinent mechanisms.

Puac, N.; Maletic, D.; Lazovic, S.; Malovic, G.; Petrovic, Z. Lj. [Institute of Physics, University of Belgrade, Pregrevica 118, 11080 Belgrade (Serbia); Dordevic, A. [School of Electrical Engineering, University of Belgrade, Bul. kralja Aleksandra 73, 11000 Belgrade (Serbia)

2012-07-09

157

Layer-by-layer self-assembled mesoporous PEDOT-PSS and carbon black hybrid films for platinum free dye-sensitized-solar-cell counter electrodes.  

PubMed

A thin film of poly(3,4-ethylenedioxythiophene)-poly(4-styrenesulfonic acid) (PEDOT-PSS), which is an alternative cathodic catalyst for Pt in dye-sensitized solar cells, was prepared using the layer-by-layer self-assembly method (LbL). The film is highly adhesive to the substrate and has a controllable thickness. Therefore, the PEDOT-PSS film prepared using LbL is expected have high performance and durability as a counter electrode. Moreover, when carbon black was added to the PEDOT-PSS solution, highly mesoporous PEDOT-PSS and carbon black hybrid films were obtained. These films showed high cathodic activity. In this study, we investigated the change in morphology in the obtained film with increasing carbon black content, and the influence of the porosity and thickness on the performance of the cells. In this study, a Pt-free counter electrode with performance similar to that of Pt-based counter electrodes was successfully fabricated. The achieved efficiency of 4.71% was only a factor of 8% lower than that of the cell using conventional thermally deposited Pt on fluorine-doped tin oxide glass counter electrodes. PMID:21430326

Kitamura, Koji; Shiratori, Seimei

2011-05-13

158

The facile preparation of a cobalt disulfide-reduced graphene oxide composite film as an efficient counter electrode for dye-sensitized solar cells.  

PubMed

Cobalt disulfide (CoS2)-reduced graphene oxide (RGO) composite (CSG) films, which are prepared by combining the layer by layer assembly method and thermal treatment process, are used as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The DSSC with CSG CE exhibits comparable efficiency to the cell with the Pt CE. PMID:25525643

Sun, Lijuan; Bai, Yu; Zhang, Naiqing; Sun, Kening

2015-01-20

159

Control of light absorption in organic solar cells using semi-transparent metal electrodes  

NASA Astrophysics Data System (ADS)

In this contribution we combine optical modeling and device fabrication/characterization techniques to demonstrate that semitransparent metal electrodes can improve light harvesting in organic photovoltaic (OPV) devices. We show that inverted P3HT:PCBM solar cells using a thin ~8 nm silver film as a front electrode outperform the ITO-based devices, despite the lower transmittance of silver films in comparison to ITO. The variation of silver thickness allows tailoring the field distribution inside the cell, which leads to a broad resonance window where the absorption is enhanced. Thereby the short-circuit current was increased by 84% and the solar-cell efficiency was doubled. These results show that semitransparent metal electrodes can be efficiently used for light trapping and also form a very promising alternative to ITO in OPV devices. The stacked silver electrodes used in this work are flexible and can be easily produced on a large scale, including printing techniques.

Neutzner, Stefanie; van de Groep, Jorik; Bakulin, Artem A.; Bakker, Huib J.

2013-09-01

160

Inverted semi-transparent organic solar cells with spray coated, surfactant free polymer top-electrodes  

Microsoft Academic Search

Depositing a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) buffer layer or top-electrode from aqueous solution on a non-polar active layer in inverted organic solar cells is commonly considered a very challenging task. In this work we utilize spray deposited PEDOT:PSS seeds to effectively reduce the surface free energy atop the active layer in poly-hexylthiophene polymer solar cells before applying a PEDOT:PSS top-electrode. Though aqueous

Alexander Colsmann; Manuel Reinhard; Tae-Hyuk Kwon; Christian Kayser; Felix Nickel; Jens Czolk; Uli Lemmer; Noel Clark; Jacek Jasieniak; Andrew B. Holmes; David Jones

161

A low-cost bio-inspired integrated carbon counter electrode for high conversion efficiency dye-sensitized solar cells.  

PubMed

A novel bio-inspired Pt- and FTO-free integrated pure carbon counter electrode (CE) for dye-sensitized solar cells (DSSCs) has been designed and fabricated using a porous carbon sheet as a conducting substrate and ordered mesoporous carbon (OMC) as the catalytic layer. A rigid, crustose lichen-like, integrated carbon-carbon composite architecture with a catalytic layer rooted in a porous conducting substrate was formed by a process of polymer precursor spin coating, infiltration and pyrolysis. The integrated pure carbon CE shows very low series resistance (R(s)), owing to the high conductivity of the carbon sheet (sheet resistance of 488 m? ?(-1)) and low charge-transfer resistance (R(ct)), due to the large specific surface area of the OMC layer that is accessible to the redox couple. The values of R(s) and R(ct) are much lower than those of a platinized fluorine-doped thin oxide glass (Pt/FTO) electrode. Cells with this CE show high solar-to-electricity conversion efficiencies (8.11%), comparable to that of Pt/FTO based devices (8.16%). PMID:23881167

Wang, Chunlei; Meng, Fanning; Wu, Mingxing; Lin, Xiao; Wang, Tonghua; Qiu, Jieshan; Ma, Tingli

2013-09-14

162

Electron beam irradiated ITO films as highly transparent p-type electrodes for GaN-based LEDs.  

PubMed

We have investigated the effect of electron beam irradiation on the electrical and optical properties of ITO film prepared by magnetron sputtering method at room temperature. Electron beam irradiation to the ITO films resulted in a significant decrease in sheet resistance from 1.28 x 10(-3) omega cm to 2.55 x 10(-4) omega cm and in a great increase in optical band gap from 3.72 eV to 4.16 eV, followed by improved crystallization and high transparency of 97.1% at a wavelength of 485 nm. The overall change in electrical, optical and structural properties of ITO films is related to annealing effect and energy transfer of electron by electron beam irradiation. We also fabricated GaN-based light-emitting diodes (LEDs) by using the ITO p-type electrode with/without electron beam irradiation. The results show that the LEDs having ITO p-electrode with electron beam irradiation produced higher output power due to the low absorption of light in the p-type electrode. PMID:23882772

Hong, C H; Wie, S M; Park, M J; Kwak, J S

2013-08-01

163

FTO-free counter electrodes for dye-sensitized solar cells using carbon nanosheets synthesised from a polymeric carbon source.  

PubMed

Highly conductive carbon nanosheets (CNSs) are fabricated using a polymeric carbon source and subsequently applied as the counter electrodes (CNS-CEs) for dye-sensitized solar cells (DSSCs). The CNSs have a similar structure to multilayered graphene, and their high electrical conductivity and electrocatalytic activity enable them to have a dual-function as both CEs and charge supporting electrodes. CNSs form a unique CE material that functions successfully while being metal- and fluorine doped tin oxide (FTO)-free and allowing DSSCs to achieve ?5% power conversion efficiency. The chemical structure, electrical properties, electrocatalytic activity, and work function of the CNS-CEs prepared under various conditions of carbonization are investigated, and their effects on the performance of the corresponding DSSCs are discussed. Carbonization temperature is shown to have influenced the size of graphitic domains and the presence of heteroatoms and functional groups in CNS-CEs. The change in the graphitic domain size has a marginal influence on the work function of the CNS-CEs and the overpotential for the reduction of the redox couples (I(-)/I3(-)). However, the electrical conductivity of CNS-CEs and the charge transfer resistance at CE/electrolyte interfaces in the DSSCs are considerably influenced by the carbonization condition. Our study shows that CNSs serve as efficient, FTO-free CE materials for DSSCs, and they are appropriate materials with which the effects of the chemical/physical properties of graphene-based materials on the electrode performance of various electrochemical devices may be studied. PMID:25026395

Akbar, Zico Alaia; Lee, Jae-Seon; Kang, Jinhyeon; Joh, Han-Ik; Lee, Sungho; Jang, Sung-Yeon

2014-09-01

164

A facile and rapid process to fabricate platinum counter electrode in dye-sensitized solar cell using nanosecond pulsed laser sintering at room temperature.  

PubMed

To fabricate the platinum (Pt) counter electrode in dye-sensitized solar cells (DSSCs), rapid and low sintering process was carried out using nanosecond pulsed laser sintering (LS) method based on third harmonic (355 nm) of an Nd:YAG laser at room temperature. The surface morphology of LS-Pt on fluorine-doped tin oxide (FTO) electrode showed thin and compact structure, consisting of particles size of - 10-30 nm and thickness of below 30 nm. The DSSCs with the LS-Pt/FTO counter electrodes displayed the power conversion efficiency of 4.4% with short-circuit current = 9.07 mA/cm2, open-circuit voltage = 0.79 V and fill factor = 61.3. PMID:24758023

Kang, Tae Yeon; Yoo, Kicheon; Lee, Jin Ah; Lee, Wonjoo; Kim, Kyungkon; Lee, Doh-Kwon; Kim, Honggon; Ko, Min Jae

2014-07-01

165

Room temperature flexible and transparent ITO\\/Ag\\/ITO electrode grown on flexile PES substrate by continuous roll-to-roll sputtering for flexible organic photovoltaics  

Microsoft Academic Search

We prepared a flexible and transparent indium tin oxide (ITO)\\/Ag\\/ITO electrode on a polyethersulfone (PES) substrate using a specially designed roll-to-roll sputtering system at room temperature for use in flexible organic solar cells (OSCs). By the continuous roll-to-roll sputtering of the ITO and Ag targets, we fabricated a flexible ITO\\/Ag\\/ITO electrode with a sheet resistance (Rsh) of 4.28 Omega\\/square, optical

Yong-Seok Park; Kwang-Hyuk Choi; Han-Ki Kim

2009-01-01

166

Graphene transparent electrode for enhanced optical power and thermal stability in GaN light-emitting diodes  

NASA Astrophysics Data System (ADS)

We report an improvement of the optical power and thermal stability of GaN LEDs using a chemically doped graphene transparent conducting layer (TCL) and a low-resistance contact structure. In order to obtain low contact resistance between the TCL and p-GaN surface, a patterned graphene TCL with Cr/Au electrodes is suggested. A bi-layer patterning method of a graphene TCL was utilized to prevent the graphene from peeling off the p-GaN surface. To improve the work function and the sheet resistance of graphene, CVD (chemical vapor deposition) graphene was doped by a chemical treatment using a HNO3 solution. The effect of the contact resistance on the power degradation of LEDs at a high injection current level was investigated. In addition, the enhancement of the optical power via an increase in the current spreading and a decrease in the potential barrier of the graphene TCL was investigated.

Youn, Doo-Hyeb; Yu, Young-Jun; Choi, HongKyw; Kim, Suck-Hwan; Choi, Sung-Yool; Choi, Choon-Gi

2013-02-01

167

Dye-sensitized solar cell with a titanium-oxide-modified carbon nanotube transparent electrode  

E-print Network

reaction limits their application as a working electrode in a liquid-type dye-sensitized solar cell (DSSC in a DSSC containing iodide/triiodide redox couples. This implementation is realized by inhibiting-sensitized solar cell (DSSC) to date because of their well-known catalytic property to redox reaction. Thus, it has

Demir, Hilmi Volkan

168

Transparent Conductive Electrodes from Graphene/PEDOT:PSS Hybrid Inks for Ultrathin Organic Photodetectors.  

PubMed

A novel solution fabrication of large-area, highly conductive graphene films by spray-coating of a hybrid ink of exfoliated graphene (EG)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) (PH1000) is demonstrated. The fabricated graphene films exhibit excellent mechanical properties, thus enabling their application as bottom electrodes in ultrathin organic photodetector devices with performance comparable to that of the state-of-the-art Si-based inorganic photodetectors. PMID:25448315

Liu, Zhaoyang; Parvez, Khaled; Li, Rongjin; Dong, Renhao; Feng, Xinliang; Müllen, Klaus

2014-11-29

169

Laser direct imaging of transparent indium tin oxide electrodes using high speed stitching techniques  

NASA Astrophysics Data System (ADS)

To accomplish an electrode patterning in large area, we present a high speed stitching technique used in an ultraviolet laser processing system and investigate the interaction between laser beams and indium tin oxide (ITO) thin films deposited on glass substrates. After optimizing the process parameters of the laser direct imaging (LDI) for the large-area electrode patterning, the ablated lines looked like regularly fish-scale marks of about a 40 ?m diameter and a 120 nm depth around the processing path. The parameters includes the laser power of 1W, the scanning speed of galvanometers of 800 mm/s, and the laser pulse repetition frequency of 50 kHz. Moreover, the resistance value of the ablated ITO thin film is larger than 200M? that is electrically insulated from the other regions of electrode structure. LDI technology with UV laser beam has great potential applications in patterning on wafer or sapphire substrates and patterning a conductive layer deposited on the touch panels for semiconductor and optoelectric industries, respectively.

Cheng, Pi-Ying; Hsiao, Wen-Tse; Chung, Chien-Kai; Tseng, Shih-Feng; Liao, Ien-Chang

2014-09-01

170

Mechanical reliability of transparent conducting IZTO film electrodes for flexible panel displays  

NASA Astrophysics Data System (ADS)

The mechanical reliability of transparent In-Zn-Sn-O (IZTO) films grown using pulsed DC magnetron sputtering with a single oxide alloyed ceramic target on a transparent polyimide (PI) substrate at room temperature is investigated. All IZTO films deposited at room temperature have an amorphous structure. However, their optical and electrical properties change depending on the oxygen partial pressure applied during depositing process. At an oxygen partial pressure of 3%, the films exhibit a resistivity of 8.3 × 10-4 ? cm and an optical transmittance of 86%. Outer bending tests show that the critical bending radius decreases from 10 mm to 7.5 mm when the oxygen partial pressure increases from 1% to 3%. In the inner bending test, the critical bending radius is independent of oxygen partial pressure at 3.5 mm, indicating excellent film flexibility. In the dynamic fatigue test, the electrical resistance of the films reduces by less than 1% for more than 2000 bending cycles. These results suggest that IZTO films have excellent mechanical durability and flexibility in comparison to ITO films.

Kim, Young Sung; Hwang, Woo Jin; Eun, Kyung Tae; Choa, Sung-Hoon

2011-07-01

171

Enhancement of the efficiency of dye-sensitized solar cell with multi-wall carbon nanotubes/polypyrrole composite counter electrodes prepared by electrophoresis/electrochemical polymerization  

SciTech Connect

Graphical abstract: The overall energy conversion efficiency of the DSSC employing the MWCNT/PPy CE reached 3.78%. Compared with a reference DSSC using single MWCNT film CE with efficiency of 2.68%, the energy conversion efficiency was increased by 41.04%. Highlights: ? MWCNT/PPy composite film prepared by electrodeposition layer by layer was used as counter electrode in DSSC. ? The overall energy conversion efficiency of the DSSC was 3.78% by employing the composite film. ? The energy conversion efficiency increased by 41.04% compared with efficiency of 2.68% by using the single MWCNT film. ? We analyzed the mechanism and influence factor of electron transfer in the composite electrode by EIS. - Abstract: For the purpose of replacing the precious Pt counter electrode in dye-sensitized solar cells (DSSCs) with higher energy conversion efficiency, multi-wall carbon nanotube (MWCNT)/polypyrrole (PPy) double layers film counter electrode (CE) was fabricated by electrophoresis and cyclic voltammetry (CV) layer by layer. Atom force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscope (TEM) demonstrated the morphologies of the composite electrode and Raman spectroscopy verified the PPy had come into being. The overall energy conversion efficiency of the DSSC employing the MWCNT/PPy CE reached 3.78%. Compared with a reference DSSC using single MWCNT film CE with efficiency of 2.68%, the energy conversion efficiency was increased by 41.04%. The result of impedance showed that the charge transfer resistance R{sub ct} of the MWCNT/PPy CE had the lowest value compared to that of MWCNT or PPy electrode. These results indicate that the composite film with high conductivity, high active surface area, and good catalytic properties for I{sub 3}{sup ?} reduction can potentially be used as the CE in a high-performance DSSC.

Luo, Jun; Niu, Hai-jun; Wen, Hai-lin [Key Laboratory of Functional Inorganic Material Chemistry (Heilongjiang University), Ministry of Education, Department of Macromolecular Material and Engineering, Heilongjiang University, Harbin 150086 (China); Wu, Wen-jun; Zhao, Ping [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237 (China); Wang, Cheng; Bai, Xu-duo [Key Laboratory of Functional Inorganic Material Chemistry (Heilongjiang University), Ministry of Education, Department of Macromolecular Material and Engineering, Heilongjiang University, Harbin 150086 (China); Wang, Wen, E-mail: haijunniu@hotmail.com [School of Material Science and Engineering, Harbin Institute of Technology, Harbin 150080 (China)

2013-03-15

172

Dually functional, N-doped porous graphene foams as counter electrodes for dye-sensitized solar cells.  

PubMed

A series of nitrogen-doped porous graphene foams (NPGFs) have been prepared by hydrothermally treating a mixed solution of graphite oxide (GO) and ammonia. The NPGFs are used as the counter electrode (CE) material for dye-sensitized solar cells (DSCs) in conjunction with the conventional iodide-based electrolyte and the recently developed sulfide-based electrolyte. Tafel-polarization tests and electrochemical impedance spectroscopic (EIS) measurements confirmed that the NPGFs work efficiently in both electrolyte systems, and under air mass (AM) 1.5G 100 mW cm(-2) light illumination, optimal efficiencies of 4.5% and 2.1% were obtained for the iodide-based electrolyte and sulfide-based electrolyte, respectively. To the best of our knowledge, this is the first study on N-doped graphene CEs in conjunction with sulfide-based electrolytes and therefore, the current results are deemed to provide new insights into developing novel low-cost and metal-free CEs for DSCs. PMID:25199841

Song, Long; Luo, Qiang; Zhao, Fei; Li, Yang; Lin, Hong; Qu, Liangti; Zhang, Zhipan

2014-10-21

173

Highly effective nickel sulfide counter electrode catalyst prepared by optimal hydrothermal treatment for quantum dot-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Nickel sulfide (NiS) thin film has been deposited on a fluorine-doped tin oxide substrate by a hydrothermal method using 3-mercaptopropionic acid and used as an efficient counter electrode (CE) for polysulfide redox reactions in quantum dot-sensitized solar cells (QDSSCs). NiS has low toxicity and environmental compatibility. In the present study, the size of the NiS nanoparticle increases with the hydrothermal deposition time. The performance of the QDSSCs is examined in detail using polysulfide electrolyte with the NiS CE. A TiO2/CdS/CdSe/ZnS-based QDSSC using the NiS CE shows enhanced photovoltaic performance with a power conversion efficiency (PCE) of 3.03%, which is superior to that of a cell with Pt CE (PCE 2.20%) under one sun illumination (AM 1.5, 100 mW cm-2). The improved photovoltaic performance of the NiS-based QDSSC may be attributed to a low charge transfer resistance (5.08 ?) for the reduction of polysulfide on the CE, indicating greater electrocatalytic activity of the NiS. Electrochemical impedance spectroscopy, cyclic voltammetry, and Tafel-polarization measurements were used to investigate the electrocatalytic activity of the NiS and Pt CEs.

Gopi, Chandu V. V. M.; Srinivasa Rao, S.; Kim, Soo-Kyoung; Punnoose, Dinah; Kim, Hee-Je

2015-02-01

174

Porous, single crystalline titanium nitride nanoplates grown on carbon fibers: excellent counter electrodes for low-cost, high performance, fiber-shaped dye-sensitized solar cells.  

PubMed

An excellent, platinum free fiber counter electrode (CE) was successfully fabricated, consisting of porous, single crystalline titanium nitride (TiN) nanoplates grown on carbon fibers (CF). The fiber-shaped dye-sensitized solar cells (FDSSCs) based on the TiN-CF CE show a high conversion efficiency of 7.20%, comparable or even superior to that of the Pt wire (6.23%). PMID:25068835

Chen, Liang; Dai, Hui; Zhou, Yong; Hu, Yingjie; Yu, Tao; Liu, Jianguo; Zou, Zhigang

2014-11-28

175

Full Printable Processed Mesoscopic CH3NH3PbI3/TiO2 Heterojunction Solar Cells with Carbon Counter Electrode  

NASA Astrophysics Data System (ADS)

A mesoscopic methylammonium lead iodide (CH3NH3PbI3) perovskite/TiO2 heterojunction solar cell is developed with low-cost carbon counter electrode (CE) and full printable process. With carbon black/spheroidal graphite CE, this mesoscopic heterojunction solar cell presents high stability and power conversion efficiency of 6.64%, which is higher than that of the flaky graphite based device and comparable to the conventional Au version.

Ku, Zhiliang; Rong, Yaoguang; Xu, Mi; Liu, Tongfa; Han, Hongwei

2013-11-01

176

Optimization of transparent and reflecting electrodes for amorphous silicon solar cells  

NASA Astrophysics Data System (ADS)

This report describes work to improve the performance of solar cells by improving the electrical and optical properties of their transparent conducting oxide (TCO) layers. Boron-doped zinc-oxide films were deposited by atmospheric pressure chemical vapor deposition in a laminar-flow reactor from diethyl zinc, tert-butanol, and diborane in the temperature range between 300 C and 420 C. When the deposition temperature was above 320 C, both doped and undoped films have highly oriented crystallites with their c-axes perpendicular to the substrate plane. Films deposited from 0.07% diethyl zinc and 2.4% tert-butanol have electron densities between 3.5 x 10(exp 20)/cu cm and 5.5 x 10(exp 20)/cu cm, conductivities between 250/Omega and 2500/Omega and mobilities between 2.5 sq cm/V-s and 35.0 sq cm/V-s, depending on dopant concentration, film thickness, and deposition temperature. Optical measurements show that the maximum infrared reflectance of the doped films is close to 90%, compared to about 20% for undoped films. Film visible absorption and film conductivity were found to increase with film thickness. The ratio of conductivity to visible absorption coefficient for doped films was between 0.1 Omega and 1.1/Omega. The band gap of the film changes from 3.3 eV to 3.7 eV when the film is doped with 0.012% diborane.

Gordon, R. G.

1993-04-01

177

Mechanical Integrity of Flexible In-Zn-Sn-O Film for Flexible Transparent Electrode  

NASA Astrophysics Data System (ADS)

The mechanical integrity of transparent In-Zn-Sn-O (IZTO) films is investigated using outer/inner bending, stretching, and twisting tests. Amorphous IZTO films are grown using a pulsed DC magnetron sputtering system with an IZTO target on a polyimide substrate at room temperature. Changes in the optical and electrical properties of IZTO films depend on the oxygen partial pressure applied during the film deposition process. In the case of 3% oxygen partial pressure, the IZTO films exhibit s resistivity of 8.3×10-4 ? cm and an optical transmittance of 86%. The outer bending test shows that the critical bending radius decreases from 10 to 7.5 mm when the oxygen partial pressure is increased from 1 to 3%. The inner bending test reveals that the critical bending radius of all IZTO films is 3.5 mm regardless of oxygen partial pressure. The IZTO films also show excellent mechanical reliability in the bending fatigue tests of more than 10,000 cycles. In the uniaxial stretching tests, the electrical resistance of the IZTO film does not change until a strain of 2.4% is reached. The twisting tests demonstrate that the electrical resistance of IZTO films remains unchanged up to 25°. These results suggest that IZTO films have excellent mechanical durability and flexibility in comparison with already reported crystallized indium tin oxide (ITO) films.

Kim, Young Sung; Oh, Se-In; Choa, Sung-Hoon

2013-05-01

178

Silver nanowires for transparent conductive electrode to GaN-based light-emitting diodes  

NASA Astrophysics Data System (ADS)

Transparent, conductive, and uniform Ag nanowires (NWs) were introduced to improve the optical performance of GaN-based light-emitting diodes (LEDs) by a spin-coating technique. The Ag NWs acted as a current spreading layer, exhibiting high transmittance and low sheet resistance, and ultimately leading to high performance GaN-based LEDs with an ultra large size of 5 × 5 mm2. Compared to the transmittance of conventional LEDs without Ag NWs, the relative transmittance of LEDs with Ag NWs was approximately 90% of the overall wavelength region. However, the electroluminescence (EL) intensity of LED with Ag NWs was much higher than that of conventional LEDs without Ag NWs for injection current above 45 mA. In addition, the EL full width at half maximum of LEDs with Ag NWs was much lower than that of conventional LEDs without Ag NWs. Based on these results, we believe that the enhanced optical performance of ultra large LEDs was due to an increase in the current spreading effect.

Jeong, Gyu-Jae; Lee, Jae-Hwan; Han, Sang-Hyun; Jin, Won-Yong; Kang, Jae-Wook; Lee, Sung-Nam

2015-01-01

179

Laser synthesized super-hydrophobic conducting carbon with broccoli-type morphology as a counter-electrode for dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

A laser photochemical process is introduced to realize superhydrophobic conducting carbon coatings with broccoli-type hierarchical morphology for use as a metal-free counter electrode in a dye sensitized solar cell. The process involves pulsed excimer laser irradiation of a thin layer of liquid haloaromatic organic solvent o-dichlorobenzene (DCB). The coating reflects a carbon nanoparticle-self assembled and process-controlled morphology that yields solar to electric power conversion efficiency of 5.1% as opposed to 6.2% obtained with the conventional Pt-based electrode.A laser photochemical process is introduced to realize superhydrophobic conducting carbon coatings with broccoli-type hierarchical morphology for use as a metal-free counter electrode in a dye sensitized solar cell. The process involves pulsed excimer laser irradiation of a thin layer of liquid haloaromatic organic solvent o-dichlorobenzene (DCB). The coating reflects a carbon nanoparticle-self assembled and process-controlled morphology that yields solar to electric power conversion efficiency of 5.1% as opposed to 6.2% obtained with the conventional Pt-based electrode. Electronic supplementary information (ESI) available: Materials and equipment details, solar cell fabrication protocol, electrolyte spreading time measurement details, XPS spectra, electronic study, film adhesion test detailed analysis and field emission results. See DOI: 10.1039/c2nr32082g

Gokhale, Rohan; Agarkar, Shruti; Debgupta, Joyashish; Shinde, Deodatta; Lefez, Benoit; Banerjee, Abhik; Jog, Jyoti; More, Mahendra; Hannoyer, Beatrice; Ogale, Satishchandra

2012-10-01

180

Optimization of transparent and reflecting electrodes for amorphous silicon solar cells  

NASA Astrophysics Data System (ADS)

The specific objectives of this research are to: (1) deposit and characterize textured zinc oxide with improved conductivities (less than 8 ohms/square sheet resistance) and optical transmission (greater than 85 percent for 450 to 700 nm), for use as front and back contacts in hydrogenated amorphous silicon p-i-n devices; (2) study the surface morphology of zinc oxide films deposited by chemical vapor deposition at atmospheric pressure (APCVD), their crystallite sizes, shapes and orientations, and their nucleation (early growth) as a function of chemical precursors and reaction conditions; (3) optimize the growth process to produce structures that provide good light trapping in an amorphous silicon film deposited on the zinc oxide film; (4) study the deposition rate of zinc oxide films as a function of temperature, and concentration and types of reactants; (5) maximize the growth rate, subject to the conditions of maintaining satisfactory film properties, including high transparency (85 percent), high conductivity (8 ohm/square sheet resistance), and good light trapping; (6) develop techniques for deposition of fluorinated zinc oxide films by APCVD on amorphous silicon films in the temperature range of 250 to 280 C for use as back contacts; (7) deposit titanium nitride films at a temperature of about 250 C by APCVD on amorphous silicon as diffusion barrier, and then deposit highly reflective metals such as aluminum or silver; (8) anneal samples and test for metal diffusion through the TiN into the silicon; (9) optimize the TiN film for minimum diffusion consistent with maintaining desirable TiN film properties; and (10) incorporate the front and back contacts including the TiN barrier layer developed under this research into amorphous silicon p-i-n devices and determine the film parameters that provide the greatest improvement in the device solar energy conversion efficiency.

Gordon, R. G.; Hu, Jianhua; Musher, J.; Giunta, C.

1991-02-01

181

Improved optoelectronics properties of ITO-based transparent conductive electrodes with the insertion of Ag/Ni under-layer  

NASA Astrophysics Data System (ADS)

ITO-based transparent conductive electrodes (TCE) with Ag/Ni thin metal under-layer were deposited on Si and glass substrates by thermal evaporator and RF magnetron sputtering system. Ceramic ITO with purity of 99.99% and In2O3:SnO2 weight ratio of 90:10 was used as a target at room temperature. Post-deposition annealing was performed on the TCE at moderate temperature of 500 °C, 600 °C and 700 °C under N2 ambient. It was observed that the structural properties, optical transmittance, electrical characteristics and surface morphology were improved significantly after the post-annealing process. Post-annealed ITO/Ag/Ni at 600 °C shows the best quality of TCE with figure-of-merit (FOM) of 1.5 × 10-2 ?-1 and high optical transmittance of 83% at 470 nm as well as very low electrical resistivity of 4.3 × 10-5 ?-cm. The crystalline quality and surface morphological plays an important role in determining the quality of the TCE multilayer thin films properties.

Ali, Ahmad Hadi; Abu Bakar, Ahmad Shuhaimi; Hassan, Zainuriah

2014-10-01

182

Solution-Processable Transparent Conductive Hole Injection Electrode for OLED SSL  

SciTech Connect

An interconnected network of silver nanowires has been used as transparent anode in OLED devices. This layer was deposited by spin-coating and slot-die coating from an aqueous nanowire suspension. The sheet resistance of the film was 10ohms/sq with a transmission (including the glass substrate) of higher than 85%. The first phase of the project focused on the implementation of this nanowire layer with a hole-injection-layer (HIL) which has been developed at Plextronics and has been shown to provide good stability and efficiency in conventional OLED devices. We modified the HIL solution such that it coated reasonably well with suitable surface morphology so that actual devices can be manufactured. During the second phase we investigated the hole-injection and stability of hole-onlydevices. We determined that the use of the nanowire network as anode does not introduce an additional degradation mechanism since the observed device characteristics did not differ from those made with ITO anode. We then proceeded to make actual OLED devices with this nanowire / HIL stack and achieved device characteristics similar state-of-the-art OLED devices with a single junction. In order to gain traction with potential OLED manufacturers, we decided to contract Novaled to prepare large-area demonstrators for us. For these devices, we used an allevaporated stack, i.e. we did use Novaledâ??s HIL material instead of Plextronicsâ??. We successfully fabricated demonstrators with an area of 25cm2 with a double or triple junction stack. Minor stack optimizations were necessary to achieve efficacies and lifetime equivalent with ITO devices made with the same devices stack. Due to the reduced microcavity effect, the color of the emitted light is significantly more stable with respect to the viewing angle compared to ITO devices. This fact in conjunction with the promise of lower production cost due to the elimination of the ITO sputtering process and the direct patterning of the anode layer are the obvious advantages of this technology. The project has shown that this nanowire technology is a viable option to achieve OLED devices with good lifetime and efficiency and we are currently working with manufacturers to utilize this technology in a production setting.

None

2012-07-15

183

Controlled On-chip Stimulation of Quantal Catecholamine Release from Chromaffin Cells Using Photolysis of Caged Ca2+ on Transparent Indium-Tin-Oxide Microchip Electrodes  

PubMed Central

Photorelease of caged Ca2+ is a uniquely powerful tool to study the dynamics of Ca2+-triggered exocytosis from individual cells. Using photolithography and other microfabrication techniques, we have developed transparent microchip devices to enable photorelease of caged Ca2+ together with electrochemical detection of quantal catecholamine secretion from individual cells or cell arrays as a step towards developing high-throughput experimental devices. A 100 nm - thick transparent Indium-Tin-Oxide (ITO) film was sputter-deposited onto glass coverslips, which were then patterned into 24 cell-sized working electrodes (?20 ?m by 20 ?m). We loaded bovine chromaffin cells with acetoxymethyl (AM) ester derivatives of the Ca2+ cage NP-EGTA and Ca2+ indicator dye Fura-4F, then transferred these cells onto the working ITO electrodes for amperometric recordings. Upon flash photorelease of caged Ca2+, a uniform rise of [Ca2+]i within the target cell leads to quantal release of oxidizable catecholamines measured amperometrically by the underlying ITO electrode. We observed a burst of amperometric spikes upon rapid elevation of [Ca2+]i and a “priming” effect of sub-stimulatory [Ca2+]i on the response of cells to subsequent [Ca2+]i elevation, similar to previous reports using different techniques. We conclude that UV photolysis of caged Ca2+ is a suitable stimulation technique for higher-throughput studies of Ca2+-dependent exocytosis on transparent electrochemical microelectrode arrays. PMID:18094774

Chen, Xiaohui; Gao, Yuanfang; Hossain, Maruf; Gangopadhyay, Shubhra; Gillis, Kevin D.

2008-01-01

184

Enhancing light out-coupling of organic light-emitting devices using indium tin oxide-free low-index transparent electrodes  

NASA Astrophysics Data System (ADS)

With its increasing and sufficient conductivity, the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been capable of replacing the widely used but less cost-effective indium tin oxides (ITOs) as alternative transparent electrodes for organic light-emitting devices (OLEDs). Intriguingly, PEDOT:PSS also possesses an optical refractive index significantly lower than those of ITO and typical organic layers in OLEDs and well matching those of typical OLED substrates. Optical simulation reveals that by replacing ITO with such a low-index transparent electrode, the guided modes trapped within the organic/ITO layers in conventional OLEDs can be substantially suppressed, leading to more light coupled into the substrate than the conventional ITO device. By applying light out-coupling structures onto outer surfaces of substrates to effectively extract radiation into substrates, OLEDs using such low-index transparent electrodes achieve enhanced optical out-coupling and external quantum efficiencies in comparison with conventional OLEDs using ITO.

