Nanostructured hybrid ZnO thin films for energy conversion

PubMed Central

2011-01-01

We report on hybrid films based on ZnO/organic dye prepared by electrodeposition using tetrasulfonated copper phthalocyanines (TS-CuPc) and Eosin-Y (EoY). Both the morphology and porosity of hybrid ZnO films are highly dependent on the type of dyes used in the synthesis. High photosensitivity was observed for ZnO/EoY films, while a very weak photoresponse was obtained for ZnO/TS-CuPc films. Despite a higher absorption coefficient of TS-CuPc than EoY, in ZnO/EoY hybrid films, the excited photoelectrons between the EoY levels can be extracted through ZnO, and the porosity of ZnO/EoY can also be controlled. PMID:21711909

Zeolite-loaded poly(dimethylsiloxane) hybrid films for highly efficient thin-film microextraction of organic volatiles in water.

PubMed

Wang, Tao; Ansai, Toshihiro; Lee, Seung-Woo

2017-01-15

ZSM-5 zeolite-loaded poly(dimethylsiloxane) (PDMS) hybrid thin films were demonstrated for efficient thin-film microextraction (TFME) coupled with gas chromatography-mass spectrometry for analyzing organic volatiles in water. The extraction efficiency for a series of aliphatic alcohols and two aromatic compounds was significantly improved owing to the presence of ZSM-5 zeolites. The extraction efficiency of the hybrid films was increased in proportion to the content of ZSM-5 in the PDMS film, with 20wt% of ZSM-5 showing the best results. The 20wt% ZSM-5/PDMS hybrid film exhibited higher volatile organic content extraction compared with the single-component PDMS film or PDMS hybrid films containing other types of zeolite (e.g., SAPO-34). Limits of detection and limits of quantitation for individual analytes were in the range of 0.0034-0.049ppb and of 0.010-0.15 ppb, respectively. The effects of experimental parameters such as extraction time and temperature were optimized, and the molecular dispersion of the zeolites in/on the hybrid film matrix was confirmed with scanning electron microscopy and atomic force microscopy. Furthermore, the optimized hybrid film was preliminarily tested for the analysis of organic volatiles contained in commercially available soft drinks. Copyright © 2016 Elsevier B.V. All rights reserved.

Hybridization effects on wave packet dynamics in topological insulator thin films.

PubMed

Yar, Abdullah; Naeem, Muhammad; Khan, Safi Ullah; Sabeeh, Kashif

2017-11-22

Theoretical study of electron wave packet dynamics in topological insulator (TI) thin films is presented. We have investigated real space trajectories and spin dynamics of electron wave packets in TI thin films. Our focus is on the role of hybridization between the electronic states of the two surfaces. This allows us to access the crossover regime of a thick film with no hybridization to a thin film with finite hybridization. We show that the electron wave packet undergoes side-jump motion in addition to zitterbewegung. The oscillation frequency of zitterbewegung can be tuned by the strength of hybridization, which in turn can be tuned by the thickness of the film. We find that the spin expectations also exhibit zitterbewegung tunable by hybridization. We also show that it is possible to obtain persistent zitterbewegung, oscillations which do not decay, in both the real space trajectories as well as spin dynamics. The zitterbewegung oscillation frequency in TI thin films falls in a parameter regime where it might be possible to observe these effects using present day experimental techniques.

Organic/carbon nanotubes hybrid thin films for chemical detection

NASA Astrophysics Data System (ADS)

Banimuslem, Hikmat Adnan

Metallophthalocyanines (MPcs) are classified as an important class of conjugated materials and they possess several advantages attributed to their unique chemical structure. Carbon nanotubes (CNT), on the other hand, are known to enhance the properties of nano-composites in the conjugated molecules, due to their one dimensional electronic skeleton, high surface area and high aspect ratio. In this thesis, work has been carried out on the investigation of different substituted metal-phthalocyanines with the aim of developing novel hybrid film structures which incorporates these phthalocyanines and single-walled carbon nanotubes (SWCNT) for chemical detection applications. Octa-substituted copper phthalocyanines (CuPcR[8]) have been characterised using UV-visible absorption spectroscopy. Obtained spectra have yielded an evidence of a thermally induced molecular reorganization in the films. Influence of the nature of substituents in the phthalocyanine molecule on the thin films conductivity was also investigated. Octa-substituted lead (II) phthalocyanines (PbPcR[8]) have also been characterized using UV-visible spectroscopy. Sandwich structures of ITO/PbPcR[8]/In were prepared to investigate the electronic conduction in PbPcR[8]. The variation in the J(V) behavior of the films as a result of heat treatment is expected to be caused by changes in the alignment inside the columnar stacking of the molecules of the films. Thin films of non-covalently hybridised SWCNT and tetra-substituted copper phthalocyanine (CuPcR[4]) molecules have been produced. FTIR, DC conductivity, SEM and AFM results have revealed the [mathematical equation]; interaction between SWCNTs and CuPCR[4] molecules and shown that films obtained from the acid-treated SWCNTs/CuPcR[4] hybrids demonstrated more homogenous surface. Thin films of pristine CuPCR[4] and CuPcR[4]/S WCNT were prepared by spin coating onto gold-coated glass slides and applied as active layers for the detection of benzo

Developmental toxicity of CdTe QDs in zebrafish embryos and larvae

NASA Astrophysics Data System (ADS)

Duan, Junchao; Yu, Yongbo; Li, Yang; Yu, Yang; Li, Yanbo; Huang, Peili; Zhou, Xianqing; Peng, Shuangqing; Sun, Zhiwei

2013-07-01

Quantum dots (QDs) have widely been used in biomedical and biotechnological applications. However, few studies focus on the assessing toxicity of QDs exposure in vivo. In this study, zebrafish embryos were treated with CdTe QDs (4 nm) during 4-96 h post-fertilization (hpf). Mortality, hatching rate, malformation, heart rate, and QDs uptake were detected. We also measured the larval behavior to analyze whether QDs had persistent effects on larvae locomotor activity at 144 hpf. The results showed that as the exposure dosages increased, the hatching rate and heart rate of zebrafish embryos were decreased, while the mortality increased. Exposure to QDs caused embryonic malformations, including head malformation, pericardial edema, yolk sac edema, bent spine, and yolk not depleted. QDs fluorescence was mainly localized in the intestines region. The larval behavior testing showed that the total swimming distance was decreased in a dose-dependent manner. The lowest dose (2.5 nM QDs) produced substantial hyperactivity while the higher doses groups (5, 10, and 20 nM QDs) elicited remarkably hypoactivity in dark periods. In summary, the data of this article indicated that QDs caused embryonic developmental toxicity, resulted in persistent effects on larval behavior.

High-mobility ambipolar ZnO-graphene hybrid thin film transistors

PubMed Central

Song, Wooseok; Kwon, Soon Yeol; Myung, Sung; Jung, Min Wook; Kim, Seong Jun; Min, Bok Ki; Kang, Min-A; Kim, Sung Ho; Lim, Jongsun; An, Ki-Seok

2014-01-01

In order to combine advantages of ZnO thin film transistors (TFTs) with a high on-off ratio and graphene TFTs with extremely high carrier mobility, we present a facile methodology for fabricating ZnO thin film/graphene hybrid two-dimensional TFTs. Hybrid TFTs exhibited ambipolar behavior, an outstanding electron mobility of 329.7 ± 16.9 cm2/V·s, and a high on-off ratio of 105. The ambipolar behavior of the ZnO/graphene hybrid TFT with high electron mobility could be due to the superimposed density of states involving the donor states in the bandgap of ZnO thin films and the linear dispersion of monolayer graphene. We further established an applicable circuit model for understanding the improvement in carrier mobility of ZnO/graphene hybrid TFTs. PMID:24513629

High-mobility ambipolar ZnO-graphene hybrid thin film transistors.

PubMed

Song, Wooseok; Kwon, Soon Yeol; Myung, Sung; Jung, Min Wook; Kim, Seong Jun; Min, Bok Ki; Kang, Min-A; Kim, Sung Ho; Lim, Jongsun; An, Ki-Seok

2014-02-11

In order to combine advantages of ZnO thin film transistors (TFTs) with a high on-off ratio and graphene TFTs with extremely high carrier mobility, we present a facile methodology for fabricating ZnO thin film/graphene hybrid two-dimensional TFTs. Hybrid TFTs exhibited ambipolar behavior, an outstanding electron mobility of 329.7 ± 16.9 cm(2)/V·s, and a high on-off ratio of 10(5). The ambipolar behavior of the ZnO/graphene hybrid TFT with high electron mobility could be due to the superimposed density of states involving the donor states in the bandgap of ZnO thin films and the linear dispersion of monolayer graphene. We further established an applicable circuit model for understanding the improvement in carrier mobility of ZnO/graphene hybrid TFTs.

The toxicity and invasive effects of QDs on mung bean development

NASA Astrophysics Data System (ADS)

Zhai, Peng; Wang, Xiaomei; Wang, Ruhua; Huang, Xuan; Feng, Gang; Lin, Guimiao; Chen, Qiang; Xu, Gaixia; Chen, Danni

2014-09-01

Objective: Nowadays, the nanomaterials have been applied in every aspects of our life, including cosmetics, fresh-keeping, antisepsis and medicines. However, we know little about the toxic effects of nanoparticles towards plants. In this thesis, we synthesized quantum dots (QDs), and then toxicity and invasive effects of QDs for mung beans were investigated. Methods: We synthesised red CdTe QDs in water sphase with L-Cystein stabilizers, then prepared different concentration of QDs solution to cultivate mung bean plant, the radical length of mung beans was measured after four days every day, after 7 days, the distribution of QDs in mung bean plant was recorded under the microscopic. Results: The result showed the QDs inhibited the growth of mung beans, the higher the concentration of QDs was, the greater the inhibition effect was. After 7 days, the radicle average lengths of mung beans in different concentrations of QDs solution - blank 0.1μmol/L 0.2μmol/L 0.5 μmol/L 1 μmol/L - were 19.350+/- 0.427, 14.050+/- 0.879, 10.525+/- 0.554, 7.250+/- 0.522, 7.650+/- 0.229. The QDs mostly adhered onto the root surface and hairs. Conclusion: In conclusion, the QDs synthesized with L-cystein have effects on the growth of mung beans. However, it is necessary to do more experiments to confirm the mechanism of the toxicity effect of QDs on plants.

Perovskite Quantum Dots with Near Unity Solution and Neat-Film Photoluminescent Quantum Yield by Novel Spray Synthesis.

PubMed

Dai, Shu-Wen; Hsu, Bo-Wei; Chen, Chien-Yu; Lee, Chia-An; Liu, Hsiao-Yun; Wang, Hsiao-Fang; Huang, Yu-Ching; Wu, Tien-Lin; Manikandan, Arumugam; Ho, Rong-Ming; Tsao, Cheng-Si; Cheng, Chien-Hong; Chueh, Yu-Lun; Lin, Hao-Wu

2018-02-01

In this study, a novel perovskite quantum dot (QD) spray-synthesis method is developed by combining traditional perovskite QD synthesis with the technique of spray pyrolysis. By utilizing this new technique, the synthesis of cubic-shaped perovskite QDs with a homogeneous size of 14 nm is demonstrated, which shows an unprecedented stable absolute photoluminescence quantum yield ≈100% in the solution and even in the solid-state neat film. The highly emissive thin films are integrated with light emission devices (LEDs) and organic light emission displays (OLEDs). The color conversion type QD-LED (ccQD-LED) hybrid devices exhibit an extremely saturated green emission, excellent external quantum efficiency of 28.1%, power efficiency of 121 lm W -1 , and extraordinary forward-direction luminescence of 8 500 000 cd m -2 . The conceptual ccQD-OLED hybrid display also successfully demonstrates high-definition still images and moving pictures with a 119% National Television System Committee 1931 color gamut and 123% Digital Cinema Initiatives-P3 color gamut. These very-stable, ultra-bright perovskite QDs have the properties necessary for a variety of useful applications in optoelectronics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaporation-induced self-assembly of quantum dots-based concentric rings on polymer-based nanocomposite films.