Huang, Yi-Hsiang; Lu, Chun-Yang; Tsai, Shang-Ta; Tsai, Yu-Tang; Chen, Chien-Yu; Tsai, Wei-Lung; Lin, Chun-Yu; Chang, Hong-Wei; Lee, Wei-Kai; Jiao, Min; Wu, Chung-Chih

2014-05-01

185

Enhancing light out-coupling of organic light-emitting devices using indium tin oxide-free low-index transparent electrodes  

SciTech Connect

With its increasing and sufficient conductivity, the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been capable of replacing the widely used but less cost-effective indium tin oxides (ITOs) as alternative transparent electrodes for organic light-emitting devices (OLEDs). Intriguingly, PEDOT:PSS also possesses an optical refractive index significantly lower than those of ITO and typical organic layers in OLEDs and well matching those of typical OLED substrates. Optical simulation reveals that by replacing ITO with such a low-index transparent electrode, the guided modes trapped within the organic/ITO layers in conventional OLEDs can be substantially suppressed, leading to more light coupled into the substrate than the conventional ITO device. By applying light out-coupling structures onto outer surfaces of substrates to effectively extract radiation into substrates, OLEDs using such low-index transparent electrodes achieve enhanced optical out-coupling and external quantum efficiencies in comparison with conventional OLEDs using ITO.

Huang, Yi-Hsiang; Lu, Chun-Yang; Tsai, Shang-Ta; Tsai, Yu-Tang; Chen, Chien-Yu; Tsai, Wei-Lung; Lin, Chun-Yu; Chang, Hong-Wei; Lee, Wei-Kai; Jiao, Min; Wu, Chung-Chih, E-mail: wucc@ntu.edu.tw [Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, Graduate Institute of Electronics Engineering, and Innovative Photonics Advanced Research Center (i-PARC), National Taiwan University, Taipei 10617, Taiwan (China)

2014-05-05

186

In situ synthesis of a NiS/Ni3S2 nanorod composite array on Ni foil as a FTO-free counter electrode for dye-sensitized solar cells.  

PubMed

A NiS/Ni3S2 nanorod composite array that directly grows on Ni foil has been used as a counter electrode for dye-sensitized solar cells; these nickel sulfide nanorods exhibit excellent photo-electrical conversion efficiency when compared with conventional noble-metal Pt electrodes. PMID:25533110

Liao, Yongping; Pan, Kai; Pan, Qingjiang; Wang, Guofeng; Zhou, Wei; Fu, Honggang

2015-01-22

187

TiN nanoparticles on CNT-graphene hybrid support as noble-metal-free counter electrode for quantum-dot-sensitized solar cells.  

PubMed

The development of an efficient noble-metal-free counter electrode is crucial for possible applications of quantum-dot-sensitized solar cells (QDSSCs). Herein, we present TiN nanoparticles on a carbon nanotube (CNT)-graphene hybrid support as a noble-metal-free counter electrode for QDSSCs employing a polysulfide electrolyte. The resulting TiN/CNT-graphene possesses an extremely high surface roughness, a good metal-support interaction, and less aggregation relative to unsupported TiN; it also has superior solar power conversion efficiency (4.13 %) when applying a metal mask, which is much higher than that of the state-of-the-art Au electrode (3.35 %). Based on electrochemical impedance spectroscopy measurements, the enhancement is ascribed to a synergistic effect between TiN nanoparticles and the CNT-graphene hybrid, the roles of which are to provide active sites for the reduction of polysulfide ions and electron pathways to TiN nanoparticles, respectively. The combination of graphene and CNTs leads to a favorable morphology that prevents stacking of graphene or bundling of CNTs, which maximizes the contact of the support with TiN nanoparticles and improves electron-transfer capability relative to either carbon material alone. PMID:23303691

Youn, Duck Hyun; Seol, Minsu; Kim, Jae Young; Jang, Ji-Wook; Choi, Youngwoo; Yong, Kijung; Lee, Jae Sung

2013-02-01

188

Mesoporous Bi2S3 nanorods with graphene-assistance as low-cost counter-electrode materials in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

In this work, we report the synthesis of mesoporous Bi2S3 nanorods under hydrothermal conditions without additives, and investigated their catalytic activities as the CE in DSCs by I-V curves and tested conversion efficiency. To further improve their power conversion efficiency, we added different amounts of reduced graphene by simple physical mixing. With the addition of 9 wt% reduced graphene (rGO), the short-circuit current density, open-circuit voltage and fill factor were Jsc = 15.33 mA cm-2, Voc = 0.74 V and FF = 0.609. More importantly, the conversion efficiency reached 6.91%, which is slightly inferior to the commercial Pt counter electrode (7.44%). Compared to the conventional Pt counter electrodes of solar cells, this new material has the advantages of low-cost, facile synthesis and high efficiency with graphene assistance. To the best of our knowledge, this Bi2S3 + 9 wt% rGO system has the best performance ever recorded in all Bi2S3-based CEs in the DSCs system.In this work, we report the synthesis of mesoporous Bi2S3 nanorods under hydrothermal conditions without additives, and investigated their catalytic activities as the CE in DSCs by I-V curves and tested conversion efficiency. To further improve their power conversion efficiency, we added different amounts of reduced graphene by simple physical mixing. With the addition of 9 wt% reduced graphene (rGO), the short-circuit current density, open-circuit voltage and fill factor were Jsc = 15.33 mA cm-2, Voc = 0.74 V and FF = 0.609. More importantly, the conversion efficiency reached 6.91%, which is slightly inferior to the commercial Pt counter electrode (7.44%). Compared to the conventional Pt counter electrodes of solar cells, this new material has the advantages of low-cost, facile synthesis and high efficiency with graphene assistance. To the best of our knowledge, this Bi2S3 + 9 wt% rGO system has the best performance ever recorded in all Bi2S3-based CEs in the DSCs system. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04274c

Guo, Sheng-Qi; Jing, Tian-Zeng; Zhang, Xiao; Yang, Xiao-Bing; Yuan, Zhi-Hao; Hu, Fang-Zhong

2014-11-01

189

Part I. Carbon and mercury-carbon optically transparent electrodes. Part II. Investigation of redox properties of technetium by cyclic voltammetry and thin layer spectroelectrochemistry  

SciTech Connect

A carbon optically transparent electrode (C OTE) has been prepared by vapor-deposithing a thin carbon film (150 to 310 A thick) on glass and quartz. Optical transparency is good throughout the ultraviolet-visible region. Electrochemical and spectroelectrochemical measurements were made with ferricyanide and o-tolidine respectively. The C OTE serves as a good substrate for deposition of a thin mercury film to form a mercury film transparent electrode (Hg-C OTE). The Hg-C OTE exhibits electrochemical properties of conventional mercury film electrodes as evidenced by Pb/sup 2 +/ cyclic voltammograms. The Hg-C OTE exhibits electrochemical properties of conventional mercury film electrodes as evidenced by Pb/sup 2 -/ cyclic VOHammograms. The Hg-C OTE enabled the spectrochemical characterization of cysteine oxidation, which was shown to involve the oxidation of mercury to form mercurous cysteinate. An 8080 based microcomputer has been interfaced with a Harrick oscillating mirror rapid scanning uv-visible spectrophotometer. Two different approaches are compared for controlling the galvanometer. The first utilizes the digital hardware on the Harrick processing module to derive the mirror drive waveform, while the second creates the waveform under direct software control. A potentiostat is also interfaced and the system is demonstrated by the spectroelectrochemical determination of the redox potential of o-tolidine. Redox potentials are also determined for a series of technetium complexes by the spectropotentiostatic technique. These include hexahalogens, ditertiary arsine, and 1,2-bis(diphenylphosphino) ethane complexes of technetium. Transient hexavalent technetium is produced, detected, and characterized in aqueous alkaline media by pulse radiolysis and very fast scan cyclic voltammetry. The lifetime is of the order of milliseconds. This species is potentially useful in the preparation of technetium radiopharmaceuticals.

Hurst, R.W.

1980-01-01

190

Large-scale synthesis of Cu2SnS3 and Cu(1.8)S hierarchical microspheres as efficient counter electrode materials for quantum dot sensitized solar cells.  

PubMed

Exploration of new catalytic semiconductors with novel structures as counter electrode materials is a promising approach to improve performances of quantum dot sensitized solar cells (QDSSCs). In this work, nearly mono-disperse tetragonal Cu(2)SnS(3) (CTS) and rhombohedral Cu(1.8)S hierarchical microspheres with nanometer-to-micrometer dimensions have been synthesized respectively via a simple solvothermal approach. These microspheres are also demonstrated as efficient counter electrode materials in solar cells using ZnO/ZnSe/CdSe nanocables as photoanode and polysulfide (S(n)(2-)/S(2-)) solution as electrolyte. While copper sulfide is regarded as one of the most effective counter electrode materials in QDSSCs, we demonstrate the CTS microspheres to show higher electrocatalytic activity for the reduction of polysulfide electrolyte than the Cu(1.8)S microspheres. This contributes to obvious enhancement of photocurrent density (J(SC)) and fill factor (FF). Power conversion efficiency (PCE) is significantly enhanced from 0.25% for the cell using a pure FTO (SnO(2):F) glass as counter electrode, to 3.65 and 4.06% for the cells using counter electrodes of FTO glasses coated respectively with Cu(1.8)S and CTS microspheres. PMID:22968176

Xu, Jun; Yang, Xia; Wong, Tai-Lun; Lee, Chun-Sing

2012-10-21

191

Healable capacitive touch screen sensors based on transparent composite electrodes comprising silver nanowires and a furan/maleimide diels-alder cycloaddition polymer.  

PubMed

A healable transparent capacitive touch screen sensor has been fabricated based on a healable silver nanowire-polymer composite electrode. The composite electrode features a layer of silver nanowire percolation network embedded into the surface layer of a polymer substrate comprising an ultrathin soldering polymer layer to confine the nanowires to the surface of a healable Diels-Alder cycloaddition copolymer and to attain low contact resistance between the nanowires. The composite electrode has a figure-of-merit sheet resistance of 18 ?/sq with 80% transmittance at 550 nm. A surface crack cut on the conductive surface with 18 ? is healed by heating at 100 °C, and the sheet resistance recovers to 21 ? in 6 min. A healable touch screen sensor with an array of 8 × 8 capacitive sensing points is prepared by stacking two composite films patterned with 8 rows and 8 columns of coupling electrodes at 90° angle. After deliberate damage, the coupling electrodes recover touch sensing function upon heating at 80 °C for 30 s. A capacitive touch screen based on Arduino is demonstrated capable of performing quick recovery from malfunction caused by a razor blade cutting. After four cycles of cutting and healing, the sensor array remains functional. PMID:25486240

Li, Junpeng; Liang, Jiajie; Li, Lu; Ren, Fengbo; Hu, Wei; Li, Juan; Qi, Shuhua; Pei, Qibing

2014-12-23

192

Platinum-Free Counter Electrode Comprised of Metal-Organic-Framework (MOF)-Derived Cobalt Sulfide Nanoparticles for Efficient Dye-Sensitized Solar Cells (DSSCs)  

NASA Astrophysics Data System (ADS)

We fabricated a highly efficient (with a solar-to-electricity conversion efficiency (?) of 8.1%) Pt-free dye-sensitized solar cell (DSSC). The counter electrode was made of cobalt sulfide (CoS) nanoparticles synthesized via surfactant-assisted preparation of a metal organic framework, ZIF-67, with controllable particle sizes (50 to 320 nm) and subsequent oxidation and sulfide conversion. In contrast to conventional Pt counter electrodes, the synthesized CoS nanoparticles exhibited higher external surface areas and roughness factors, as evidenced by X-ray diffraction (XRD), scanning electron microscopy (SEM) element mapping, and electrochemical analysis. Incident photon-to-current conversion efficiency (IPCE) results showed an increase in the open circuit voltage (VOC) and a decrease in the short-circuit photocurrent density (Jsc) for CoS-based DSSCs compared to Pt-based DSSCs, resulting in a similar power conversion efficiency. The CoS-based DSSC fabricated in the study show great potential for economically friendly production of Pt-free DSSCs.

Hsu, Shao-Hui; Li, Chun-Ting; Chien, Heng-Ta; Salunkhe, Rahul R.; Suzuki, Norihiro; Yamauchi, Yusuke; Ho, Kuo-Chuan; Wu, Kevin C.-W.

2014-11-01

193

Platinum-free counter electrode comprised of metal-organic-framework (MOF)-derived cobalt sulfide nanoparticles for efficient dye-sensitized solar cells (DSSCs).  

PubMed

We fabricated a highly efficient (with a solar-to-electricity conversion efficiency (?) of 8.1%) Pt-free dye-sensitized solar cell (DSSC). The counter electrode was made of cobalt sulfide (CoS) nanoparticles synthesized via surfactant-assisted preparation of a metal organic framework, ZIF-67, with controllable particle sizes (50 to 320?nm) and subsequent oxidation and sulfide conversion. In contrast to conventional Pt counter electrodes, the synthesized CoS nanoparticles exhibited higher external surface areas and roughness factors, as evidenced by X-ray diffraction (XRD), scanning electron microscopy (SEM) element mapping, and electrochemical analysis. Incident photon-to-current conversion efficiency (IPCE) results showed an increase in the open circuit voltage (VOC) and a decrease in the short-circuit photocurrent density (Jsc) for CoS-based DSSCs compared to Pt-based DSSCs, resulting in a similar power conversion efficiency. The CoS-based DSSC fabricated in the study show great potential for economically friendly production of Pt-free DSSCs. PMID:25382139

Hsu, Shao-Hui; Li, Chun-Ting; Chien, Heng-Ta; Salunkhe, Rahul R; Suzuki, Norihiro; Yamauchi, Yusuke; Ho, Kuo-Chuan; Wu, Kevin C-W

2014-01-01

194

Platinum-Free Counter Electrode Comprised of Metal-Organic-Framework (MOF)-Derived Cobalt Sulfide Nanoparticles for Efficient Dye-Sensitized Solar Cells (DSSCs)  

PubMed Central

We fabricated a highly efficient (with a solar-to-electricity conversion efficiency (?) of 8.1%) Pt-free dye-sensitized solar cell (DSSC). The counter electrode was made of cobalt sulfide (CoS) nanoparticles synthesized via surfactant-assisted preparation of a metal organic framework, ZIF-67, with controllable particle sizes (50 to 320?nm) and subsequent oxidation and sulfide conversion. In contrast to conventional Pt counter electrodes, the synthesized CoS nanoparticles exhibited higher external surface areas and roughness factors, as evidenced by X-ray diffraction (XRD), scanning electron microscopy (SEM) element mapping, and electrochemical analysis. Incident photon-to-current conversion efficiency (IPCE) results showed an increase in the open circuit voltage (VOC) and a decrease in the short-circuit photocurrent density (Jsc) for CoS-based DSSCs compared to Pt-based DSSCs, resulting in a similar power conversion efficiency. The CoS-based DSSC fabricated in the study show great potential for economically friendly production of Pt-free DSSCs. PMID:25382139

Hsu, Shao-Hui; Li, Chun-Ting; Chien, Heng-Ta; Salunkhe, Rahul R.; Suzuki, Norihiro; Yamauchi, Yusuke; Ho, Kuo-Chuan; Wu, Kevin C.-W.

2014-01-01

195

Mesoporous Bi?S? nanorods with graphene-assistance as low-cost counter-electrode materials in dye-sensitized solar cells.  

PubMed

In this work, we report the synthesis of mesoporous Bi?S? nanorods under hydrothermal conditions without additives, and investigated their catalytic activities as the CE in DSCs by I-V curves and tested conversion efficiency. To further improve their power conversion efficiency, we added different amounts of reduced graphene by simple physical mixing. With the addition of 9 wt% reduced graphene (rGO), the short-circuit current density, open-circuit voltage and fill factor were Jsc = 15.33 mA cm(-2), Voc = 0.74 V and FF = 0.609. More importantly, the conversion efficiency reached 6.91%, which is slightly inferior to the commercial Pt counter electrode (7.44%). Compared to the conventional Pt counter electrodes of solar cells, this new material has the advantages of low-cost, facile synthesis and high efficiency with graphene assistance. To the best of our knowledge, this Bi?S? + 9 wt% rGO system has the best performance ever recorded in all Bi?S?-based CEs in the DSCs system. PMID:25341187

Guo, Sheng-qi; Jing, Tian-zeng; Zhang, Xiao; Yang, Xiao-bing; Yuan, Zhi-hao; Hu, Fang-zhong

2014-11-01

196

Rapid charge-transfer in polypyrrole-single wall carbon nanotube complex counter electrodes: Improved photovoltaic performances of dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cell (DSSC) is a promising solution to global energy and environmental problems because of its clean, high efficiency, good durability, and easy fabrication. However, enhancement of power conversion efficiency and high cost of Pt counter electrode are still significant issues in commercial application of DSSCs. Herein, pyrrole-single wall nanotube (pyrrole-SWCNT) complexes are pioneerly synthesized by a reflux technique and subsequently in-situ polymerized and employed as counter electrodes (CEs) for DSSCs. Different from traditional polypyrrole/SWCNT (PPy/SWCNT) composites, the resultant PPy-SWCNT complexes are expected to fulfill the good electrical-conduction of SWCNT and electrocatalytic behaviors of PPy in accelerating electrochemical activity and charge transfer owing to the covalent bond between PPy (N atoms) and SWCNT (C atoms). The DSSCs employing PPy-SWCNT complex CEs exhibit significantly enhanced photovoltaic performances, in which a promising power conversion efficiency of 8.30% is obtained from PPy-2 wt‰ SWCNT complex CE in comparison with 6.31% from PPy-only CE. The high conversion efficiency, rapid charge-transfer in combination with simple preparation, relatively low cost, and scalability demonstrates the potential use of PPy-SWCNT complexes in robust DSSCs.

He, Benlin; Tang, Qunwei; Luo, Jinghuan; Li, Qinghua; Chen, Xiaoxu; Cai, Hongyuan

2014-06-01

197

Very long Ag nanowire synthesis and its application in a highly transparent, conductive and flexible metal electrode touch panel.  

PubMed

The future electronics will be soft, flexible and even stretchable to be more human friendly in the form of wearable computers. However, conventional electronic materials are usually brittle. Recently, carbon based materials are intensively investigated as a good candidate for flexible electronics but with limited mechanical and electrical performances. Metal is still the best material for electronics with great electrical properties but with poor transparency and mechanical performance. Here we present a simple approach to develop a synthesis method for very long metallic nanowires and apply them as new types of high performance flexible and transparent metal conductors as an alternative to carbon nanotubes, graphene and short nanowire based flexible transparent conductors and indium tin oxide based brittle transparent conductors. We found that very long metallic nanowire network conductors combined with a low temperature laser nano-welding process enabled superior transparent flexible conductors with high transmittance and high electrical conductivity. Further, we demonstrated highly flexible metal conductor LED circuits and transparent touch panels. The highly flexible and transparent metal conductors can be mounted on any non-planar surfaces and applied for various opto-electronics and ultimately for future wearable electronics. PMID:22952107

Lee, Jinhwan; Lee, Phillip; Lee, Hyungman; Lee, Dongjin; Lee, Seung Seob; Ko, Seung Hwan

2012-10-21

198

Cherenkov Counters  

SciTech Connect

When a charged particle passes through an optically transparent medium with a velocity greater than the phase velocity of light in that medium, it emits prompt photons, called Cherenkov radiation, at a characteristic polar angle that depends on the particle velocity. Cherenkov counters are particle detectors that make use of this radiation. Uses include prompt particle counting, the detection of fast particles, the measurement of particle masses, and the tracking or localization of events in very large, natural radiators such as the atmosphere, or natural ice fields, like those at the South Pole in Antarctica. Cherenkov counters are used in a number of different fields, including high energy and nuclear physics detectors at particle accelerators, in nuclear reactors, cosmic ray detectors, particle astrophysics detectors and neutrino astronomy, and in biomedicine for labeling certain biological molecules.

Barbero, Marlon

2012-04-19

199

Indium-free transparent organic light emitting diodes with Al doped ZnO electrodes grown by atomic layer and pulsed laser deposition  

NASA Astrophysics Data System (ADS)

We present highly efficient transparent organic light emitting diodes (OLEDs) with Al doped ZnO (AZO) electrodes prepared by atomic layer deposition and pulsed laser deposition (PLD). The power and current efficiencies exceed 27 lm/W and 44 cd/A at a brightness level of 100 cd/m2, respectively. At the same time, the transmissivity of the devices is above 73% in the visible part of the spectrum. Owing to an efficient WO3 buffer layer and an optimized PLD process for the deposition of the top AZO electrode, the OLEDs show leakage current densities as low as 3×10-5 mA/cm2 at a reverse bias of 6 V. Therefore, our study paves the way for indium-free, see-through OLED displays.

Meyer, J.; Görrn, P.; Hamwi, S.; Johannes, H.-H.; Riedl, T.; Kowalsky, W.

2008-08-01

200

Oxygen-assisted low-pressure chemical vapor deposition for the low-temperature direct growth of graphitic nanofibers on fluorine-doped tin oxide glass as a counter electrode for dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

In this paper, we report an oxygen-assisted low-pressure chemical vapor deposition (LPCVD) method for the direct growth of graphitic nanofibers (GNFs) on a fluorine-doped tin oxide (FTO) glass substrate at a low temperature (550 °C). By adding moderate concentrations of oxygen in a gas mixture of argon, ethylene, and hydrogen during LPCVD, an extremely dense GNF forest can be obtained on a nickel-coated FTO glass substrate. Though this process, the graphitic nanofibers are grown homogenously on a large area of FTO glass. It was observed that oxygen-assisted LPCVD leads to the direct growth of high-quality GNFs as a counter electrode for dye-sensitized solar cells (DSSCs). In combination with an N719 dye-sensitized TiO2 working electrode and an iodine-based electrolyte, the DSSC with a GNF counter electrode showed a power conversion efficiency of 5.51% under AM 1.5 (100 mW cm?2) illumination, which approached that of the DSSC with a Pt counter electrode (5.44%). The results demonstrated that our directly grown GNFs could be promising candidates for counter electrodes to achieve high performance in DSSCs.

Chen, Chih-Sheng; Hsieh, Chien-Kuo

2014-11-01

201

In situ synthesis of a NiS/Ni3S2 nanorod composite array on Ni foil as a FTO-free counter electrode for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

A NiS/Ni3S2 nanorod composite array that directly grows on Ni foil has been used as a counter electrode for dye-sensitized solar cells; these nickel sulfide nanorods exhibit excellent photo-electrical conversion efficiency when compared with conventional noble-metal Pt electrodes.A NiS/Ni3S2 nanorod composite array that directly grows on Ni foil has been used as a counter electrode for dye-sensitized solar cells; these nickel sulfide nanorods exhibit excellent photo-electrical conversion efficiency when compared with conventional noble-metal Pt electrodes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06534d

Liao, Yongping; Pan, Kai; Pan, Qingjiang; Wang, Guofeng; Zhou, Wei; Fu, Honggang

2015-01-01

202

Platinum/titanium bilayer deposited on polymer film as efficient counter electrodes for plastic dye-sensitized solar cells  

SciTech Connect

A surface-rich platinum/titanium bilayer was deposited on poly(ethylene naphthalate) film by vacuum sputtering as counterelectrode for plastic dye-sensitized solar cells (DSSCs). Compared to the electrodes made of pure Pt layer, this electrode maintained similar electrochemical catalytic effect at relative low Pt usage. Current-voltage characteristics of the plastic DSSC at this stage stand at 0.69 V on V{sub OC}, 9.97 mA/cm{sup 2} on I{sub SC}, 0.69 on fill factor, and 4.31% cell efficiency under AM1.5, 100 mW/cm{sup 2} illumination.

Ikegami, M.; Miyoshi, K.; Miyasaka, T.; Teshima, K.; Wei, T. C.; Wan, C. C.; Wang, Y. Y. [Graduate School of Engineering, Toin University of Yokohama, Yokohama, Kanagawa 225-8502 (Japan); Peccell Technologies, Inc., Yokohama, Kanagawa 225-8502 (Japan); Department of Chemical Engineering, National Tsing-Hua University, Hsin-Chu, Taiwan 30013 (China)

2007-04-09

203

Photoresist-Free Patterning by Mechanical Abrasion of Water-Soluble Lift-Off Resists and Bare Substrates: Toward Green Fabrication of Transparent Electrodes  

PubMed Central

This paper describes the fabrication of transparent electrodes based on grids of copper microwires using a non-photolithographic process. The process—“abrasion lithography”—takes two forms. In the first implementation (Method I), a water-soluble commodity polymer film is abraded with a sharp tool, coated with a conductive film, and developed by immersion in water. Water dissolves the polymer film and lifts off the conductive film in the unabraded areas. In the second implementation (Method II), the substrate is abraded directly by scratching with a sharp tool (i.e., no polymer film necessary). The abraded regions of the substrate are recessed and roughened. Following deposition of a conductive film, the lower profile and roughened topography in the abraded regions prevents mechanical exfoliation of the conductive film using adhesive tape, and thus the conductive film remains only where the substrate is scratched. As an application, conductive grids exhibit average sheet resistances of 17 ? sq–1 and transparencies of 86% are fabricated and used as the anode in organic photovoltaic cells in concert with the conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). Compared to devices in which PEDOT:PSS alone serves as an anode, devices comprising grids of copper/nickel microwires and PEDOT:PSS exhibit lowered series resistance, which manifests in greater fill factor and power conversion efficiency. This simple method of forming micropatterns could find use in applications where cost and environmental impact should be minimized, especially as a potential replacement for the transparent electrode indium tin oxide (ITO) in thin-film electronics over large areas (i.e., solar cells) or as a method of rapid prototyping for laboratory-scale devices. PMID:24358321

Printz, Adam D.; Chan, Esther; Liong, Celine; Martinez, René S.; Lipomi, Darren J.

2013-01-01

204

Notable catalytic activity of oxygen-vacancy-rich WO(2.72) nanorod bundles as counter electrodes for dye-sensitized solar cells.  

PubMed

For the first time, nonstoichiometric WO2.72 was used as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). Oxygen-vacancy-rich WO2.72 nanorod bundles with notable catalytic activity for triiodide and thiolate reduction were prepared in this study. The photovoltaic parameters of dye-sensitized solar cells (DSSCs) with WO2.72 nanorod bundles as CEs are superior compared with those of the WO3-based cells, and nearly the same as those of the precious metal Pt-based cells. In a non-corrosive organic redox couple, the performance of WO2.72 CEs is better than that of Pt and WO3 CEs in DSSCs. PMID:23872931

Zhou, Huawei; Shi, Yantao; Wang, Liang; Zhang, Hong; Zhao, Chunyu; Hagfeldt, Anders; Ma, Tingli

2013-09-01

205

High electrocatalytic and wettable nitrogen-doped microwave-exfoliated graphene nanosheets as counter electrode for dye-sensitized solar cells.  

PubMed

In this paper, high electrocatalytic and wettable nitrogen-doped microwave-exfoliated graphene (N-MEG) nanosheets are used as Pt-free counter electrode (CE) for dye-sensitized solar cells (DSSCs). A low cost solution-based process is developed by using cyanamide (NH2 CN) at room temperature and normal pressure. The pyrrolic and pyridinic N atoms are doped into the carbon conjugated lattice to enhance electrocatalytic activity. N-MEG film having N-doping active sites and large porosity provides a wettable surface to facilitate electrolyte diffusion so that improves fill factor. Moreover, the control of the air exposure time after completing N-MEG film is found to be crucial to obtain a reliable N-MEG CE. A high DSSC efficiency up to 7.18% can be achieved based on N-MEG CE, which is nearly comparable to conventional Pt CE. PMID:24833284

Zhai, Peng; Wei, Tzu-Chien; Chang, Ya-Huei; Huang, Yu-Ting; Yeh, Wei-Ting; Su, Haijun; Feng, Shien-Ping

2014-08-27

206

Low-cost porous Cu2ZnSnSe4 film remarkably superior to noble Pt as counter electrode in quantum dot-sensitized solar cell system  

NASA Astrophysics Data System (ADS)

Lost-cost counter electrodes (CEs) based on Cu2ZnSnS(Se)4 nanoparticles have been successfully introduced to quantum dot-sensitized solar cells (QDSCs). The investigation has demonstrated that the catalytic activity of Cu2ZnSnS(Se)4 based CEs is sensitive to the composition and thermal annealing condition. The Cu2ZnSnSe4 CE with porous structure, fabricated by spray deposition method and sintered at 450 °C in Argon atmosphere, exhibits an excel power conversion efficiency of 4.35% under AM 1.5 solar (100 mW cm-2) irradiation in a QDSC, which is about 70% higher than that of device using the conventional thermally platinized conducting glass CEs.

Zeng, Xianwei; Zhang, Wenjun; Xie, Yan; Xiong, Dehua; Chen, Wei; Xu, Xiaobao; Wang, Mingkui; Cheng, Yi-Bing

2013-03-01

207

Synthesis of Honeycomb-like Mesoporous Pyrite FeS2 Microspheres as Efficient Counter Electrode in Quantum Dots Sensitized Solar Cells.  

PubMed

Honeycomb-like mesoporous pyrite FeS2 microspheres, with diameters of 500-800 nm and pore sizes of 25-30 nm, are synthesized by a simple solvothermal approach. The mesoporous FeS2 microspheres are demonstrated to be an outstanding counter electrode (CE) material in quantum dot sensitized solar cells (QDSSCs) for electrocatalyzing polysulfide electrolyte regeneration. The cell using mesoporous FeS2 microspheres as CE shows 86.6% enhancement in power conversion efficiency (PCE) than the cell using traditional noble Pt CE. Furthermore, it also shows 11.4% enhancement in PCE than the cell using solid FeS2 microspheres as CE, due to the mesoporous structure facilitating better contact with polysulfide electrolyte and fast diffusion of redox couple species in electrolyte. PMID:24986216

Xu, Jun; Xue, Hongtao; Yang, Xia; Wei, Huaixin; Li, Wenyue; Li, Zhangpeng; Zhang, Wenjun; Lee, Chun-Sing

2014-11-01

208

The maximum limiting performance improved counter electrode based on a porous fluorine doped tin oxide conductive framework for dye-sensitized solar cells.  

PubMed

A novel porous fluorine doped tin oxide (PFTO) conductive framework was introduced to counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). When modified by platinum (Pt) or carbon (C), the PFTO conductive framework displays high catalytic activity to I(-)/I3(-) redox couples. Power conversion efficiencies of 6.09% and 5.81% were obtained in the DSSCs based on Pt and C modified PFTO CEs respectively, which were close to that of DSSCs with Pt coated FTO glass (6.05%) and Pt sheet (6.26%) CEs. Maximum limiting performances of the CEs were obtained from the polarization curves. The CE based on PFTO showed higher maximum limiting power conversion efficiency (~20%) compared with the planar FTO substrate Pt CE (~18%), with the increase of its surface area and electrocatalytic activity. PMID:23632829

Bao, Chunxiong; Huang, Huan; Yang, Jie; Gao, Hao; Yu, Tao; Liu, Jianguo; Zhou, Yong; Li, Zhaosheng; Zou, Zhigang

2013-06-01

209

Photovoltaic performance of multi-wall carbon nanotube/PEDOT:PSS composite on the counter electrode of a dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

A composite of poly(3,4-ethylendioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and multi-walled carbon nanotubes (MWCNTs) was cyclovoltametrically electropolymerized on a fluorine-doped tin oxide (FTO) substrate and used as a counter electrode for a dye-sensitized solar cell. The PEDOT:PSS-MWCNT composite film was investigated using scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The CV diagrams showed that the PEDOT:PSS-MWCNT composite film has better electro-catalytic activity for the I-/I3- redox reaction than the conventional platinized FTO. The best energy conversion efficiency was observed in EIS data with an MWCNT content of 0.002 wt %.

Rhee, Yonghoon; Ko, Minjae; Jin, Hwayoung; Jin, Joon-Hyung; Min, Nam Ki

2014-08-01

210

Self-assembled free-standing polypyrrole nanotube membrane as an efficient FTO- and Pt-free counter electrode for dye-sensitized solar cells.  

PubMed

The construction of nanoporous conductive polymer membranes has potential applications in catalysts and energy-conversion devices. In this letter, we present a facile method to prepare free-standing polypyrrole (PPy) nanotube films by simply heating pulp-like homogeneous suspensions at a low temperature, which can be employed as a novel counter electrode (CE) to substitute for the expensive fluorine-doped tin oxide (FTO) glass and Pt used in dye-sensitized solar cells (DSSCs). The DSSCs assembled with these paper-like PPy membranes show an impressive conversion efficiency of 5.27%, which is about 84% of the cell with a conventional Pt/FTO CE (6.25%). PMID:24341831

Peng, Tao; Sun, Weiwei; Huang, Chengliang; Yu, Wenjing; Sebo, Bobby; Dai, Zhigao; Guo, Shishang; Zhao, Xing-Zhong

2014-01-01

211

Two-step electrochemical synthesis of polypyrrole/reduced graphene oxide composites as efficient Pt-free counter electrode for plastic dye-sensitized solar cells.  

PubMed

Polypyrrole/reduced graphene oxide (PPy/RGO) composites on the rigid and plastic conducting substrates were fabricated via a facile two-step electrochemical process at low temperature. The polypyrrole/graphene oxide (PPy/GO) composites were first prepared on the substrate with electrochemical polymerization method, and the PPy/RGO composites were subsequently obtained by electrochemically reducing the PPy/GO. The resultant PPy/GO and PPy/RGO composites were porous, in contrast to the dense and flat pristine PPy films. The cyclic voltammetry measurement revealed that resultant composites exhibited a superior catalytic performance for triiodide reduction in the order of PPy/RGO > PPy/GO > PPy. The catalytic activity of PPy/RGO was comparable to that of Pt counter electrode (CE). Under the optimal conditions, an energy conversion efficiency of 6.45% was obtained for a rigid PPy/RGO-based dye-sensitized solar cell, which is 90% of that for a thermally deposited Pt-based device (7.14%). A plastic counter electrode was fabricated by depositing PPy/RGO composites on the plastic ITO/PEN substrate, and then an all-plastic device was assembled and exhibited an energy conversion efficiency of 4.25%, comparable to that of the counterpart using a sputtered-Pt CE (4.83%) on a plastic substrate. These results demonstrated that electrochemical synthesis is a facile low-temperature method to fabricate high-performance RGO/polymer composite-based CEs for plastic DSCs. PMID:25162375

Liu, Wantao; Fang, Yanyan; Xu, Peng; Lin, Yuan; Yin, Xiong; Tang, Guangshi; He, Meng

2014-09-24

212

Development of Carbon Based optically Transparent Electrodes from Pyrolyzed Photoresist for the Investigation of Phenomena at Electrified Carbon-Solution Interfaces  

SciTech Connect

The work presented herein describes a fundamental investigations of carbon as electrode material by using the pyrolysis of photoresist to create an optically transparent material. The development of these carbon-based optically transparent electrodes (C-OTEs) enables investigations of molecular interactions within the electrical double layer, processes that are central to a wide range of important phenomena, including the impact of changes in the surface charge density on adsorption. The electrochemical importance of carbon cannot be understated, having relevance to separations and detection by providing a wide potential window and low background current in addition to being low cost and light weight. The interactions that govern the processes at the carbon electrode surface has been studied extensively. A variety of publications from the laboratories of McCreery and Kinoshita provide in depth summaries about carbon and its many applications in electrochemistry. These studies reveal that defects, impurities, oxidation, and a variety of functional groups create adsorption sites on carbon surfaces with different characteristics. The interest in C-OTEs was sparked by the desire to study and understand the behavior of individual molecules at electrified interfaces. It draws on the earlier development of Electrochemically Modulated Liquid Chromatography (EMLC), which uses carbon as the stationary phase. EMLC takes advantage of changing the applied potential to the carbon electrode to influence the retention behavior of analytes. However, perspectives gained from, for example, chromatographic measurements reflect the integrated response of a large ensemble of potentially diverse interactions between the adsorbates and the carbon electrode. Considering the chemically and physically heterogeneous surface of electrode materials such as glassy carbon, the integrated response provides little insight into the interactions at a single molecule level. To investigate individual processes, they have developed C-OTEs in order to couple electrochemistry with single molecule spectroscopy (SMS). Like EMLC, the novel merger of SMS with electrochemistry is a prime example of how a hybrid method can open new and intriguing avenues that are of both fundamental and technological importance. They show that by taking the benefits of total internal reflection fluorescence microscopy (TIRFM) and incorporating carbon as electrode material observations central to the interactions between single DNA molecules and an electrified carbon surface can be delineated. Using TIRFM while applying a positive potential to the electrode, individual molecules can be observed as they reversibly and irreversibly adsorb to the carbon surface. The positive potential attracts the negatively charged DNA molecules to the electrode surface. Dye labels on the DNA within the evanescent wave are excited and their fluorescence is captured by an intensified charge coupled device (ICCD) camera. Results are therefore presented regarding the interactions of {lambda}-DNA, 48,502 base pairs (48.5 kbp), HPV-16, 7.9 kbp, and 1 kbp fraction of pBR322 DNA. In addition to the influence of molecular size on adsorption, the fabrication, characterization, and more conventional spectroelectrochemical applications of these novel C-OTEs are presented.

Sebastian Donner

2007-12-01

213

A spray-coating process for highly conductive silver nanowire networks as the transparent top-electrode for small molecule organic photovoltaics.  

PubMed

We present a novel top-electrode spray-coating process for the solution-based deposition of silver nanowires (AgNWs) onto vacuum-processed small molecule organic electronic solar cells. The process is compatible with organic light emitting diodes (OLEDs) and organic light emitting thin film transistors (OLETs) as well. By modifying commonly synthesized AgNWs with a perfluorinated methacrylate, we are able to disperse these wires in a highly fluorinated solvent. This solvent does not dissolve most organic materials, enabling a top spray-coating process for sensitive small molecule and polymer-based devices. The optimized preparation of the novel AgNW dispersion and spray-coating at only 30 °C leads to high performance electrodes directly after the deposition, exhibiting a sheet resistance of 10.0 ? ?(-1) at 87.4% transparency (80.0% with substrate). By spraying our novel AgNW dispersion in air onto the vacuum-processed organic p-i-n type solar cells, we obtain working solar cells with a power conversion efficiency (PCE) of 1.23%, compared to the air exposed reference devices employing thermally evaporated thin metal layers as the top-electrode. PMID:25584968

Selzer, Franz; Weiß, Nelli; Kneppe, David; Bormann, Ludwig; Sachse, Christoph; Gaponik, Nikolai; Eychmüller, Alexander; Leo, Karl; Müller-Meskamp, Lars

2015-01-28

214

Dye sensitized solar cells (DSSCs) based on modified iron phthalocyanine nanostructured TiO 2 electrode and PEDOT:PSS counter electrode  

Microsoft Academic Search

An iron phthalocyanine with tetra-sulphonated substituents (FeTsPc) was used as photosentizer for the development of dye sensitized nanostructured TiO2 solar cells. The influence of surface modification (TiO2 film treated with HCl and HNO3) and thermal annealing of TiO2 photo-electrode on the performance of dye sensitized solar cell (DSSC) having structure FTO\\/TiO2–FeTsPc\\/electrolyte\\/PEDOT:PSS (carbon added)\\/FTO was investigated through the analysis of current–voltage

P. Balraju; Manish Kumar; M. S. Roy; G. D. Sharma

2009-01-01

215

Optimization of transparent and reflecting electrodes for amorphous silicon solar cells. Annual technical report, April 1, 1995--March 31, 1996  

SciTech Connect

The general objective is to develop methods to deposit materials which can be used to make more efficient solar cells. The work is organized into three general tasks: Task 1. Develop improved methods for depositing and using transparent conductors of fluorine-doped zinc oxide in amorphous silicon solar cells Task 2. Deposit and evaluate titanium oxide as a reflection-enhancing diffusion barrier between amorphous silicon and an aluminum or silver back-reflector. Task 3. Deposit and evaluate electrically conductive titanium oxide as a transparent conducting layer on which more efficient and more stable superstrate cells can be deposited. About one-third of the current project resources are allocated to each of these three objectives.

Gordon, R.G.; Sato, H.; Liang, H.; Liu, X.; Thornton, J. [Harvard Univ., Cambridge, MA (United States)

1996-08-01

216

Synergistically enhanced stability of highly flexible silver nanowire/carbon nanotube hybrid transparent electrodes by plasmonic welding.  

PubMed

Here, we report highly transparent and flexible AgNW/SWCNT hybrid networks on PET substrates combined with plasmonic welding for securing ultrahigh stability in mechanical and electrical properties under severe bending. Plasmonic welding produces local heating and welding at the junction of AgNWs and leads strong adhesion between AgNW and SWCNT as well as between hybrid structure and substrate. The initial sheet resistance of plasmon treated AgNW/SWCNT hybrid film was 26 ? sq(-1), with >90% optical transmittance over the wavelength range 400-2700 nm. Following 200 cycles of convex/concave bending with a bending radius of 5 mm, the sheet resistance changed from 26 to 29 ? sq(-1). This hybrid structure combined with the plasmonic welding process provided excellent stability, low resistance, and high transparency, and is suitable for highly flexible electronics applications, including touch panels, solar cells, and OLEDs. PMID:24972024

Lee, Jongsoo; Woo, Ju Yeon; Kim, Ju Tae; Lee, Byung Yang; Han, Chang-Soo

2014-07-23

217

Low-noise solar-blind photodetectors based on LaAlO3 single crystal with transparent indium-tin-oxide electrode as detection window.  

PubMed

The low-noise solar-blind photodetectors of indium-tin-oxide/LaAlO(3)/Ag (ITO/LAO/Ag) have been fabricated based on the properties of LAO bandgap excitation and the transparent conductance of ITO thin film. The ITO thin films are epitaxially grown on LAO wafers as the electrodes and detection windows of the photodetectors. The photodetectors have low noise and excellent electromagnetic shielding. The influence of the thickness of ITO thin films on the responsivity of the photodetectors has been studied. The photocurrent responsivity can reach 10.3 mA/W under the irradiation of 200-220 nm for a photodetector with 5 nm thick ITO film. The noise current is 1 pA order magnitude under the sunlight at midday. The experiment results suggest that ITO/LAO/Ag is one of the promising structures for the solar-blind deep-ultraviolet photodetectors. PMID:20935715

Guo, Er-Jia; Lu, Hui-Bin; He, Meng; Jin, Kui-Juan; Yang, Guo-Zhen

2010-10-10

218

Ga-doped ZnO transparent electrodes with TiO2 blocking layer/nanoparticles for dye-sensitized solar cells  

PubMed Central

Ga-doped ZnO [GZO] thin films were employed for the transparent electrodes in dye-sensitized solar cells [DSSCs]. The electrical property of the deposited GZO films was as good as that of commercially used fluorine-doped tin oxide [FTO]. In order to protect the GZO and enhance the photovoltaic properties, a TiO2 blocking layer was deposited on the GZO surface. Then, TiO2 nanoparticles were coated on the blocking layer, and dye was attached for the fabrication of DSSCs. The fabricated DSSCs with the GZO/TiO2 glasses showed an enhanced conversion efficiency of 4.02% compared to the devices with the normal GZO glasses (3.36%). Furthermore, they showed better characteristics even than those using the FTO glasses, which can be attributed to the reduced charge recombination and series resistance. PMID:22222148

2012-01-01

219

Zinc Oxide Modified with Benzylphosphonic Acids as Transparent Electrodes in Regular and Inverted Organic Solar Cell Structures  

E-print Network

An approach is presented to modify the WF of solution-processed sol-gel derived ZnOover an exceptionally wide range of more than 2.3 eV. This approach relies on the formation of dense and homogeneous self-assembled monolayers based on phosphonic acids with different dipole moments. This allows us to apply ZnO as charge selective bottom electrodes in either regular or inverted solar cell structures, using P3HT:PCBM as the active layer. These devices compete with or even exceed the performance of the reference cell on ITO/PEDOT:PSS. Our finding challenges the current view that bottom electrodes in inverted solar cells need to be electron-blocking for good device performance.

Ilja Lange; Sina Reiter; Juliane Kniepert; Fortunato Piersimoni; Michael Paetzel; Jana Hildebrandt; Thomas Brenner; Stefan Hecht; Dieter Neher

2015-02-05

220

A transparent conductive adhesive laminate electrode for high-efficiency organic-inorganic lead halide perovskite solar cells.  

PubMed

A self-adhesive laminate solar-cell electrode is presented based on a metal grid embedded in a polymer film (x-y conduction) and set in contact with the active layer using a pressure-sensitive adhesive containing a very low quantity (1.8%) of organic conductor, which self-organizes to provide z conduction to the grid. This ITO-free material performs in an identical fashion to evaporated gold in high-efficiency perovskite solar cells. PMID:25257313

Bryant, Daniel; Greenwood, Peter; Troughton, Joel; Wijdekop, Maarten; Carnie, Mathew; Davies, Matthew; Wojciechowski, Konrad; Snaith, Henry J; Watson, Trystan; Worsley, David

2014-11-26

221

Efficient Organic Excitonic Solar Cells with Carbon Nanotubes Replacing In2O3:Sn as the Transparent Electrode (Presentation)  

SciTech Connect

The conclusions of this report are that: (1) organic solar cells with efficiencies of up to 1.43% conversion efficiency that use no ITO and no PEDOT:PSS, are demonstrated; (2) a cell without ITO, but with PEDOT:PSS gave 2.6% conversion efficiency; (3) due to porous nature of SWCNT substrates, optimization of the active layer is essential; and (4) SWCNT electrodes bring one step closer the goal of a fully printable, organic solar cell.

van de Lagemaat, J.; Barnes, T.; Rumbles, G.; Shaheen, S.; Coutts, T. J.; Weeks, C.; Glatkowski, P.; Levitsky, I.; Peltola, J.

2006-05-01

222

Performances of some low-cost counter electrode materials in CdS and CdSe quantum dot-sensitized solar cells  

PubMed Central

Different counter electrode (CE) materials based on carbon and Cu2S were prepared for the application in CdS and CdSe quantum dot-sensitized solar cells (QDSSCs). The CEs were prepared using low-cost and facile methods. Platinum was used as the reference CE material to compare the performances of the other materials. While carbon-based materials produced the best solar cell performance in CdS QDSSCs, platinum and Cu2S were superior in CdSe QDSSCs. Different CE materials have different performance in the two types of QDSSCs employed due to the different type of sensitizers and composition of polysulfide electrolytes used. The poor performance of QDSSCs with some CE materials is largely due to the lower photocurrent density and open-circuit voltage. The electrochemical impedance spectroscopy performed on the cells showed that the poor-performing QDSSCs had higher charge-transfer resistances and CPE values at their CE/electrolyte interfaces. PMID:24512605

2014-01-01

223

Spray deposited copper zinc tin sulphide (Cu2ZnSnS4) film as a counter electrode in dye sensitized solar cells.  

PubMed

Stoichiometric thin films of Cu2ZnSnS4 (CZTS) were deposited by the spray technique on a FTO coated glass substrate, with post-annealing in a H2S environment to improve the film properties. CZTS films were used as a counter electrode (CE) in Dye-Sensitized Solar Cells (DSCs) with N719 dye and an iodine electrolyte. The DSC of 0.25 cm(2) area using a CE of CZTS film annealed in a H2S environment under AM 1.5G illumination (100 mW cm(-2)) exhibited a short circuit current density (JSC) = 18.63 mA cm(-2), an open circuit voltage (VOC) = 0.65 V and a fill factor (FF) = 0.53, resulting in an overall power conversion efficiency (PCE) = 6.4%. While the DSC using as deposited CZTS film as a CE showed the PCE = 3.7% with JSC = 13.38 mA cm(-2), VOC = 0.57 V and FF = 0.48. Thus, the spray deposited CZTS films can play an important role as a CE in the large area DSC fabrication. PMID:25286339

Swami, Sanjay Kumar; Chaturvedi, Neha; Kumar, Anuj; Chander, Nikhil; Dutta, Viresh; Kumar, D Kishore; Ivaturi, A; Senthilarasu, S; Upadhyaya, Hari M

2014-11-21

224

Efficient Quasisolid Dye- and Quantum-Dot-Sensitized Solar Cells Using Thiolate/Disulfide Redox Couple and CoS Counter Electrode.  

PubMed

For the first time, a quasisolid thiolate/disulfide-based electrolyte was prepared using succinonitrile as a matrix. An optimized configuration of the quasisolid electrolyte contains 5-mercapto-1-methyltetrazole N-tetramethylammonium/disulfide/LiClO4/N-methylbenzimidazole in the molar ratio of 0.8:0.8:0.1:0.1. Dye-sensitized solar cells fabricated using this quasisolid electrolyte, together with N719 dye-sensitized photoelectrode and CoS counter electrode, attained power conversion efficiencies of 4.25% at 1 sun and 6.19% at 0.1 sun illumination intensities. The optimized quasisolid electrolyte, when introduced to quasisolid CdS quantum-dot-sensitized solar cells, exhibited a power conversion efficiency of 0.94%, despite the fact that CdS absorbs only a small fraction of the visible light, unlike dyes. The encouraging results show the potential for the utilization of the quasisolid thiolate/disulfide-based electrolyte in sensitized solar cells. PMID:25380236

Meng, Ke; Thampi, K Ravindranathan

2014-12-10

225

Water-soluble polyelectrolyte-grafted multiwalled carbon nanotube thin films for efficient counter electrode of dye-sensitized solar cells.  

PubMed

Water-soluble, polyelectrolyte-grafted multiwalled carbon nanotubes (MWCNTs), MWCNT-g-PSSNa, were synthesized using a "grafting to" route. MWCNT-g-PSSNa thin films fabricated by an electrostatic spray (e-spray) technique were used as the counter electrode (CE) for dye-sensitized solar cells (DSSCs). The e-sprayed MWCNT-g-PSSNa thin-film-based CEs (MWCNT-CE) were uniform over a large area, and the well-exfoliated MWCNTs formed highly interconnected network structures. The electrochemical catalytic activity of the MWCNT-CE at different thicknesses was investigated. The MWCNT-g-PSSNa thin film showed high efficiency as a CE in DSSCs. The power conversion efficiency (PCE) of the DSSCs using the MWCNT-g-PSSNa thin-film-based CE (DSSC-MWCNT) was >6% at a CE film thickness of approximately 0.3 microm. The optimum PCE was >7% at a film thickness of approximately 1 microm, which is 20-50 times thinner than conventional carbon-based CE. The charge transfer resistance at the MWCNT-CE/electrolyte interface was 1.52 Omega cm(2) at a MWCNT-CE thickness of 0.31 microm, which is lower than that of a Pt-CE/electrolyte interface, 1.78 Omega cm(2). This highlights the potential for the low-cost CE fabrication of DSSCs using a facile deposition technique from an environmentally "friendly" solution at low temperatures. PMID:20509667

Han, Jinkyu; Kim, Hyunju; Kim, Dong Young; Jo, Seong Mu; Jang, Sung-Yeon

2010-06-22

226

Investigation of electrodeposited cobalt sulphide counter electrodes and their application in next-generation dye sensitized solar cells featuring organic dyes and cobalt-based redox electrolytes  

NASA Astrophysics Data System (ADS)

Cobalt sulphide (CoS) films are potentiodynamically deposited on fluorine-doped tin oxide (FTO) coated glass substrates employing one, three and five sweep cycles (CoS-I, CoS-III and CoS-V respectively). Analysis of the CoS-III film by impedance spectroscopy reveals a lower charge transfer resistance (RCT) than that measured for Pt CE (0.75 ? cm-2 and 0.85 ? cm-2, respectively). The CoS films are used as counter electrodes (CE) in dye-sensitized solar cells (DSSCs) featuring the combination of a high absorption coefficient organic dye (C218) and the cobalt-based redox electrolyte [Co(bpy)3]2/3+. DSSCs fabricated with the CoS-III CE yield the highest short-circuit current density (JSC) of 12.84 mA cm-2, open circuit voltage (VOC) of 805 mV and overall power conversion efficiency (PCE) of 6.72% under AM 1.5G illumination (100 mW cm-2). These values are comparable to the performance of an analogous cell fabricated with the Pt CE (PCE = 6.94%). Owing to relative lower cost (due to the inherit earth abundance of Co) and non-toxicity, CoS can be considered as a promising alternative to the more expensive Pt as a CE material for next-generation DSSCs that utilize organic dyes and cobalt-based redox electrolytes.

Swami, Sanjay Kumar; Chaturvedi, Neha; Kumar, Anuj; Kapoor, Raman; Dutta, Viresh; Frey, Julien; Moehl, Thomas; Grätzel, Michael; Mathew, Simon; Nazeeruddin, Mohammad Khaja

2015-02-01

227

Catalytic, conductive, and transparent platinum nanofiber webs for FTO-free dye-sensitized solar cells.  

PubMed

We report a multifunctional platinium nanofiber (PtNF) web that can act as a catalyst layer in dye-sensitized solar cell (DSSC) to simultaneously function as a transparent counter electrode (CE), i.e., without the presence of an indium-doped tin oxide (ITO) or fluorine-doped tin oxide (FTO) glass. This PtNF web can be easily produced by electrospinning, which is highly cost-effective and suitable for large-area industrial-scale production. Electrospun PtNFs are straight and have a length of a few micrometers, with a common diameter of 40-70 nm. Each nanofiber is composed of compact, crystalline Pt grains and they are well-fused and highly interconnected, which should be helpful to provide an efficient conductive network for free electron transport and a large surface area for electrocatalytic behavior. A PtNF web is served as a counter electrode in DSSC and the photovoltaic performance increases up to a power efficiency of 6.0%. It reaches up to 83% of that in a conventional DSSC using a Pt-coated FTO glass as a counter electrode. Newly designed DSSCs containing PtNF webs display highly stable photoelectric conversion efficiencies, and excellent catalytic, conductive, and transparent properties, as well as long-term stability. Also, while the DSSC function is retained, the fabrication cost is reduced by eliminating the transparent conducting layer on the counter electrode. The presented method of fabricating DSSCs based on a PtNF web can be extended to other electrocatalytic optoelectronic devices that combine superior catalytic activity with high conductivity and transparency. PMID:23517275

Kim, Jongwook; Kang, Jonghyun; Jeong, Uiyoung; Kim, Heesuk; Lee, Hyunjung

2013-04-24

228

High performance electrocatalyst consisting of CoS nanoparticles on an organized mesoporous SnO2 film: its use as a counter electrode for Pt-free, dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

High energy conversion efficiencies of 6.6% and 7.5% are demonstrated in solid and liquid states, Pt-free, dye-sensitized solar cells (DSSCs), respectively, based on CoS nanoparticles on an organized mesoporous SnO2 (om-SnO2) counter electrode. These results correspond to improvements of 14% and 9%, respectively, compared to a conventional Pt counter electrode and are among the highest values reported for Pt-free DSSCs. The om-SnO2 layer plays a pivotal role as a platform to deposit a large amount of highly electrocatalytically active CoS nanoparticles via a facile solvothermal reaction. The om-SnO2 platform with a high porosity, larger pores, and good interconnectivity is derived from a poly(vinyl chloride)-g-poly(oxyethylene methacrylate) (PVC-g-POEM) graft copolymer template, which provides not only improved interaction sites for the formation of CoS nanoparticles but also enhanced electron transport. The structural, morphological, chemical, and electrochemical properties of CoS on the om-SnO2 platform are investigated using field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) measurements. The performance enhancement results from the excellent electron transport at the fluorine-doped tin oxide (FTO)/counter electrode/electrolyte interface, reduced resistance at the FTO/CoS interface, and better catalytic reduction at the counter electrode/electrolyte interface.High energy conversion efficiencies of 6.6% and 7.5% are demonstrated in solid and liquid states, Pt-free, dye-sensitized solar cells (DSSCs), respectively, based on CoS nanoparticles on an organized mesoporous SnO2 (om-SnO2) counter electrode. These results correspond to improvements of 14% and 9%, respectively, compared to a conventional Pt counter electrode and are among the highest values reported for Pt-free DSSCs. The om-SnO2 layer plays a pivotal role as a platform to deposit a large amount of highly electrocatalytically active CoS nanoparticles via a facile solvothermal reaction. The om-SnO2 platform with a high porosity, larger pores, and good interconnectivity is derived from a poly(vinyl chloride)-g-poly(oxyethylene methacrylate) (PVC-g-POEM) graft copolymer template, which provides not only improved interaction sites for the formation of CoS nanoparticles but also enhanced electron transport. The structural, morphological, chemical, and electrochemical properties of CoS on the om-SnO2 platform are investigated using field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) measurements. The performance enhancement results from the excellent electron transport at the fluorine-doped tin oxide (FTO)/counter electrode/electrolyte interface, reduced resistance at the FTO/CoS interface, and better catalytic reduction at the counter electrode/electrolyte interface. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05779a

Park, Jung Tae; Lee, Chang Soo; Kim, Jong Hak

2014-12-01

229

High performance electrocatalyst consisting of CoS nanoparticles on an organized mesoporous SnO2 film: its use as a counter electrode for Pt-free, dye-sensitized solar cells.  

PubMed

High energy conversion efficiencies of 6.6% and 7.5% are demonstrated in solid and liquid states, Pt-free, dye-sensitized solar cells (DSSCs), respectively, based on CoS nanoparticles on an organized mesoporous SnO2 (om-SnO2) counter electrode. These results correspond to improvements of 14% and 9%, respectively, compared to a conventional Pt counter electrode and are among the highest values reported for Pt-free DSSCs. The om-SnO2 layer plays a pivotal role as a platform to deposit a large amount of highly electrocatalytically active CoS nanoparticles via a facile solvothermal reaction. The om-SnO2 platform with a high porosity, larger pores, and good interconnectivity is derived from a poly(vinyl chloride)-g-poly(oxyethylene methacrylate) (PVC-g-POEM) graft copolymer template, which provides not only improved interaction sites for the formation of CoS nanoparticles but also enhanced electron transport. The structural, morphological, chemical, and electrochemical properties of CoS on the om-SnO2 platform are investigated using field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) measurements. The performance enhancement results from the excellent electron transport at the fluorine-doped tin oxide (FTO)/counter electrode/electrolyte interface, reduced resistance at the FTO/CoS interface, and better catalytic reduction at the counter electrode/electrolyte interface. PMID:25429695

Park, Jung Tae; Lee, Chang Soo; Kim, Jong Hak

2014-12-11

230

Highly efficient inverted top emitting organic light emitting diodes using a transparent top electrode with color stability on viewing angle  

SciTech Connect

We report a highly efficient phosphorescent green inverted top emitting organic light emitting diode with excellent color stability by using the 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile/indium zinc oxide top electrode and bis(2-phenylpyridine)iridium(III) acetylacetonate as the emitter in an exciplex forming co-host system. The device shows a high external quantum efficiency of 23.4% at 1000?cd/m{sup 2} corresponding to a current efficiency of 110?cd/A, low efficiency roll-off with 21% at 10?000?cd/m{sup 2} and low turn on voltage of 2.4?V. Especially, the device showed very small color change with the variation of ?x?=?0.02, ?y?=?0.02 in the CIE 1931 coordinates as the viewing angle changes from 0° to 60°. The performance of the device is superior to that of the metal/metal cavity structured device.

Kim, Jung-Bum; Lee, Jeong-Hwan; Moon, Chang-Ki; Kim, Jang-Joo, E-mail: jjkim@snu.ac.kr [Department of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)

2014-02-17

231

Liquid-phase exfoliation of chemical vapor deposition-grown single layer graphene and its application in solution-processed transparent electrodes for flexible organic light-emitting devices  

NASA Astrophysics Data System (ADS)

Efficient and low-cost methods for obtaining high performance flexible transparent electrodes based on chemical vapor deposition (CVD)-grown graphene are highly desirable. In this work, the graphene grown on copper foil was exfoliated into micron-size sheets through controllable ultrasonication. We developed a clean technique by blending the exfoliated single layer graphene sheets with conducting polymer to form graphene-based composite solution, which can be spin-coated on flexible substrate, forming flexible transparent conducting film with high conductivity (˜8 ?/?), high transmittance (˜81% at 550 nm), and excellent mechanical robustness. In addition, CVD-grown-graphene-based polymer light emitting diodes with excellent bendable performances were demonstrated.

Wu, Chaoxing; Li, Fushan; Wu, Wei; Chen, Wei; Guo, Tailiang

2014-12-01

232

The Preparation and Properties of Al-Doped ZnO Thin Films as Transparent Electrodes for Solar Cell  

NASA Astrophysics Data System (ADS)

Transparent conductive oxides based on ZnO are promising materials for application in thin-film solar photovoltaic cells. Al-doped ZnO thin films with a large area of 1 m × 1.5 m were prepared by magnetic sputtering on glass substrate using a ceramic target (98 wt. % ZnO, 2 wt. % Al2O3) in different Ar+H2 ambient at different substrate temperature. SiO2 layer with a thickness of 20 nm was deposited as a resistant layer. To investigate the influence of H2-flow on the properties of AZO films, H2-flow rate was changed during the growth process with a fixed Ar-flow rate. The effect of the substrate temperature and the H2-flow rate on the structure, electrical and optical properties was studied. In order to enhance light scattering and absorption inside the cell, suitable surface texture is needed. The influence of wet chemical etching on surface roughness and haze of AZO were also investigated.

Ding, J. N.; Tan, C. B.; Yuan, N. Y.; Feng, X. W.; Chang, X. Y.; Ye, F.

233

Efficient p-type dye-sensitized solar cells with all-nano-electrodes: NiCo2S4 mesoporous nanosheet counter electrodes directly converted from NiCo2O4 photocathodes  

PubMed Central

We report the successful growth of NiCo2S4 nanosheet films converted from NiCo2O4 nanosheet films on fluorine-doped tin oxide substrates by a low-temperature solution process. Low-cost NiCo2S4 and NiCo2O4 nanosheet films were directly used for replacing conventional Pt and NiO as counter electrodes and photocathodes, respectively, to construct all-nano p-type dye-sensitized solar cells (p-DSSCs) with high performance. Compared to Pt, NiCo2S4 showed higher catalytic activity towards the I-/I3- redox in electrolyte, resulting in an improved photocurrent density up to 2.989 mA/cm2, which is the highest value in reported p-DSSCs. Present p-DSSCs demonstrated a cell efficiency of 0.248 % that is also comparable with typical NiO-based p-DSSCs. PMID:25489277

2014-01-01

234

Efficient p-type dye-sensitized solar cells with all-nano-electrodes: NiCo2S4 mesoporous nanosheet counter electrodes directly converted from NiCo2O4 photocathodes.  

PubMed

We report the successful growth of NiCo2S4 nanosheet films converted from NiCo2O4 nanosheet films on fluorine-doped tin oxide substrates by a low-temperature solution process. Low-cost NiCo2S4 and NiCo2O4 nanosheet films were directly used for replacing conventional Pt and NiO as counter electrodes and photocathodes, respectively, to construct all-nano p-type dye-sensitized solar cells (p-DSSCs) with high performance. Compared to Pt, NiCo2S4 showed higher catalytic activity towards the I(-)/I3 (-) redox in electrolyte, resulting in an improved photocurrent density up to 2.989 mA/cm(2), which is the highest value in reported p-DSSCs. Present p-DSSCs demonstrated a cell efficiency of 0.248 % that is also comparable with typical NiO-based p-DSSCs. PMID:25489277

Shi, Zhiwei; Lu, Hao; Liu, Qiong; Cao, Fengren; Guo, Jun; Deng, Kaimo; Li, Liang

2014-01-01

235

Alternative methods to fabricate and evaluate copper zinc tin sulfide based absorber layers on transparent conducting electrodes  

NASA Astrophysics Data System (ADS)

This study is focused on fabrication and characterization of Cu 2ZnSnS4 (CZTS) films on transparent conducting substrate. CZTS films were synthesized using solution based methods. A specially designed sequential and single stage electrochemical method as well as spin coating method was used to grow layers of precursors. Deposition of constituent metallic layers was carried out on SnO2/F (Fluorinated tin oxide or FTO) coated glass substrates. The electrodeposited/spin coated layers were annealed in a sulfur environment to obtain CZTS. Structural, morphological and optical characterization experiments were performed using several techniques including x-ray diffraction, Raman and UV-visible spectroscopy, scanning electron microscopy, and atomic force microscopy. All characterization experiments indicated the films are single phase with a measured direct band gap of ˜1.5 eV. Photocurrent response of CZTS film grown on FTO substrate was measured using alternating front illumination and rear illumination in a Eu 3+/Eu2+ solution environment. The photoelectrochemical response exhibited during rear illumination is comparable to that obtained for front illumination. The promising photocurrent data for CZTS films suggest these films have potential application in a variety of photovoltaic devices. A comparative study revealed that photoelectrochemical response exhibited by the films grown on molybdenum substrate is greater than that obtained for film grown on FTO substrate. A modified form of the Gartner model to explain J-V characteristics for CZTS-electrolyte solution has been proposed. Fundamental information such as energy band gap-temperature relationship and temperature dependent study of Raman 'A' mode for CZTS thin films were also investigated in this research.

Sarswat, Prashant Kumar

236

Optical-to-optical interface device. [consisting of two transparent electrodes on glass substrates that enclose thin film photoconductor and thin layer of nematic liquid crystal  

NASA Technical Reports Server (NTRS)

Studies were conducted on the performance of a photoactivated dc liquid crystal light valve. The dc light valve is a thin film device that consists of two transparent electrodes, deposited on glass substrates, that enclose a thin film photoconductor (cadmium sulfide) and a thin layer of a nematic liquid crystal that operates in the dynamic scattering mode. The work was directed toward application of the light valve to high resolution non-coherent light to coherent light image conversion. The goal of these studies was to improve the performance and quality of the already existing dc light valve device and to evaluate quantitatively the properties and performance of the device as they relate to the coherent optical data processing application. As a result of these efforts, device sensitivity was improved by a factor of ten, device resolution was improved by a factor of three, device lifetime was improved by two-orders of magnitude, undesirable secondary liquid crystal scattering effects were eliminated, the scattering characteristics of the liquid crystal were thoroughly documented, the cosmetic quality of the devices was dramatically improved, and the performance of the device was fully documented.

Jacobson, A. D.

1973-01-01

237

Dynamic and static photoresponse of ultraviolet-detecting thin-film transistors based on transparent NiO{sub x} electrodes and an n-ZnO channel  

SciTech Connect

We report on the fabrication of an ultraviolet (UV)-detecting thin-film transistor (TFT) using NiO{sub x} as source/drain electrodes and n-ZnO as its channel layer deposited on a SiO{sub 2}/p-Si substrate. Rapid thermal annealing of the TFT was carried out in an O{sub 2} ambient at 350 deg. C for 1 min to increase the transparency of NiO{sub x}. In an accumulation mode with a gate bias of 40 V, a drain current of only 2 {mu}A was obtained in the dark. However, under an illumination of UV light with wavelength 325 nm, the drain current dramatically increased up to 13 {mu}A. Under UV photons with wavelength 254 nm or energy of 4.9 eV, much higher than 4.1 eV, the energy gap of NiO{sub x}, the photocurrent slightly decreased to {approx}10 {mu}A due to the absorption by NiO{sub x}. These photoelectric effects were more pronounced under a gate-bias condition for a depletion (off) mode. The UV-dynamic behavior of our TFTs was also investigated, yielding the UV response time of {approx}300 ms and UV-on/off ratio of about 10.