PubMed

Zhang, Shaofu; Luan, Weiling; Zhong, Qixin; Yin, Shaofeng; Yang, Fuqian

2016-10-12

The "ball-on-film" template is used to construct concentric rings on the surface of PMMA-QDs (polymethyl methacrylate - quantum dots) nanocomposite films via the evaporation of pure chloroform droplets, which are confined by a steel ball. The concentric rings consist of QDs, as revealed by the fluorescence images of the concentric rings. The photoluminescence intensity of the concentric rings increases with the increase of the distance to the ball center, suggesting that the amount of QDs accumulated around the contact line at individual stick state increases with the increase of the distance to the ball center. Both the wavelength and cross-sectional area (width) of the concentric rings increase approximately linearly with increasing distance to the ball center, independent of the ball size, the film thickness and the QDs concentration. For the PMMA-QDs nanocomposite films prepared from the same QDs concentration in chloroform, the thicker the PMMA-QDs nanocomposite film, the larger the wavelength for the same distance to the ball center. The effect of confinement of two steel balls on the surface patterns over the PMMA-QDs nanocomposite films is studied via a template of "two spheres on film". Symmetric surface patterns are formed. There exist two types of featureless zone between the two balls, depending on the distance between the two balls: one is the inner featureless zone and the other is the outer featureless zone. The size of both featureless zones increases with the increase of the ball distance.

Improved performance of colloidal CdSe quantum dot-sensitized solar cells by hybrid passivation.

PubMed

Huang, Jing; Xu, Bo; Yuan, Chunze; Chen, Hong; Sun, Junliang; Sun, Licheng; Agren, Hans

2014-11-12

A hybrid passivation strategy is employed to modify the surface of colloidal CdSe quantum dots (QDs) for quantum dot-sensitized solar cells (QDSCs), by using mercaptopropionic acid (MPA) and iodide anions through a ligand exchange reaction in solution. This is found to be an effective way to improve the performance of QDSCs based on colloidal QDs. The results show that MPA can increase the coverage of the QDs on TiO2 electrodes and facilitate the hole extraction from the photoxidized QDs, and simultaneously, that the iodide anions can remedy the surface defects of the CdSe QDs and thus reduce the recombination loss in the device. This hybrid passivation treatment leads to a significant enhancement of the power conversion efficiency of the QDSCs by 41%. Furthermore, an optimal ratio of iodide ions to MPA was determined for favorable hybrid passivation; results show that excessive iodine anions are detrimental to the loading of the QDs. This study demonstrates that the improvement in QDSC performance can be realized by using a combination of different functional ligands to passivate the QDs, and that ligand exchange in solution can be an effective approach to introduce different ligands.

Highly Efficient Inverted Perovskite Solar Cells with CdSe QDs/LiF Electron Transporting Layer

NASA Astrophysics Data System (ADS)

Tan, Furui; Xu, Weizhe; Hu, Xiaodong; Yu, Ping; Zhang, Weifeng

2017-12-01

Organic/inorganic hybrid perovskite solar cell has emerged as a very promising candidate for the next generation of near-commercial photovoltaic devices. Here in this work, we focus on the inverted perovskite solar cells and have found that remarkable photovoltaic performance could be obtained when using cadmium selenide (CdSe) quantum dots (QDs) as electron transporting layer (ETL) and lithium fluoride (LiF) as the buffer, with respect to the traditionally applied and high-cost [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The easily processed and low-cost CdSe QDs/LiF double layer could facilitate convenient electron-transfer and collection at the perovskite/cathode interface, promoting an optoelectric conversion efficiency of as high as 15.1%, very close to that with the traditional PCBM ETL. Our work provides another promising choice on the ETL materials for the highly efficient and low-cost perovskite solar cells.

Novel Structure for High Performance UV Photodetector Based on BiOCl/ZnO Hybrid Film.

PubMed

Teng, Feng; Ouyang, Weixin; Li, Yanmei; Zheng, Lingxia; Fang, Xiaosheng

2017-06-01

A novel type of high performance ultraviolet (UV) photodetector (PD) based on a ZnO film has been prepared by incorporating a BiOCl nanostructure into the film. The responsivity of the BiOCl/ZnO hybrid film PD in UV region can reach 182.87 mA W -1 , which is about 2.72 and 6.87 times for that of TiO 2 /ZnO hybrid film PD and pure ZnO film PD. The rise/decay time of BiOCl/ZnO hybrid film PD is 25.83/11.25 s, which is much shorter than that of TiO 2 /ZnO hybrid film PD (51.94/26.05 s) and pure ZnO film PD (69.34/>120 s). The BiOCl nanostructure can inject photogenerated electrons into the ZnO film under UV light illumination, leading to the increase of photocurrent, and forms barriers to block the straight transmission of electrons between electrodes, resulting in the decrease of decay time. The results of control experiment show that the transfer path of photogenerated electrons formed by p-n junction will be cut off after depositing gold nanoparticles on the film surface, which means this hybrid film is a unique and novel structure to improve the optoelectronic performance of photodetectors. This novel BiOCl/ZnO hybrid structure paves new route for the development of film PDs based on ZnO film. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cage and linear structured polysiloxane/epoxy hybrids for coatings: Surface property and film permeability.

PubMed

Ma, Yanli; He, Ling; Jia, Mengjun; Zhao, Lingru; Zuo, Yanyan; Hu, Pingan

2017-08-15

Three polysiloxane/epoxy hybrids obtained by evolving cage- or linear-structured polysiloxane into poly glycidyl methacrylate (PGMA) matrix are compared used as coatings. One is the cage-structured hybrid of P(GMA/MA-POSS) copolymer obtained by GMA and methacrylisobutyl polyhedral oligomeric silsesquioxane (MA-POSS) via free radical polymerization, the other two are PGMA/NH 2 -POSS and PGMA/NH 2 -PDMS hybrids by cage-structured aminopropyllsobutyl POSS (NH 2 -POSS) or linear-structured diamino terminated poly(dimethylsiloxane) (NH 2 -PDMS) to cure PGMA. The effect of MA-POSS, NH 2 -POSS and NH 2 -PDMS on polysiloxane/epoxy hybrid films is characterized according to their surface morphology, transparency, permeability, adhesive strength and thermo-mechanical properties. Due to caged POSS tending to agglomerate onto the film surface, P(GMA/MA-POSS) and PGMA/NH 2 -POSS films exhibit much more heterogeneous surfaces than PGMA/NH 2 -PDMS film, but the well-compatibility between epoxy matrix and MA-POSS has provided P(GMA/MA-POSS) film with much higher transmittance (98%) than PGMA/NH 2 -POSS film (24%), PGMA/NH 2 -PDMS film (27%) and traditional epoxy resin film (5%). The introduction of polysiloxane into epoxy matrix is confirmed to create hybrids with strong adhesive strength (526-1113N) and high thermos-stability (T g =262-282°C), especially the cage-structured P(GMA/MA-POSS) hybrid (1113N and 282°C), but the flexible PDMS improves PGMA/NH 2 -PDMS hybrid with much higher storage modulus (519MPa) than PGMA/NH 2 -POSS (271MPa), which suggests that PDMS is advantage in improving the film stiffness than POSS cages. However, cage-structured P(GMA/MA-POSS) and PGMA/NH 2 -POSS indicate higher permeability than PGMA/NH 2 -PDMS and traditional epoxy resin. Comparatively, the cage-structured P(GMA/MA-POSS) hybrid is the best coating in transparency, permeability, adhesive strength and thermostability, but linear-structured PGMA/NH 2 -PDMS hybrid behaviors the best coating in

Graphene Oxide Transparent Hybrid Film and Its Ultraviolet Shielding Property.

PubMed

Xie, Siyuan; Zhao, Jianfeng; Zhang, Bowu; Wang, Ziqiang; Ma, Hongjuan; Yu, Chuhong; Yu, Ming; Li, Linfan; Li, Jingye

2015-08-19

Herein, we first reported a facile strategy to prepare functional Poly(vinyl alcohol) (PVA) hybrid film with well ultraviolet (UV) shielding property and visible light transmittance using graphene oxide nanosheets as UV-absorber. The absorbance of ultraviolet light at 300 nm can be up to 97.5%, while the transmittance of visible light at 500 nm keeps 40% plus. This hybrid film can protect protein from UVA light induced photosensitive damage, remarkably.

Preparation and gas sensing properties of novel CdS-supramolecular organogel hybrid films

NASA Astrophysics Data System (ADS)

Xia, Huiyun; Peng, Junxia; Liu, Kaiqiang; Li, Chen; Fang, Yu

2008-05-01

A novel CdS-supramolecular organogel hybrid film with unusual morphology has been fabricated by exposing a supramolecular organogel film containing Cd(Ac)2 in an H2S atmosphere at room temperature. The organogel film was prepared by spin-coating a LMOG (low-molecular weight organic gelator) gel of dmethyl sulfoxide onto a glass plate substrate. XRD, SEM, EDS, TG-DTA, UV-vis, PL (photoluminescence) spectroscopy and PL lifetime measurements were employed to characterize the film. It was shown that the organogel film had functioned as a template to control the morphology of the final hybrid film. The quantities and sizes of the CdS particles embedded in the organogel films can be easily altered by varying the initial concentration of Cd(Ac)2. Importantly, the PL of the hybrid film is sensitive to the presence of some volatile organic monoamines and diamines. The selectivity and reversibility of the sensing process were investigated.

Hybrid morphology dependence of CdTe:CdSe bulk-heterojunction solar cells

PubMed Central

2014-01-01

A nanocrystal thin-film solar cell operating on an exciton splitting pattern requires a highly efficient separation of electron-hole pairs and transportation of separated charges. A hybrid bulk-heterojunction (HBH) nanostructure providing a large contact area and interpenetrated charge channels is favorable to an inorganic nanocrystal solar cell with high performance. For this freshly appeared structure, here in this work, we have firstly explored the influence of hybrid morphology on the photovoltaic performance of CdTe:CdSe bulk-heterojunction solar cells with variation in CdSe nanoparticle morphology. Quantum dot (QD) or nanotetrapod (NT)-shaped CdSe nanocrystals have been employed together with CdTe NTs to construct different hybrid structures. The solar cells with the two different hybrid active layers show obvious difference in photovoltaic performance. The hybrid structure with densely packed and continuously interpenetrated two phases generates superior morphological and electrical properties for more efficient inorganic bulk-heterojunction solar cells, which could be readily realized in the NTs:QDs hybrid. This proved strategy is applicable and promising in designing other highly efficient inorganic hybrid solar cells. PMID:25386107

Hybrid morphology dependence of CdTe:CdSe bulk-heterojunction solar cells.