Bae, H.S.; Choi, C.M.; Kim, Jae Hoon; Im, Seongil [Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of)

2005-04-01

238

Transparent lithium-ion batteries , Sangmoo Jeongb  

E-print Network

Transparent lithium-ion batteries Yuan Yanga , Sangmoo Jeongb , Liangbing Hua , Hui Wua , Seok Woo, and solar cells; however, transparent batteries, a key component in fully integrated transparent devices, have not yet been reported. As battery electrode materials are not transpar- ent and have to be thick

Cui, Yi

239

Transparent lithium-ion batteries  

PubMed Central

Transparent devices have recently attracted substantial attention. Various applications have been demonstrated, including displays, touch screens, and solar cells; however, transparent batteries, a key component in fully integrated transparent devices, have not yet been reported. As battery electrode materials are not transparent and have to be thick enough to store energy, the traditional approach of using thin films for transparent devices is not suitable. Here we demonstrate a grid-structured electrode to solve this dilemma, which is fabricated by a microfluidics-assisted method. The feature dimension in the electrode is below the resolution limit of human eyes, and, thus, the electrode appears transparent. Moreover, by aligning multiple electrodes together, the amount of energy stored increases readily without sacrificing the transparency. This results in a battery with energy density of 10 Wh/L at a transparency of 60%. The device is also flexible, further broadening their potential applications. The transparent device configuration also allows in situ Raman study of fundamental electrochemical reactions in batteries. PMID:21788483

Yang, Yuan; Jeong, Sangmoo; Hu, Liangbing; Wu, Hui; Lee, Seok Woo; Cui, Yi

2011-01-01

240

Room-Temperature Synthesis of Cu2-x E (E=S, Se) Nanotubes with Hierarchical Architecture as High-Performance Counter Electrodes of Quantum-Dot-Sensitized Solar Cells.  

PubMed

Copper chalcogenide nanostructures (e.g. one- dimensional nanotubes) have been the focus of interest because of their unique properties and great potential in various applications. Their current fabrications mainly rely on high-temperature or complicated processes. Here, with the assistance of theoretical prediction, we prepared Cu2-x E (E=S, Se) micro-/nanotubes (NTs) with a hierarchical architecture by using copper nanowires (Cu NWs), stable sulfur and selenium powder as precursors at room temperature. The influence of reaction parameters (e.g. precursor ratio, ligands, ligand ratio, and reaction time) on the formation of nanotubes was comprehensively investigated. The resultant Cu2-x E (E=S, Se) NTs were used as counter electrodes (CE) of quantum-dot-sensitized solar cells (QDSSCs) to achieve a conversion efficiency (?) of 5.02 and 6.25?%, respectively, much higher than that of QDSSCs made with Au CE (?=2.94?%). PMID:25400022

Chen, Xin Qi; Li, Zhen; Bai, Yang; Sun, Qiao; Wang, Lian Zhou; Dou, Shi Xue

2015-01-12

241

Facile water-based spray pyrolysis of earth-abundant Cu2FeSnS4 thin films as an efficient counter electrode in dye-sensitized solar cells.  

PubMed

A novel approach to produce earth-abundant Cu2FeSnS4 (CFTS) thin film using spray pyrolysis of nontoxic aqueous precursors followed by sulfurization is reported. The CFTS phase formation was confirmed by both Raman spectroscopy and X-ray diffraction techniques. Hall measurements of these films reveal p-type conductivity with good charge carrier density and mobilities appropriate for solar harvesting devices. To the best of our knowledge, this is the first report on the electrical properties of solution-processed Cu2FeSnS4 thin films estimated using Hall measurements. Dye-sensitized solar cells (DSSC) fabricated with CFTS thin film as a photocathode in iodine/iodide electrolyte exhibit good power conversion efficiency, 8.03%, indicating that CFTS would be a promising cheaper alternative to replace Pt as a counter electrode in DSSCs. PMID:25255739

Prabhakar, Rajiv Ramanujam; Huu Loc, Nguyen; Kumar, Mulmudi Hemant; Boix, Pablo P; Juan, Sun; John, Rohit Abraham; Batabyal, Sudip K; Wong, Lydia Helena

2014-10-22

242

A novel system of electrodes transparent to ultrasound for simultaneous detection of myoelectric activity and B-mode ultrasound images of skeletal muscles  

PubMed Central

Application of two-dimensional surface electrode arrays can provide a means of mapping motor unit action potentials on the skin surface above a muscle. The resulting muscle tissue displacement can be quantified, in a single plane, using ultrasound (US) imaging. Currently, however, it is not possible to simultaneously map spatio-temporal propagation of activation and resulting tissue strain. In this paper, we developed and tested a material that will enable concurrent measurement of two-dimensional surface electromyograms (EMGs) with US images. Specific protocols were designed to test the compatibility of this new electrode material, both with EMG recording and with US analysis. Key results indicate that, for this new electrode material, 1) the electrode-skin impedance is similar to that of arrays of electrodes reported in literature; 2) the reflection of US at the electrode-skin interface is negligible; 3) the likelihood of observing missing contacts, short-circuits, and artifacts in EMGs is not affected by the US probe; 4) movement of tissues sampled by US can be tracked accurately. We, therefore, conclude this approach will facilitate multimodal imaging of muscle to provide new spatio-temporal information regarding electromechanical function of muscle. This is relevant to basic physiology-biomechanics of active and passive force transmission through and between muscles, of motor unit spatio-temporal activity patterns, of their variation with architecture and task-related function, and of their adaptation with aging, training-exercise-disuse, neurological disease, and injury. PMID:23908313

Vieira, T. M. M.; Loram, I. D.; Merletti, R.; Hodson-Tole, E. F.

2013-01-01

243

“Brick-like” N-doped graphene/carbon nanotube structure forming three-dimensional films as high performance metal-free counter electrodes in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

The "brick-like" N-doped graphene-carbon nanotube (NGC) composites are designed by mechanically grinding the filtration films, which are fabricated to form a three-dimensional structure film as a counter electrode (CE). The N-doped graphene/carbon nanotube films with a three-dimensional "brick-like" structure can provide numerous vertical active edge sites. The excellent electrochemical catalytic activities of CE can be obtained by adjusting the different ratio of graphene to CNTs to control the size and N-doping content of breaking particles. NGC17 CE based dye-sensitized solar cells (DSSC) have reached a high efficiency (6.74%) close to platinum-based cells (6.89%). The excellent efficiency may be attributed to the following factors: a) the ?EP of NGC17 (304 mV) is lower than that of the Pt electrode (389 mV); b) the charge transfer resistance (Rct) at the NGC17-CE/electrolyte interface was 1.78 ? cm-2, which is lower than that of a Pt-CE/electrolyte interface (8.97 ? cm-2).

Ma, Jie; Li, Cheng; Yu, Fei; Chen, Junhong

2015-01-01

244

Two wireless imaging proportional counters  

NASA Astrophysics Data System (ADS)

Two wireless position-sensitive X-ray proportional counters that are being developed at the Danish Space Research Institute are described: the microstrip proportional counter (MSPC) and the parallel gas proportional counter (PGPC). The MSPC employs very narrowly spaced conducting strips deposited on an isolating substrate, thus avoiding the use of fragile wires. This detector is built like a normal axial ionization chamber with the electric field parallel to the direction of the incident radiation. The PGPC employs a uniform electric field between two parallel electrodes. The parallel gap is formed between an etched Ni mesh cathode and a segmented anode; the X-ray photon energy is derived from the mesh electrode, while the position information is obtained from the anode. Both detectors display energy signals of a very high rise-time and background rejection based on pulse shape analysis, and are, therefore, very efficient.

Budtz-Jorgensen, C.; Madsen, M. M.; Jonasson, P.; Westergaard, N. J.; Bahnsen, A.

1989-11-01

245

Conductive and transparent multilayer films for low-temperature TiO2/Ag/SiO2 electrodes by E-beam evaporation with IAD  

PubMed Central

Conductive and transparent multilayer thin films consisting of three alternating layers (TiO2/Ag/SiO2, TAS) have been fabricated for applications as transparent conducting oxides. Metal oxide and metal layers were prepared by electron-beam evaporation with ion-assisted deposition, and the optical and electrical properties of the resulting films as well as their energy bounding characteristics and microstructures were carefully investigated. The optical properties of the obtained TAS material were compared with those of well-known transparent metal oxide glasses such as ZnO/Ag/ZnO, TiO2/Ag/TiO2, ZnO/Cu/ZnO, and ZnO/Al/ZnO. The weathering resistance of the TAS film was improved by using a protective SiO2 film as the uppermost layer. The transmittance spectra and sheet resistance of the material were carefully measured and analyzed as a function of the layer thickness. By properly adjusting the thickness of the metal and dielectric films, a low sheet resistance of 6.5 ohm/sq and a high average transmittance of over 89% in the 400 to 700 nm wavelength regions were achieved. We found that the Ag layer played a significant role in determining the optical and electrical properties of this film. PMID:24433437

2014-01-01

246

Direct transparent electrode patterning on layered GaN substrate by screen printing of indium tin oxide nanoparticle ink for Eu-doped GaN red light-emitting diode  

NASA Astrophysics Data System (ADS)

Transparent electrodes were formed on Eu-doped GaN-based red-light-emitting diode (GaN:Eu LED) substrates by the screen printing of indium tin oxide nanoparticle (ITO np) inks as a wet process. The ITO nps with a mean diameter of 25 nm were synthesized by the controlled thermolysis of a mixture of indium complexes and tin complexes. After the direct screen printing of ITO np inks on GaN:Eu LED substrates and sintering at 850 °C for 10 min under atmospheric conditions, the resistivity of the ITO film was 5.2 m? cm. The fabricated LED up to 3 mm square surface emitted red light when the on-voltage was exceeded.

Kashiwagi, Y.; Koizumi, A.; Takemura, Y.; Furuta, S.; Yamamoto, M.; Saitoh, M.; Takahashi, M.; Ohno, T.; Fujiwara, Y.; Murahashi, K.; Ohtsuka, K.; Nakamoto, M.

2014-12-01

247

Vacuum-free, maskless patterning of Ni electrodes by laser reductive sintering of NiO nanoparticle ink and its application to transparent conductors.  

PubMed

We introduce a method for direct patterning of Ni electrodes through selective laser direct writing (LDW) of NiO nanoparticle (NP) ink. High-resolution Ni patterns are generated from NiO NP thin films by a vacuum-free, lithography-free, and solution-processable route. In particular, a continuous wave laser is used for the LDW reductive sintering of the metal oxide under ambient conditions with the aid of reducing agents in the ink solvent. Thin (? 40 nm) Ni electrodes of glossy metallic surfaces with smooth morphology and excellent edge definition can be fabricated. By applying this method, we demonstrate a high transmittance (>87%), electrically conducting panel for a touch screen panel application. The resistivity of the Ni electrode is less than an order of magnitude higher compared to that of the bulk Ni. Mechanical bending test, tape-pull test, and ultrasonic bath test confirm the robust adhesion of the electrodes on glass and polymer substrates. PMID:25130917

Lee, Daeho; Paeng, Dongwoo; Park, Hee K; Grigoropoulos, Costas P

2014-10-28

248

A thin-layer spectroelectrochemical study of 3,3?,5,5?-tetramethylbenzidine at SnO 2 :F film optically transparent electrode  

Microsoft Academic Search

The electrooxidation of 3,3?, 5,5?-tetramethylbenzidine (TMB) is dependent on the pH value of Britton-Robinson (B-R) buffer\\u000a solution. In this work, the electrooxidation behavior of TMB was investigated with a SnO2:F film optically transparent thin-layer\\u000a spectroelectrochemical cell. TMB underwent one two-electron electrooxidation process in the pH range from 2.0 to < 4.0, and\\u000a two successive one-electron electrooxidation processes in the pH

Kui Jiao; Tao Yang; Shuyan Niu

2004-01-01

249

One-step synthesis of carbon nanosheets converted from a polycyclic compound and their direct use as transparent electrodes of ITO-free organic solar cells  

NASA Astrophysics Data System (ADS)

Through a catalyst- and transfer-free process, we fabricated indium tin oxide (ITO)-free organic solar cells (OSCs) using a carbon nanosheet (CNS) with properties similar to graphene. The morphological and electrical properties of the CNS derived from a polymer of intrinsic microporosity-1 (PIM-1), which is mainly composed of several aromatic hydrocarbons and cycloalkanes, can be easily controlled by adjusting the polymer concentration. The CNSs, which are prepared by simple spin-coating and heat-treatment on a quartz substrate, are directly used as the electrodes of ITO-free OSCs, showing a high efficiency of approximately 1.922% under 100 mW cm-2 illumination and air mass 1.5 G conditions. This catalyst- and transfer-free approach is highly desirable for electrodes in organic electronics.Through a catalyst- and transfer-free process, we fabricated indium tin oxide (ITO)-free organic solar cells (OSCs) using a carbon nanosheet (CNS) with properties similar to graphene. The morphological and electrical properties of the CNS derived from a polymer of intrinsic microporosity-1 (PIM-1), which is mainly composed of several aromatic hydrocarbons and cycloalkanes, can be easily controlled by adjusting the polymer concentration. The CNSs, which are prepared by simple spin-coating and heat-treatment on a quartz substrate, are directly used as the electrodes of ITO-free OSCs, showing a high efficiency of approximately 1.922% under 100 mW cm-2 illumination and air mass 1.5 G conditions. This catalyst- and transfer-free approach is highly desirable for electrodes in organic electronics. Electronic supplementary information (ESI) available: Detailed experimental methods; chemical structure and 1H NMR spectra; AFM images; TGA spectra; shunt and series resistances; Raman spectra and optical images; atomic contents of the CNSs. See DOI: 10.1039/c3nr04828d

Son, Su-Young; Noh, Yong-Jin; Bok, Changsuk; Lee, Sungho; Kim, Byoung Gak; Na, Seok-In; Joh, Han-Ik

2013-12-01

250

Counter Square  

NSDL National Science Digital Library

This interactive 100 grid has a variety of open-ended uses. Users can "make" as many counters as they choose from among three different kinds, and then drag them onto the grid, allowing any number to be covered by up to 3 different markers at one time. An Ideas page offers possible tasks and games suited to the applet.

2000-01-01

251

Synthesis and microstructural studies of annealed Cu(2)O/Cu(x)S bilayer as transparent electrode material for photovoltaic and energy storage devices.  

PubMed

Cu2 O thin film and a transparent bilayer have been fabricated by electrodeposition method. The growths were obtained in potentiostatic mode with gradual degradation of anodic current. X-ray diffraction (XRD) study showed that the bilayer is polycrystalline and it possesses mixture of different crystallite phases of copper oxides. Surface morphology of the films was investigated by scanning electron microscopy (SEM). The SEM images revealed that the films were uniformly distributed and the starting material (Cu2 O) had cubical structure. Grains agglomeration and crystallinity were enhanced by annealing. Optical studies indicated that all the samples have direct allowed transition. Energy band gap of the bilayer film was reduced by annealing treatment thus corroborating quantum confinement upshot. PMID:25088932

Taleatu, B A; Arbab, E A A; Omotoso, E; Mola, G T

2014-10-01

252

Electrospun TiC/C nano-felt surface-decorated with Pt nanoparticles as highly efficient and cost-effective counter electrode for dye-sensitized solar cells.  

PubMed

Electrospun nano-felt consisting of overlaid TiC/C composite nanofibers was surface-decorated with Pt nanoparticles (Pt NPs) for use as highly efficient and cost-effective counter electrode (CE) in dye-sensitized solar cells (DSSCs). In the nanofibers, the self-generated TiC crystallites (~70 wt%) with sizes of ~20 nm were randomly embedded in carbon (~30 wt%). Upon surface-decoration, most Pt NPs were distributed on TiC crystallites, leading to substantial enhancement in the electrocatalytic activity/efficiency of Pt due to the strong interaction between Pt and TiC as well as the resulting synergetic effect on electrocatalysis. Electrochemical measurements indicated that the TiC/C-Pt CE exhibited low charge transfer resistance (Rct), large capacitance (C), and fast reaction rate towards the reduction of I3(-) ions, and the prototype DSSC exhibited a performance comparable to that with conventional Pt CE in terms of short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF), and energy conversion efficiency (?). PMID:24121304

Zhao, Yong; Thapa, Amit; Feng, Quan; Xi, Min; Qiao, Qiquan; Fong, Hao

2013-12-01

253

Silver nanowire-based transparent, flexible, and conductive thin film  

Microsoft Academic Search

The fabrication of transparent, conductive, and uniform silver nanowire films using the scalable rod-coating technique is described in this study. Properties of the transparent conductive thin films are investigated, as well as the approaches to improve the performance of transparent silver nanowire electrodes. It is found that silver nanowires are oxidized during the coating process. Incubation in hydrogen chloride (HCl)

Cai-Hong Liu; Xun Yu

2011-01-01

254

General strategy for fabricating transparent TiO2 nanotube arrays for dye-sensitized photoelectrodes: illumination geometry and transport properties.  

PubMed

We report on the preparation of transparent oriented titania nanotube (NT) photoelectrodes and the effect of illumination direction on light harvesting, electron transport, and recombination in dye-sensitized solar cells (DSSCs) incorporating these electrodes. High solar conversion efficiency requires that the incident light enters the cell from the photoelectrode side. However, it has been synthetically challenging to prepare transparent TiO(2) NT electrodes by directly anodizing Ti metal films on transparent conducting oxide (TCO) substrates because of the difficulties of controlling the synthetic conditions. We describe a general synthetic strategy for fabricating transparent TiO(2) NT films on TCO substrates. With the aid of a conducting Nb-doped TiO(2) (NTO) layer between the Ti film and TCO substrate, the Ti film was anodized completely without degrading the TCO. The NTO layer was found to protect the TCO from degradation through a self-terminating mechanism by arresting the electric field-assisted dissolution process at the NT-NTO interface. The illumination direction and wavelength of the light incident on the DSSCs were shown to strongly influence the incident photon-to-current conversion efficiency, light-harvesting, and charge-collection properties, which, in turn, affect the photocurrent density, photovoltage, and solar energy conversion efficiency. Effects of NT film thickness on the properties and performance of DSSCs were also examined. Illuminating the cell from the photoelectrode substantially increased the conversion efficiency compared with illuminating it from the counter-electrode side. PMID:21395234

Kim, Jin Young; Noh, Jun Hong; Zhu, Kai; Halverson, Adam F; Neale, Nathan R; Park, Sangbaek; Hong, Kug Sun; Frank, Arthur J

2011-04-26

255

Semitransparent inverted polymer solar cells employing a sol-gel-derived TiO2 electron-selective layer on FTO and MoO3/Ag/MoO3 transparent electrode  

PubMed Central

We report a new semitransparent inverted polymer solar cell (PSC) with a structure of glass/FTO/nc-TiO2/P3HT:PCBM/MoO3/Ag/MoO3. Because high-temperature annealing which decreased the conductivity of indium tin oxide (ITO) must be handled in the process of preparation of nanocrystalline titanium oxide (nc-TiO2), we replace glass/ITO with a glass/fluorine-doped tin oxide (FTO) substrate to improve the device performance. The experimental results show that the replacing FTO substrate enhances light transmittance between 400 and 600 nm and does not change sheet resistance after annealing treatment. The dependence of device performances on resistivity, light transmittance, and thickness of the MoO3/Ag/MoO3 film was investigated. High power conversion efficiency (PCE) was achieved for FTO substrate inverted PSCs, which showed about 75% increase compared to our previously reported ITO substrate device at different thicknesses of the MoO3/Ag/MoO3 transparent electrode films illuminated from the FTO side (bottom side) and about 150% increase illuminated from the MoO3/Ag/MoO3 side (top side). PMID:25332693

2014-01-01

256

Semitransparent inverted polymer solar cells employing a sol-gel-derived TiO2 electron-selective layer on FTO and MoO3/Ag/MoO3 transparent electrode.  

PubMed

We report a new semitransparent inverted polymer solar cell (PSC) with a structure of glass/FTO/nc-TiO2/P3HT:PCBM/MoO3/Ag/MoO3. Because high-temperature annealing which decreased the conductivity of indium tin oxide (ITO) must be handled in the process of preparation of nanocrystalline titanium oxide (nc-TiO2), we replace glass/ITO with a glass/fluorine-doped tin oxide (FTO) substrate to improve the device performance. The experimental results show that the replacing FTO substrate enhances light transmittance between 400 and 600 nm and does not change sheet resistance after annealing treatment. The dependence of device performances on resistivity, light transmittance, and thickness of the MoO3/Ag/MoO3 film was investigated. High power conversion efficiency (PCE) was achieved for FTO substrate inverted PSCs, which showed about 75% increase compared to our previously reported ITO substrate device at different thicknesses of the MoO3/Ag/MoO3 transparent electrode films illuminated from the FTO side (bottom side) and about 150% increase illuminated from the MoO3/Ag/MoO3 side (top side). PMID:25332693

Li, Fumin; Chen, Chong; Tan, Furui; Li, Chunxi; Yue, Gentian; Shen, Liang; Zhang, Weifeng

2014-01-01

257

Color transparency  

SciTech Connect

The anomously large transmission of nucleons through a nucleus following a hard collision is explored. This effect, known as color transparency, is believed to be a prediction of QCD. The necessary conditions for its occurrence and the effects that must be included a realistic calculation are discussed.

Jennings, B.K. [TRIUMF, Vancouver, BC (Canada); Miller, G.A. [Washington Univ., Seattle, WA (United States). Dept. of Physics

1993-11-01

258

Transparency International  

NSDL National Science Digital Library

Transparency International (TI) is a non-governmental organization concerned with "increasing governmental accountability and curbing both international and national corruption." Best known for its Corruption Perceptions Index (see the February 26, 1998 Scout Report for Business and Economics), Transparency International also offers a host of other corruption-related resources, including the TI Bribers's Pay Survey and TI Bribers's Pay Index, two resources on bribe-paying in international trade; an anti-corruption directory which serves as a reference guide to efforts in central and eastern European countries to support anti-corruption programs; working papers; and other publications. Also worthy of note is TI's ten-point program directed at pressuring the World Bank Organization to help strengthen its anti-corruption programs. The layout of the TI Website is somewhat confusing, but most of the organization's research efforts can be found in the Info Centre.

259

Electrodynamic Arrays Having Nanomaterial Electrodes  

NASA Technical Reports Server (NTRS)

An electrodynamic array of conductive nanomaterial electrodes and a method of making such an electrodynamic array. In one embodiment, a liquid solution containing nanomaterials is deposited as an array of conductive electrodes on a substrate, including rigid or flexible substrates such as fabrics, and opaque or transparent substrates. The nanomaterial electrodes may also be grown in situ. The nanomaterials may include carbon nanomaterials, other organic or inorganic nanomaterials or mixtures.

Trigwell, Steven (Inventor); Biris, Alexandru S. (Inventor); Calle, Carlos I. (Inventor)

2013-01-01

260

Nanoimprint-assisted fabrication of high haze metal mesh electrode for solar cells  

NASA Astrophysics Data System (ADS)

We propose a concept of transparent electrode for solar cells surpassing conventional transparent conductive oxide. Transparent electrode requires low electrical resistivity, high optical transparency, and high optical haze. Although transparent conductive oxide by chemical vapor deposition is widely used as a transparent electrode for solar cells, a breakthrough of the trade-off between electrical and optical properties is required for further improvement of solar cell efficiency. We demonstrate solution-processed electrode fabrication by using nanoimprint technology and metal nanoparticle ink. Silver mesh electrode is self-aligned on nanoimprinted texture with concave pattern as a template for mesh grid. Our electrode concept can realize desired high optical haze by nanoimprinted texture, as well as low electrical resistivity and high optical transparency by metal mesh electrode simultaneously, which boosts solar cell efficiency.

Iwahashi, Takashi; Yang, Rong; Okabe, Noriaki; Sakurai, Junpei; Lin, Jun; Matsunaga, Daisuke

2014-12-01

261

SMART COUNTER The smart counter can  

E-print Network

SMART COUNTER The smart counter can detect countertop cooking actions. We assume that all food how a user mixes food ingredients and the nutrition information of the resulting mixtures. SMART STOVE The smart stove embedded with a load cell and a RFID reader to detect the weight of containers placed over

Ouhyoung, Ming

262

Optically transparent piezoelectric transducer for ultrasonic particle manipulation.  

PubMed

We report an optically transparent ultrasonic device, consisting of indium-tin-oxide-coated lithium niobate (LNO), for use in particle manipulation. This device shows good transparency in the visible and near-infrared wavelengths and, acoustically, compares favorably with conventional prototype devices with silver electrodes. PMID:24569243

Brodie, Graham W J; Qiu, Yongqiang; Cochran, Sandy; Spalding, Gabriel C; MacDonald, Michael P

2014-03-01

263

Particle Countin' Geiger Counter  

NSDL National Science Digital Library

This simulation demonstrates the detection of radioactivity using a Geiger counter. The source of radiation and counter shielding can be selected. The radioactivity measurement is simulated with both a dial reading and audible clicks.

2004-07-12

264

Transparent switchboard  

NASA Technical Reports Server (NTRS)

A tin oxide coating is formed on a plate of glass and the coating is then etched away from the glass in thin lines to form separate electrical conductors which extend to one end of the plate and connect to either a vertical (column) or horizontal (row) position sensing SCR circuit. A thin transparent insulating coating is formed over the oxide layer except at selected touch points which are positioned in a matrix pattern of vertical columns and horizontal rows. Touching one of these points with a finger bridges the thin line between adjacent conductors to activate trigger circuits in the particular row and column sensing circuits associated with the point touched. The row and column sensing circuits are similar and are powered with a low frequency, ac voltage source. The source for the row circuits is 180 out of phase with the source for the column circuits so that one circuit acts as ground for the other during half of the supply voltage cycle. The signals from the sensing circuits are input to a logic circuit which determines the presence of a valid touch, stores a binary matrix number associated with the touched point, signals a computer of the presence of a stored number and prevents storage of a new number before receiving an enable signal from the computer.

Rasmussen, H. P. (inventor)

1973-01-01

265

Electrical and optical properties of Zn–In–Sn–O transparent conducting thin films  

Microsoft Academic Search

Indium tin oxide (ITO) is one of the widely used transparent conductive oxides (TCO) for application as transparent electrode in thin film silicon solar cells or thin film transistors owing to its low resistivity and high transparency. Nevertheless, indium is a scarce and expensive element and ITO films require high deposition temperature to achieve good electrical and optical properties. On

Paz Carreras; Aldrin Antony; Fredy Rojas; Joan Bertomeu

266

Transparent Conducting Metallic Film for Applications in Photovoltaics and Optoelectronic Devices  

Microsoft Academic Search

Oxides such as Indium-Tin Oxide (ITO) known as transparent conducting oxide (TCO) have been used for a long time in most of the thin film solar cell fabrications. It simultaneously works as an electrically conducting and optically transparent electrode. However, the electrical conductivity and optical transparency are not good enough. Here, we discuss our experimental and simulated results on nanostructured

Trilochan Paudel; Piotr Patoka; Wen-Chen Chen; Michael Giersig; Willie Padilla; Zhifeng Ren; Kris Kempa

2011-01-01

267

Transparent, flexible supercapacitors from nano-engineered carbon films  

PubMed Central

Here we construct mechanically flexible and optically transparent thin film solid state supercapacitors by assembling nano-engineered carbon electrodes, prepared in porous templates, with morphology of interconnected arrays of complex shapes and porosity. The highly textured graphitic films act as electrode and current collector and integrated with solid polymer electrolyte, function as thin film supercapacitors. The nanostructured electrode morphology and the conformal electrolyte packaging provide enough energy and power density for the devices in addition to excellent mechanical flexibility and optical transparency, making it a unique design in various power delivery applications. PMID:23105970

Jung, Hyun Young; Karimi, Majid B.; Hahm, Myung Gwan; Ajayan, Pulickel M.; Jung, Yung Joon

2012-01-01

268

Solution-processed poly(3,4-ethylenedioxythiophene) thin films as transparent conductors: effect of p-toluenesulfonic acid in dimethyl sulfoxide.  

PubMed

Conductivity enhancement of thin transparent films based on poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) by a solution-processed route involving mixture of an organic acid and organic solvent is reported. The combined effect of p-toluenesulfonic acid and dimethyl sulfoxide on spin-coated films of PEDOT-PSS on glass substrates, prepared from its commercially available aqueous dispersion, was found to increase the conductivity of the PEDOT-PSS film to ?3500 S·cm(-1) with a high transparency of at least 94%. Apart from conductivity and transparency measurements, the films were characterized by Raman, infrared, and X-ray photoelectron spectroscopy along with atomic force microscopy and secondary ion mass spectrometry. Combined results showed that the conductivity enhancement was due to doping, rearrangement of PEDOT particles owing to phase separation, and removal of PSS matrix throughout the depth of the film. The temperature dependence of the resistance for the treated films was found to be in accordance with one-dimensional variable range hopping, showing that treatment is effective in reducing energy barrier for interchain and interdomain charge hopping. Moreover, the treatment was found to be compatible with flexible poly(ethylene terephthalate) (PET) substrates as well. Apart from being potential candidates to replace inorganic transparent conducting oxide materials, the films exhibited stand-alone catalytic activity toward I(-)/I3(-) redox couple as well and successfully replaced platinum and fluorinated tin oxide as counter electrode in dye-sensitized solar cells. PMID:25230160

Mukherjee, Smita; Singh, Rekha; Gopinathan, Sreelekha; Murugan, Sengottaiyan; Gawali, Suhas; Saha, Biswajit; Biswas, Jayeeta; Lodha, Saurabh; Kumar, Anil

2014-10-22

269

A transparent ?ECoG array for simultaneous recording and optogenetic stimulation  

Microsoft Academic Search

In this paper we report for the first time the design, fabrication and characterization of an optically transparent electrode array for micro-electrocorticography. We present a 49-channel ?ECoG array with an electrode pitch of 800 ?m and a 16-channel linear ?ECoG array with an electrode pitch of 200 ?m. The backing material was Parylene C. Transparent, sputtered indium tin oxide (ITO)

Peter Ledochowitsch; Elisa Olivero; Tim Blanche; Michel M. Maharbiz

2011-01-01

270

An Inexpensive Radiation Counter.  

ERIC Educational Resources Information Center

Describes a radiation counter comparable to commercial units which costs less than $100. It consists of six sections: Geiger-Mueller tube and holder; high voltage supply; low voltage supply; pulse shaping circuit; "start/stop counts" gating circuit; and counter/display. List of materials needed and schematic diagrams are included. (JN)

Holton, Brian; Balla, Zsolt

1985-01-01

271

Condensation Particle Counter  

E-print Network

Model 3007 Condensation Particle Counter Operation and Service Manual 1930035, Revision C August 2002 P a r t i c l e I n s t r u m e n t s #12;#12;Model 3007 Condensation Particle Counter Operation............................................................................V 1. UNPACKING AND PARTS IDENTIFICATION..................................1 Unpacking the Condensation

Weber, Rodney

272

Soils. Transparency Masters.  

ERIC Educational Resources Information Center

This document is a collection of 43 overhead transparency masters to be used as teaching aids in a course of study involving soils such as geology, agronomy, hydrology, earth science, or land use study. Some transparencies are in color. Selected titles of transparencies may give the reader a better understanding of the graphic content. Titles are:…

Clemson Univ., SC. Vocational Education Media Center.

273

The art of transparency.  

PubMed

Artists throughout the ages have discovered a number of techniques to depict transparency. With only a few exceptions, these techniques follow closely the properties of physical transparency. The two best known properties are X-junctions and the luminance relations described by Metelli. X-junctions are seen where the contours of a transparent material cross contours of the surface behind; Metelli's constraints on the luminance relations between the direct and filtered portions of the surface specify a range of luminance values that are consistent with transparency. These principles have been used by artists since the time of ancient Egypt. However, artists also discovered that stimuli can be seen as transparent even when these physical constraints are not met. Ancient Greek artists, for example, were able to depict transparent materials in simple black-and-white line drawings. Artists also learned how to represent transparency in cases where neither X-junctions nor Metelli's constraints could apply: for example, where no portions of the objects behind the transparent material extend beyond it. Many painters convincingly portrayed transparency in these cases by depicting the effects the transparent medium would have on material or object properties. Here, we show how artists employed these and other techniques revealing their anticipation of current formalizations of perceived transparency, and we suggest new, as-yet-untested principles. PMID:23145252

Sayim, Bilge; Cavanagh, Patrick

2011-01-01

274

The art of transparency  

PubMed Central

Artists throughout the ages have discovered a number of techniques to depict transparency. With only a few exceptions, these techniques follow closely the properties of physical transparency. The two best known properties are X-junctions and the luminance relations described by Metelli. X-junctions are seen where the contours of a transparent material cross contours of the surface behind; Metelli's constraints on the luminance relations between the direct and filtered portions of the surface specify a range of luminance values that are consistent with transparency. These principles have been used by artists since the time of ancient Egypt. However, artists also discovered that stimuli can be seen as transparent even when these physical constraints are not met. Ancient Greek artists, for example, were able to depict transparent materials in simple black-and-white line drawings. Artists also learned how to represent transparency in cases where neither X-junctions nor Metelli's constraints could apply: for example, where no portions of the objects behind the transparent material extend beyond it. Many painters convincingly portrayed transparency in these cases by depicting the effects the transparent medium would have on material or object properties. Here, we show how artists employed these and other techniques revealing their anticipation of current formalizations of perceived transparency, and we suggest new, as-yet-untested principles. PMID:23145252

Sayim, Bilge; Cavanagh, Patrick

2011-01-01

275

Samus Counter Lifting Fixture  

SciTech Connect

A lifting fixture has been designed to handle the Samus counters. These counters are being removed from the D-zero area and will be transported off site for further use at another facility. This fixture is designed specifically for this particular application and will be transferred along with the counters. The future use of these counters may entail installation at a facility without access to a crane and therefore a lift fixture suitable for both crane and/or fork lift usage has been created The counters weigh approximately 3000 lbs. and have threaded rods extended through the counter at the top comers for lifting. When these counters were first handled/installed these rods were used in conjunction with appropriate slings and handled by crane. The rods are secured with nuts tightened against the face of the counter. The rod thread is M16 x 2({approx}.625-inch dia.) and extends 2-inch (on average) from the face of the counter. It is this cantilevered rod that the lift fixture engages with 'C' style plates at the four top comers. The strongback portion of the lift fixture is a steel rectangular tube 8-inch (vertical) x 4-inch x .25-inch wall, 130-inch long. 1.5-inch square bars are welded perpendicular to the long axis of the rectangular tube at the appropriate lift points and the 'C' plates are fastened to these bars with 3/4-10 high strength bolts -grade 8. Two short channel sections are positioned-welded-to the bottom of the rectangular tube on 40 feet centers, which are used as locators for fork lift tines. On the top are lifting eyes for sling/crane usage and are rated at 3500 lbs. safe working load each - vertical lift only.

Stredde, H.; /Fermilab

1998-05-27

276

Fully transparent and rollable electronics.  

PubMed

Major obstacles toward the manufacture of transparent and flexible display screens include the difficulty of finding transparent and flexible semiconductors and electrodes, temperature restrictions of flexible plastic substrates, and bulging or warping of the flexible electronics during processing. Here we report the fabrication and performance of fully transparent and rollable thin-film transistor (TFT) circuits for display applications. The TFTs employ an amorphous indium-gallium-zinc oxide semiconductor (with optical band gap of 3.1 eV) and amorphous indium-zinc oxide transparent conductive electrodes, and are built on 15-?m-thick solution-processed colorless polyimide (CPI), resulting in optical transmittance >70% in the visible range. As the CPI supports processing temperatures >300 °C, TFT performance on plastic is similar to that on glass, with typical field-effect mobility, turn-on voltage, and subthreshold voltage swing of 12.7 ± 0.5 cm(2)/V·s, -1.7 ± 0.2 V, and 160 ± 29 mV/dec, respectively. There is no significant degradation after rolling the TFTs 100 times on a cylinder with a radius of 4 mm or when shift registers, each consisting of 40 TFTs, are operated while bent to a radius of 2 mm. For handling purposes, carrier glass is used during fabrication, together with a very thin (?1 nm) solution-processed carbon nanotube (CNT)/graphene oxide (GO) backbone that is first spin-coated on the glass to decrease adhesion of the CPI to the glass; peel strength of the CPI from glass decreases from 0.43 to 0.10 N/cm, which eases the process of detachment performed after device fabrication. Given that the CNT/GO remains embedded under the CPI after detachment, it minimizes wrinkling and decreases the substrate's tensile elongation from 8.0% to 4.6%. Device performance is also stable under electrostatic discharge exposures up to 10 kV, as electrostatic charge can be released via the conducting CNTs. PMID:25526282

Mativenga, Mallory; Geng, Di; Kim, Byungsoon; Jang, Jin

2015-01-28

277

Shower counter resolution scaling  

SciTech Connect

The EM shower counter for the SDC detector has a resolution expression containing two stochastic terms plus a constant term. Recent measurements clarifying the sources of these terms are presented here. 3 refs., 4 figs.

Kirk, T.B.W.

1991-10-14

278

Flexible and optically transparent silver nano-islands film  

NASA Astrophysics Data System (ADS)

We report a cost effective and facile way to synthesize flexible, transparent conductor using oblique angle deposition (OAD). A flexible Ag islands film with transmittance of 28.02 % at 550 nm is obtained with only one step on Polydimethylsiloxane (PDMS) substrate before stretching. The transperacy of the film increased upto 35.29 % at 550 nm under tensile strain of 40 %. As an application, these stretchable, transparent conductive films can be used as electrodes, capacitive pressure sensors for mechanically compliant optoelectronic devices.

Goel, Pratibha; Kumar, Samir; Singh, J. P.

2014-04-01

279

Electrode compositions  

DOEpatents

An electrode composition for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C.sub.8 -C.sub.15 alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5-4.5 volts.

Block, Jacob (Rockville, MD); Fan, Xiyun (Orange, TX)

1998-01-01

280

Two different features of ZnO: Transparent ZnO:Ga electrodes for InGaN-LEDs and homoepitaxial ZnO films for UV-LEDs  

NASA Astrophysics Data System (ADS)

We have used molecular beam epitaxy (MBE) to deposit gallium (Ga) doped ZnO (ZnO:Ga) films. The as-deposited ZnO:Ga films have worked as ohmic contacts for the p-type GaN layers without any kinds of post annealing process. The as-deposited ZnO:Ga films on a-plane sapphire substrates have resistivities of 2-4×10 -4 ?cm, and over 80 % transparency in the near-UV and visible wavelength regions. The brightness of InGaN light-emitting diodes (LEDs) with ZnO:Ga p-contacts has doubled compared to LEDs with conventional Ni/Au semi-transparent p-contacts when measuring the brightness from right above the device surfaces. In addition, using MBE, we have grown homoepitaxial polar ZnO films on (000+1)-plane (+c-plane) ZnO substrates, and also grown non-polar ZnO films on (1-100)-plane (m-plane) and (11-20)-plane (a-plane) ZnO substrates. Growth temperatures have not affected nitrogen-doping levels for +c-axis oriented (Zn-polar) nitrogen doped ZnO (ZnO:N) films. The phenomena were quite different from that for (000-1)-axis (-c-axis) oriented (oxygen-polar) growth, where nitrogen concentrations in ZnO decrease with increasing growth temperatures. We have observed c-axis direction growth for both of m-axis and a-axis oriented films. Oxygen-rich growth conditions flatten surfaces for both m-axis and a-axis oriented films, and the surfaces of m-axis oriented ZnO films flatten with increasing growth temperatures. Nitrogen concentrations in m-axis oriented ZnO:N films have been independent on growth temperatures.

Nakahara, K.; Yuji, H.; Tamura, K.; Akasaka, S.; Tampo, H.; Niki, S.; Tsukazaki, A.; Ohtomo, A.; Kawasaki, M.

2006-02-01

281

Semitransparent Organic Photovoltaic Cells with Laminated Top Electrode  

E-print Network

Semitransparent Organic Photovoltaic Cells with Laminated Top Electrode Jung-Yong Lee, Steve T demonstrate semitransparent small molecular weight organic photovoltaic cells using a laminated silver metal cathode due to differences in optical absorption. KEYWORDS Organic photovoltaics, transparent

Cui, Yi

282

Working Electrodes  

NASA Astrophysics Data System (ADS)

In electrochemistry an electrode is an electronic conductor in contact with an ionic conductor. The electronic conductor can be a metal, or a semiconductor, or a mixed electronic and ionic conductor. The ionic conductor is usually an electrolyte solution; however, solid electrolytes and ionic melts can be used as well. The term "electrode" is also used in a technical sense, meaning the electronic conductor only. If not specified otherwise, this meaning of the term "electrode" is the subject of the present chapter. In the simplest case the electrode is a metallic conductor immersed in an electrolyte solution. At the surface of the electrode, dissolved electroactive ions change their charges by exchanging one or more electrons with the conductor. In this electrochemical reaction both the reduced and oxidized ions remain in solution, while the conductor is chemically inert and serves only as a source and sink of electrons. The technical term "electrode" usually also includes all mechanical parts supporting the conductor (e.g., a rotating disk electrode or a static mercury drop electrode). Furthermore, it includes all chemical and physical modifications of the conductor, or its surface (e.g., a mercury film electrode, an enzyme electrode, and a carbon paste electrode). However, this term does not cover the electrolyte solution and the ionic part of a double layer at the electrode/solution interface. Ion-selective electrodes, which are used in potentiometry, will not be considered in this chapter. Theoretical and practical aspects of electrodes are covered in various books and reviews [1-9].

Komorsky-Lovri?, Šebojka

283

Transparencies and Reflections.  

ERIC Educational Resources Information Center

Discusses the use of perspective, or showing things as the human eye sees them, when creating reflections and transparencies in works of art. Provides examples of artwork using transparency, reflection, and refraction by M. C. Escher, Richard Estes, and Janet Fish to give students an opportunity to learn about these three art techniques. (CMK)

Hubbard, Guy

1999-01-01

284

Magnetron cathodes in plasma electrode Pockels cells  

DOEpatents

Magnetron cathodes, which produce high current discharges, form greatly improved plasma electrodes on each side of an electro-optic crystal. The plasma electrode has a low pressure gas region on both sides of the crystal. When the gas is ionized, e.g., by a glow discharge in the low pressure gas, the plasma formed is a good conductor. The gas electrode acts as a highly uniform conducting electrode. Since the plasma is transparent to a high energy laser beam passing through the crystal, the plasma is transparent. A crystal exposed from two sides to such a plasma can be charged up uniformly to any desired voltage. A typical configuration utilizes helium at 50 millitorr operating pressure and 2 kA discharge current. The magnetron cathode produces a more uniform plasma and allows a reduced operating pressure which leads to lower plasma resistivity and a more uniform charge on the crystal. 5 figs.

Rhodes, M.A.

1995-04-25

285

Liquid electrode  

DOEpatents

A dropping electrolyte electrode for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions.

Ekechukwu, Amy A. (Augusta, GA)

1994-01-01

286

Doped graphene electrodes for organic solar cells  

NASA Astrophysics Data System (ADS)

In this work graphene sheets grown by chemical vapor deposition (CVD) with controlled numbers of layers were used as transparent electrodes in organic photovoltaic (OPV) devices. It was found that for devices with pristine graphene electrodes, the power conversion efficiency (PCE) is comparable to their counterparts with indium tin oxide (ITO) electrodes. Nevertheless, the chances for failure in OPVs with pristine graphene electrodes are higher than for those with ITO electrodes, due to the surface wetting challenge between the hole-transporting layer and the graphene electrodes. Various alternative routes were investigated and it was found that AuCl3 doping on graphene can alter the graphene surface wetting properties such that a uniform coating of the hole-transporting layer can be achieved and device success rate can be increased. Furthermore, the doping both improves the conductivity and shifts the work function of the graphene electrode, resulting in improved overall PCE performance of the OPV devices. This work brings us one step further toward the future use of graphene transparent electrodes as a replacement for ITO.

Park, Hyesung; Rowehl, Jill A.; Kim, Ki Kang; Bulovic, Vladimir; Kong, Jing

2010-12-01

287

A Dictionary for Transparency  

SciTech Connect

There are many terms that are used in association with the U.S. Defense Threat Reduction Agency (DTRA) Transparency Project associated with the Mayak Fissile Materials Storage Facility. This is a collection of proposed definitions of these terms.

Kouzes, Richard T.

2001-11-15

288

COUNTER-CLOSURE Federico Luzzi  

E-print Network

COUNTER-CLOSURE Federico Luzzi The focus of this paper is the prima facie plausible view, expressed by the principle of Counter-Closure, that knowledge-yielding competent deductive inference must issue from known of response that might help retain Counter-Closure. I argue that three are problematic. Of the two remaining

Fitelson, Branden

289

Supersymmetric transparent optical intersections.  

PubMed

Supersymmetric (SUSY) optical structures provide a versatile platform to manipulate the scattering and localization properties of light, with potential applications to mode conversion, spatial multiplexing, and invisible devices. Here we show that SUSY can be exploited to realize broadband transparent intersections between guiding structures in optical networks for both continuous and discretized light. These include transparent crossing of high-contrast-index waveguides and directional couplers, as well as crossing of guiding channels in coupled resonator lattices. PMID:25680125

Longhi, Stefano

2015-02-15

290

What color transparency measures  

NASA Astrophysics Data System (ADS)

Color transparency is commonly accepted to be a prediction of perturbative QCD. However it is more a phenomenon probing the interface between the perturbative and nonperturbative regimes, leading to some intricacy in its theoretical description. In this paper we study the consequences of the impulse approximation to the theory in various quantum mechanical bases. We show that the fully interacting hadronic basis, which consists of eigenstates of the exact Hamiltonian in the presence of the nucleus, provides a natural basis to study color transparency. In this basis we can relate the quark wave function at a small transverse separation distance b2<1/Q2 directly to transparency ratios measured in experiment. With the formalism, experiment can be used to map out the quark wave function in this region. We exhibit several loopholes in existing arguments predicting a rise in transparency ratios with energy, and suggest alternatives. Among the results, we argue that the theoretical prediction of a rising transparency ratio with energy may be on better footing for heavy-quark bound states than for relativistic light-quark systems. We also point out that transparency ratios can be constant with energy and not at variance with perturbative QCD.

Jain, P.; Ralston, John P.

1992-11-01

291

Transparency and International Portfolio Holdings  

Microsoft Academic Search

Does country transparency affect international portfolio investment? We examine this question by constructing new measures of transparency and by making use of a unique microdata set on portfolio holdings of emerging market funds around the world. We distinguish between government and corporate transparency. There is clear evidence that funds systematically invest less in less transparent countries. Moreover, funds have a

R. GASTON GELOS; SHANG-JIN WEI

2005-01-01

292

Countering the New Terrorism  

NSDL National Science Digital Library

_Countering the New Terrorism_, a new 153-page book published by RAND, has recently been made available online. The book contains four chapters that address the changes, trends, and implications of the new terrorism. The introductory chapter, written by Ian O. Lesser, overviews the changes in terrorism in a changing world. The second chapter, "Terrorism Trends and Prospects," by Bruce Hoffman, looks at trends in international terrorism. Chapter three, "Networks, Netwar, and Information-Age Terrorism," by John Arquilla, David Ronfeldt, and Michele Zanini, examines the special problem of terrorism in the information age. The final chapter, "Countering the New Terrorism: Implications for Strategy," also by Lesser, suggests how to meet terrorist challenges to US interests. The book also includes three figures, one table, an index, and a foreword by Brian Michael Jenkins. Each part of the online book is provided as an individual .pdf file.

Arquilla, John.; Hoffman, Bruce, 1954-; Jenkins, Brian M.; Lesser, Ian O., 1957-; Ronfeldt, David F.; Zanini, Michele.

1999-01-01

293

Semi-transparent inverted organic solar cells  

NASA Astrophysics Data System (ADS)

We will present efficient semi-transparent bulk-heterojunction [regioregular of poly(3-hexylthiophene): (6,6)-phenyl C61 butyric acid methyl ester] solar cells with an inverted device architecture. Highly transparent ZnO and TiO2 films prepared by Atomic Layer Deposition are used as cathode interlayers on top of ITO. The topanode consists of a RF-sputtered ITO layer. To avoid damage due to the plasma deposition of this layer, a sputtering buffer layer of MoO3 is used as protection. This concept allows for devices with a transmissivity higher than 60 % for wavelengths 650 nm. The thickness of the MoO3 buffer has been varied in order to study its effect on the electrical properties of the solar cell and its ability to prevent possible damage to the organic active layers upon ITO deposition. Without this buffer or for thin buffers it has been found that device performance is very poor concerning the leakage current, the fill factor, the short circuit current and the power conversion efficiencies. As a reference inverted solar cells with a metal electrode (Al) instead of the ITO-top contact are used. The variation between the PCE of top versus conventional illumination of the semi-transparent cells was also examined and will be interpreted in view of the results of the optical simulation of the dielectric device stack with and without reflection top electrode. Power conversion efficiencies of 2-3 % for the opaque inverted solar cells and 1.5-2.5 % for the semi-transparent devices were obtained under an AM1.5G illumination.

Schmidt, H.; Winkler, T.; Tilgner, M.; Flügge, H.; Schmale, S.; Bülow, T.; Meyer, J.; Johannes, H.-H.; Riedl, T.; Kowalsky, W.

2009-08-01

294

Bean Counter Accounting Tutorial  

NSDL National Science Digital Library

Frustrated with the lack of free accounting information available on the internet, Dave Marshall, small business owner of Bean Counter accounting services, created a tutorial of his own. Designed for the lay person, the tutorial steps the user through the basics of accounting. The tutorial is split into seven lessons, starting with basic definitions and terminology and then introduces the user to topics such as double entry bookkeeping and property rights.

Marshall, Dave

2006-11-29

295

Simple Coulter Counter  

NSDL National Science Digital Library

Students build and use a very basic Coulter electric sensing zone particle counter to count an unknown number of particles in a sample of "paint" to determine if enough particles per ml of "paint" exist to meet a quality standard. In a lab experiment, student teams each build an apparatus and circuit, set up data acquisition equipment, make a salt-soap solution, test liquid flow in the apparatus, take data, and make graphs to count particles.

Nsf Career Award And Ret Program

296

Development of a Transparent Self Cleaning Dust Shield for Solar Panels  

Microsoft Academic Search

Development of a transparent electrodynamic shield to protect panels from dust deposition is described. The shield contains a clear panel with embed- ded parallel electrodes connected to a single-phase AC supply for producing an electromagnetic wave. The electromagnetic field produced by the electrodes on the surface of the panel repels dust particles that have already deposited on the panel surface,

R. A. Sims; A. S. Biris; J. D. Wilson; C. U. Yurteri; M. K. Mazumder; C. I. Calle; C. R. Buhler

297

Silver Nanowires (AgNWs) Embedded Electrodes for Gel Actuator  

NASA Astrophysics Data System (ADS)

In the field of electronic devices, the demand of polymer electrodes, which have high conductivity, high flexibility and transparence, is increasing. The polyelectrolyte of high-strength gels was made to improve the mechanical properties in our previous study [1]. In this study, we attempt to make a transparent polymer electrode by laminating polymer thin film and silver nanowires (AgNWs). High transparence poly(methyl methacrylate) (PMMA) film, which is produced by using solvent cast method. AgNWs are prepared by reacting Silver chloride (AgCl) with Silver nitrate (AgNO3) based on previous study[2]. The AgNWs taking on different shapes are obtained. Particle and fibrous AgNWs are formed by using low and high molecular weight polyvinylpyrrolidone (PVP), respectively (Fig. 1). The possibility of developing the polymer electrode with high conductivity, high flexibility and transparence is shown from these results.

Abe, Yuta; Gong, Jin; Hasnat Kabir, M.; Makino, Masato; Furukawa, Hidemitsu

298

Liquid electrode  

DOEpatents

A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.

Ekechukwu, A.A.

1994-07-05

299

Flexible electrochromic films based on CVD-graphene electrodes  

NASA Astrophysics Data System (ADS)

Graphene synthesized via chemical vapor deposition is a notable candidate for flexible large-area transparent electrodes due to its great physical properties and its 2D activated surface area. Electrochromic devices in optical displays, smart windows, etc are suitable applications for graphene when used as a transparent conductive electrode. In this study, various-layer graphene was synthesized via chemical vapor deposition, and inorganic WOx was deposited on the layers, which have advantageous columnar structures and W6+ and W4+ oxidation states. The characteristics of graphene and WOx were verified using optical transmittance, Raman spectroscopy, x-ray photoelectron spectroscopy and scanning electron microscopy. The optimum transparent conductive electrode condition for controlling graphene layers was investigated based on the optical density and cyclic voltammetry. Electrochromic devices were fabricated using a three-layer graphene electrode, which had the best optical density. The graphene in the flexible electrochromic device demonstrated a potential for replacing ITO in flexible electronics.

Choi, Dong Soo; Han, Seung Ho; Kim, Hyeongkeun; Kang, So Hee; Kim, Yena; Yang, Cheol-Min; Kim, Tae Young; Yoon, Dae Ho; Yang, Woo Seok

2014-09-01

300

Subdural Electrodes  

PubMed Central

Subdural electrodes are frequently used to aid in the neurophysiological assessment of patients with intractable seizures. We review the indications for these, their uses for localizing epileptogenic regions and for localizing cortical regions supporting movement, sensation, and language. PMID:20573543

Lesser, Ronald P.; Crone, Nathan E.; Webber, W.R.S.

2010-01-01

301

Working Electrodes  

Microsoft Academic Search

\\u000a In electrochemistry an electrode is an electronic conductor in contact with an ionic conductor. The electronic conductor can\\u000a be a metal, or a semiconductor, or a mixed electronic and ionic conductor. The ionic conductor is usually an electrolyte solution;\\u000a however, solid electrolytes and ionic melts can be used as well. The term “electrode” is also used in a technical sense,

Šebojka Komorsky-Lovri?

302

Low latency counter event indication  

DOEpatents

A hybrid counter array device for counting events with interrupt indication includes a first counter portion comprising N counter devices, each for counting signals representing event occurrences and providing a first count value representing lower order bits. An overflow bit device associated with each respective counter device is additionally set in response to an overflow condition. The hybrid counter array includes a second counter portion comprising a memory array device having N addressable memory locations in correspondence with the N counter devices, each addressable memory location for storing a second count value representing higher order bits. An operatively coupled control device monitors each associated overflow bit device and initiates incrementing a second count value stored at a corresponding memory location in response to a respective overflow bit being set. The incremented second count value is compared to an interrupt threshold value stored in a threshold register, and, when the second counter value is equal to the interrupt threshold value, a corresponding "interrupt arm" bit is set to enable a fast interrupt indication. On a subsequent roll-over of the lower bits of that counter, the interrupt will be fired.

Gara, Alan G. (Mount Kisco, NY); Salapura, Valentina (Chappaqua, NY)

2010-08-24

303

Low latency counter event indication  

DOEpatents

A hybrid counter array device for counting events with interrupt indication includes a first counter portion comprising N counter devices, each for counting signals representing event occurrences and providing a first count value representing lower order bits. An overflow bit device associated with each respective counter device is additionally set in response to an overflow condition. The hybrid counter array includes a second counter portion comprising a memory array device having N addressable memory locations in correspondence with the N counter devices, each addressable memory location for storing a second count value representing higher order bits. An operatively coupled control device monitors each associated overflow bit device and initiates incrementing a second count value stored at a corresponding memory location in response to a respective overflow bit being set. The incremented second count value is compared to an interrupt threshold value stored in a threshold register, and, when the second counter value is equal to the interrupt threshold value, a corresponding "interrupt arm" bit is set to enable a fast interrupt indication. On a subsequent roll-over of the lower bits of that counter, the interrupt will be fired.

Gara, Alan G. (Mount Kisco, NY); Salapura, Valentina (Chappaqua, NY)

2008-09-16

304

Subsidiarity and Transparency  

Microsoft Academic Search

Subsidiarity and transparency are entirely different concepts. … However different, both concepts are twins in the continuing quest of the Framers of European integration to increase the legitimacy of Community decision-making vis-à-vis the citizens. Indeed, there always has been, and there still is a very serious problem of lack of legitimacy. … Increasing the powers of the European Parliament is

Christian Timmermans

1998-01-01

305

The most transparent research  

Microsoft Academic Search

Biomedicine would be a breeze if organisms were transparent. With the ability to see through tissues, scientists could spot the development of tumors more easily in study animals. And biologists could study exactly how an animal's organs develop by observing them as they grow. In effect, the secrets of the body would be out there for everyone to see.The thought

Melinda Wenner

2009-01-01

306

Remote Monitoring Transparency Program  

SciTech Connect

The objective of the Remote Monitoring Transparency Program is to evaluate and demonstrate the use of remote monitoring technologies to advance nonproliferation and transparency efforts that are currently being developed by Russia and the United States without compromising the national security to the participating parties. Under a lab-to-lab transparency contract between Sandia National Laboratories (SNL) and the Kurchatov Institute (KI RRC), the Kurchatov Institute will analyze technical and procedural aspects of the application of remote monitoring as a transparency measure to monitor inventories of direct- use HEU and plutonium (e.g., material recovered from dismantled nuclear weapons). A goal of this program is to assist a broad range of political and technical experts in learning more about remote monitoring technologies that could be used to implement nonproliferation, arms control, and other security and confidence building measures. Specifically, this program will: (1) begin integrating Russian technologies into remote monitoring systems; (2) develop remote monitoring procedures that will assist in the application of remote monitoring techniques to monitor inventories of HEU and Pu from dismantled nuclear weapons; and (3) conduct a workshop to review remote monitoring fundamentals, demonstrate an integrated US/Russian remote monitoring system, and discuss the impacts that remote monitoring will have on the national security of participating countries.

Sukhoruchkin, V.K.; Shmelev, V.M.; Roumiantsev, A.N. [Gosudarstvennyj Komitet po Ispol`zovaniyu Atomnoj Ehnergii SSSR, Moscow (Russian Federation). Inst. Atomnoj Ehnergii

1996-08-01

307

Highly stretchable, conductive, and transparent nanotube thin films  

NASA Astrophysics Data System (ADS)

We have studied the electrical and optical properties of transparent and conductive nanotube thin films subjected to extremely large strains, both isotropic and anisotropic. The films maintain electrical conductivity for strains up to 700% and the eventual loss of conductivity is due primarily to the buildup of cracks in the nanotube films. We also measured the change in optical transmittance and explain the observed haziness of the films by considering the micrometer sized cluster. This study of transparent nanotube films as stretchable electrodes is crucial for many applications, in particular, for medical implantation of electronic devices.

Hu, Liangbing; Yuan, Wei; Brochu, Paul; Gruner, George; Pei, Qibing

2009-04-01

308

Cermet electrode  

DOEpatents

Disclosed is a cermet electrode consisting of metal particles of nickel, cobalt, iron, or alloys or mixtures thereof immobilized by zirconia stabilized in cubic form which contains discrete deposits of about 0.1 to about 5% by weight of praseodymium, dysprosium, terbium, or a mixture thereof. The solid oxide electrode can be made by covering a substrate with particles of nickel, cobalt, iron, or mixtures thereof, growing a stabilized zirconia solid oxide skeleton around the particles thereby immobilizing them, contacting the skeleton with a compound of praseodymium, dysprosium, terbium, or a mixture thereof, and heating the skeleton to a temperature of at least 500.degree. C. The electrode can also be made by preparing a slurry of nickel, cobalt, iron, or mixture and a compound of praseodymium, dysprosium, terbium, or a mixture thereof, depositing the slurry on a substrate, heating the slurry to dryness, and growing a stabilized zirconia skeleton around the metal particles.

Maskalick, Nicholas J. (Pittsburgh, PA)

1988-08-30

309

Multi-layer electrode for high contrast electrochromic devices  

DOEpatents

An electrochromic device includes a first substrate spaced from a second substrate. A first transparent conductive electrode is formed over at least a portion of the first substrate. A polymeric anode is formed over at least a portion of the first conductive electrode. A second transparent conductive electrode is formed over at least a portion of the second substrate. In one aspect of the invention, a multi-layer polymeric cathode is formed over at least a portion of the second conductive electrode. In one non-limiting embodiment, the multi-layer cathode includes a first cathodically coloring polymer formed over at least a portion of the second conductive electrode and a second cathodically coloring polymer formed over at least a portion of the first cathodically coloring polymer. An ionic liquid is positioned between the anode and the cathode.

Schwendeman, Irina G. (Wexford, PA); Finley, James J. (Pittsburgh, PA); Polcyn, Adam D. (Pittsburgh, PA); Boykin, Cheri M. (Wexford, PA)

2011-11-01

310

Photoelectrochemical electrodes  

NASA Technical Reports Server (NTRS)

The surface of a moderate band gap semiconductor such as p-type molybdenum sulfide is modified to contain an adherent film of charge mediating ionene polymer containing an electroactive unit such as bipyridimium. Electron transport between the electrode and the mediator film is favorable and photocorrosion and recombination processes are suppressed. Incorporation of particles of catalyst such as platinum within the film provides a reduction in overvoltage. The polymer film is readily deposited on the electrode surface and can be rendered stable by ionic or addition crosslinking. Catalyst can be predispersed in the polymer film or a salt can be impregnated into the film and reduced therein.

Williams, R. M.; Rembaum, A. (inventors)

1983-01-01

311

Space and power efficient hybrid counters array  

DOEpatents

A hybrid counter array device for counting events. The hybrid counter array includes a first counter portion comprising N counter devices, each counter device for receiving signals representing occurrences of events from an event source and providing a first count value corresponding to a lower order bits of the hybrid counter array. The hybrid counter array includes a second counter portion comprising a memory array device having N addressable memory locations in correspondence with the N counter devices, each addressable memory location for storing a second count value representing higher order bits of the hybrid counter array. A control device monitors each of the N counter devices of the first counter portion and initiates updating a value of a corresponding second count value stored at the corresponding addressable memory location in the second counter portion. Thus, a combination of the first and second count values provide an instantaneous measure of number of events received.

Gara, Alan G. (Mount Kisco, NY); Salapura, Valentina (Chappaqua, NY)

2010-03-30

312

Working Electrodes  

Microsoft Academic Search

In electrochemistry an electrode is an electronic conductor in contact with an ionic conductor. The electronic conductor can be a metal, or a semiconductor, or a mixed electronic and ionic conductor. The ionic conductor is usually an electrolyte solution; however, solid electrolytes and ionic melts can be used as well. The term \\

Sebojka Komorsky-Lovric

2010-01-01

313

Permanently calibrated interpolating time counter  

NASA Astrophysics Data System (ADS)

We propose a new architecture of an integrated time interval counter that provides its permanent calibration in the background. Time interval measurement and the calibration procedure are based on the use of a two-stage interpolation method and parallel processing of measurement and calibration data. The parallel processing is achieved by a doubling of two-stage interpolators in measurement channels of the counter, and by an appropriate extension of control logic. Such modification allows the updating of transfer characteristics of interpolators without the need to break a theoretically infinite measurement session. We describe the principle of permanent calibration, its implementation and influence on the quality of the counter. The precision of the presented counter is kept at a constant level (below 20?ps) despite significant changes in the ambient temperature (from ?10 to 60?°C), which can cause a sevenfold decrease in the precision of the counter with a traditional calibration procedure.

Jachna, Z.; Szplet, R.; Kwiatkowski, P.; Ró?yc, K.

2015-01-01

314

Highly efficient fully transparent inverted OLEDs  

NASA Astrophysics Data System (ADS)

One of the unique selling propositions of OLEDs is their potential to realize highly transparent devices over the visible spectrum. This is because organic semiconductors provide a large Stokes-Shift and low intrinsic absorption losses. Hence, new areas of applications for displays and ambient lighting become accessible, for instance, the integration of OLEDs into the windshield or the ceiling of automobiles. The main challenge in the realization of fully transparent devices is the deposition of the top electrode. ITO is commonly used as transparent bottom anode in a conventional OLED. To obtain uniform light emission over the entire viewing angle and a low series resistance, a TCO such as ITO is desirable as top contact as well. However, sputter deposition of ITO on top of organic layers causes damage induced by high energetic particles and UV radiation. We have found an efficient process to protect the organic layers against the ITO rf magnetron deposition process of ITO for an inverted OLED (IOLED). The inverted structure allows the integration of OLEDs in more powerful n-channel transistors used in active matrix backplanes. Employing the green electrophosphorescent material Ir(ppy) 3 lead to IOLED with a current efficiency of 50 cd/A and power efficiency of 24 lm/W at 100 cd/m2. The average transmittance exceeds 80 % in the visible region. The on-set voltage for light emission is lower than 3 V. In addition, by vertical stacking we achieved a very high current efficiency of more than 70 cd/A for transparent IOLED.

Meyer, J.; Winkler, T.; Hamwi, S.; Schmale, S.; Kröger, M.; Görrn, P.; Johannes, H.-H.; Riedl, T.; Lang, E.; Becker, D.; Dobbertin, T.; Kowalsky, W.

2007-09-01

315

Transparency microplates under impact.  

PubMed

Transparency microplates enable biochemical analysis in resource-limited laboratories. During the process of transfer, the analytes tittered into the wells may undergo spillage from one well to another due to lateral impact. Sidelong impact tests conducted found the absence of non-linear effects (e.g., viscoelastic behavior) but high energy loss. Finite element simulations conducted showed that the rectangular plate holding the transparencies could undergo z-axis deflections when a normal component of the force was present despite constraints being used. High speed camera sequences confirmed this and also showed the asymmetrical z-axis deflection to cause the contact line closer to impact to displace first when the advancing condition was exceeded. Capillary waves were found to travel toward the contact line at the opposite end, where if the advancing contact angle condition was exceeded, also resulted in spreading. The presence of surface scribing was found to limit contact line movement better. With water drops dispensed on scribed transparencies, immunity from momentum change of up to 9.07 kgm/s on impact was possible for volumes of 40 ?L. In the case of glycerol drops immunity from momentum change of up to 9.07 kgm/s on impact extended to volumes of 90 ?L. The improved immunity of glycerol was attributed to its heightened dampening characteristics and its higher attenuation of capillary waves. Overall, scribed transparency microplates were able to better withstand spillage from accidental impact. Accidental impact was also found not to cause any detrimental effects on the fluorescence properties of enhanced green fluorescent protein samples tested. PMID:24863765

Lau, Chun Yat; Roslan, Zulhanif; Cheong, Brandon Huey-Ping; Chua, Wei Seong; Liew, Oi Wah; Ng, Tuck Wah

2014-07-15

316

Transparent conducting oxide nanotubes.  