PubMed

Tan, Furui; Qu, Shengchun; Zhang, Weifeng; Wang, Zhanguo

2014-01-01

A nanocrystal thin-film solar cell operating on an exciton splitting pattern requires a highly efficient separation of electron-hole pairs and transportation of separated charges. A hybrid bulk-heterojunction (HBH) nanostructure providing a large contact area and interpenetrated charge channels is favorable to an inorganic nanocrystal solar cell with high performance. For this freshly appeared structure, here in this work, we have firstly explored the influence of hybrid morphology on the photovoltaic performance of CdTe:CdSe bulk-heterojunction solar cells with variation in CdSe nanoparticle morphology. Quantum dot (QD) or nanotetrapod (NT)-shaped CdSe nanocrystals have been employed together with CdTe NTs to construct different hybrid structures. The solar cells with the two different hybrid active layers show obvious difference in photovoltaic performance. The hybrid structure with densely packed and continuously interpenetrated two phases generates superior morphological and electrical properties for more efficient inorganic bulk-heterojunction solar cells, which could be readily realized in the NTs:QDs hybrid. This proved strategy is applicable and promising in designing other highly efficient inorganic hybrid solar cells.

High- and Reproducible-Performance Graphene/II-VI Semiconductor Film Hybrid Photodetectors

PubMed Central

Huang, Fan; Jia, Feixiang; Cai, Caoyuan; Xu, Zhihao; Wu, Congjun; Ma, Yang; Fei, Guangtao; Wang, Min

2016-01-01

High- and reproducible-performance photodetectors are critical to the development of many technologies, which mainly include one-dimensional (1D) nanostructure based and film based photodetectors. The former suffer from a huge performance variation because the performance is quite sensitive to the synthesis microenvironment of 1D nanostructure. Herein, we show that the graphene/semiconductor film hybrid photodetectors not only possess a high performance but also have a reproducible performance. As a demo, the as-produced graphene/ZnS film hybrid photodetector shows a high responsivity of 1.7 × 107 A/W and a fast response speed of 50 ms, and shows a highly reproducible performance, in terms of narrow distribution of photocurrent (38–65 μA) and response speed (40–60 ms) for 20 devices. Graphene/ZnSe film and graphene/CdSe film hybrid photodetectors fabricated by this method also show a high and reproducible performance. The general method is compatible with the conventional planar process, and would be easily standardized and thus pay a way for the photodetector applications. PMID:27349692

Quantum dots/silica/polymer nanocomposite films with high visible light transmission and UV shielding properties

NASA Astrophysics Data System (ADS)

Mumin, Md Abdul; Xu, William Z.; Charpentier, Paul A.

2015-08-01

The dispersion of light-absorbing inorganic nanomaterials in transparent plastics such as poly(ethylene-co-vinyl acetate) (PEVA) is of enormous current interest in emerging solar materials, including photovoltaic (PV) modules and commercial greenhouse films. Nanocrystalline semiconductor or quantum dots (QDs) have the potential to absorb UV light and selectively emit visible light, which can control plant growth in greenhouses or enhance PV panel efficiencies. This work provides a new and simple approach for loading mesoporous silica-encapsulated QDs into PEVA. Highly luminescent CdS and CdS-ZnS core-shell QDs with 5 nm size were synthesized using a modified facile approach based on pyrolysis of the single-molecule precursors and capping the CdS QDs with a thin layer of ZnS. To make both the bare and core-shell structure QDs more resistant against photochemical reactions, a mesoporous silica layer was grown on the QDs through a reverse microemulsion technique based on hydrophobic interactions. By careful experimental tuning, this encapsulation technique enhanced the quantum yield (˜65%) and photostability compared to the bare QDs. Both the encapsulated bare and core-shell QDs were then melt-mixed with EVA pellets using a mini twin-screw extruder and pressed into thin films with controlled thickness. The results demonstrated for the first time that mesoporous silica not only enhanced the quantum yield and photostability of the QDs but also improved the compatibility and dispersibility of QDs throughout the PEVA films. The novel light selective films show high visible light transmission (˜90%) and decreased UV transmission (˜75%).

Quantum dots/silica/polymer nanocomposite films with high visible light transmission and UV shielding properties.

PubMed

Mumin, Md Abdul; Xu, William Z; Charpentier, Paul A

2015-08-07

The dispersion of light-absorbing inorganic nanomaterials in transparent plastics such as poly(ethylene-co-vinyl acetate) (PEVA) is of enormous current interest in emerging solar materials, including photovoltaic (PV) modules and commercial greenhouse films. Nanocrystalline semiconductor or quantum dots (QDs) have the potential to absorb UV light and selectively emit visible light, which can control plant growth in greenhouses or enhance PV panel efficiencies. This work provides a new and simple approach for loading mesoporous silica-encapsulated QDs into PEVA. Highly luminescent CdS and CdS-ZnS core-shell QDs with 5 nm size were synthesized using a modified facile approach based on pyrolysis of the single-molecule precursors and capping the CdS QDs with a thin layer of ZnS. To make both the bare and core-shell structure QDs more resistant against photochemical reactions, a mesoporous silica layer was grown on the QDs through a reverse microemulsion technique based on hydrophobic interactions. By careful experimental tuning, this encapsulation technique enhanced the quantum yield (∼65%) and photostability compared to the bare QDs. Both the encapsulated bare and core-shell QDs were then melt-mixed with EVA pellets using a mini twin-screw extruder and pressed into thin films with controlled thickness. The results demonstrated for the first time that mesoporous silica not only enhanced the quantum yield and photostability of the QDs but also improved the compatibility and dispersibility of QDs throughout the PEVA films. The novel light selective films show high visible light transmission (∼90%) and decreased UV transmission (∼75%).

Fabrication of thickness controllable free-standing sandwich-structured hybrid carbon film for high-rate and high-power supercapacitor

PubMed Central

Wei, Helin; Wei, Sihang; Tian, Weifeng; Zhu, Daming; Liu, Yuhao; Yuan, Lili; Li, Xin

2014-01-01

Hybrid carbon films composed of graphene film and porous carbon film may give full play to the advantages of both carbon materials, and have great potential for application in energy storage and conversion devices. Unfortunately, there are very few reports on fabrication of hybrid carbon films. Here we demonstrate a simple approach to fabricate free-standing sandwich-structured hybrid carbon film composed of porous amorphous carbon film and multilayer graphene film by chemical vapor deposition in a controllable and scalable way. Hybrid carbon films reveal good electrical conductivity, excellent flexibility, and good compatibility with substrate. Supercapacitors assembled by hybrid carbon films exhibit ultrahigh rate capability, wide frequency range, good capacitance performance, and high-power density. Moreover, this approach may provide a general path for fabrication of hybrid carbon materials with different structures by using different metals with high carbon solubility, and greatly expands the application scope of carbon materials. PMID:25394410

Hydrodynamic size-dependent cellular uptake of aqueous QDs probed by fluorescence correlation spectroscopy.

PubMed

Dong, Chaoqing; Irudayaraj, Joseph

2012-10-11

Aqueous quantum dots (QDs) directly synthesized with various thiol ligands have been investigated as imaging probes in living cells. However, the effect of the surface chemistry of these ligands on QDs' cellular uptakes and their intracellular fate remains poorly understood. In this work, four CdTe QDs were directly synthesized under aqueous conditions using four different thiols as stabilizers and their interactions with cells were investigated. Fluorescence correlation spectroscopy (FCS), X-ray photoelectron spectroscopy (XPS), and zeta potential measurements on QDs primarily show that the surface structure of these QDs is highly dependent on the thiol ligands used in the preparation of QDs' precursors, including its layer thicknesses, densities, and surface charges. Subsequently, FCS integrated with the maximum-entropy-method-based FCS (MEMFCS) was used to investigate the concentration distribution and dynamics of these QDs in living A-427 cells. Our findings indicate that QDs' surface characteristics affect cell membrane adsorption and subsequent internalization. More critically, we show that the cellular uptake of aqueous QDs is dependent on their hydrodynamic diameter and might have the potential to escape trapped environments to accumulate in the cytoplasm.

Stable CdS QDs with intense broadband photoluminescence and high quantum yields

NASA Astrophysics Data System (ADS)

Mandal, Abhijit; Saha, Jony; De, Goutam

2011-11-01

Aqueous synthesis of CdS quantum dots (QDs) using thiolactic acid (TLA) as a capping agent was reported. These QDs exhibited excellent colloidal and photostability over a span of 2 years and showed intense broadband and almost white photoluminescence suitable for solid state lighting devices. The photoluminescence (PL) property of the aqueous CdS QDs is optimized by adjusting various processing parameters. The highest quantum yield (QY) achieved for TLA capped CdS QDs of average size 3.5 nm was ˜50%. Luminescence lifetime measurements of CdS-TLA QDs indicated longer lifetimes and a larger contribution of the surface-related emission, indicating removal of quenching defects.

Hybrid Organic-Inorganic Films Grown Using Molecular Layer Deposition

DTIC Science & Technology

2011-03-01

shown that zincone films based on DEZ and hydroquinone (HQ) have displayed some conductivity when alloyed with ZnO ALD films [35]. The schematic...11 Schematic showing the two-step reaction sequence for AB zincone MLD growth using diethylzinc (DEZ) and hydroquinone (HQ). The hybrid organic

Suppressed blinking behavior of CdSe/CdS QDs by polymer coating

NASA Astrophysics Data System (ADS)

Zhang, Aidi; Bian, Yannan; Wang, Jinjie; Chen, Kuiyong; Dong, Chaoqing; Ren, Jicun

2016-02-01

Semiconductor quantum dots (QDs) are very important fluorescent nanocrystals with excellent optical properties. However, QDs, at the single-particle level, show severe fluorescence intermittency (or blinking) on a wide time scale from milliseconds to minutes, which limits certain optical and biological applications. Generally, blinking behavior of QDs strongly depends on their surface state and surrounding environment. Therefore, current blinking suppression approaches are mostly focused on the introduction of an inorganic shell and organic small molecule compounds. In this study, we described a ``bottom up'' approach for the synthesis of CdSe/CdS/polymer core/shell/shell QDs via the in situ one-pot polymerization approach in order to control the blinking behavior of QDs. Three monomers (dithiothreitol (DTT), phenylenediamine (PDA), and hexamethylenediamine (HDA)) were respectively used to polymerize with hexachlorocyclotriphosphazene (HCCP), and then the polyphosphazene polymers were obtained with cyclotriphosphazene as the basic macromolecular backbone. By regulating the molar ratios of the activated comonomers, we can control the blinking behavior of CdSe/CdS/polymer QDs. Under the optimal conditions, the percentage of ``non-blinking'' CdSe/CdS/polymer QDs (the ``on time'' fraction > 99% of the overall observation time) was up to 78%. The suppression mechanism was attributed to the efficient passivation of QD surface traps by the sulfhydryl or phenyl groups in the polyphosphazene polymers.Semiconductor quantum dots (QDs) are very important fluorescent nanocrystals with excellent optical properties. However, QDs, at the single-particle level, show severe fluorescence intermittency (or blinking) on a wide time scale from milliseconds to minutes, which limits certain optical and biological applications. Generally, blinking behavior of QDs strongly depends on their surface state and surrounding environment. Therefore, current blinking suppression approaches are

Transparent and robust siloxane-based hybrid lamella film as a water vapor barrier coating.

PubMed

Tokudome, Yasuaki; Hara, Takaaki; Abe, Risa; Takahashi, Masahide

2014-11-12

Water vapor barriers are important in various application fields, such as food packaging and sealants in electronic devices. Polymer/clay composites are well-studied water vapor barrier materials, but their transparency and mechanical strength degrade with increasing clay loading. Herein, we demonstrate films with good water vapor barrier properties, high transparency, and mechanical/thermal stability. Water vapor barrier films were prepared by the solution crystallization of siloxane hybrid lamellae. The films consist of highly crystallized organic/inorganic hybrid lamellae, which provide high transparency, hardness, and thermal stability and inhibit the permeation of water vapor. The water permeability of a 6 μm thick hybrid film is comparable to that of a 200 μm thick silicon rubber film.