PubMed

Thin film or porous membranes made of hollow, transparent, conducting oxide (TCO) nanotubes, with high chemical stability, functionalized surfaces and large surface areas, can provide an excellent platform for a wide variety of nanostructured photovoltaic, photodetector, photoelectrochemical and photocatalytic devices. While large-bandgap oxide semiconductors offer transparency for incident light (below their nominal bandgap), their low carrier concentration and poor conductivity makes them unsuitable for charge conduction. Moreover, materials with high conductivity have nominally low bandgaps and hence poor light transmittance. Here, we demonstrate thin films and membranes made from TiO2 nanotubes heavily-doped with shallow Niobium (Nb) donors (up to 10%, without phase segregation), using a modified electrochemical anodization process, to fabricate transparent conducting hollow nanotubes. Temperature dependent current-voltage characteristics revealed that TiO2 TCO nanotubes, doped with 10% Nb, show metal-like behavior with resistivity decreasing from 6.5 × 10(-4) ?cm at T = 300 K (compared to 6.5 × 10(-1) ?cm for nominally undoped nanotubes) to 2.2 × 10(-4) ?cm at T = 20 K. Optical properties, studied by reflectance measurements, showed light transmittance up to 90%, within wavelength range 400 nm-1000 nm. Nb doping also improves the field emission properties of TCO nanotubes demonstrating an order of magnitude increase in field-emitter current, compared to undoped samples. PMID:25180635

Alivov, Yahya; Singh, Vivek; Ding, Yuchen; Nagpal, Prashant

2014-09-26

317

Transparent conducting oxide nanotubes  

NASA Astrophysics Data System (ADS)

Thin film or porous membranes made of hollow, transparent, conducting oxide (TCO) nanotubes, with high chemical stability, functionalized surfaces and large surface areas, can provide an excellent platform for a wide variety of nanostructured photovoltaic, photodetector, photoelectrochemical and photocatalytic devices. While large-bandgap oxide semiconductors offer transparency for incident light (below their nominal bandgap), their low carrier concentration and poor conductivity makes them unsuitable for charge conduction. Moreover, materials with high conductivity have nominally low bandgaps and hence poor light transmittance. Here, we demonstrate thin films and membranes made from TiO2 nanotubes heavily-doped with shallow Niobium (Nb) donors (up to 10%, without phase segregation), using a modified electrochemical anodization process, to fabricate transparent conducting hollow nanotubes. Temperature dependent current-voltage characteristics revealed that TiO2 TCO nanotubes, doped with 10% Nb, show metal-like behavior with resistivity decreasing from 6.5 × 10-4 ?cm at T = 300 K (compared to 6.5 × 10-1 ?cm for nominally undoped nanotubes) to 2.2 × 10-4 ?cm at T = 20 K. Optical properties, studied by reflectance measurements, showed light transmittance up to 90%, within wavelength range 400 nm-1000 nm. Nb doping also improves the field emission properties of TCO nanotubes demonstrating an order of magnitude increase in field-emitter current, compared to undoped samples.

Alivov, Yahya; Singh, Vivek; Ding, Yuchen; Nagpal, Prashant

2014-09-01

318

Wearable solar cells by stacking textile electrodes.  

PubMed

A new and general method to produce flexible, wearable dye-sensitized solar cell (DSC) textiles by the stacking of two textile electrodes has been developed. A metal-textile electrode that was made from micrometer-sized metal wires was used as a working electrode, while the textile counter electrode was woven from highly aligned carbon nanotube fibers with high mechanical strengths and electrical conductivities. The resulting DSC textile exhibited a high energy conversion efficiency that was well maintained under bending. Compared with the woven DSC textiles that are based on wire-shaped devices, this stacked DSC textile unexpectedly exhibited a unique deformation from a rectangle to a parallelogram, which is highly desired in portable electronics. This lightweight and wearable stacked DSC textile is superior to conventional planar DSCs because the energy conversion efficiency of the stacked DSC textile was independent of the angle of incident light. PMID:24789065

Pan, Shaowu; Yang, Zhibin; Chen, Peining; Deng, Jue; Li, Houpu; Peng, Huisheng

2014-06-10

319

The most transparent research.  

PubMed

Biomedicine would be a breeze if organisms were transparent. With the ability to see through tissues, scientists could spot the development of tumors more easily in study animals. And biologists could study exactly how an animal's organs develop by observing them as they grow. In effect, the secrets of the body would be out there for everyone to see.The thought of peering into our tissues may sound like science fiction, but one day it could be science. Using ideas from genetics, electrical engineering, chemistry and solid-state physics, a handful of researchers are working on ways to render biological tissues transparent.Some have already succeeded: in 2007, Richard White, a biologist at the Dana Farber Cancer Institute in Boston, used careful breeding techniques to create a transparent adult zebrafish named casper, evoking a reference to the famous cartoon ghost by the same name. Now, more than 100 labs around the world are using these transparent fish to study cancer pathology and development in real time. "The field of in vivo imaging-looking at things that are happening inside an actual organism-is growing rapidly," White says.Researchers are even making strides toward turning human tissue transparent. The primary reason we can't see what's inside of us is that light scatters when it passes through tissue. The body is densely packed with many types of substances, such as bone and fat, and light travels through them at different speeds because they have what physicists refer to as different refractive indices. The result is that light can't pass through biological tissues in a straight line, much as car headlights don't pass through dense fog. To fix this problem, scientists are working on developing ways to stop tissues from scattering light. Indeed, "if you take away the scattering properties of human tissues, we would look more or less like jellyfish," explains Changhuei Yang, an electrical engineer and bioengineer at the California Institute of Technology.Though their approaches (described in the following pages) are diverse, these researchers share the common goal of making it one day possible to see what's going on deep inside of the body-a feat that would provide new insights into our biology and help doctors diagnose and treat disease much more easily. "We're trying to push the limits in terms of what can we uncover," says Bernard Choi, a bioengineer at the University of California-Irvine. PMID:19812559

Wenner, Melinda

2009-10-01

320

High resolution time interval counter  

NASA Technical Reports Server (NTRS)

In recent years, we have developed two types of high resolution, multi-channel time interval counters. In the NIST two-way time transfer MODEM application, the counter is designed for operating primarily in the interrupt-driven mode, with 3 start channels and 3 stop channels. The intended start and stop signals are 1 PPS, although other frequencies can also be applied to start and stop the count. The time interval counters used in the NIST Frequency Measurement and Analysis System are implemented with 7 start channels and 7 stop channels. Four of the 7 start channels are devoted to the frequencies of 1 MHz, 5 MHz or 10 MHz, while triggering signals to all other start and stop channels can range from 1 PPS to 100 kHz. Time interval interpolation plays a key role in achieving the high resolution time interval measurements for both counters. With a 10 MHz time base, both counters demonstrate a single-shot resolution of better than 40 ps, and a stability of better than 5 x 10(exp -12) (sigma(sub chi)(tau)) after self test of 1000 seconds). The maximum rate of time interval measurements (with no dead time) is 1.0 kHz for the counter used in the MODEM application and is 2.0 kHz for the counter used in the Frequency Measurement and Analysis System. The counters are implemented as plug-in units for an AT-compatible personal computer. This configuration provides an efficient way of using a computer not only to control and operate the counters, but also to store and process measured data.

Zhang, Victor S.; Davis, Dick D.; Lombardi, Michael A.

1995-01-01

321

Electrode structures  

SciTech Connect

In a sodium sulphur cell, a cathode electrode of annular form comprising a plurality of segments, each of trapezoidal form in cross-section and joined by webs along a longer edge of each segment so that the assembly is foldable to form a substantially annular structure. This electrode may be made by compressing a blanket or sheet of carbon or graphite felt or fibres in a heated mould, which is shaped to produce the segments joined by thin webs, the material being impregnated with sulphur or sodium polysulphide before or after insertion in the mould, and the material being cooled before removal from the mould. Alternatively, the segments may be formed from the blanket or sheet by using shaped rolls, the material being cooled, E.G. By water or air, as it leaves the rolls.

Brennan, M.P.

1981-01-06

322

Single-walled carbon nanotube transparent conductive films fabricated by reductive dissolution and spray coating for organic photovoltaics  

NASA Astrophysics Data System (ADS)

Solutions of unbundled and unbroken single-walled carbon nanotubes have been prepared using a reductive dissolution process. Transparent conductive films spray-coated from these solutions show a nearly twofold improvement in the ratio of electrical conductivity to optical absorptivity versus those deposited from conventional aqueous dispersions, due to substantial de-aggregation and sizable nanotube lengths. These transparent electrodes have been utilized to fabricate P3HT-PCBM organic solar cells achieving power conversion efficiencies up to 2.3%, comparable to those of solar cells using indium tin oxide transparent electrodes.

Ostfeld, Aminy E.; Catheline, Amélie; Ligsay, Kathleen; Kim, Kee-Chan; Chen, Zhihua; Facchetti, Antonio; Fogden, Siân; Arias, Ana Claudia

2014-12-01

323

Multiple channel programmable coincidence counter  

DOEpatents

A programmable digital coincidence counter having multiple channels and featuring minimal dead time. Neutron detectors supply electrical pulses to a synchronizing circuit which in turn inputs derandomized pulses to an adding circuit. A random access memory circuit connected as a programmable length shift register receives and shifts the sum of the pulses, and outputs to a serializer. A counter is input by the adding circuit and downcounted by the seralizer, one pulse at a time. The decoded contents of the counter after each decrement is output to scalers.

Arnone, Gaetano J. (Los Alamos, NM)

1990-01-01

324

Evaluation of Solution-Processed Reduced Graphene Oxide Films as Transparent Conductors  

Microsoft Academic Search

Processable, single-layered graphene oxide (GO) is an intriguing nanomaterial with tremendous potential for electronic applications. We spin-coated GO thin-films on quartz and characterized their sheet resistance and optical transparency using different reduction treatments. A thermal graphitization procedure wasmosteffective,producingfilmswithsheetresistancesaslowas102103\\/squarewith80%transmittance for 550 nm light. Our experiments demonstrate solution-processed GOfilms have potential as transparent electrodes.

Héctor A. Becerril; Jie Mao; Zunfeng Liu; Randall M. Stoltenberg; Zhenan Bao; Yongsheng Chen

2008-01-01

325

Flexible and Transparent Field Emission Devices based on Graphene-Nanowire Hybrid Structures  

Microsoft Academic Search

Recent developments in wafer scale synthesis and transfer of graphene have made it possible to fabricate electrodes for versatile flexible devices. However, a flexible and transparent graphene-based field emission device has not been explored yet. Herein, we report the fabrication of flexible and transparent field emission devices based on graphene-nanowire hybrid structures. In this work, we successfully grew vertically-aligned Au

Muhammad Arif; Kwang Heo; Byung Yang Lee; David H. Seo; Sunae Seo; Jikang Jian; Seunghun Hong

2011-01-01

326

Transparent, Translucent and Opaque  

NSDL National Science Digital Library

In this activity, students examine everyday objects with a flashlight and determine if they are transparent, translucent, or opaque. Common household materials such as wax paper, plastic wrap, aluminum foil, tissue, and food coloring are required. This activity can be used with pre-readers. The resource is part of the teacher's guide accompanying the video, NASA Why Files: The Case of the Mysterious Red Light. Lesson objectives supported by the video, additional resources, teaching tips and an answer sheet are included in the teacher's guide.

2012-08-03

327

Over-the-Counter Medicines  

MedlinePLUS

Over-the-counter (OTC) medicines are drugs you can buy without a prescription. Some OTC medicines relieve aches, pains ... Others help manage recurring problems, like migraines. In the United States, the Food and Drug Administration decides ...

328

One-way transparent sheets  

E-print Network

In this paper we introduce the concept of metasurfaces which are fully transparent when looking from one of the two sides of the sheet and have controllable functionalities for waves hitting the opposite side (one-way transparent sheets). We address the question on what functionalities are allowed, considering limitations due to reciprocity and passivity. In particular, we have found that it is possible to realize one-way transparent sheets which have the properties of a twist-polarizer in reflection or transmission when illuminated from the other side. Also one-way transparent sheets with controllable co-polarized reflection and transmission from the opposite side are feasible. We show that particular non-reciprocal magneto-electric coupling inside the sheet is necessary to realize lossless non-active transparent sheets. Furthermore, we derive the required polarizabilities of constituent dipole particles such that the layers composed of them form one-way transparent sheets. We conclude with design and simula...

Ra'di, Younes; Tretyakov, Sergei

2013-01-01

329

Maximal light-energy transfer through a dielectric/metal-layered electrode on a photoactive device.  

PubMed

We report the fabrication of an optimized low reflective dielectric/metal-layered electrode that provides significant electrical conductivity and light transparency in the near-infrared wavelength regime. By making the metal film thickness thick enough and choosing a proper dielectric layer with a certain thickness, we show that our suggested electrode significantly reduces the light reflection while preserving high electrical conductivity. We demonstrate our optimized electrodes present a highly conductive surface with a sheet resistance of 5.2 ?/sq and a high light transmittance of near 85% in the near-infrared regime. We also apply our optimized electrode to thin-film organic photovoltaic devices and show the electrode helps in absorbing light energy inside an active layer. We believe that this simple but powerful layered electrode will pave the way for designing transparent electrodes on photoactive devices. PMID:24515205

Kim, Kyoung-Ho; Park, Q-Han

2014-01-27

330

Nanostructured Solid Oxide Fuel Cell Electrodes  

SciTech Connect

The ability of Solid Oxide Fuel Cells (SOFC) to directly and efficiently convert the chemical energy in hydrocarbon fuels to electricity places the technology in a unique and exciting position to play a significant role in the clean energy revolution. In order to make SOFC technology cost competitive with existing technologies, the operating temperatures have been decreased to the range where costly ceramic components may be substituted with inexpensive metal components within the cell and stack design. However, a number of issues have arisen due to this decrease in temperature: decreased electrolyte ionic conductivity, cathode reaction rate limitations, and a decrease in anode contaminant tolerance. While the decrease in electrolyte ionic conductivities has been countered by decreasing the electrolyte thickness, the electrode limitations have remained a more difficult problem. Nanostructuring SOFC electrodes addresses the major electrode issues. The infiltration method used in this dissertation to produce nanostructure SOFC electrodes creates a connected network of nanoparticles; since the method allows for the incorporation of the nanoparticles after electrode backbone formation, previously incompatible advanced electrocatalysts can be infiltrated providing electronic conductivity and electrocatalysis within well-formed electrolyte backbones. Furthermore, the method is used to significantly enhance the conventional electrode design by adding secondary electrocatalysts. Performance enhancement and improved anode contamination tolerance are demonstrated in each of the electrodes. Additionally, cell processing and the infiltration method developed in conjunction with this dissertation are reviewed.

Sholklapper, Tal Zvi

2007-12-15

331

High Temperature Transparent Furnace Development  

NASA Technical Reports Server (NTRS)

This report describes the use of novel techniques for heat containment that could be used to build a high temperature transparent furnace. The primary objective of the work was to experimentally demonstrate transparent furnace operation at 1200 C. Secondary objectives were to understand furnace operation and furnace component specification to enable the design and construction of a low power prototype furnace for delivery to NASA in a follow-up project. The basic approach of the research was to couple high temperature component design with simple concept demonstration experiments that modify a commercially available transparent furnace rated at lower temperature. A detailed energy balance of the operating transparent furnace was performed, calculating heat losses through the furnace components as a result of conduction, radiation, and convection. The transparent furnace shells and furnace components were redesigned to permit furnace operation at at least 1200 C. Techniques were developed that are expected to lead to significantly improved heat containment compared with current transparent furnaces. The design of a thermal profile in a multizone high temperature transparent furnace design was also addressed. Experiments were performed to verify the energy balance analysis, to demonstrate some of the major furnace improvement techniques developed, and to demonstrate the overall feasibility of a high temperature transparent furnace. The important objective of the research was achieved: to demonstrate the feasibility of operating a transparent furnace at 1200 C.

Bates, Stephen C.

1997-01-01

332

Transparent Conductive Oxides in Thin Film Photovoltaics  

NASA Astrophysics Data System (ADS)

This paper show results from the development of transparent conductive oxides (TCO's) on large areas for the use as front electrode in thin film silicon solar modules. It is focused on two types of zinc oxide, which are cheap to produce and scalable to a substrate size up to 6 m2. Low pressure CVD with temperatures below 200°C can be used for the deposition of boron doped ZnO with a native surface texture for good light scattering, while sputtered aluminum doped ZnO needs a post deposition treatment in an acid bath for a rough surface. The paper presents optical and electrical characterization of large area samples, and also results about long term stability of the ZnO samples with respect to the so called TCO corrosion.

Hamelmann, Frank U.

2014-11-01

333

Electrochromic and transparent conducting oxide nanorods  

NASA Astrophysics Data System (ADS)

Electrochromic materials are of interest for a wide variety of applications, such as displays and smart windows. Many electrochromic oxide materials are synthesized through sol-gel processing. We have demonstrated a general technique for the synthesis of oxide nanorods using sol electrophoretic deposition with an appropriate template. This technique can be applied for the synthesis of nanorods of electrochromic materials, such as TiO2, V2O5 and Nb2O5, with diameters of ~100 nm and a length of ~10 ?m. By attaching these nanorods to a conducting substrate (such as ITO coated glass), it is possible to characterize the electrochromic behavior of these materials via UV-Vis absorbance spectroscopy. A similar technique has been used to make nanorods of the transparent conducting oxide indium tin oxide (ITO), which is often used as a working electrode in electrochromic devices. Such ITO nanorods have diameters of ~75-140 nm and lengths up to 60 ?m.

Limmer, Steven J.; Takahashi, Katsunori; Cao, Guozhong

2003-11-01

334

Effect of geometric lattice design on optical/electrical properties of transparent silver grid for organic solar cells.  

PubMed

Silver (Ag) grid transparent electrode is one of the most promising transparent conducting electrodes (TCEs) to replace conventional indium tin oxide (ITO). We systematically investigate an effect of geometric lattice modifications on optical and electrical properties of Ag grid electrode. The reference Ag grid with 5 ?m width and 100 ?m pitch (duty of 0.05) prepared by conventional photo-lithography and lift-off processes shows the sheet resistance of 13.27 ?/sq, transmittance of 81.1%, and resultant figure of merit (FOM) of 129.05. Three different modified Ag grid electrodes with stripe added-mesh (SAM), triangle-added mesh (TAM), and diagonal-added mesh (DAM) are suggested to improve optical and electrical properties. Although all three of SAM, TAM, and DAM Ag grid electrodes exhibit the lower transmittance values of about 72 - 77%, they showed much decreased sheet resistance of 6 - 8 ?/sq. As a result, all of the lattice-modified Ag grid electrodes display significant improvement of FOM and the highest value of 171.14 is obtained from DAM Ag grid, which is comparable to that of conventional ITO electrode (175.46). Also, the feasibility of DAM Ag gird electrode for use in organic solar cell is confirmed by finite difference time domain (FDTD) simulations. Unlike a conventional ITO electrode, DAM Ag grid electrode can induce light scattering and trapping due to the diffuse transmission that compensates for the loss in optical transparency, resulting in comparable light absorption in the photo active layer of poly(3-hexylthiophene) (P3HT): [6,6]-phenyl-C61-butyric acid methyl ester (PC??BM). P3HT:PC??BM based OSCs with the DAM Ag grid electrode were fabricated, which also showed the potential for ITO-free transparent electrode. PMID:25401837

Lim, Ju Won; Lee, Young Tack; Pandey, Rina; Yoo, Tae-Hee; Sang, Byoung-In; Ju, Byeong-Kwon; Hwang, Do Kyung; Choi, Won Kook

2014-11-01

335

ENGINEERED ELECTRODES AND ELECTRODE-ORGANIC INTERFACES FOR HIGH-EFFICIENCY ORGANIC PHOTOVOLTAICS  

SciTech Connect

Organic photovoltaic (OPV) cells offer the ultimate promise of low cost, readily manufacturable, and durable solar power. While recent advances have led to cells with impressive performance levels, OPV cells have yet to break the double-digit efficiency barrier. Further gains in efficiency and durability, to that competitive with high-performance inorganic photovoltaics will require breakthroughs in transparent electrode and interfacial materials science and engineering. This project involved an integrated basic research effort carried out by an experienced and highly collaborative interdisciplinary team to address in unconventional ways, critical electrode-interfacial issues underlying OPV performance--controlling band offsets between transparent electrodes and organics, addressing current loss/leakage problems at interfaces, enhancing adhesion, interfacial stability, and device durability while minimizing cost. It synergistically combined materials and interfacial reagent synthesis, nanostructural and photovoltaic characterization, and high level quantum theory. The research foci were: 1) understanding of/development of superior transparent electrode materials and materials morphologies--i.e., better matched electronically and chemically to organic active layers, 2) understanding-based development of inorganic interfacial current-collecting/charge-blocking layers, and 3) understanding-based development of self-assembled adhesion/current-collecting/charge-blocking/cross-linking layers for high-efficiency OPV interfaces. Pursing the goal of developing the fundamental scientific understanding needed to design, fabricate, prototype and ultimately test high-efficiency OPV cells incorporating these new concepts, we achieved a record power conversion efficiency of 5.2% for an organic bulk-heterjunction solar cell.

Tobin J. Marks; R.P.H. Chang; Tom Mason; Ken Poeppelmeier; Arthur J. Freeman

2008-11-13

336

[Data transparency - an ethical imperative? Approaching the issues].  

PubMed

Several studies show that the findings of clinical trials are often not published in full, resulting in a biased presentation of results (publication bias). First, this paper discusses the ethical arguments in favour of complete transparency of biomedical research data. There are relevant deontological (like obligations towards study participants and research sponsors) and consequentialist (harm for patients and misallocation of scarce resources) ethical reasons for the full publication of all trial results, which cannot be overridden by counter arguments like freedom of research, data protection or the individual interests of researchers and manufacturers. The article therefore discusses (1) which strategies are appropriate to guarantee data transparency and (2) who bears responsibility for the implementation of these strategies. Finally, open questions and the need for further action will be discussed. PMID:21530911

Marckmann, Georg; Strech, Daniel

2011-01-01

337

Highly transparent nonvolatile resistive memory devices from silicon oxide and graphene.  

PubMed

Transparent electronic memory would be useful in integrated transparent electronics. However, achieving such transparency produces limits in material composition, and hence, hinders processing and device performance. Here we present a route to fabricate highly transparent memory using SiO(x) as the active material and indium tin oxide or graphene as the electrodes. The two-terminal, nonvolatile resistive memory can also be configured in crossbar arrays on glass or flexible transparent platforms. The filamentary conduction in silicon channels generated in situ in the SiO(x) maintains the current level as the device size decreases, underscoring their potential for high-density memory applications, and as they are two-terminal based, transitions to three-dimensional memory packages are conceivable. As glass is becoming one of the mainstays of building construction materials, and conductive displays are essential in modern handheld devices, to have increased functionality in form-fitting packages is advantageous. PMID:23033077

Yao, Jun; Lin, Jian; Dai, Yanhua; Ruan, Gedeng; Yan, Zheng; Li, Lei; Zhong, Lin; Natelson, Douglas; Tour, James M

2012-01-01

338

Trapping atoms on a transparent permanent-magnet atom chip  

E-print Network

We describe experiments on trapping of atoms in microscopic magneto-optical traps on an optically transparent permanent-magnet atom chip. The chip is made of magnetically hard ferrite-garnet material deposited on a dielectric substrate. The confining magnetic fields are produced by miniature magnetized patterns recorded in the film by magneto-optical techniques. We trap Rb atoms on these structures by applying three crossed pairs of counter-propagating laser beams in the conventional magneto-optical trapping (MOT) geometry. We demonstrate the flexibility of the concept in creation and in-situ modification of the trapping geometries through several experiments.

A. Shevchenko; M. Heilio; T. Lindvall; A. Jaakkola; I. Tittonen; M. Kaivola; T. Pfau

2006-04-21

339

Compliant composite electrodes and large strain bistable actuation  

NASA Astrophysics Data System (ADS)

Dielectric elastomer actuators (DEA) and bistable electroactive polymers (BSEP) both require compliant electrodes with rubbery elasticity and high conductivity at large strains. Stretchable opto-electronic devices additionally require the compliant electrodes to be optically transparent. Many candidate materials have been investigated. We report a new approach to mechanically robust, stretchable compliant electrodes. A facile in-situ composite synthesis and transfer technique is employed, and the resulting composite electrodes retain the high surface conductivity of the original conductive network formed by nanowires or nanotubes, while exhibiting the mechanical flexibility of the matrix polymer. The composite electrodes have high transparency and low surface roughness useful for the fabrication of polymer thinfilm electronic devices. The new electrodes are suitable for high-strain actuation, as a complaint resistive heating element to administer the temperature of shape memory polymers, and as the charge injection electrodes for flexible/stretchable polymer light emitting diodes. Bistable electroactive polymers employing the composite electrodes can be actuated to large strains via heating-actuation-cooling cycles.

Yun, Sungryul; Yu, Zhibin; Niu, Xiaofan; Hu, Weili; Li, Lu; Brochu, Paul; Pei, Qibing

2012-04-01

340

Transparent Recovery in Distributed Systems  

Microsoft Academic Search

We are investigating transparent optimistic solutions to problems in dis-tributed systems such as recovery [6], replication [3], parallelization [2], and concurrent competing alternatives [4]. By a transparent solution to such a problem we mean that a program is transformed automatically, and that the behavior of the program is equivalent to a possible behavior of the un-transformed program; in addition, the

David F. Bacon

1991-01-01

341

Modiolus-hugging intracochlear electrode array with shape memory alloy.  

PubMed

In the cochlear implant system, the distance between spiral ganglia and the electrodes within the volume of the scala tympani cavity significantly affects the efficiency of the electrical stimulation in terms of the threshold current level and spatial selectivity. Because the spiral ganglia are situated inside the modiolus, the central axis of the cochlea, it is desirable that the electrode array hugs the modiolus to minimize the distance between the electrodes and the ganglia. In the present study, we propose a shape-memory-alloy-(SMA-) embedded intracochlear electrode which gives a straight electrode a curved modiolus-hugging shape using the restoration force of the SMA as triggered by resistive heating after insertion into the cochlea. An eight-channel ball-type electrode array is fabricated with an embedded titanium-nickel SMA backbone wire. It is demonstrated that the electrode array changes its shape in a transparent plastic human cochlear model. To verify the safe insertion of the electrode array into the human cochlea, the contact pressures during insertion at the electrode tip and the contact pressures over the electrode length after insertion were calculated using a 3D finite element analysis. The results indicate that the SMA-embedded electrode is functionally and mechanically feasible for clinical applications. PMID:23762181

Min, Kyou Sik; Jun, Sang Beom; Lim, Yoon Seob; Park, Se-Ik; Kim, Sung June

2013-01-01

342

Pyrochemical neutron multiplicity counter design  

SciTech Connect

Pyrochemical process materials are difficult to measure using conventional neutron counting methods because of significant self- multiplication and variable ({alpha},n) reaction rates. Multiplicity counters measure the first three moments of the neutron multiplicity distribution and thus make it possible to determine sample mass even when multiplication and ({alpha},n) rate are unknown. A new multiplicity counter suitable for inplant measurement of pyrochemical process materials has been designed using Monte Carlo simulations. The goals were to produce a counter that has high neutron detection efficiency, low die-away time, a flat spatial efficiency profile, and is insensitive to the neutron energy spectrum. Monte Carlo calculations were performed for several prototype models consisting of four rings of 71-cm active length {sup 3}He tubes in a polyethylene body. The cadmium-lined sample well is 25 cm in diameter to accommodate a wide variety of inplant sample containers. The counter can be free-standing or in-line without mechanical modification. The calculations were performed to determine the above design criteria for several configurations of tube spacing, cadmium liners, and sample height. Calculations were also performed for distributed sample sources to understand the integrated effects of variable neutron spectra on the counter. 5 refs., 8 figs., 1 tab.

Langner, D.G.; Ensslin, N.; Krick, M.S.

1990-01-01

343

Counter-rotating accretion discs  

NASA Astrophysics Data System (ADS)

Counter-rotating discs can arise from the accretion of a counter-rotating gas cloud on to the surface of an existing corotating disc or from the counter-rotating gas moving radially inwards to the outer edge of an existing disc. At the interface, the two components mix to produce gas or plasma with zero net angular momentum which tends to free-fall towards the disc centre. We discuss high-resolution axisymmetric hydrodynamic simulations of viscous counter-rotating discs for the cases where the two components are vertically separated and radially separated. The viscosity is described by an isotropic ?-viscosity including all terms in the viscous stress tensor. For the vertically separated components, a shear layer forms between them and the middle part of this layer free-falls to the disc centre. The accretion rates are increased by factors of ˜102-104 over that for a conventional disc rotating in one direction with the same viscosity. The vertical width of the shear layer and the accretion rate are strongly dependent on the viscosity and the mass fraction of the counter-rotating gas. In the case of radially separated components where the inner disc corotates and the outer disc rotates in the opposite direction, a gap between the two components opens and closes quasi-periodically. The accretion rates are ?25 times larger than those for a disc rotating in one direction with the same viscosity.

Dyda, S.; Lovelace, R. V. E.; Ustyugova, G. V.; Romanova, M. M.; Koldoba, A. V.

2015-01-01

344

Access resistance of stimulation electrodes as a function of electrode proximity to the retina  

NASA Astrophysics Data System (ADS)

Objective. Epiretinal prostheses seek to effectively stimulate the retina by positioning electrode arrays close to its surface so current pulses generate narrow retinal electric fields. Our objective was to evaluate the use of the electrical impedance of insulated platinum electrodes as a measure of the proximity of insulated platinum electrodes to the inner surface of the retina. Approach. We examined the impedance of platinum disk electrodes, 0.25 mm in diameter, insulated with two widths (0.8 and 1.6 mm outer diameter) of transparent fluoropolymer in a rabbit retinal eyecup preparation. Optical coherence tomography measured the electrode’s proximity to the retinal surface which was correlated with changes in the voltage waveform at the electrode. Electrode impedance changes during retinal deformation were also studied. Main results. When the 1.6 mm diameter insulated electrodes advanced towards the retinal surface from 1000 ?m, their voltage step at current pulse onset increased, reflecting an access resistance increase of 3880 ± 630 ?, with the 50% midpoint averaging 30 ?m, while thin 0.8 mm insulated electrode advancement showed an access resistance increase 50% midpoint averaging 16 ?m. Using impedance spectroscopy, electrode–retina proximity differences were seen in the 1.6 mm insulated electrode impedance modulus between 1 and 100 kHz and the waveform phase angle at 0.3–10 kHz, while thin 0.8 mm insulated electrode advancement produced smaller impedance modulus changes with retinal proximity between 3 and 100 kHz. These impedance changes with retinal proximity may reflect different sized zones of eye wall being coupled in series with the insulated platinum electrode. Significance. The proximity of stimulus electrodes to neural tissue in fluid-filled spaces can be estimated from access resistance changes in the stimulus pulse waveform. Because many prosthetic devices allow back telemetry communication of the stimulus electrode waveform, it is possible these series resistance increases observed with retinal proximity could be used as a metric of stimulus electrode placement.

Majdi, Joseph A.; Minnikanti, Saugandhika; Peixoto, Nathalia; Agrawal, Anant; Cohen, Ethan D.

2015-02-01

345

sensor electrodes  

NASA Astrophysics Data System (ADS)

In this work, an ultrafast and facile method is developed to synthesize Au(I)-dodecanethiolate nanotubes (Au(I)NTs) with the assistance of glycyl-glycyl-glycine (G-G-G). Transmission electron microscopy (TEM) images reveal that the as-prepared Au(I)NTs can be obtained in a 2-h reaction instead of a previous 24-h reaction and are uniform with a hollow structure and smooth surface by virtue of the G-G-G peptide tubular template. According to structural analysis, a possible preparative mechanism is proposed that the G-G-G peptide could help to curl into tube-like morphology in alkaline situation spontaneously to accelerate the formation of Au(I)NTs. Meanwhile, PVDF-stabilized Au(I)NT-modified glassy carbon electrodes present their promising potential for Hg2+ detection.

Zhang, Zhiqiang; Ma, Congcong; He, Lian; Zhu, Shijin; Hao, Xiaodong; Xie, Wanyi; Zhang, Wei; Zhang, Yuxin

2014-11-01

346

Magnesium insertion electrodes for rechargeable nonaqueous batteries — a competitive alternative to lithium?  

Microsoft Academic Search

Magnesium-based rechargeable batteries might be an interesting future alternative to lithium-based batteries. Here the available results of research, both on rechargeable negative electrodes based either on metallic magnesium or alternative materials, and on materials suitable as positive, magnesium-inserting (counter)electrodes for secondary magnesium batteries, are critically reviewed. The reversible magnesium-metal electrode was scarcely investigated and remains poorly understood. More data are

Petr Novák; Roman Imhof; Otto Haas

1999-01-01

347

The interfacial impedance variation of V 6O 13 composite electrodes during lithium insertion and extraction  

Microsoft Academic Search

Composite V6O13 electrodes were characterized in cells having metallic lithium counter and reference electrodes. The overall impedance changes closely follow the variation of the V6O13 unit cell volume. An abrupt change in unit cell volume if reflected in a corresponding abrupt change in the interfacial impedance. The variation of the interface impedance implies that the integrity of the electrode structure

J. Barker; R. Koksbang

1995-01-01

348

Access resistance of stimulation electrodes as a function of electrode proximity to the retina.  

PubMed

Objective. Epiretinal prostheses seek to effectively stimulate the retina by positioning electrode arrays close to its surface so current pulses generate narrow retinal electric fields. Our objective was to evaluate the use of the electrical impedance of insulated platinum electrodes as a measure of the proximity of insulated platinum electrodes to the inner surface of the retina. Approach. We examined the impedance of platinum disk electrodes, 0.25 mm in diameter, insulated with two widths (0.8 and 1.6 mm outer diameter) of transparent fluoropolymer in a rabbit retinal eyecup preparation. Optical coherence tomography measured the electrode's proximity to the retinal surface which was correlated with changes in the voltage waveform at the electrode. Electrode impedance changes during retinal deformation were also studied. Main results. When the 1.6 mm diameter insulated electrodes advanced towards the retinal surface from 1000 ?m, their voltage step at current pulse onset increased, reflecting an access resistance increase of 3880 ± 630 ?, with the 50% midpoint averaging 30 ?m, while thin 0.8 mm insulated electrode advancement showed an access resistance increase 50% midpoint averaging 16 ?m. Using impedance spectroscopy, electrode-retina proximity differences were seen in the 1.6 mm insulated electrode impedance modulus between 1 and 100 kHz and the waveform phase angle at 0.3-10 kHz, while thin 0.8 mm insulated electrode advancement produced smaller impedance modulus changes with retinal proximity between 3 and 100 kHz. These impedance changes with retinal proximity may reflect different sized zones of eye wall being coupled in series with the insulated platinum electrode. Significance. The proximity of stimulus electrodes to neural tissue in fluid-filled spaces can be estimated from access resistance changes in the stimulus pulse waveform. Because many prosthetic devices allow back telemetry communication of the stimulus electrode waveform, it is possible these series resistance increases observed with retinal proximity could be used as a metric of stimulus electrode placement. PMID:25474329

Majdi, Joseph A; Minnikanti, Saugandhika; Peixoto, Nathalia; Agrawal, Anant; Cohen, Ethan D

2015-02-01

349

Enhanced ultraviolet response using graphene electrodes in organic solar cells  

NASA Astrophysics Data System (ADS)

We demonstrate enhanced ultraviolet (UV) response in organic photovoltaic devices using few-layer graphene as the transparent and conducting electrode. This is compared to the same device stack fabricated on a conventional indium tin oxide (ITO) electrode. The enhanced UV response was confirmed by examining the photocurrent spectra over a wide spectral range and is consistent with the excellent UV transmittance of graphene over ITO. The results render the graphene electrode a promising alternative to ITO to enable applications for UV photodetectors or other optoelectronic devices with a wider optical window.

Zhao, Zhouying; Fite, John D.; Haldar, Pradeep; Ung Lee, Ji

2012-08-01

350

Transparent conductors composed of nanomaterials.  

PubMed

This is a review on recent developments in the field of transparent conductive coatings (TCCs) for ITO replacement. The review describes the basic properties of conductive nanomaterials suitable for fabrication of such TCCs (metallic nanoparticles and nanowires, carbon nanotubes and graphene sheets), various methods of patterning the metal nanoparticles with formation of conductive transparent metallic grids, honeycomb structures and 2D arrays of interconnected rings as well as fabrication of TCCs based on graphene and carbon nanotubes. Applications of TCCs in electronic and optoelectronic devices, such as solar cells, electroluminescent and electrochromic devices, touch screens and displays, and transparent EMI shielders, are discussed. PMID:24777332

Layani, Michael; Kamyshny, Alexander; Magdassi, Shlomo

2014-06-01

351

Air transparent soundproof window  

NASA Astrophysics Data System (ADS)

A soundproof window or wall which is transparent to airflow is presented. The design is based on two wave theories: the theory of diffraction and the theory of acoustic metamaterials. It consists of a three-dimensional array of strong diffraction-type resonators with many holes centered on each individual resonator. The negative effective bulk modulus of the resonators produces evanescent wave, and at the same time the air holes with subwavelength diameter existed on the surfaces of the window for macroscopic air ventilation. The acoustic performance levels of two soundproof windows with air holes of 20mm and 50mm diameters were measured. The sound level was reduced by about 30 - 35dB in the frequency range of 400 - 5,000Hz with the 20mm window, and by about 20 - 35dB in the frequency range of 700 - 2,200Hz with the 50mm window. Multi stop-band was created by the multi-layers of the window. The attenuation length or the thickness of the window was limited by background noise. The effectiveness of the soundproof window with airflow was demonstrated by a real installation.

Kim, Sang-Hoon; Lee, Seong-Hyun

2014-11-01

352

High-performance and stable organic transistors and circuits with patterned polypyrrole electrodes.  

PubMed

High performance p-/n-type transistors and complementary inverter circuits are demonstrated using patterned polypyrrole (PPY) as pure electrodes. Strikingly, these devices show good stability under continuous operation and long-term storage conditions. Furthermore, PPY electrodes also exhibit good applicability in solution-processed and flexible devices. All these results indicate the great potential of PPY electrodes in solution-processed, all-organic, flexible, transparent, and low-power electronics. PMID:22431264

Li, Liqiang; Jiang, Lin; Wang, Wenchong; Du, Chuan; Fuchs, Harald; Hu, Wenping; Chi, Lifeng

2012-04-24

353

Laminated ultrathin chemical vapor deposition graphene films based stretchable and transparent high-rate supercapacitor.  

PubMed

Due to their exceptional flexibility and transparency, CVD graphene films have been regarded as an ideal replacement of indium tin oxide for transparent electrodes, especially in applications where electronic devices may be subjected to large tensile strain. However, the search for a desirable combination of stretchability and electrochemical performance of such devices remains a huge challenge. Here, we demonstrate the implementation of a laminated ultrathin CVD graphene film as a stretchable and transparent electrode for supercapacitors. Transferred and buckled on PDMS substrates by a prestraininig-then-buckling strategy, the four-layer graphene film maintained its outstanding quality, as evidenced by Raman spectra. Optical transmittance of up to 72.9% at a wavelength of 550 nm and stretchability of 40% were achieved. As the tensile strain increased up to 40%, the specific capacitance showed no degradation and even increased slightly. Furthermore, the supercapacitor demonstrated excellent frequency capability with small time constants under stretching. PMID:25144124

Xu, Ping; Kang, Junmo; Choi, Jae-Boong; Suhr, Jonghwan; Yu, Jianyong; Li, Faxue; Byun, Joon-Hyung; Kim, Byung-Sun; Chou, Tsu-Wei

2014-09-23

354

Flexible Organic Light-Emitting Diodes on a Poly(3,4-ethylenedioxythiophene)/Metal-Grid Hybrid Electrode  

NASA Astrophysics Data System (ADS)

We fabricated flexible organic light-emitting diodes (OLEDs) on a transparent hybrid electrode. The electrode was prepared on a poly(ethylene naphthalate) (PEN) substrate and was composed of a poly(3,4-ethylenedioxythiophene) and aluminum grid. An efficient moisture-barrier structure was deposited underneath the electrode to protect the OLEDs from the moisture outgassed from the PEN substrate. The hybrid electrode showed sheet resistance and optical transmittance of 8.5 ?/square and 74%, respectively. The performance of the flexible OLEDs on a hybrid electrode with a moisture barrier was compared with that on a conventional indium tin oxide electrode with glass and plastic substrates.

Lee, Haksoo; Seo, Seung-Woo; Jung, Eun; Chae, Heeyeop; Cho, Sung Min

2013-04-01

355

Basic Research Needs for Countering Terrorism  

SciTech Connect

To identify connections between technology needs for countering terrorism and underlying science issues and to recommend investment strategies to increase the impact of basic research on efforts to counter terrorism

Stevens, W.; Michalske, T.; Trewhella, J.; Makowski, L.; Swanson, B.; Colson, S.; Hazen, T.; Roberto, F.; David Franz, D.; Resnick, G.; Jacobson, S.; Valdez, J.; Gourley, P.; Tadros, M.; Sigman, M.; Sailor, M.; Ramsey, M.; Smith, B.; Shea, K.; Hrbek, J.; Rodacy, P.; Tevault, D.; Edelstein, N.; Beitz, J.; Burns, C.; Choppin, G.; Clark, S.; Dietz, M.; Rogers, R.; Traina, S.; Baldwin, D.; Thurnauer, M.; Hall, G.; Newman, L.; Miller, D.; Kung, H.; Parkin, D.; Shuh, D.; Shaw, H.; Terminello, L.; Meisel, D.; Blake, D.; Buchanan, M.; Roberto, J.; Colson, S.; Carling, R.; Samara, G.; Sasaki, D.; Pianetta, P.; Faison, B.; Thomassen, D.; Fryberger, T.; Kiernan, G.; Kreisler, M.; Morgan, L.; Hicks, J.; Dehmer, J.; Kerr, L.; Smith, B.; Mays, J.; Clark, S.

2002-03-01

356

Transparency in Cooperative Online Education  

Microsoft Academic Search

Abstract The purpose of this article is to discuss the following question: What is the potential of social networking within cooperative online education? Social networking does not necessarily involve communication, dialogue, or collaboration. Instead, the authors argue that transparency is a unique,feature of social networking,services. Transparency gives students insight into each other?s actions. Cooperative learning seeks to develop virtual learning

Christian Dalsgaard; Morten Flate Paulsen

357

HSPES membrane electrode assembly  

NASA Technical Reports Server (NTRS)

An improved fuel cell electrode, as well as fuel cells and membrane electrode assemblies that include such an electrode, in which the electrode includes a backing layer having a sintered layer thereon, and a non-sintered free-catalyst layer. The invention also features a method of forming the electrode by sintering a backing material with a catalyst material and then applying a free-catalyst layer.

Kindler, Andrew (Inventor); Yen, Shiao-Ping (Inventor)

2000-01-01

358

Lossy Counter Machines Decidability Cheat Sheet  

NASA Astrophysics Data System (ADS)

Lossy counter machines (LCM's) are a variant of Minsky counter machines based on weak (or unreliable) counters in the sense that they can decrease nondeterministically and without notification. This model, introduced by R. Mayr [TCS 297:337-354 (2003)], is not yet very well known, even though it has already proven useful for establishing hardness results.

Schnoebelen, Philippe

359

UN Action To Counter Terrorism  

NSDL National Science Digital Library

The United Nations has been concerned about the growing threat of terrorism for decades, and in 2006, their member states adopted a comprehensive global strategy to counter terrorism. Visitors with an interest in their strategy will want to visit the site to read about the strategy and to also learn about some of their related activities. After reading a brief introduction about the overall strategy, visitors can read the complete United Nations Counter-Terrorism Handbook and also view the latest news updates related to their efforts to combat terrorism around the globe. Along the left-hand side of the homepage, visitors can also look over sections that include "Strategic Framework", "International Instruments", and "Human Rights". Visitors should also be aware that these materials are also available in Arabic, French, Russian, Spanish, and Chinese.

360

Micromachined electrode array  

DOEpatents

An electrode array is disclosed which has applications for neural stimulation and sensing. The electrode array, in certain embodiments, can include a plurality of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. In other embodiments of the electrode array, the electrodes can be fixed to the substrate. The electrode array can be formed from a combination of bulk and surface micromachining, and can include electrode tips having an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis.

Okandan, Murat (Edgewood, NM); Wessendorf, Kurt O. (Albuquerque, NM)

2007-12-11

361

Flexible retinal electrode array  

DOEpatents

An electrode array which has applications for neural stimulation and sensing. The electrode array can include a large number of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. The electrode array can be formed from a combination of bulk and surface micromachining, with electrode tips that can include an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis where the electrodes can be tailored to provide a uniform gentle contact pressure with optional sensing of this contact pressure at one or more of the electrodes.

Okandan, Murat (Albuquerque, NM); Wessendorf, Kurt O. (Albuquerque, NM); Christenson, Todd R. (Albuquerque, NM)

2006-10-24

362

High frequency reference electrode  

DOEpatents

A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or halo' at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes. 4 figs.

Kronberg, J.W.

1994-05-31

363

High frequency reference electrode  

DOEpatents

A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or "halo" at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes.

Kronberg, James W. (Aiken, SC)

1994-01-01

364

Large-area transparent in visible range silicon carbide photodiode  

NASA Astrophysics Data System (ADS)

This paper describes the construction, fabrication and properties of large-area ultra violet detector that is transparent in the visible range. The device was made on n-type 4H SiC substrate with a double epitaxial layer in which aluminum was implanted to form a p-n junction close to the surface, and a SiO2 layer was formed for passivation, without a guard ring. The design of the top and bottom electrodes of 4mm diameter UV sensitive area allows not less than 20% visible range transmission. This transmission was measured across sensitive area of examined devices and was only 5% lower than that of the substrate before implantation and electrodes deposition.

Borecki, M.; Kociubi?ski, A.; Duk, M.; Kwietniewski, N.; Korwin-Pawlowski, M. L.; Doroz, P.; Szmidt, J.

2013-10-01

365

High performance cermet electrodes  

DOEpatents

Disclosed is a method of increasing the operating cell voltage of a solid oxide electrochemical cell having metal electrode particles in contact with an oxygen-transporting ceramic electrolyte. The metal electrode is heated with the cell, and oxygen is passed through the oxygen-transporting ceramic electrolyte to the surface of the metal electrode particles so that the metal electrode particles are oxidized to form a metal oxide layer between the metal electrode particles and the electrolyte. The metal oxide layer is then reduced to form porous metal between the metal electrode particles and the ceramic electrolyte.

Isenberg, Arnold O. (Forest Hills Boro, PA); Zymboly, Gregory E. (Penn Hills, PA)

1986-01-01

366

Electrochemical behavior of LiCoO2 as aqueous lithium-ion battery electrodes Riccardo Ruffo a  

E-print Network

Electrochemical behavior of LiCoO2 as aqueous lithium-ion battery electrodes Riccardo Ruffo material Counter electrode a b s t r a c t Despite the large number of studies on the behavior of LiCoO2 potential range matches the electrochemical stability window of the aqueous electrolyte. The experimental

Cui, Yi

367

Transparent Ti-In-Sn-O multicomponent anodes for highly efficient phosphorescent organic light emitting diodes  

NASA Astrophysics Data System (ADS)

We report on transparent Ti-In-Sn-O (TITO) multicomponent anodes prepared by co-sputtering anatase TiO2-x and ITO targets to produce highly efficient phosphorescent organic light emitting diodes (OLEDs). In spite of the incorporation of low cost TiO2, the crystalline TITO electrode annealed at temperature of 600 °C showed a sheet resistance of 18.06 ?/sq, an optical transmittance of 87.96% at a wavelength of 550 nm, and a work function of 4.71 eV comparable to conventional ITO electrode. Both the quantum (21.69%) and power efficiencies (90.92 lm/W) of the phosphorescent OLED fabricated on the TITO anode were higher than those of the OLED with the reference ITO anode due to the high transparency of the TITO electrodes. This indicates that the TITO electrode is a promising indium-saving electrode that can replace high-cost ITO electrodes in the manufacture of low-cost, highly efficient phosphorescent OLEDs.

Lim, Jong-Wook; Jun Kang, Seong; Lee, Sunghun; Kim, Jang-Joo; Kim, Han-Ki

2012-07-01

368

Switching from "absorption within transparency" to "transparency within transparency" in an electromagnetically induced absorption dominated transition.  

PubMed

The absorption of a resonant coupling laser driving a closed degenerate two-level system in an atomic cesium beam was investigated as a function of the detuning of a second laser probing the same transition. The measurements were performed for four different polarization combinations of the two laser beams. Except for the beams of counterrotating polarizations all coupling-laser absorption profiles showed "absorption within transparency," i.e., the absorption in the region around the two-photon resonance was smaller than the absorption corresponding to the one-photon transition induced by the coupling laser, and an extra absorption peak was observed on this curve at the two-photon resonance. With regard to the beams of counterrotating polarizations we observed a switch from absorption within transparency to "transparency within transparency" when the probe-laser power exceeded the constant coupling-laser power. In other words, the cesium ensemble became mostly transparent to the coupling-laser beam at the two-photon resonance. PMID:18451960

Dahl, Katrin; Molella, Luca Spani; Rinkleff, Rolf-Hermann; Danzmann, Karsten

2008-05-01

369

Transparent white organic light emitting diodes with improved cathode transparency  

NASA Astrophysics Data System (ADS)

We have fabricated transparent white organic light emitting diode (WOLED) for lighting application based on a hybrid white OLED and a phosphorescence white OLED. For the hybrid WOLED, a blue fluorescence emitting layer (FLEML) and green and red phosphorescence emitting layers (PH-EMLs) have been used in the device structure of ITO/hole transporting layer (HTL)/PH-EMLs/interlayer/FL-EML/ETL/LiF/Al. The balanced emissions from the FLEML and the PH-EMLs have been obtained by using appropriate carrier (hole) trapping effects in the PH-EMLs, which resulted in external and power efficiencies of 15 % and 27 lm/W, respectively, at a luminance of 1000 cd/m2 without any out-coupling enhancement. The Commission Internationale de L'Eclairage (CIE) coordinates of this hybrid WOLED is (0.43,0.44) with color rendering index (CRI) of 80 and correlated color temperature (CCT) of 3200 K, respectively, in the bottom emission structure. Based on this hybrid WOLED, we established highly efficient transparent WOLED by introduction of a transparent cathode, and obtained over 19 lm/W of power efficiency at a total luminance of 1000 cd/m2 as well as over 60 % of transmittance at 550 nm with the conventional glass encapsulation. Moreover, when the phosphorescent white OLED was combined with a transparent cathode, the power efficiency was reached up to 24 lm/W of power efficiency at a total luminance of 1000 cd/m2.

Lee, Jeong-Ik; Lee, Jonghee; Lee, Joowon; Shin, Jae-Heon; Hwang, Chi-Sun; Chu, Hye Yong

2009-08-01

370

Flexible electrochromic films based on CVD-graphene electrodes.  

PubMed

Graphene synthesized via chemical vapor deposition is a notable candidate for flexible large-area transparent electrodes due to its great physical properties and its 2D activated surface area. Electrochromic devices in optical displays, smart windows, etc are suitable applications for graphene when used as a transparent conductive electrode. In this study, various-layer graphene was synthesized via chemical vapor deposition, and inorganic WO(x) was deposited on the layers, which have advantageous columnar structures and W(6+) and W(4+) oxidation states. The characteristics of graphene and WO(x) were verified using optical transmittance, Raman spectroscopy, x-ray photoelectron spectroscopy and scanning electron microscopy. The optimum transparent conductive electrode condition for controlling graphene layers was investigated based on the optical density and cyclic voltammetry. Electrochromic devices were fabricated using a three-layer graphene electrode, which had the best optical density. The graphene in the flexible electrochromic device demonstrated a potential for replacing ITO in flexible electronics. PMID:25201016

Soo Choi, Dong; Ho Han, Seung; Kim, Hyeongkeun; Hee Kang, So; Kim, Yena; Yang, Cheol-Min; Kim, Tae Young; Ho Yoon, Dae; Seok Yang, Woo

2014-10-01

371

Corneal-shaping electrode  

DOEpatents

The disclosure relates to a circulating saline electrode for changing corneal shape in eyes. The electrode comprises a tubular nonconductive electrode housing having an annular expanded base which has a surface substantially matched to a subject corneal surface. A tubular conductive electrode connected to a radiofrequency generating source is disposed within the electrode housing and longitudinally aligned therewith. The electrode has a generally hemispherical head having at least one orifice. Saline solution is circulated through the apparatus and over the cornea to cool the corneal surface while radiofrequency electric current emitted from the electrode flows therefrom through the cornea to a second electrode, on the rear of the head. This current heats the deep corneal stroma and thereby effects corneal reshaping as a biological response to the heat.

Doss, James D. (Los Alamos, NM); Hutson, Richard L. (Los Alamos, NM)

1982-01-01

372

Electrochemical growth of vertically aligned ZnO nanorod arrays on oxidized bi-layer graphene electrode  

E-print Network

Electrochemical growth of vertically aligned ZnO nanorod arrays on oxidized bi-layer graphene arrays were directly grown on flexible and transparent oxidized bi-layer graphene electrodes by seedless-quality vertical ZnO NR arrays directly on oxidized bi-layer graphene electrodes from pure zinc nitrate aqueous

Hwang, Sung Woo

373

Continuous, highly flexible, and transparent graphene films by chemical vapor deposition for organic photovoltaics.  

PubMed

We report the implementation of continuous, highly flexible, and transparent graphene films obtained by chemical vapor deposition (CVD) as transparent conductive electrodes (TCE) in organic photovoltaic cells. Graphene films were synthesized by CVD, transferred to transparent substrates, and evaluated in organic solar cell heterojunctions (TCE/poly-3,4-ethylenedioxythiophene:poly styrenesulfonate (PEDOT:PSS)/copper phthalocyanine/fullerene/bathocuproine/aluminum). Key to our success is the continuous nature of the CVD graphene films, which led to minimal surface roughness ( approximately 0.9 nm) and offered sheet resistance down to 230 Omega/sq (at 72% transparency), much lower than stacked graphene flakes at similar transparency. In addition, solar cells with CVD graphene and indium tin oxide (ITO) electrodes were fabricated side-by-side on flexible polyethylene terephthalate (PET) substrates and were confirmed to offer comparable performance, with power conversion efficiencies (eta) of 1.18 and 1.27%, respectively. Furthermore, CVD graphene solar cells demonstrated outstanding capability to operate under bending conditions up to 138 degrees , whereas the ITO-based devices displayed cracks and irreversible failure under bending of 60 degrees . Our work indicates the great potential of CVD graphene films for flexible photovoltaic applications. PMID:20394355

Gomez De Arco, Lewis; Zhang, Yi; Schlenker, Cody W; Ryu, Koungmin; Thompson, Mark E; Zhou, Chongwu

2010-05-25

374

Enhanced mobility of neural cells with a transparent electric field stimulator.  

PubMed

Mobility is one of the important characteristics of living cells. It also plays a significant role in therapeutic cell transplantation with target location specificity. To enhance cell mobility, a neural cell stimulator was assembled with graphenes, which are two-dimensional nanocarbon materials that form a transparent electrode over the cover glass in a cell culture dish. This transparent stimulator applies electrical field stimulation to the neural cells. The advantages of this new transparent electrical field stimulator (TEFS) with a graphene electrode include transparency, because few layered graphenes are optically transparent, and biocompatibility, because the cover glass is coated with laminin. In this paper, it is reported that constant electric field stimulation, which is at a specific strength, facilitates the mobility of a neural cell and makes the visibility of cellular behavior on the electrode much better than that of any other existing cell stimulator that has metal electrodes. The strength of the electrical field for stimulating cells varies from 4.5 mV/mm to 450 mV/mm. When continuous electric field stimulation was applied for 4 hours at the electric field strength of 45 mV/mm, the mobility of the neural cells was significantly enhanced compared to the control conditions, wherein there was no electric field stimulation. Thus, the feasibility of the TEFS with the nanothickness of graphene was tested to modulate the mobility of neural cells in vitro. The result suggests that electrical field stimulation could enhance neural cell alignment, cell-to-cell coupling, and networks, and may be applied to cell transplantation to boost therapeutic effectiveness. PMID:22966549

Heo, Chaejeong; Yoo, Jeongwan; Lee, Si Young; Lee, Sohee; Joo, Eun Yeon; Hong, Seung Bong; Lee, Young Hee; Suh, Minah

2012-07-01

375

Low resistance fuel electrodes  

DOEpatents

An electrode 6 bonded to a solid, ion conducting electrolyte 5 is made, where the electrode 6 comprises a ceramic metal oxide 18, metal particles 17, and heat stable metal fibers 19, where the metal fibers provide a matrix structure for the electrode. The electrolyte 5 can be bonded to an air electrode cathode 4, to provide an electrochemical cell 2, preferably of tubular design.

Maskalick, Nichols J. (Pittsburgh, PA); Folser, George R. (Lower Burrell, PA)

1989-01-01

376

A Simple Hydrogen Electrode  

ERIC Educational Resources Information Center

This article describes the construction of an inexpensive, robust, and simple hydrogen electrode, as well as the use of this electrode to measure "standard" potentials. In the experiment described here the students can measure the reduction potentials of metal-metal ion pairs directly, without using a secondary reference electrode. Measurements…

Eggen, Per-Odd

2009-01-01

377

Longitudinal discharge laser electrodes  

DOEpatents

The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window.

Warner, Bruce E. (Livermore, CA); Miller, John L. (Dublin, CA); Ault, Earl R. (Dublin, CA)

1994-01-01

378

Near-electrode imager  

DOEpatents

An apparatus, near-electrode imager, for employing nuclear magnetic resonance imaging to provide in situ measurements of electrochemical properties of a sample as a function of distance from a working electrode. The near-electrode imager uses the radio frequency field gradient within a cylindrical toroid cavity resonator to provide high-resolution nuclear magnetic resonance spectral information on electrolyte materials.

Rathke, Jerome W. (Lockport, IL); Klingler, Robert J. (Westmont, IL); Woelk, Klaus (Wachtberg, DE); Gerald, II, Rex E. (Brookfield, IL)

2000-01-01

379

Longitudinal discharge laser electrodes  

DOEpatents

The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window. 2 figs.

Warner, B.E.; Miller, J.L.; Ault, E.R.

1994-08-23

380

Paper-based transparent flexible thin film supercapacitors  

NASA Astrophysics Data System (ADS)

Paper-based transparent flexible thin film supercapacitors were fabricated using CNF-[RGO]n hybrid paper as an electrode material and charge collector. Owing to the self-anti-stacking of distorted RGO nanosheets and internal electrolyte nanoscale-reservoirs, the device exhibited good electrochemical performance (about 1.73 mF cm-2), and a transmittance of about 56% (at 550 nm).Paper-based transparent flexible thin film supercapacitors were fabricated using CNF-[RGO]n hybrid paper as an electrode material and charge collector. Owing to the self-anti-stacking of distorted RGO nanosheets and internal electrolyte nanoscale-reservoirs, the device exhibited good electrochemical performance (about 1.73 mF cm-2), and a transmittance of about 56% (at 550 nm). Electronic supplementary information (ESI) available: Experimental, TEM image, IR spectra, and XRD spectra of cellulose nanofibers, TEM image, and XRD spectra of RGO, graphite, GO nanosheets, CNF paper, and CNF-[RGO]20 hybrid paper, high-resolution C1s spectra of GO, Raman spectra of GO nanosheets, cross-sectional FESEM image of CNF-[RGO]20 hybrid paper and stress-strain curve of T-SC-20. See DOI: 10.1039/c3nr00674c

Gao, Kezheng; Shao, Ziqiang; Wu, Xue; Wang, Xi; Zhang, Yunhua; Wang, Wenjun; Wang, Feijun

2013-05-01

381

High temperature transparent furnace development  

Microsoft Academic Search

A prototype transparent furnace was designed, fabricated, and tested at temperatures up to 1473 K. Radiation containment using an outer infrared mirror tube and convection elimination using vacuum insulation reduce electrical power consumption and heat loads on critical components. High vacuum was necessary to eliminate convection; even 0.001% atmosphere pressure caused large convective heat losses. A heat transfer model was

Stephen C. Bates; Kim S. Knight; David W. Yoel

1998-01-01

382

Three-terminal resistive switching memory in a transparent vertical-configuration device  

SciTech Connect

The resistive switching phenomenon has attracted much attention recently for memory applications. It describes the reversible change in the resistance of a dielectric between two non-volatile states by the application of electrical pulses. Typical resistive switching memories are two-terminal devices formed by an oxide layer placed between two metal electrodes. Here, we report on the fabrication and operation of a three-terminal resistive switching memory that works as a reconfigurable logic component and offers an increased logic density on chip. The three-terminal memory device we present is transparent and could be further incorporated in transparent computing electronic technologies.

Ungureanu, Mariana; Llopis, Roger [CIC nanoGUNE Consolider, Donostia - San Sebastian (Spain)] [CIC nanoGUNE Consolider, Donostia - San Sebastian (Spain); Casanova, Fèlix; Hueso, Luis E. [CIC nanoGUNE Consolider, Donostia - San Sebastian (Spain) [CIC nanoGUNE Consolider, Donostia - San Sebastian (Spain); Ikerbasque, Basque Foundation for Science, Bilbao (Spain)

2014-01-06

383

Optimization of Ferroelectric PolymerGraphene Films for Transparent and Flexible Electronics  

NASA Astrophysics Data System (ADS)

Nonvolatile, electrostatic doping of graphene-based devices with ferroelectric polymers such as Poly (vinylidene fluoride-trifluoroethylene) are promising for realizing ultra-fast, flexible memory devices, nanogenerators and actuators. More recently, the same approach has been shown to provide an alternative route in enabling graphene based transparent electrodes for touch screen applications. Here, we report a systematic study of optimizing the ferroelectric polymer-graphene heterostructure as a function of thickness, various copolymer blends and coating techniques. Optimized films show outstanding mechanical properties, low sheet resistance (˜ 100?/sq) and optical transparency levels as high as 96%.

Kahya, Orhan; Wu, Jing; Ni, Guang-Xin; Toh, Chee-Tat; Bae, Sang-Hoon; Ahn, Jong-Hyun; Oezyilmaz, Barbaros

2013-03-01

384

Generalized counter-rotating oscillators: Mixed synchronization  

E-print Network

In this paper, we report mixed synchronization between two counter rotating chaotic oscillators. We describe a procedure how to obtain a counter rotating oscillator for generalized oscillators. We elaborate the method with numerical examples of the Sprott system, Pikovsky-Rabinovich (PR) circuit model. Noise-induced mixed synchronization is also reported in PR circuit model. The physical realization of mixed synchronization in an electronic circuit of two counters-rotating Sprott systems also shown.

Sourav K. Bhowmick; Bidesh K. Bera; Dibakar Ghosh

2014-12-18

385

All solution-processed, fully transparent resistive memory devices.  

PubMed

We fabricated all-solution processed, fully transparent resistive random access memory (sol-TRRAM) with a configuration of ITO/GaZnO(GZO)/ITO. All layers, including an active layer and top and bottom ITO electrodes, were deposited on a glass substrate by either spin coating or inkjet printing using a sol-gel solution. Our sol-TRRAM was transparent, with 86.5% transmittance at 550 nm. An initial forming process is unnecessary for the production of transparent memory due to the presence of sufficient inherent nonlattice oxygen ions in the solution-processed GZO layer. The sol-TRRAM also showed reasonable bipolar resistance switching with a low operation current (<100 ?A) and excellent cycle endurance properties (>300 cycles). The main conduction mechanism during the set process can be explained by the trap-controlled space-charge limited conduction, and the resistance change occurred by the modification of the potential barrier height because of the charge injection by Fowler-Nordheim tunneling. PMID:22010837

Kim, Areum; Song, Keunkyu; Kim, Youngwoo; Moon, Jooho

2011-11-01

386

Study of Influence of Electrode Geometry on Impedance Spectroscopy  

SciTech Connect

Electrochemical Impedance Spectroscopy (EIS) is a powerful and proven tool for analyzing AC impedance response. A conventional three electrode EIS method was used to perform the investigation in the present study. Saturated potassium chloride solution was used as the electrolyte and three different material rods were used as working electrodes. Different configurations of electrode area were exposed to the electrolyte as an active area to investigate electrode geometry effects. Counter to working electrode distance was also altered while keeping the working electrode effective area constant to explore the AC response dependence on the variation of ion travel distance. Some controlled experiments were done to validate the experimental setup and to provide a control condition for comparison with experimental results. A frequency range of 100 mHz to 1 MHz was used for all experiments. In our analysis, we have found a noteworthy influence of electrode geometry on AC impedance response. For all electrodes, impedance decreases with the increase of effective area of the electrolyte. High frequency impedance is not as dependent on geometry as low frequency response. The observed phase shift angle drops in the high frequency region with increased working electrode area, whereas at low frequency the reverse is true. Resistance and capacitive reactance both decrease with an increase of area, but resistance response is more pronounce than reactance. For lower frequencies, small changes in working area produce very distinctive EIS variations. Electrode material as well as geometry was systematically varied in the present study. From these and other studies, we hope to develop a fundamental foundation for understanding specific changes in local geometry in fuel cell (and other) electrodes as a method of designing local morphology for specific performance.

Ahmed, Riaz; Reifsnider, Kenneth L

2011-01-01

387

Transparent and Flexible Carbon Nanotube Transistors  

E-print Network

Transparent and Flexible Carbon Nanotube Transistors E. Artukovic, M. Kaempgen, D. S. Hecht, S We report the fabrication of transparent and flexible transistors where both the bottom gate not influence the transmission in the visible spectral range. The quest for flexible and transparent transistors

Gruner, George

388

Transparent metals for ultrabroadband electromagnetic waves.  

PubMed

Making metals transparent, which could lead to fascinating applications, has long been pursued. Here we demonstrate that with narrow slit arrays metallic plates become transparent for extremely broad bandwidths; the high transmission efficiency is insensitive to the metal thickness. This work provides a guideline to develop novel devices, including transparent conducting panels, broadband metamaterials, and antireflective solar cells. PMID:22431279

Fan, Ren-Hao; Peng, Ru-Wen; Huang, Xian-Rong; Li, Jia; Liu, Yongmin; Hu, Qing; Wang, Mu; Zhang, Xiang

2012-04-17

389

Transparency and Oversight in Local Wellness Policies  

ERIC Educational Resources Information Center

Background: Advocates have called for increased wellness policy transparency and oversight through the use of health advisory councils. This study examines (1) wellness policy transparency, (2) advisory council requirements, (3) factors associated with each, and (4) whether transparency or advisory council requirements are indicative of a stronger…

Chriqui, Jamie F.; Chaloupka, Frank J.

2011-01-01

390

Growth and characterization of transparent Pb(Zi, Ti)O{sub 3} capacitor on glass substrate.  

SciTech Connect

(Pb)(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} (PZT) films were fabricated on LaNiO{sub 3} (LNO)/In{sub 2}O{sub 3} 90%SnO{sub 2}10% (ITO) layered transparent electrodes on glass substrates using chemical solution deposition. The structural, electrical, and optical properties of semitransparent Pd/PZT/LNO/ITO and transparent ITO/LNO/PZT/LNO/ITO capacitors fabricated on glass substrates were studied. X-ray diffraction revealed an improved crystalline structure of PZT on ITO-buffered glass substrates by interposing a LNO layer between PZT and ITO. Atomic force microscopy showed a smoother surface topography for the LNO/ITO layered electrode on glass, as compared to that of the single ITO layer on glass. The remnant polarization (P{sub r}) of the Pd/PZT/LNO/ITO/glass capacitors and transparent ITO/LNO/PZT/LNO/ITO/glass capacitors was estimated from P-E hysteresis loops. The Pd/PZT/LNO/ITO capacitors on glass revealed significant improvement in the P{sub r} as compared to PZT film based capacitors with ITO electrodes only. Excellent optical transmittance was observed for the whole capacitor structure. The importance of a high performance transparent capacitor is that this structure may enable high efficiency transparent electronic devices such as solar energy storage, photovoltaic, and intelligent windows, among others.