Film Delivery Module For Fiber Placement Fabrication of Hybridized Composite Structures

NASA Technical Reports Server (NTRS)

Hulcher, Anthony Bruce; Young, Greg

2005-01-01

A new fabrication technology has been developed at the NASA Marshall Space Flight Center that will allow for the fabrication of hybridized composite structures using fiber placement processing. This technology was originally developed in response to a need to address the issue of hydrogen permeation and microcracking in cryogenic propellant tanks. Numerous thin polymeric and metallized films were investigated under low temperatures conditions for use as barrier films in a composite tank. Manufacturing studies conducted at that time did not address the processing issues related to fabrication of a hybridized tank wall. A film processing head was developed that will allow for the processing of thin polymeric and metallized films, metallic foils, and adhesives using fiber placement processing machinery. The film head is designed to enable the simultaneous processing of film materials and composite tape/tow during the composite part layup process and is also capable of processing the film during an independent operation. Several initial demonstrations were conducted to assess the performance of the film module device. Such assessments included film strip lay-up accuracy, capability to fabricate panels having internal film liners, and fabrication of laminates with embedded film layers.

Organic-inorganic hybrid materials as semiconducting channels in thin-film field-effect transistors

PubMed

Kagan; Mitzi; Dimitrakopoulos

1999-10-29

Organic-inorganic hybrid materials promise both the superior carrier mobility of inorganic semiconductors and the processability of organic materials. A thin-film field-effect transistor having an organic-inorganic hybrid material as the semiconducting channel was demonstrated. Hybrids based on the perovskite structure crystallize from solution to form oriented molecular-scale composites of alternating organic and inorganic sheets. Spin-coated thin films of the semiconducting perovskite (C(6)H(5)C(2)H(4)NH(3))(2)SnI(4) form the conducting channel, with field-effect mobilities of 0.6 square centimeters per volt-second and current modulation greater than 10(4). Molecular engineering of the organic and inorganic components of the hybrids is expected to further improve device performance for low-cost thin-film transistors.

Single-photon sources based on InAs/GaAs QDs for solar cell

NASA Astrophysics Data System (ADS)

Jia, Wei; Liu, Zhi; Wang, Xunchun

2013-08-01

We have grown InAs/GaAs quantum dots (QDs) by droplet epitaxy for application in single photon sources. This growth method enables the formation of QDs without strain, with emission wavelengths of around 1.3μm within the optimal detection range of cost effective silicon detector, and with reduced surface density of several tens to a few QDs per μm2 for easier isolation of single QDs. The optical properties of QDs were envisaged by exciton and biexciton emission peaks identified from power dependent and time-resolved micro-photoluminescence (μ-PL) measurements.

Ag2S/CdS/TiO2 Nanotube Array Films with High Photocurrent Density by Spotting Sample Method.

PubMed

Sun, Hong; Zhao, Peini; Zhang, Fanjun; Liu, Yuliang; Hao, Jingcheng

2015-12-01

Ag2S/CdS/TiO2 hybrid nanotube array films (Ag2S/CdS/TNTs) were prepared by selectively depositing a narrow-gap semiconductor-Ag2S (0.9 eV) quantum dots (QDs)-in the local domain of the CdS/TiO2 nanotube array films by spotting sample method (SSM). The improvement of sunlight absorption ability and photocurrent density of titanium dioxide (TiO2) nanotube array films (TNTs) which were obtained by anodic oxidation method was realized because of modifying semiconductor QDs. The CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs fabricated by uniformly depositing the QDs into the TNTs via the successive ionic layer adsorption and reaction (SILAR) method were synthesized, respectively. The X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectrum (XPS) results demonstrated that the Ag2S/CdS/TNTs prepared by SSM and other films were successfully prepared. In comparison with the four films of TNTs, CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs by SILAR, the Ag2S/CdS/TNTs prepared by SSM showed much better absorption capability and the highest photocurrent density in UV-vis range (320~800 nm). The cycles of local deposition have great influence on their photoelectric properties. The photocurrent density of Ag2S/CdS/TNTs by SSM with optimum deposition cycles of 6 was about 37 times that of TNTs without modification, demonstrating their great prospective applications in solar energy utilization fields.

The Role of Trap-assisted Recombination in Luminescent Properties of Organometal Halide CH3NH3PbBr3 Perovskite Films and Quantum Dots

NASA Astrophysics Data System (ADS)

Zhang, Zhen-Yu; Wang, Hai-Yu; Zhang, Yan-Xia; Hao, Ya-Wei; Sun, Chun; Zhang, Yu; Gao, Bing-Rong; Chen, Qi-Dai; Sun, Hong-Bo

2016-06-01

Hybrid metal halide perovskites have been paid enormous attentions in photophysics research, whose excellent performances were attributed to their intriguing charge carriers proprieties. However, it still remains far from satisfaction in the comprehensive understanding of perovskite charge-transport properities, especially about trap-assisted recombination process. In this Letter, through time-resolved transient absorption (TA) and photoluminescence (PL) measurements, we provided a relative comprehensive investigation on the charge carriers recombination dynamics of CH3NH3PbBr3 (MAPbBr3) perovskite films and quantum dots (QDs), especially about trap-assisted recombination. It was found that the integral recombination mode of MAPbBr3 films was highly sensitive to the density distribution of generated charge carriers and trap states. Additional, Trap effects would be gradually weakened with elevated carrier densities. Furthermore, the trap-assisted recombination can be removed from MAPbBr3 QDs through its own surface passivation mechanism and this specialty may render the QDs as a new material in illuminating research. This work provides deeper physical insights into the dynamics processes of MAPbBr3 materials and paves a way toward more light-harvesting applications in future.

Highly Transparent and Self-Extinguishing Nanofibrillated Cellulose-Monolayer Clay Nanoplatelet Hybrid Films.

PubMed

Ming, Siyi; Chen, Gang; He, Jiahao; Kuang, Yudi; Liu, Yu; Tao, Ruiqiang; Ning, Honglong; Zhu, Penghui; Liu, Yingyao; Fang, Zhiqiang

2017-08-29

A viable solution toward "green" optoelectronics is rooted in our ability to fabricate optoelectronics on transparent nanofibrillated cellulose (NFC) film substrates. However, the flammability of transparent NFC film poses a severe fire hazard in optoelectronic devices. Despite many efforts toward enhancing the fire-retardant features of transparent NFC film, making NFC film fire-retardant while maintaining its high transparency (≥90%) remains an ambitious objective. Herein, we combine NFC with NFC-dispersed monolayer clay nanoplatelets as a fire retardant to prepare highly transparent NFC-monolayer clay nanoplatelet hybrid films with a superb self-extinguishing behavior. Homogeneous and stable monolayer clay nanoplatelet dispersion was initially obtained by using NFC as a green dispersing agent with the assistance of ultrasonication and then used to blend with NFC to prepare highly transparent and self-extinguishing hybrid films by a water evaporation-induced self-assembly process. As the content of monolayer clay nanoplatelets increased from 5 wt % to 50 wt %, the obtained hybrid films presented enhanced self-extinguishing behavior (limiting oxygen index sharply increased from 21% to 96.5%) while retaining a ∼90% transparency at 600 nm. More significantly, the underlying mechanisms for the high transparency and excellent self-extinguishing behavior of these hybrid films with a clay nanoplatelet content of over 30 wt % were unveiled by a series of characterizations such as SEM, XRD, TGA, and limiting oxygen index tester. This work offers an alternative environmentally friendly, self-extinguishing, and highly transparent substrate to next-generation optoelectronics, and is aimed at providing a viable solution to environmental concerns that are caused by ever-increasing electronic waste.

Quantum dots-hyperbranched polyether hybrid nanospheres towards delivery and real-time detection of nitric oxide.

PubMed

Liu, Shuiping; Gu, Tianxun; Fu, Jiajia; Li, Xiaoqiang; Chronakis, Ioannis S; Ge, Mingqiao

2014-12-01

In this work, novel hybrid nanosphere vehicles were synthesized for nitric oxide (NO) donating and real-time detection. The hybrid nanosphere vehicles consist of cadmium selenide quantum dots (CdSe QDs) as NO fluorescent probes, and the modified hyperbranched polyether (mHP)-based diazeniumdiolates as NO donors, respectively. The nanospheres have spherical outline with dimension of ~127 nm. The data of systematic characterization demonstrated that the mHP-based hybrid nanosphere vehicles (QDs-mHP-NO) can release and real-time detect NO with the low limit of 25 nM, based on fluorescence quenching mechanism. The low cell-toxicity of QDs-mHP-NO nanospheres was verified by means of MTT assay on L929 cells viability. The QDs-mHP-NO nanospheres provide perspectives for designing a new class of biocompatible NO donating and imaging systems. Copyright © 2014 Elsevier B.V. All rights reserved.

Nano CaCO₃ imprinted starch hybrid polyethylhexylacrylate\\polyvinylalcohol nanocomposite thin films.

PubMed

Prusty, Kalyani; Swain, Sarat K

2016-03-30

Starch hybrid polyethylhexylacrylate (PEHA)/polyvinylalcohol (PVA) nanocomposite thin films are prepared by different composition of nano CaCO3 in aqueous medium. The chemical interaction of nano CaCO3 with PEHA in presence of starch and PVA is investigated by Fourier transforms infrared spectroscopy (FTIR). X-ray diffraction (XRD) is used in order to study the change in crystallite size and d-spacing during the formation of nanocomposite thin film. The surface morphology of nanofilms is studied by scanning electron microscope (SEM). The topology and surface roughness of the films is noticed by atomic force microscope (AFM). The tensile strength, thermal stability and thermal conductivity of films are increased with increase in concentrations of CaCO3 nanopowder. The chemical resistance and biodegradable properties of the nanocomposite thin films are also investigated. The growth of bacteria and fungi in starch hybrid PEHA film is reduced substantially with imprint of nano CaCO3. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fabrication of genetically engineered polypeptide@quantum dots hybrid nanogels for targeted imaging

NASA Astrophysics Data System (ADS)

Yang, Jie; Yao, Ming-Hao; Zhao, Dong-Hui; Zhang, Xiao-Shuai; Jin, Rui-Mei; Zhao, Yuan-Di; Liu, Bo

2017-08-01

Nanogels have been widely used as multifunctional drug delivery carriers because of high water content, biocompatibility, and high loading capability. We designed and biosynthesized two triblock artificial polypeptides PC10A and PC10ARGD as vehicles for encapsulating hydrophobic materials. These polypeptides can form nanogels by self-assembly when the concentration is below 2% ( w/ v). The physical properties of nanogels, including size, surface potential, and targeting domain, are able to be tuned. Hydrophobic materials from molecular size to nano-size can be loaded into the polypeptide nanogels to form hybrid nanogels. Hydrophobic quantum dots CdSe@ZnS below 10 nM were loaded into the polypeptide nanogels by ultrasonic treatment. Encapsulation endows hydrophobic QDs with good tunability of size, water solubility, stability, targeting, and biocompatibility. PC10ARGD nanogels and PC10ARGD@QDs hybrid nanogels showed excellent biocompatibility, which the cellular viabilities of HeLa and MCF-7 cells treated with 1% PC10ARGD nanogels and PC10ARGD@QDs hybrid nanogels contained 20 nM QDs were above 90 and 80%, respectively. PC10ARGD@QDs hybrid nanogels with an arginine-glycine-aspartic acid motif present efficient receptor-mediated endocytosis in α v β 3 overexpressing HeLa cells but not in the control MCF-7 cells as analyzed by confocal microscopy. These results demonstrate that such polypeptide nanogels as nanocarriers are expected to have great potential applications in biomedicine.

Resistive switching characteristics of manganese oxide thin film and nanoparticle assembly hybrid devices

NASA Astrophysics Data System (ADS)

Abbas, Haider; Park, Mi Ra; Abbas, Yawar; Hu, Quanli; Kang, Tae Su; Yoon, Tae-Sik; Kang, Chi Jung

2018-06-01

Improved resistive switching characteristics are demonstrated in a hybrid device with Pt/Ti/MnO (thin film)/MnO (nanoparticle)/Pt structure. The hybrid devices of MnO thin film and nanoparticle assembly were fabricated. MnO nanoparticles with an average diameter of ∼30 nm were chemically synthesized and assembled as a monolayer on a Pt bottom electrode. A MnO thin film of ∼40 nm thickness was deposited on the nanoparticle assembly to form the hybrid structure. Resistive switching could be induced by the formation and rupture of conducting filaments in the hybrid oxide layers. The hybrid device exhibited very stable unipolar switching with good endurance and retention characteristics. It showed a larger and stable memory window with a uniform distribution of SET and RESET voltages. Moreover, the conduction mechanisms of ohmic conduction, space-charge-limited conduction, Schottky emission, and Poole–Frenkel emission have been investigated as possible conduction mechanisms for the switching of the devices. Using MnO nanoparticles in the thin film and nanoparticle heterostructures enabled the appropriate control of resistive random access memory (RRAM) devices and markedly improved their memory characteristics.

Conjugated polymer-titania nanoparticle hybrid films: random lasing action and ultrasensitive detection of explosive vapors.

PubMed

Deng, Changmin; He, Qingguo; He, Chao; Shi, Liqi; Cheng, Jiangong; Lin, Tong

2010-04-08

We have first demonstrated that a random laser action generated by a hybrid film composed of a semiconducting organic polymer (SOP) and TiO(2) nanoparticles can be used to detect 2,4,6-trinitrotoluene (TNT) vapors. The hybrid film was fabricated by spin-casting SOP solution dispersed with nanosized TiO(2) particles on quartz glass. The SOP in the hybrid film functioned as both the gain medium and the sensory transducer. A random lasing action was observed with a certain pump power when the size (diameter of 50 nm) and concentration (8.9 x 10(12)/cm(3)) of TiO(2) nanoparticles were optimized. Measurements of fluorescence quenching behavior of the hybrid film in TNT vapor atmosphere (10 ppb) showed that attenuated lasing in optically pumped hybrid film displayed a sensitivity to vapors of explosives more than 20 times higher than was observed from spontaneous emission. This phenomenon has been explained with the four-level laser model. Since the sensory transducer used in the hybrid polymer/nanoparticles system could be replaced by other functional materials, the concept developed could be extended to more general domains of chemical or environment detection.

Ligand-surface interactions and surface oxidation of colloidal PbSe quantum dots revealed by thin-film positron annihilation methods

NASA Astrophysics Data System (ADS)

Shi, Wenqin; Eijt, Stephan W. H.; Suchand Sandeep, C. S.; Siebbeles, Laurens D. A.; Houtepen, Arjan J.; Kinge, Sachin; Brück, Ekkes; Barbiellini, Bernardo; Bansil, Arun

2016-02-01

Positron Two Dimensional Angular Correlation of Annihilation Radiation (2D-ACAR) measurements reveal modifications of the electronic structure and composition at the surfaces of PbSe quantum dots (QDs), deposited as thin films, produced by various ligands containing either oxygen or nitrogen atoms. In particular, the 2D-ACAR measurements on thin films of colloidal PbSe QDs capped with oleic acid ligands yield an increased intensity in the electron momentum density (EMD) at high momenta compared to PbSe quantum dots capped with oleylamine. Moreover, the EMD of PbSe QDs is strongly affected by the small ethylenediamine ligands, since these molecules lead to small distances between QDs and favor neck formation between near neighbor QDs, inducing electronic coupling between neighboring QDs. The high sensitivity to the presence of oxygen atoms at the surface can be also exploited to monitor the surface oxidation of PbSe QDs upon exposure to air. Our study clearly demonstrates that positron annihilation spectroscopy applied to thin films can probe surface transformations of colloidal semiconductor QDs embedded in functional layers.

Atmospheric deposition process for enhanced hybrid organic-inorganic multilayer barrier thin films for surface protection

NASA Astrophysics Data System (ADS)

Rehman, Mohammad Mutee ur; Kim, Kwang Tae; Na, Kyoung Hoan; Choi, Kyung Hyun

2017-11-01

In this study, organic polymer poly-vinyl acetate (PVA) and inorganic aluminum oxide (Al2O3) have been used together to fabricate a hybrid barrier thin film for the protection of PET substrate. The organic thin films of PVA were developed through roll to roll electrohydrodynamic atomization (R2R-EHDA) whereas the inorganic thin films of Al2O3 were grown by roll to roll spatial atmospheric atomic layer deposition (R2R-SAALD) for mass production. The use of these two technologies together to develop a multilayer hybrid organic-inorganic barrier thin films under atmospheric conditions is reported for the first time. These multilayer hybrid barrier thin films are fabricated on flexible PET substrate. Each layer of Al2O3 and PVA in barrier thin film exhibited excellent morphological, chemical and optical properties. Extremely uniform and atomically thin films of Al2O3 with average arithmetic roughness (Ra) of 1.64 nm and 1.94 nm respectively concealed the non-uniformity and irregularities in PVA thin films with Ra of 2.9 nm and 3.6 nm respectively. The optical transmittance of each layer was ∼ 80-90% while the water vapor transmission rate (WVTR) of hybrid barrier was in the range of ∼ 2.3 × 10-2 g m-2 day-1 with a total film thickness of ∼ 200 nm. Development of such hybrid barrier thin films with mass production and low cost will allow various flexible electronic devices to operate in atmospheric conditions without degradation of their properties.

Quantum Dot/Siloxane Composite Film Exceptionally Stable against Oxidation under Heat and Moisture.

PubMed

Kim, Hwea Yoon; Yoon, Da-Eun; Jang, Junho; Lee, Daewon; Choi, Gwang-Mun; Chang, Joon Ha; Lee, Jeong Yong; Lee, Doh C; Bae, Byeong-Soo

2016-12-21

We report on the fabrication of a siloxane-encapsulated quantum dot (QD) film (QD-silox film), which exhibits stable emission intensity for over 1 month even at elevated temperature and humidity. QD-silox films are solidified via free radical addition reaction between oligosiloxane resin and ligand molecules on QDs. We prepare the QD-oligosiloxane resin by sol-gel condensation reaction of silane precursors with QDs blended in the precursor solution, forgoing ligand-exchange of QDs. The resulting QD-oligosiloxane resin remains optically clear after 40 days of storage, in contrast to other QD-containing resins which turn turbid and ultimately form sediments. QDs also disperse uniformly in the QD-silox film, whose photoluminescence (PL) quantum yield (QY) remains nearly unaltered under harsh conditions; for example, 85 °C/5% relative humidity (RH), 85 °C/85% RH, strongly acidic, and strongly basic environments for 40 days. The QD-silox film appears to remain equally emissive even after being immersed into boiling water (100 °C). Interestingly, the PL QY of the QD-silox film noticeably increases when the film is exposed to a moist environment, which opens a new, facile avenue to curing dimmed QD-containing films. Given its excellent stability, we envision that the QD-silox film is best suited in display applications, particularly as a PL-type down-conversion layer.

Glucose biosensor based on nanocomposite films of CdTe quantum dots and glucose oxidase.

PubMed

Li, Xinyu; Zhou, Yunlong; Zheng, Zhaozhu; Yue, Xiuli; Dai, Zhifei; Liu, Shaoqin; Tang, Zhiyong

2009-06-02

A blood glucose sensor has been developed based on the multilayer films of CdTe semiconductor quantum dots (QDs) and glucose oxidase (GOD) by using the layer-by-layer assembly technique. When the composite films were contacted with glucose solution, the photoluminescence of QDs in the films was quickly quenched because the enzyme-catalyzed reaction product (H2O2) of GOD and glucose gave rise to the formation of surface defects on QDs. The quenching rate was a function of the concentration of glucose. The linear range and sensitivity for glucose determination could be adjusted by controlling the layers of QDs and GOD. The biosensor was used to successfully determine the concentration of blood glucose in real serum samples without sample pretreatment and exhibited satisfactory reproducibility and accuracy.

Investigations of LRE-HRE-TM thin films for hybrid recording

NASA Astrophysics Data System (ADS)

Li, Zuoyi; Cheng, Xiaomin; Jin, Fang; Li, Zhen; Lin, Gengqi; Yang, Xiaofei

2005-09-01

Light rare earth-heavy rare earth-transition metal (LRE-HRE-TM) thin films are a kind of important recording media. A lot of researches have been carried out on the LRE-HRE-TM thin films to improve its properties for data storage application and fruitful results have been achieved. This report gives a glance on the evolution of the research on LRE-HRE-TM recording media. At the same time, combined with the hybrid recording technology, some experimental results obtained on LRE-HRE-TM recording media are discussed, which suggest the promising prospect of the LRE-HRE-TM media in hybrid recording application.

High Refractive Organic–Inorganic Hybrid Films Prepared by Low Water Sol-Gel and UV-Irradiation Processes

PubMed Central

Ma, Hsiao-Yuan; Wang, Tzong-Liu; Chang, Pei-Yu; Yang, Chien-Hsin

2016-01-01

Organic-inorganic hybrid sols (Ti–O–Si precursor) were first synthesized by the sol-gel method at low addition of water, and were then employed to prepare a highly refractive hybrid optical film. This film was obtained by blending the Ti–O–Si precursor with 2-phenylphenoxyethyl acrylate (OPPEA) to perform photo-polymerization by ultraviolet (UV) irradiation. Results show that the film transparency of poly(Ti–O–Si precursor-co-OPPEA) film is higher than that of a pure poly(Ti–O–Si precursor) film, and that this poly(Ti–O–Si precursor-co-OPPEA) hybrid film exhibits a high transparency of ~93.7% coupled with a high refractive index (n) of 1.83 corresponding to a thickness of 2.59 μm. PMID:28344303

Quantum dots electrochemical aptasensor based on three-dimensionally ordered macroporous gold film for the detection of ATP.

PubMed

Zhou, Jinjun; Huang, Haiping; Xuan, Jie; Zhang, Jianrong; Zhu, Jun-Jie

2010-10-15

A sensitive electrochemical aptasensor was successfully fabricated for the detection of adenosine triphosphate (ATP) by combining three-dimensionally ordered macroporous (3DOM) gold film and quantum dots (QDs). The 3DOM gold film was electrochemically fabricated with an inverted opal template, making the active surface area of the electrode up to 9.52 times larger than that of a classical bare flat one. 5′-thiolated ATP-binding aptamer (ABA) was first assembled onto the 3DOM gold film via sulfur–gold affinity. Then, 5′-biotinated complementary strand (BCS) was immobilized via hybridization reaction to form the DNA/DNA duplex. Since the tertiary structure of the aptamer was stabilized in the presence of target ATP, the duplex can be denatured to liberate BCS. The reaction was monitored by electrochemical stripping analysis of dissolved QDs which were bound to the residual BCS through biotin-streptavidin system. The decrease of peak current was proportional to the amount of ATP. The unique interconnected structure in 3DOM gold film along with the "built-in" preconcentration remarkably improved the sensitivity. ATP detection with high selectivity, wide linear dynamic range of 4 orders of magnitude and high sensitivity down to 0.01 nm were achieved. The results demonstrated that the novel strategy was feasible for sensitive ATP assay and provided a promising model for the detection of small molecules.