Uprety, K. K.; Ocola, L. E.; Auciello, O.

2007-10-15

391

Evaluation of waste crate counter  

SciTech Connect

A novel nondestructive measurement system has been developed to perform combined gamma-ray, passive neutron, and active neutron analyses of radioactive waste packaged in large crates. The system will be used to examine low level and transuranic waste at the Waste Receiving and Processing facility at Westinghouse-Hanford Corp. Prior to delivery of the system, an extensive evaluation of its performance characteristics will be conducted. The evaluation is to include an assessment of the mechanical properties of the system, gamma-ray attenuation correction algorithms, instrument response as a function of source positions, performance of the high resolution gamma-ray detector for ``hot spot`` and isotopic analyses, active and passive neutron counter response, instrument sensitivity, matrix effects, and packaging effects. This report will discuss the findings of the evaluation program, to date, and indicate future directions for the program.

Wachter, J.R. [Los Alamos National Lab., NM (United States). Nuclear Materials Measurement and Accountability; Bieri, J.M. [Pajarito Scientific Corp., Los Alamos, NM (United States); Shaw, S.W. [Westinghouse Hanford Co., Richland, WA (United States)

1994-08-01

392

Compact multiwire proportional counters for the detection of fission fragments  

NASA Astrophysics Data System (ADS)

Two large area multistep position sensitive (two dimensional) multiwire proportional counters have been developed for experiments involving study of fission dynamics using general purpose scattering chamber facility at IUAC. Both detectors have an active area of 20×10 cm2 and provide position signals in horizontal (X) and vertical (Y) planes, timing signal for time of flight measurements and energy signal giving the differential energy loss in the active volume. The design features are optimized for the detection of low energy heavy ions at very low gas pressures. Special care was taken in setting up the readout electronics, constant fraction discriminators for position signals in particular, to get optimum position and timing resolutions along with high count rate handling capability of low energy heavy ions. A custom made charge sensitive preamplifier, having lower gain and shorter decay time, has been developed for extracting the differential energy loss signal. The position and time resolutions of the detectors were determined to be 1.1 mm full width at half maximum (FWHM) and 1.7 ns FWHM, respectively. The detector could handle heavy ion count rates exceeding 20 kHz without any breakdown. Time of flight signal in combination with differential energy loss signal gives a clean separation of fission fragments from projectile and target like particles. The timing and position signals of the detectors are used for fission coincidence measurements and subsequent extraction of their mass, angular, and total kinetic energy distributions. This article describes systematic study of these fission counters in terms of efficiency, time resolution, count rate handling capability, position resolution, and the readout electronics. The detector has been operated with both five electrode geometry and four electrode geometry, and a comparison has been made in their performances.

Jhingan, Akhil; Sugathan, P.; Golda, K. S.; Singh, R. P.; Varughese, T.; Singh, Hardev; Behera, B. R.; Mandal, S. K.

2009-12-01

393

Dipole-Induced Electromagnetic Transparency  

E-print Network

We determine the optical response of a thin and dense layer of interacting quantum emitters. We show that in such a dense system, the Lorentz redshift and the associated interaction broadening can be used to control the transmission and reflection spectra. In the presence of overlapping resonances, a Dipole-Induced Electromagnetic Transparency (DIET) regime, similar to Electromagnetically Induced Transparency (EIT), may be achieved. DIET relies on destructive interference between the electromagnetic waves emitted by quantum emitters. Carefully tuning material parameters allows to achieve narrow transmission windows in otherwise completely opaque media. We analyze in details this coherent and collective effect using a generalized Lorentz model and show how it can be controlled. Several potential applications of the phenomenon, such as slow light, are proposed.

Raiju Puthumpally-Joseph; Maxim Sukharev; Osman Atabek; Eric Charron

2014-07-08

394

Dipole-induced electromagnetic transparency.  

PubMed

We determine the optical response of a thin and dense layer of interacting quantum emitters. We show that, in such a dense system, the Lorentz redshift and the associated interaction broadening can be used to control the transmission and reflection spectra. In the presence of overlapping resonances, a dipole-induced electromagnetic transparency (DIET) regime, similar to electromagnetically induced transparency (EIT), may be achieved. DIET relies on destructive interference between the electromagnetic waves emitted by quantum emitters. Carefully tuning material parameters allows us to achieve narrow transmission windows in, otherwise, completely opaque media. We analyze in detail this coherent and collective effect using a generalized Lorentz model and show how it can be controlled. Several potential applications of the phenomenon, such as slow light, are proposed. PMID:25361258

Puthumpally-Joseph, Raiju; Sukharev, Maxim; Atabek, Osman; Charron, Eric

2014-10-17

395

Gyromagnetically Induced Transparency of Metasurfaces  

NASA Astrophysics Data System (ADS)

We demonstrate that the presence of a (gyro) magnetic substrate can produce an analog of electromagnetically induced transparency in Fano-resonant metamolecules. The simplest implementation of such gyromagnetically induced transparency (GIT) in a metasurface, comprised of an array of resonant antenna pairs placed on a gyromagnetic substrate and illuminated by a normally incident electromagnetic wave, is analyzed. Time reversal and spatial inversion symmetry breaking introduced by the dc magnetization makes metamolecules bianisotropic. This causes Fano interference between the otherwise uncoupled symmetric and antisymmetric resonances of the metamolecules giving rise to a sharp transmission peak through the otherwise reflective metasurface. We show that, for an oblique wave incidence, one-way GIT can be achieved by the combination of spatial dispersion and gyromagnetic effect. These theoretically predicted phenomena pave the way to nonreciprocal switches and isolators that can be dynamically controlled by electric currents.

Mousavi, S. Hossein; Khanikaev, Alexander B.; Allen, Jeffery; Allen, Monica; Shvets, Gennady

2014-03-01

396

NANOCELLULOSE REINFORCEMENT OF TRANSPARENT COMPOSITES  

E-print Network

In this work, we evaluate the impact of nanocellulose reinforcement on transparent composite properties. Due to the small diameter, high modulus, and high strength of cellulose nanocrystals, transparent composites that utilize these materials should show improvement in bulk mechanical performances without a corresponding reduction in optical properties. In this study composites were reinforced using dispersed nanoparticles as well as continuous architecture developed from hydrogel-based processes. Poly(methyl methacrylate) and Bisphenol F resin systems were integrated with nanocellulose of varying crystallinity, fiber size, and surface functionalization. Mechanical performance was determined from dual cantilever dynamic analysis, tensile, and charpy tests following ASTM standards. Optical properties were evaluated for transmittance and scattering behavior, and compared to baseline studies of aqueous and organic solvent dispersions. 1.

Joshua Steele; Hong Dong; James F. Snyder; Josh A. Orlicki; Richard S. Reiner; Alan W. Rudie

397

Gyromagnetically induced transparency of metasurfaces.  

PubMed

We demonstrate that the presence of a (gyro) magnetic substrate can produce an analog of electromagnetically induced transparency in Fano-resonant metamolecules. The simplest implementation of such gyromagnetically induced transparency (GIT) in a metasurface, comprised of an array of resonant antenna pairs placed on a gyromagnetic substrate and illuminated by a normally incident electromagnetic wave, is analyzed. Time reversal and spatial inversion symmetry breaking introduced by the dc magnetization makes metamolecules bianisotropic. This causes Fano interference between the otherwise uncoupled symmetric and antisymmetric resonances of the metamolecules giving rise to a sharp transmission peak through the otherwise reflective metasurface. We show that, for an oblique wave incidence, one-way GIT can be achieved by the combination of spatial dispersion and gyromagnetic effect. These theoretically predicted phenomena pave the way to nonreciprocal switches and isolators that can be dynamically controlled by electric currents. PMID:24702414

Mousavi, S Hossein; Khanikaev, Alexander B; Allen, Jeffery; Allen, Monica; Shvets, Gennady

2014-03-21

398

Dipole-Induced Electromagnetic Transparency  

NASA Astrophysics Data System (ADS)

We determine the optical response of a thin and dense layer of interacting quantum emitters. We show that, in such a dense system, the Lorentz redshift and the associated interaction broadening can be used to control the transmission and reflection spectra. In the presence of overlapping resonances, a dipole-induced electromagnetic transparency (DIET) regime, similar to electromagnetically induced transparency (EIT), may be achieved. DIET relies on destructive interference between the electromagnetic waves emitted by quantum emitters. Carefully tuning material parameters allows us to achieve narrow transmission windows in, otherwise, completely opaque media. We analyze in detail this coherent and collective effect using a generalized Lorentz model and show how it can be controlled. Several potential applications of the phenomenon, such as slow light, are proposed.

Puthumpally-Joseph, Raiju; Sukharev, Maxim; Atabek, Osman; Charron, Eric

2014-10-01

399

Monolithic Parallel Tandem Organic Photovoltaic Cell with Transparent Carbon Nanotube Interlayer  

NASA Technical Reports Server (NTRS)

We demonstrate an organic photovoltaic cell with a monolithic tandem structure in parallel connection. Transparent multiwalled carbon nanotube sheets are used as an interlayer anode electrode for this parallel tandem. The characteristics of front and back cells are measured independently. The short circuit current density of the parallel tandem cell is larger than the currents of each individual cell. The wavelength dependence of photocurrent for the parallel tandem cell shows the superposition spectrum of the two spectral sensitivities of the front and back cells. The monolithic three-electrode photovoltaic cell indeed operates as a parallel tandem with improved efficiency.

Tanaka, S.; Mielczarek, K.; Ovalle-Robles, R.; Wang, B.; Hsu, D.; Zakhidov, A. A.

2009-01-01

400

A focusing gas scintillation proportional counter  

NASA Technical Reports Server (NTRS)

An improved large-area gas scintillation proportional counter has been built, suitable for use in X-ray astronomy. This counter employs electron focusing in a drift region to achieve uniform response. It is shown that a window area of 60 sq cm and a spectral resolution of 10% fwhm or better at 5.9 keV can be obtained.

Anderson, D. F.; Bodine, O. H.; Novick, R.; Wolff, R. S.

1977-01-01

401

Israel-EU Cooperation on Counter Terrorism  

Microsoft Academic Search

This chapter evaluates the nature of counter terrorism cooperation between the EU and Israel in recent years. Counter terrorism policy and cooperation comprise a spectrum of activities ranging from declaratory statements, through intelligence exchange and police operations, to micro interventions and finally the large scale use of military force (Lassse 2002: 43-50). Both in Israel and the EU there are

Limor Nobel

402

Countering Aging Effects through Field Gate Sizing  

E-print Network

COUNTERING AGING EFFECTS THROUGH FIELD GATE SIZING A Thesis by TRENTON DEAN HENRICHSON Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 2008 Major Subject: Computer Engineering COUNTERING AGING EFFECTS THROUGH FIELD GATE SIZING A Thesis by TRENTON DEAN HENRICHSON Submitted...

Henrichson, Trenton D.

2010-01-14

403

Optically transparent/colorless polyimides  

NASA Technical Reports Server (NTRS)

Several series of linear aromatic polyimide films have been synthesized and characterized with the objective of obtaining maximum optical transparency. Two approaches have been used as part of this structure-property relationship study. The first approach is to vary the molecular structure so as to separate chromophoric centers and reduce electronic interactions between polymer chains to lower the intensity of color in the resulting polymer films. A second and concurrent approach is to perform polymerizations with highly purified monomers. Glass transition temperatures of thermally cured polyimide films are obtained by thermomechanical analysis and thermal decomposition temperatures are determined by thermogravimetric analysis. Transmittance UV-visible spectra of the polyimide films are compared to that of a commercial polyimide film. Fully imidized films are tested for solubility in common organic solvents. The more transparent films prepared in this study are evaluated for use on second-surface mirror thermal control coating systems. Lightly colored to colorless films are characterized by UV-visible spectroscopy before and after exposure to 300 equivalent solar hours UV irradiation and varying doses of 1 MeV electron irradiation. The effects of monomer purity, casting solvent and cure atmosphere on polyimide film transparency are also investigated.

Stclair, A. K.; Stclair, T. L.; Slemp, W.; Ezzell, K. S.

1985-01-01

404

Nanoscopic electrode molecular probes  

DOEpatents

The present invention relates to a method and apparatus for enhancing the electron transport property measurements of a molecule when the molecule is placed between chemically functionalized carbon-based nanoscopic electrodes to which a suitable voltage bias is applied. The invention includes selecting a dopant atom for the nanoscopic electrodes, the dopant atoms being chemically similar to atoms present in the molecule, and functionalizing the outer surface and terminations of the electrodes with the dopant atoms.

Krstic, Predrag S. (Knoxville, TN); Meunier, Vincent (Knoxville, TN)

2012-05-22

405

Transparent polymer solar cells employing a layered light-trapping architecture  

NASA Astrophysics Data System (ADS)

Organic solar cells have unique properties that make them very attractive as a renewable energy source. Of particular interest are semi-transparent cells, which have the potential to be integrated into building façades yet not completely block light. However, making organic cells transparent limits the metal electrode thickness to a few nanometres, drastically reducing its reflectivity and the device photon-harvesting capacity. Here, we propose and implement an ad hoc path for light-harvesting recovery to bring the photon-to-charge conversion up to almost 80% that of its opaque counterpart. We report semi-transparent PTB7:PC71BM cells that exhibit 30% visible light transmission and 5.6% power conversion efficiency. Non-periodic photonic crystals are used to trap near-infrared and near-ultraviolet photons. By modifying the layer structure it is possible to tune the device colour without significantly altering cell performance.

Betancur, Rafael; Romero-Gomez, Pablo; Martinez-Otero, Alberto; Elias, Xavier; Maymó, Marc; Martorell, Jordi

2013-12-01

406

Pocket ECG electrode  

NASA Technical Reports Server (NTRS)

A low noise electrode suited for sensing electrocardiograms when chronically and subcutaneously implanted in a free ranging subject is described. The electrode comprises a pocket shaped electrically conductive member with a single entrance adapted to receive body fluids. The exterior of the member and the entrance region is coated with electrical insulation so that the only electrolyte/electrode interface is within the member, remote from artifact-generating tissue. Cloth straps are bonded to the member to permit the electrode to be sutured to tissue and to provide electrical lead flexure relief.

Lund, G. F. (inventor)

1980-01-01

407

Pocket ECG electrode  

NASA Technical Reports Server (NTRS)

A low-noise electrode suited for sensing electrocardiograms when chronically and subcutaneously implanted in a free-ranging subject. The electrode comprises a pocket-shaped electrically conductive member with a single entrance adapted to receive body fluids. The exterior of the member and the entrance region is coated with electrical insulation so that the only electrolyte/electrode interface is within the member remote from artifact-generating tissue. Cloth straps are bonded to the member to permit the electrode to be sutured to tissue and to provide electrical lead flexure relief.

Lund, Gordon F. (Inventor)

1982-01-01

408

Optical phase modulator utilizing a transparent piezofilm for use with the extrinsic fiber interferometer  

NASA Astrophysics Data System (ADS)

A piezoelectnc polyvinylidene flouride (PVF2) film with transparent indium tin oxide electrode metallization is placed directly in the path of a single mode fiber output, to form an extrinsic optical interferometer. This device can be used concurrently with another extrinsic inteferometer on a fiber directional coupler to generate a carrier phase modulation on which the signal phase shift is superimposed. Experimental results of the induced phase shifting coefficient are presented for two arrangements of the piezofilm differing in their boundary clamping conditions.

Sudarshanam, V. S.; Claus, Richard O.

1993-03-01

409

21 CFR 864.5200 - Automated cell counter.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Automated cell counter. 864.5200 Section 864.5200...Hematology Devices § 864.5200 Automated cell counter. (a) Identification. An automated cell counter is a fully-automated or...

2013-04-01

410

21 CFR 864.5220 - Automated differential cell counter.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Automated differential cell counter. 864.5220 Section 864... § 864.5220 Automated differential cell counter. (a) Identification. An automated differential cell counter is a device used to...

2011-04-01

411

21 CFR 864.5220 - Automated differential cell counter.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Automated differential cell counter. 864.5220 Section 864... § 864.5220 Automated differential cell counter. (a) Identification. An automated differential cell counter is a device used to...

2010-04-01

412

21 CFR 864.5200 - Automated cell counter.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Automated cell counter. 864.5200 Section 864.5200...Hematology Devices § 864.5200 Automated cell counter. (a) Identification. An automated cell counter is a fully-automated or...

2011-04-01

413

21 CFR 864.5200 - Automated cell counter.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Automated cell counter. 864.5200 Section 864.5200...Hematology Devices § 864.5200 Automated cell counter. (a) Identification. An automated cell counter is a fully-automated or...

2010-04-01

414

21 CFR 864.5220 - Automated differential cell counter.  

...2014-04-01 false Automated differential cell counter. 864.5220 Section 864... § 864.5220 Automated differential cell counter. (a) Identification. An automated differential cell counter is a device used to...

2014-04-01

415

21 CFR 864.5200 - Automated cell counter.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Automated cell counter. 864.5200 Section 864.5200...Hematology Devices § 864.5200 Automated cell counter. (a) Identification. An automated cell counter is a fully-automated or...

2012-04-01

416

21 CFR 864.5220 - Automated differential cell counter.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Automated differential cell counter. 864.5220 Section 864... § 864.5220 Automated differential cell counter. (a) Identification. An automated differential cell counter is a device used to...

2013-04-01

417

21 CFR 864.5220 - Automated differential cell counter.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Automated differential cell counter. 864.5220 Section 864... § 864.5220 Automated differential cell counter. (a) Identification. An automated differential cell counter is a device used to...

2012-04-01

418

21 CFR 864.5200 - Automated cell counter.  

...2014-04-01 2014-04-01 false Automated cell counter. 864.5200 Section 864.5200...Hematology Devices § 864.5200 Automated cell counter. (a) Identification. An automated cell counter is a fully-automated or...

2014-04-01

419

Fully transparent quantum dot light-emitting diode integrated with graphene anode and cathode.  

PubMed

A fully transparent quantum dot light-emitting diode (QD-LED) was fabricated by incorporating two types (anode and cathode) of graphene-based electrodes, which were controlled in their work functions and sheet resistances. Either gold nanoparticles or silver nanowires were inserted between layers of graphene to control the work function, whereas the sheet resistance was determined by the number of graphene layers. The inserted gold nanoparticles or silver nanowires in graphene films caused a charge transfer and changed the work function to 4.9 and 4.3 eV, respectively, from the original work function (4.5 eV) of pristine graphene. Moreover the sheet resistance values for the anode and cathode electrodes were improved from ?63?000 to ?110 ?/sq and from ?100?000 to ?741 ?/sq as the number of graphene layers increased from 1 to 12 and from 1 to 8, respectively. The main peak wavelength, luminance, current efficiency, and optical transmittance of the fully transparent QD-LED integrated with graphene anode and cathode were 535 nm, ?358 cd/m(2), ?0.45 cd/A, and 70-80%, respectively. The findings of the study are expected to lay a foundation for the production of high-efficiency, fully transparent, and flexible displays using graphene-based electrodes. PMID:25426762

Seo, Jung-Tak; Han, Junebeom; Lim, Taekyung; Lee, Ki-Heon; Hwang, Jungseek; Yang, Heesun; Ju, Sanghyun

2014-12-23

420

Monte Carlo Shower Counter Studies  

NASA Technical Reports Server (NTRS)

Activities and accomplishments related to the Monte Carlo shower counter studies are summarized. A tape of the VMS version of the GEANT software was obtained and installed on the central computer at Gallaudet University. Due to difficulties encountered in updating this VMS version, a decision was made to switch to the UNIX version of the package. This version was installed and used to generate the set of data files currently accessed by various analysis programs. The GEANT software was used to write files of data for positron and proton showers. Showers were simulated for a detector consisting of 50 alternating layers of lead and scintillator. Each file consisted of 1000 events at each of the following energies: 0.1, 0.5, 2.0, 10, 44, and 200 GeV. Data analysis activities related to clustering, chi square, and likelihood analyses are summarized. Source code for the GEANT user subprograms and data analysis programs are provided along with example data plots.

Snyder, H. David

1991-01-01

421

Membrane Bioprobe Electrodes  

ERIC Educational Resources Information Center

Describes the design of ion selective electrodes coupled with immobilized enzymes which operate either continuously or on drop-sized samples. Cites techniques for urea, L-phenylalanine and amygdalin. Micro size electrodes for use in single cells are discussed. (GH)

Rechnitz, Garry A.

1975-01-01

422

Electrostatic curved electrode actuators  

Microsoft Academic Search

This paper presents the design and performance of an electrostatic actuator consisting of a laterally compliant cantilever beam and a fixed curved electrode, both suspended above a ground plane. A theoretical description of the static behavior of the cantilever as it is pulled into contact with the rigid fixed-electrode structure is given. Two models are presented: a simplified semi-analytical model

Rob Legtenberg; John Gilbert; Stephen D. Senturia; Miko Elwenspoek

1997-01-01

423

Electrostatic curved electrode actuators  

Microsoft Academic Search

In this paper, the design, fabrication, and first experimental results of electrostatic curved electrode actuators are addressed. The actuator design is based upon the deformation of a movable micromechanical structure by electrostatic forces using a fixed curved electrode. When a voltage is applied, an electrostatic force is created that will deform the free structure along the outline of the fixed

Rob Legtenberg; Erwin Berenschot; Miko Elwenspoek; J. H. J. Fluitman

1995-01-01

424

Electrode Type and Placement Configuration for Quadriceps Activation Evaluation  

PubMed Central

Context: The ability to accurately estimate quadriceps voluntary activation is an important tool for assessing neuromuscular function after a variety of knee injuries. Different techniques have been used to assess quadriceps volitional activation, including various stimulating electrode types and electrode configurations, yet the optimal electrode types and configurations for depolarizing motor units in the attempt to assess muscle activation are unknown. Objective: To determine whether stimulating electrode type and configuration affect quadriceps central activation ratio (CAR) and percentage-of-activation measurements in healthy participants. Design: Crossover study. Setting: Research laboratory. Patients and Other Participants: Twenty participants (13 men, 7 women; age = 26 ± 5.3 years, height = 173.85 ± 7.3 cm, mass = 77.37 ± 16 kg) volunteered. Intervention(s): All participants performed 4 counter-balanced muscle activation tests incorporating 2 different electrode types (self-adhesive, carbon-impregnated) and 2 electrode configurations (vastus, rectus). Main Outcome Measure(s): Quadriceps activation was calculated with the CAR and percentage-of-activation equations, which were derived from superimposed burst and resting torque measurements. Results: No differences were found between conditions for CAR and percentage-of-activation measurements, whereas resting twitch torque was higher in the rectus configuration for both self-adhesive (216 ± 66.98 Nm) and carbon-impregnated (209.1 ± 68.22 Nm) electrodes than in the vastus configuration (209.5 ± 65.5 Nm and 204 ± 62.7 Nm, respectively) for these electrode types (F1,19 = 4.87, P = .04). In addition, resting twitch torque was greater for both electrode configurations with self-adhesive electrodes than with carbon-impregnated electrodes (F1,19 = 9.33, P = .007). Bland-Altman plots revealed acceptable mean differences for agreement between electrode type and configuration for CAR and percentage of activation, but limits of agreement were wide. Conclusions: Although these electrode configurations and types might not necessarily be able to be used interchangeably, differences in electrode type and configuration did not seem to affect CAR and percentage-of-activation outcome measures. PMID:22488187

Pietrosimone, Brian G.; Selkow, Noelle M.; Ingersoll, Christopher D.; Hart, Joseph M.; Saliba, Susan A.

2011-01-01

425

Transparent redundant computing with MPI.  

SciTech Connect

Extreme-scale parallel systems will require alternative methods for applications to maintain current levels of uninterrupted execution. Redundant computation is one approach to consider, if the benefits of increased resiliency outweigh the cost of consuming additional resources. We describe a transparent redundancy approach for MPI applications and detail two different implementations that provide the ability to tolerate a range of failure scenarios, including loss of application processes and connectivity.We compare these two approaches and show performance results from micro-benchmarks that bound worst-case message passing performance degradation.We propose several enhancements that could lower the overhead of providing resiliency through redundancy.

Riesen, Rolf E.; Ferreira, Kurt Brian; Brightwell, Ronald Brian

2010-04-01

426

Is Every Transparent Liquid Water?  

NASA Astrophysics Data System (ADS)

The accepted description for water in schools worldwide is a transparent and colorless liquid. Since students in lower grades (ages 8-13) often see warning signs "Do not drink this liquid--it is not water", we believe that presenting experiments that demonstrate the inadequacy of the accepted description for water would be beneficial for teachers and their students to practice in their schools. These activities provide simple experiments that introduce students to important characteristics of different compounds that have similar external appearance. The characteristics presented here include polarity, electric conductivity, color change due to presence of an acid-base indicator, and electrolysis.

Hugerat, Muhamad; Basheer, Sobhi

2001-08-01

427

Accountability, Transparency, and Inflation Targeting  

E-print Network

Inflation targeting regimes define a performance measure for the central bank. A regime that places a large (small) weight on achieving the target is analogous to a high (low) power incentive scheme. High powered incentive structures promote accountability but may distort stabilization policy. The optimal power under inflation targeting is derived under perfect and imperfect information. The fundamental trade off between accountability and stabilization depends on the degree of transparency, defined as the ability to monitor the central banks performance. Multiplicative uncertainty increases the optimal weight to place on achieving an inflation target.

Carl E. Walsh

2001-01-01

428

Advanced electrodes for AMTEC  

SciTech Connect

Texas A&M University has begun an investigation of materials and fabrication methods which will improve AMTEC electrode performance. The study currently involves gathering data on materials which meet the basic requirements of operating in an AMTEC cell, and sorting out candidates possessing characteristics conducive to efficient AMTEC operation. An initial assessment has shown Iridium as a promising metal electrode candidate. Sodium-containing double-oxides, with melting temperatures above AMTEC operating temperatures, including NaNbO{sub 3} and Na{sub 2}Ti{sub 3}O{sub 7}, have been identified as possible electrode dopants, to enhance the sodium conductivity of an electrode. Photo-deposition and Evaporative-deposition will be investigated further as electrode fabrication techniques. {copyright} {ital 1999 American Institute of Physics.}

Fiebig, Brad; Schuller, Michael; Hudson, Patricia [Center for Space Power, Texas AM University, College Station, Texas 77843 (United States); Williams, Roger [Jet Propulsion Laboratory, 4800 Oak Grove Dr., Pasadena, California 91109 (United States)

1999-01-01

429

Bifunctional catalytic electrode  

NASA Technical Reports Server (NTRS)

The present invention relates to an oxygen electrode for a unitized regenerative hydrogen-oxygen fuel cell and the unitized regenerative fuel cell having the oxygen electrode. The oxygen electrode contains components electrocatalytically active for the evolution of oxygen from water and the reduction of oxygen to water, and has a structure that supports the flow of both water and gases between the catalytically active surface and a flow field or electrode chamber for bulk flow of the fluids. The electrode has an electrocatalyst layer and a diffusion backing layer interspersed with hydrophilic and hydrophobic regions. The diffusion backing layer consists of a metal core having gas diffusion structures bonded to the metal core.

Cisar, Alan (Inventor); Murphy, Oliver J. (Inventor); Clarke, Eric (Inventor)

2005-01-01

430

Electrodes for microfluidic applications  

DOEpatents

An electrode device for high pressure applications. These electrodes, designed to withstand pressure of greater than 10,000 psi, are adapted for use in microfluidic devices that employ electrokinetic or electrophoretic flow. The electrode is composed, generally, of an outer electrically insulating tubular body having a porous ceramic frit material disposed in one end of the outer body. The pores of the porous ceramic material are filled with an ion conductive polymer resin. A conductive material situated on the upper surface of the porous ceramic frit material and, thus isolated from direct contact with the electrolyte, forms a gas diffusion electrode. A metal current collector, in contact with the gas diffusion electrode, provides connection to a voltage source.

Crocker, Robert W. (Fremont, CA); Harnett, Cindy K. (Livermore, CA); Rognlien, Judith L. (Livermore, CA)

2006-08-22

431

Transparency and social responsibility issues for Wikipedia  

Microsoft Academic Search

Wikipedia is known as a free online encyclopedia. Wikipedia uses largely transparent writing and editing processes, which\\u000a aim at providing the user with quality information through a democratic collaborative system. However, one aspect of these\\u000a processes is not transparent—the identity of contributors, editors, and administrators. We argue that this particular lack\\u000a of transparency jeopardizes the validity of the information being

Adele Santana; Donna J. Wood

2009-01-01

432

Metamaterial transparency induced by cooperative electromagnetic interactions  

E-print Network

We propose a cooperative asymmetry-induced transparency, CAIT, formed by collective excitations in metamaterial arrays of discrete resonators. CAIT can display a sharp transmission resonance even when the constituent resonators individually exhibit broad resonances. We further show how dynamically reconfiguring the metamaterial allows one to actively control the transparency. While reminiscent of electromagnetically induced transparency, which can be described by independent emitters, CAIT relies on a cooperative response resulting from strong radiative couplings between the resonators.

Stewart D. Jenkins; Janne Ruostekoski

2013-05-16

433

Metamaterial transparency induced by cooperative electromagnetic interactions.  

PubMed

We propose a cooperative asymmetry-induced transparency, CAIT, formed by collective excitations in metamaterial arrays of discrete resonators. CAIT can display a sharp transmission resonance even when the constituent resonators individually exhibit broad resonances. We further show how dynamically reconfiguring the metamaterial allows one to actively control the transparency. While reminiscent of electromagnetically induced transparency, which can be described by independent emitters, CAIT relies on a cooperative response resulting from strong radiative couplings between the resonators. PMID:24138271

Jenkins, Stewart D; Ruostekoski, Janne

2013-10-01

434

Transparent furnace made of heat mirror  

Microsoft Academic Search

A new type of transparent furnace was fabricated with a heat mirror, a glass–ceramic (Neoceram-0) coated with an antimony-doped tin oxide (Sb–SnO2) film. It was compared with a gold furnace, which is the usual transparent furnace. Their performance was almost equivalent, so the Sb–SnO2-coated Neoceram is applicable to the transparent furnace.

M. Kojima; F. Takahashi; K. Kinoshita; T. Nishibe; M. Ichidate

2001-01-01

435

Foot-operated cell-counter  

NASA Technical Reports Server (NTRS)

Cell-counter for cell indices consists of a footboard with four pressure sensitive switches and an enclosure for the components and circuitry. This device increases the operators efficiency by reducing the number of required hand movements.

Eisler, W. J., Jr.; Fry, R. J. M.; Le Buis, D.

1969-01-01

436

Position sensitive counter development at the linac  

SciTech Connect

In a novel application of the multiwire proportional counter we have imaged a collimated neutron beam. Although preliminary, the results are of sufficient import to be described here because of the potential wide application of the multiwire proportional counter to Laboratory problems. The counter was operated with a counting gas pressure of 20 Torr; the counting gas was pure C/sub 4/H/sub 10/. The radiator was a /sup 235/U foil. Under these conditions, the counter is (1) relatively insensitive to charged particles (other than fission fragments), (2) insensitive to ..gamma..-radiation, and (3) has an efficiency for the detection of fission fragments independent of incident neutron energy over a wide range of neutron energies.

Becker, J.A.

1981-05-20

437

Over-the-counter pain relievers  

MedlinePLUS

... Analgesics; Acetaminophen; NSAID; Non-steroidal anti-inflammatory drug; Pain medicine - over-the-counter; Pain medicine - OTC ... Pain medicines are also called analgesics. Each kind of pain medicine has benefits and risks. Some types of ...

438

New Horizons Student Dust Counter Education  

NSDL National Science Digital Library

Three Lessons - A Dusty Dilemma, Speaking Volumes About Dust, and The White Glove Test - are intended to familiarize students with the Student Dust Counter, data collection, and analysis. Accompanying the lessons is a Flash-based data viewer.

2010-12-31

439

COUNTER DISASTER AND RECOVERY PLAN -UNIVERSITY RECORDS  

E-print Network

COUNTER DISASTER AND RECOVERY PLAN - UNIVERSITY RECORDS Records Management & Archives Murdoch.2 Managing Vital Records............................................................19 5.2.1 Managing hardcopy vital records..........................................19 5.2.2 Managing vital electronic records

440

High temperature transparent furnace development  

NASA Astrophysics Data System (ADS)

A prototype transparent furnace was designed, fabricated, and tested at temperatures up to 1473 K. Radiation containment using an outer infrared mirror tube and convection elimination using vacuum insulation reduce electrical power consumption and heat loads on critical components. High vacuum was necessary to eliminate convection; even 0.001% atmosphere pressure caused large convective heat losses. A heat transfer model was developed to predict the behavior of the transparent furnace and permit projection of performance improvements resulting from design changes. The mirror tube that reflects infrared radiation and transmits some visible radiation was modified to eliminate radiation absorption in the mirror tube itself. Radiation shields were added to the ends of the furnace to further reduce radiative heat losses. Conductive heat losses were minimized by minimizing solid connections to the cooled furnace ends and by using quartz supports. All components were designed to survive high temperature operation. Extensive experiments were performed with a succession of preliminary prototypes, leading to a final prototype successfully tested at 1473 K.

Bates, Stephen C.; Knight, Kim S.; Yoel, David W.

1998-01-01

441

Preparation of transparent conductors ferroelectric memory materials and ferrites  

DOEpatents

A process for the preparation by electrodeposition of metal oxide film and powder compounds for ferroelectric memory materials and ferrites wherein the metal oxide includes a plurality of metals. The process comprises providing an electrodeposition bath, providing soluble salts of the metals to this bath, electrically energizing the bath to thereby cause formation of a recoverable film of metal on the electrode, recovering the resulta