Preparation and characterization of cellulose acetate organic/inorganic hybrid films

Treesearch

Saeed S. Shojaie; Timothy G. Rials; Stephen S. Kelley

1995-01-01

A series of organic/inorganic hybrid (OIH) films were prepared using cellulose acetate (CA) as the organic component and tetraethyl orthosilicate (TEOS) as the inorganic component. The chemical, morphological, and mechanical properties of these films were evaluated with a variety of analytical techniques. The results of these evaluations showed that crosslinked CA OIH...

Controlled fabrication of PANI/CNF hybrid films: molecular interaction induced various micromorphologies and electrochemical properties.

PubMed

Xu, Guiheng; Xu, Dongdong; Zhang, Jianan; Wang, Kaixi; Chen, Zhimin; Chen, Jiafu; Xu, Qun

2013-12-01

In this paper, a facile and efficient method is reported to prepare polyaniline/carbon nanofiber (PANI/CNF) hybrid films by in situ chemical polymerization of aniline. The various morphologies and microstructures of PANI/CNF hybrid films can be controlled by adjusting the concentration of aniline and different acids as the protonation reagent, and the formation mechanism is illustrated in this study. The surface morphologies and chemical structure of the PANI/CNF hybrid films are characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), water contact angle (CA), FT-IR, Raman, and UV-vis spectrophotometers. The different morphology of uniformly coated, twist-tangled, and needle-like PANI built on CNF films are obtained by using HCl, H2SO4, and HClO4 as protonation reagent and the obtained hybrid films are labeled as PANI/CNF-f1, PANI/CNF-f2, and PANI/CNF-f3, respectively. We demonstrated that the different protonation reagent has the determined effect on the surface properties of the obtained hybrid films that can transfer from hydrophilic to hydrophobic. Besides, the various morphologies of PANI play an important role in their electrochemical properties. PANI/CNF-f3 exhibits higher specific capacitance and better stability than that of the PANI/CNF-f1 and PANI/CNF-f2. Considering its unique needle-like structure, this work is a proof of concept that micro-structure and morphology can determine the macro-properties. And this study supplies a facile method to fabricate PANI/CNF hybrid films that can be used as electrode materials in supercapacitors. Copyright © 2013 Elsevier Inc. All rights reserved.

A General Strategy for Hybrid Thin Film Fabrication and Transfer onto Arbitrary Substrates

PubMed Central

Zhang, Yong; Magan, John J.; Blau, Werner J.

2014-01-01

The development of thin film-based structures/devices often requires thin films to be transferred onto arbitrary substrates/surfaces. Controllable and non-destructive transfer method, although highly desired, remains quite challenging. Here we report a general method for fabrication and transfer of hybrid (ultra)thin films. The proposed solution-based in-situ transfer method shows not only its robust ability for thin film transfer onto arbitrary substrates but also its highly controlled and non-destructive characteristic. With a hole structure as the support, fully-stretched free-standing thin film is prepared. The successful transfer to a curved surface demonstrates the possibility for production of thin film-coated complex optical components. Ultrathin (35 nm) hybrid film transferred onto PET (50 μm thick) shows high transparency (>90% in visible range), conductivity (1.54 × 104 S/m), and flexibility (radius of curvature down to mm scale). The reported transfer method would provide a powerful route towards complex thin film-based structures/devices. PMID:24769689

A general strategy for hybrid thin film fabrication and transfer onto arbitrary substrates.

PubMed

Zhang, Yong; Magan, John J; Blau, Werner J

2014-04-28

The development of thin film-based structures/devices often requires thin films to be transferred onto arbitrary substrates/surfaces. Controllable and non-destructive transfer method, although highly desired, remains quite challenging. Here we report a general method for fabrication and transfer of hybrid (ultra)thin films. The proposed solution-based in-situ transfer method shows not only its robust ability for thin film transfer onto arbitrary substrates but also its highly controlled and non-destructive characteristic. With a hole structure as the support, fully-stretched free-standing thin film is prepared. The successful transfer to a curved surface demonstrates the possibility for production of thin film-coated complex optical components. Ultrathin (35 nm) hybrid film transferred onto PET (50 μm thick) shows high transparency (>90% in visible range), conductivity (1.54 × 10(4) S/m), and flexibility (radius of curvature down to mm scale). The reported transfer method would provide a powerful route towards complex thin film-based structures/devices.

Organic/Inorganic Nano-hybrids with High Dielectric Constant for Organic Thin Film Transistor Applications

NASA Astrophysics Data System (ADS)

Yu, Yang-Yen; Jiang, Ai-Hua; Lee, Wen-Ya

2016-11-01

The organic material soluble polyimide (PI) and organic-inorganic hybrid PI-barium titanate (BaTiO3) nanoparticle dielectric materials (IBX, where X is the concentration of BaTiO3 nanoparticles in a PI matrix) were successfully synthesized through a sol-gel process. The effects of various BaTiO3 contents on the hybrid film performance and performance optimization were investigated. Furthermore, pentacene-based organic thin film transistors (OTFTs) with PI-BaTiO3/polymethylmethacrylate or cyclic olefin copolymer (COC)-modified gate dielectrics were fabricated and examined. The hybrid materials showed effective dispersion of BaTiO3 nanoparticles in the PI matrix and favorable thermal properties. X-ray diffraction patterns revealed that the BaTiO3 nanoparticles had a perovskite structure. The hybrid films exhibited high formability and planarity. The IBX hybrid dielectric films exhibited tunable insulating properties such as the dielectric constant value and capacitance in ranges of 4.0-8.6 and 9.2-17.5 nF cm-2, respectively. Adding the modified layer caused the decrease of dielectric constant values and capacitances. The modified dielectric layer without cross-linking displayed a hydrophobic surface. The electrical characteristics of the pentacene-based OTFTs were enhanced after the surface modification. The optimal condition for the dielectric layer was 10 wt% hybrid film with the COC-modified layer; moreover, the device exhibited a threshold voltage of 0.12 V, field-effect mobility of 4.32 × 10-1 cm2 V-1 s-1, and on/off current of 8.4 × 107.

Luminescence and transient lifetime studies for energy transfer of PbS QD films

NASA Astrophysics Data System (ADS)

Wang, Joanna S.; Ullrich, Bruno; Dass, Chandriker K.; Das, Anirban; Wai, Chien M.; Brown, Gail J.; Hendrickson, Joshua R.

2017-08-01

Quantum confined semiconductor materials in colloidal form have drawn great attention in scientific communities due to the size-tunability, which controls their optical properties. PbS quantum dots (QDs) are exciting candidates for quantum optics, particularly due to the control of the QD sizes during the synthetic process enabling the realization of precisely tunable emission properties in the near-infrared region. Differently sized pairs of PbS QDs were deposited onto glass substrates to form thin films using supercritical CO2 (sc-CO2) deposition and solvent deposition methods (SDM). The fluorescence and photoluminescence (PL) spectra obtained from these closely packed films prepared by the sc-CO2 method reveal effective Förster resonance energy transfer (FRET) between two different sized dots, while the films composed of three different QD sizes show an even more effective FRET from the smallest to the largest ones. Energy transfer can be observed more directly by temporally resolved PL decay of mixed dots. By means of transient lifetime measurements, a mixed PbS film with 3.1 and 4.7 nm QDs was studied for FRET by time correlated single photon counting. The PL peak of the 3.1 nm QDs is quenched with respect to the emission of the 4.7 nm QDs and decays faster, and the best fit for the lifetime (decay constant)-1 is a biexponential decay mode. The long wavelength decay (4.7 nm QDs) is best fit by a mono-exponential equation. More theoretical and experimental work is required for a thorough understanding of the radiative lifetimes of PbS QDs in mixed QD systems.

Development of a dual-axis hybrid-type tactile sensor using PET film

NASA Astrophysics Data System (ADS)

Seonggi, Kim; Koo, Ja Choon; Choi, Hyouk Ryeol; Moon, Hyungpil

2013-04-01

In previous work, a dual-axis hybrid-type tactile sensor using PDMS (Polydimethylsiloxane) with a pair of metal electrodes, (which were deposited directly on the PDMS surface), was proposed. The hybrid sensor can measure the normal force and the shear force from the measurement of the change of capacitance and resistance values from the one pair of electrodes. However, the metal is hard to be deposited on the surface of the PDMS because the PDMS is hydrophobic. The hydrophobic surface can be changed to hydrophilic using O2 Plasma treatment or UV treatment. When O2 plasma treatment or UV treatment is used, there is the problem that the processing of the metal deposition and the wiring completed in a very short period of limited time. Also, the deposited metal on the surface of the PDMS is easy to break because the deposited metal is exposed in the air. In this paper, we propose a dual-axis hybrid-type tactile sensor where the PET (polyethylene terephthalate) film is inserted between the PDMS films. The deposited metal is not removed easily from the PET film because the adhesion is strong. Also, the PDMS surrounding the PET film plays the roles of dielectric elastomer and shielding the deposited metal from the external environment at same time. Experimental results verify the effectiveness of the fabricated dual-axis hybrid-type force sensor.

Polarized emission from CsPbX3 perovskite quantum dots

NASA Astrophysics Data System (ADS)

Wang, Dan; Wu, Dan; Dong, Di; Chen, Wei; Hao, Junjie; Qin, Jing; Xu, Bing; Wang, Kai; Sun, Xiaowei

2016-06-01

Compared to organic/inorganic hybrid perovskites, full inorganic perovskite quantum dots (QDs) exhibit higher stability. In this study, full inorganic CsPbX3 (X = Br, I and mixed halide systems Br/I) perovskite QDs have been synthesized and interestingly, these QDs showed highly polarized photoluminescence which is systematically studied for the first time. Furthermore, the polarization of CsPbI3 was as high as 0.36 in hexane and 0.40 as a film. The CsPbX3 perovskite QDs with high polarization properties indicate that they possess great potential for application in new generation displays with wide colour gamut and low power consumption.Compared to organic/inorganic hybrid perovskites, full inorganic perovskite quantum dots (QDs) exhibit higher stability. In this study, full inorganic CsPbX3 (X = Br, I and mixed halide systems Br/I) perovskite QDs have been synthesized and interestingly, these QDs showed highly polarized photoluminescence which is systematically studied for the first time. Furthermore, the polarization of CsPbI3 was as high as 0.36 in hexane and 0.40 as a film. The CsPbX3 perovskite QDs with high polarization properties indicate that they possess great potential for application in new generation displays with wide colour gamut and low power consumption. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01915c

Probing into hybrid organic-molecule and InAs quantum-dots nanosystem with multistacked dots-in-a-well units

NASA Astrophysics Data System (ADS)

Chen, Miaoxiang; Kobashi, Kazufumi

2012-09-01

Hybridizing air-stable organic-molecules with advanced III-V semiconductor quantum-dots (QDs) structures can be utilized to create a new generation of biochemical sensing devices. In order to enhance their optical performances, the active regions in these QDs structures commonly consist of multistacked dots-in-a-well (DWELL) units. The effects of grafted molecules on the performances of the QDs structures with multistacked DWELLs, however, still remain unclear. Here, we show the significant improvements in the optical properties of InAs QDs in a hybrid nanosystem obtained by grafting biocompatible diazonium salt compound (amine donor) atop InAs QDs structure. Since its interface between the QDs structure and molecular monolayer retains an uncontaminated and non-oxidized condition, the nanosystem is an ideal platform to study the intrinsic properties of charge-carrier transport inside the system. Because of the complexity of the energy-levels in the QDs structure due to the existing surface QDs and DWELLs, selective excitation wavelengths (400, 633, and 885 nm, respectively) with different photo-energies are used to exactly analyze the complete charging mechanism in these QDs. A clear view of charge-carrier transfer inside the nanosystem is revealed by employing photoluminescence technique under selective-wavelength excitations. The present work provides new quantitative evidences for exploiting inorganic QDs applications in complex biological systems.

High enzymatic activity preservation with carbon nanotubes incorporated in urease-lipid hybrid Langmuir-Blodgett films.

PubMed

Caseli, Luciano; Siqueira, José Roberto

2012-03-27

The search for optimized architectures, such as thin films, for the production of biosensors has been challenged in recent decades, and thus, the understanding of molecular interactions that occur at interfaces is essential to improve the construction of nanostructured devices. In this study, we investigated the possibility of using carbon nanotubes in hybrid Langmuir-Blodgett (LB) films of lipids and urease to improve the catalytic performance of the immobilized enzyme. The molecular interactions were first investigated at the air-water interface with the enzyme adsorbed from the aqueous subphase onto Langmuir monolayers of dimyristoylphosphatidic acid (DMPA). The transfer to solid supports as LB films and the subsequent incorporation of carbon nanotubes in the hybrid film permitted us to evaluate how these nanomaterials changed the physical properties of the ultrathin film. Colorimetric measurments indicated that the presence of nanotubes preserved and enhanced the enzyme activity of the film, even after 1 month. These results show that the use of such hybrid films is promising for the development of biosensors with an optimized performance. © 2012 American Chemical Society

Ultra-tough and strong, hybrid thin films based on ionically crosslinked polymers and 2D inorganic platelets

NASA Astrophysics Data System (ADS)

Ji, Dong Hwan; Choi, Suji; Kim, Jaeyun; nanobiomaterials lab Team

Integration of high strength and toughness tend to be mutually exclusive and synthesized hybrid films with superior mechanical properties have been difficult to fabricate controllable shapes and various scales. Although diverse synthesized hybrid films consisting of organic matrix and inorganic materials with brick-and-mortar structure, show improved mechanical properties, these films are still limited in toughness and fabrication methods. Herein, we report ultra-tough and strong hybrid thin films with self-assembled uniform microstructures with controllable shapes and various scale based on hydrogel-mediated process. Ca2+-crosslinking in alginate chains and well-aligned alumina platelets in alginate matrix lead to a synergistic enhancement of strength and toughness in the resulting film. Consequentially, Ca2+-crosslinked Alg/Alu films showed outstanding toughness of 29 MJ m-3 and tensile strength of 160 MPa. Furthermore, modifying Alu surface with polyvinylpyrrolidone (PVP), tensile strength was further improved up to 200 MPa. Our results suggest an alternative approach to design and processing of self-assembled hydrogel-mediated hybrid films with outstanding mechanical properties.

Intermatrix Synthesis as a rapid, inexpensive and reproducible methodology for the in situ functionalization of nanostructured surfaces with quantum dots

NASA Astrophysics Data System (ADS)

Bastos-Arrieta, Julio; Muñoz, Jose; Stenbock-Fermor, Anja; Muñoz, Maria; Muraviev, Dmitri N.; Céspedes, Francisco; Tsarkova, Larisa A.; Baeza, Mireia

2016-04-01

Intermatrix Synthesis (IMS) technique has proven to be a valid methodology for the in situ incorporation of quantum dots (QDs) in a wide range of nanostructured surfaces for the preparation of advanced hybrid-nanomaterials. In this sense, this communication reports the recent advances in the application of IMS for the synthesis of CdS-QDs with favourable distribution on sulfonated polyetherether ketone (SPEEK) membrane thin films (TFs), multiwall carbon nanotubes (MWCNTs) and nanodiamonds (NDs). The synthetic route takes advantage of the ion exchange functionality of the reactive surfaces for the loading of the QDs precursor and consequent QDs appearance by precipitation. The benefits of such modified nanomaterials were studied using CdS-QDs@MWCNTs hybrid-nanomaterials. CdS-QDs@MWCNTs has been used as conducting filler for the preparation of electrochemical nanocomposite sensors, which present electrocatalytic properties. Finally, the optical properties of the QDs contained on MWCNTs could allow a new procedure for the analytical detection of nanostructured carbon allotropes in water.

Hybrid type-I InAs/GaAs and type-II GaSb/GaAs quantum dot structure with enhanced photoluminescence

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

Ji, Hai-Ming; Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083; Liang, Baolai, E-mail: bliang@cnsi.ucla.edu

2015-03-09

We investigate the photoluminescence (PL) properties of a hybrid type-I InAs/GaAs and type-II GaSb/GaAs quantum dot (QD) structure grown in a GaAs matrix by molecular beam epitaxy. This hybrid QD structure exhibits more intense PL with a broader spectral range, compared with control samples that contain only InAs or GaSb QDs. This enhanced PL performance is attributed to additional electron and hole injection from the type-I InAs QDs into the adjacent type-II GaSb QDs. We confirm this mechanism using time-resolved and power-dependent PL. These hybrid QD structures show potential for high efficiency QD solar cell applications.

Miniature hybrid microwave IC's using a novel thin-film technology

NASA Astrophysics Data System (ADS)

Eda, Kazuo; Miwa, Tetsuji; Taguchi, Yutaka; Uwano, Tomoki

1990-12-01

A novel thin-film technology for miniature hybrid microwave ICs is presented. All passive components, such as resistors and capacitors, are fully integrated on ordinary alumina ceramic substrates using the thin-film technology with very high yield. The numbers of parts and wiring processes were significantly reduced. This technology was applied to the fabrication of Ku-band solid-state power amplifiers. This thin-film technology offers the following advantages: (1) a very high yield fabrication process of thin-film capacitor having excellent electrical characteristics in the gigahertz range (Q = 230 at 12 GHz) and reliability: (2) two kinds of thin-film resistors having different temperature coefficients of resistivity and a lift-off process to integrate them with thin-film capacitors; and (3) a matching method using the thin-film capacitor.

Photoelectrochemical Cell of Hybrid Regioregular POLY(3-HEXYLTHIOPHENE-2,5-DIYL) and Molybdenum Disulfide Film

NASA Astrophysics Data System (ADS)

Abdelmola, Fatmaelzahraa M.; Ram, Manoj K.; Takshi, Arash; Stafanakos, Elias; Kumar, Ashok; Goswami, D. Yogi

The photoelectrochemical cell attracts attention worldwide due to conversion of optical energy into electricity, production of hydrogen through water splitting and use in photodetector and photo-sensor applications. We have been working on the photochemical cell based on regioregular polyhexylthiophenes hybrid-structured films for photoelectrochemical and photovoltaic applications. This paper discusses the hybrid film studies on regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT) with 2D molybdenum disulfide (MoS2) for photoelectrochemical cell. The hybrid P3HT/MoS2 films deposited over indium tin oxide (ITO)-coated glass plate or n-type silicon substrates were characterized using FTIR, UV/vis, electrochemical and scanning electron microscopy (SEM) techniques. The optical measurements showed a higher absorption magnitude with low reflection properties of P3HT/MoS2 hybrid films revealing a superior photocurrent compared to both P3HT and MoS2 films. The P3HT/MoS2 hybrid-based photoelectrochemical cell yielded a short-circuit current (Isc) of 183.16μAṡcm-2, open-circuit voltage (Voc) of 0.92V, fill factor (FF) of 25% and power conversion efficiency (η) of 0.18% under the light intensity of 242Wṡm-2. The estimated power conversion efficiency and fill factor are comparable to organic-based photovoltaic devices.

Micropatterned 2D Hybrid Perovskite Thin Films with Enhanced Photoluminescence Lifetimes

PubMed Central

2018-01-01

The application of luminescent materials in display screens and devices requires micropatterned structures. In this work, we have successfully printed microstructures of a two-dimensional (2D), orange-colored organic/inorganic hybrid perovskite ((C6H5CH2NH3)2PbI4) using two different soft lithography techniques. Notably, both techniques yield microstructures with very high aspect ratios in the range of 1.5–1.8. X-ray diffraction reveals a strong preferential orientation of the crystallites along the c-axis in both patterned structures, when compared to nonpatterned, drop-casted thin films. Furthermore, (time-resolved) photoluminescence (PL) measurements reveal that the optical properties of (C6H5CH2NH3)2PbI4 are conserved upon patterning. We find that the larger grain sizes of the patterned films with respect to the nonpatterned film give rise to an enhanced PL lifetime. Thus, our results demonstrate easy and cost-effective ways to manufacture patterns of 2D organic/inorganic hybrid perovskites, while even improving their optical properties. This demonstrates the potential use of color-tunable 2D hybrids in optoelectronic devices. PMID:29578335

Micropatterned 2D Hybrid Perovskite Thin Films with Enhanced Photoluminescence Lifetimes.

PubMed

Kamminga, Machteld E; Fang, Hong-Hua; Loi, Maria Antonietta; Ten Brink, Gert H; Blake, Graeme R; Palstra, Thomas T M; Ten Elshof, Johan E

2018-04-18

The application of luminescent materials in display screens and devices requires micropatterned structures. In this work, we have successfully printed microstructures of a two-dimensional (2D), orange-colored organic/inorganic hybrid perovskite ((C 6 H 5 CH 2 NH 3 ) 2 PbI 4 ) using two different soft lithography techniques. Notably, both techniques yield microstructures with very high aspect ratios in the range of 1.5-1.8. X-ray diffraction reveals a strong preferential orientation of the crystallites along the c-axis in both patterned structures, when compared to nonpatterned, drop-casted thin films. Furthermore, (time-resolved) photoluminescence (PL) measurements reveal that the optical properties of (C 6 H 5 CH 2 NH 3 ) 2 PbI 4 are conserved upon patterning. We find that the larger grain sizes of the patterned films with respect to the nonpatterned film give rise to an enhanced PL lifetime. Thus, our results demonstrate easy and cost-effective ways to manufacture patterns of 2D organic/inorganic hybrid perovskites, while even improving their optical properties. This demonstrates the potential use of color-tunable 2D hybrids in optoelectronic devices.

Transparent Conducting Graphene Hybrid Films To Improve Electromagnetic Interference (EMI) Shielding Performance of Graphene.

PubMed

Ma, Limin; Lu, Zhengang; Tan, Jiubin; Liu, Jian; Ding, Xuemei; Black, Nicola; Li, Tianyi; Gallop, John; Hao, Ling

2017-10-04

Conducting graphene-based hybrids have attracted considerable attention in recent years for their scientific and technological significance in many applications. In this work, conductive graphene hybrid films, consisting of a metallic network fully encapsulated between monolayer graphene and quartz-glass substrate, were fabricated and characterized for their electromagnetic interference shielding capabilities. Experimental results show that by integration with a metallic network the sheet resistance of graphene was significantly suppressed from 813.27 to 5.53 Ω/sq with an optical transmittance at 91%. Consequently, the microwave shielding effectiveness (SE) exceeded 23.60 dB at the K u -band and 13.48 dB at the K a -band. The maximum SE value was 28.91 dB at 12 GHz. Compared with the SE of pristine monolayer graphene (3.46 dB), the SE of graphene hybrid film was enhanced by 25.45 dB (99.7% energy attenuation). At 94% optical transmittance, the sheet resistance was 20.67 Ω/sq and the maximum SE value was 20.86 dB at 12 GHz. Our results show that hybrid graphene films incorporate both high conductivity and superior electromagnetic shielding comparable to existing ITO shielding modalities. The combination of high conductivity and shielding along with the materials' earth-abundant nature, and facile large-scale fabrication, make these graphene hybrid films highly attractive for transparent EMI shielding.

Solution-processed hybrid organic-inorganic complementary thin-film transistor inverter

NASA Astrophysics Data System (ADS)

Cheong, Heajeong; Kuribara, Kazunori; Ogura, Shintaro; Fukuda, Nobuko; Yoshida, Manabu; Ushijima, Hirobumi; Uemura, Sei

2016-04-01

We investigated hybrid organic-inorganic complementary inverters with a solution-processed indium-gallium-zinc-oxide (IGZO) n-channel thin-film transistor (TFT) and p-channel TFTs using the high-uniformity polymer poly[2,5-bis(alkyl)pyrrolo[3,4-c]pyrrolo-1,4(2H,5H)-dione-alt-5,5-di(thiophene-2-yl)-2,2-(E)-2-(2-(thiophen-2-yl)vinyl)thiophene] (PDVT-10). The IGZO TFT was fabricated at 150 °C for 1 min. It showed a high field-effect mobility of 0.9 cm2·V-1·s-1 and a high on/off current ratio of 107. A hybrid complementary inverter was fabricated by combining IGZO with a PDVT-10 thin-film transistor and its operation was confirmed.

Bio-inspired, colorful, flexible, defrostable light-scattering hybrid films for the effective distribution of LED light.

PubMed

An, Seongpil; Jo, Hong Seok; Kim, Yong Il; Song, Kyo Yong; Kim, Min-Woo; Lee, Kyu Bum; Yarin, Alexander L; Yoon, Sam S

2017-07-06

Bioluminescent jellyfish has a unique structure derived from fiber/polymer interfaces that is advantageous for effective light scattering in the dark, deep sea water. Herein, we demonstrate the fabrication of bio-inspired hybrid films by mimicry of the jellyfish's structure, leading to excellent light-scattering performance and defrosting capability. A haze value reaching 59.3% and a heating temperature of up to 292 °C were achieved with the films. Accordingly, the developed surface constitutes an attractive optical device for lighting applications, especially for street or vehicle luminaries for freezing Arctic-climate countries. The morphological details of the hybrid films were revealed by scanning electron microscopy. The light-scattering properties of these films were examined by ultraviolet-visible-infrared spectrophotometry and anti-glare effect analyses. The defrosting performance of the hybrid films was evaluated via heating tests and infra-red observations.

Fast imaging of eccrine latent fingerprints with nontoxic Mn-doped ZnS QDs.

PubMed

Xu, Chaoying; Zhou, Ronghui; He, Wenwei; Wu, Lan; Wu, Peng; Hou, Xiandeng

2014-04-01

Fingerprints are unique characteristics of an individual, and their imaging and recognition is a top-priority task in forensic science. Fast LFP (latent fingerprint) acquirement can greatly help policemen in screening the potential criminal scenes and capturing fingerprint clues. Of the two major latent fingerprints (LFP), eccrine is expected to be more representative than sebaceous in LFP identification. Here we explored the heavy metal-free Mn-doped ZnS quantum dots (QDs) as a new imaging moiety for eccrine LFPs. To study the effects of different ligands on the LFP image quality, we prepared Mn-doped ZnS QDs with various surface-capping ligands using QDs synthesized in high-temperature organic media as starting material. The orange fluorescence emission from Mn-doped ZnS QDs clearly revealed the optical images of eccrine LFPs. Interestingly, N-acetyl-cysteine-capped Mn-doped ZnS QDs could stain the eccrine LFPs in as fast as 5 s. Meanwhile, the levels 2 and 3 substructures of the fingerprints could also be simultaneously and clearly identified. While in the absence of QDs or without rubbing and stamping the finger onto foil, no fluorescent fingerprint images could be visualized. Besides fresh fingerprint, aged (5, 10, and 50 days), incomplete eccrine LFPs could also be successfully stained with N-acetyl-cysteine-capped Mn-doped ZnS QDs, demonstrating the analytical potential of this method in real world applications. The method was also robust for imaging of eccrine LFPs on a series of nonporous surfaces, such as aluminum foil, compact discs, glass, and black plastic bags.

Electrical properties of films of zinc oxide nanoparticles and its hybrid with reduced graphene oxide

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

Madhuri, K. Priya; Bramhaiah, K.; John, Neena S., E-mail: jsneena@cnsms.res.in

Free-standing films of ZnO nanoparticles (NPs) and reduced graphene oxide (rGO)-ZnO NPs hybrid are prepared at a liquid/liquid interface. The films are characterized by UV-visible spectroscopy, X-ray diffraction, scanning electron microscopy and atomic force microscopy. ZnO film consists of spherical aggregated NPs while the hybrid film contains folded sheets of rGO with embedded ZnO NPs. Electrical properties of the films and its photoresponse in presence of UV radiation are investigated using current sensing atomic force microscopy (CSAFM) at nanoscale and bulk measurements using two probe methods. Enhancement in photocurrent is observed in both cases and the current imaging reveals anmore » inhomogeneous contribution by different ZnO grains in the film.« less

Nacre-like hybrid films: Structure, properties, and the effect of relative humidity.

PubMed

Abba, Mohammed T; Hunger, Philipp M; Kalidindi, Surya R; Wegst, Ulrike G K

2015-03-01

Functional materials often are hybrids composed of biopolymers and mineral constituents. The arrangement and interactions of the constituents frequently lead to hierarchical structures with exceptional mechanical properties and multifunctionality. In this study, hybrid thin films with a nacre-like brick-and-mortar microstructure were fabricated in a straightforward and reproducible manner through manual shear casting using the biopolymer chitosan as the matrix material (mortar) and alumina platelets as the reinforcing particles (bricks). The ratio of inorganic to organic content was varied from 0% to 15% and the relative humidities from 36% to 75% to determine their effects on the mechanical properties. It was found that increasing the volume fraction of alumina from 0% to 15% results in a twofold increase in the modulus of the film, but decreases the tensile strength by up to 30%, when the volume fraction of alumina is higher than 5%. Additionally, this study quantifies and illustrates the critical role of the relative humidity on the mechanical properties of the hybrid film. Increasing the relative humidity from 36% to 75% decreases the modulus and strength by about 45% and triples the strain at failure. These results suggest that complex hybrid materials can be manufactured and tailor made for specific applications or environmental conditions. Copyright © 2015. Published by Elsevier Ltd.

Nongeminate Radiative Recombination of Free Charges in Cation-Exchanged PbS Quantum Dot Films

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

Marshall, Ashley R.; Beard, Matthew C.; Johnson, Justin C.

2016-06-01

Using photoluminescence (PL) spectroscopy we explore the radiative recombination pathways in PbS quantum dots (QDs) synthesized by two methods. We compare conventionally synthesized PbS from a PbO precursor to PbS synthesized using cation-exchange from CdS QDs. We show that strongly coupled films of PbS QDs from the cation-exchange luminesce with significant efficiency at room temperature. This is in stark contrast to conventional PbS QDs, which have exceedingly weak room temperature emission. Moreover, the power dependence of the emission is quadratic, indicating bimolecular radiative recombination that is reasonably competitive with trap-assisted recombination, a feature previously unreported in coupled PbS QD films.more » We interpret these results in terms of a greatly reduced defect concentration for cation-exchanged QDs that mitigates the influence of trap-assisted recombination. Cation-exchanged QDs have recently been employed in highly efficient and air-stable lead chalcogenide QD devices, and the reduced number of trap states inferred here may lead to improved current collection and higher open circuit voltage.« less

Nongeminate radiative recombination of free charges in cation-exchanged PbS quantum dot films

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

Marshall, Ashley R.; Beard, Matthew C.; Johnson, Justin C.

2016-06-01

Using photoluminescence (PL) spectroscopy we explore the radiative recombination pathways in PbS quantum dots (QDs) synthesized by two methods. We compare conventionally synthesized PbS from a PbO precursor to PbS synthesized using cation-exchange from CdS QDs. We show that strongly coupled films of PbS QDs from the cation-exchange luminesce with significant efficiency at room temperature. This is in stark contrast to conventional PbS QDs, which have exceedingly weak room temperature emission. Moreover, the power dependence of the emission is quadratic, indicating bimolecular radiative recombination that is reasonably competitive with trap-assisted recombination, a feature previously unreported in coupled PbS QD films.more » We interpret these results in terms of a greatly reduced defect concentration for cation-exchanged QDs that mitigates the influence of trap-assisted recombination. Cation-exchanged QDs have recently been employed in highly efficient and air-stable lead chalcogenide QD devices, and the reduced number of trap states inferred here may lead to improved current collection and higher open circuit voltage.« less

Carbon nanotube TiO2 hybrid films for detecting traces of O2

NASA Astrophysics Data System (ADS)

Llobet, E.; Espinosa, E. H.; Sotter, E.; Ionescu, R.; Vilanova, X.; Torres, J.; Felten, A.; Pireaux, J. J.; Ke, X.; Van Tendeloo, G.; Renaux, F.; Paint, Y.; Hecq, M.; Bittencourt, C.

2008-09-01

Hybrid titania films have been prepared using an adapted sol-gel method for obtaining well-dispersed hydrogen plasma-treated multiwall carbon nanotubes in either pure titania or Nb-doped titania. The drop-coating method has been used to fabricate resistive oxygen sensors based on titania or on titania and carbon nanotube hybrids. Morphology and composition studies have revealed that the dispersion of low amounts of carbon nanotubes within the titania matrix does not significantly alter its crystallization behaviour. The gas sensitivity studies performed on the different samples have shown that the hybrid layers based on titania and carbon nanotubes possess an unprecedented responsiveness towards oxygen (i.e. more than four times higher than that shown by optimized Nb-doped TiO2 films). Furthermore, hybrid sensors containing carbon nanotubes respond at significantly lower operating temperatures than their non-hybrid counterparts. These new hybrid sensors show a strong potential for monitoring traces of oxygen (i.e. <=10 ppm) in a flow of CO2, which is of interest for the beverage industry.

Alumina/polymer-coated nanocrystals with extremely high stability used as a color conversion material in LEDs

NASA Astrophysics Data System (ADS)

Woo, Ju Yeon; Lee, Jongsoo; Han, Chang-Soo

2013-12-01

The long-term stability of quantum dot (QD)-based devices under harsh environmental conditions has been a critical bottleneck to be resolved for commercial use. Here, we demonstrate an extremely stable QD/alumina/polymer hybrid structure by combining internal atomic layer deposition (ALD) infilling with polymer encapsulation. ALD infilling and polymer encapsulation of QDs synergistically prohibit the degradation of QDs in terms of optical, thermal and humid attacks. Our hybrid QD/alumina/polymer film structure showed no noticeable reduction in photoluminescence even in a commercial grade test (85% humidity at 85 ° C) over 28 days. In addition, we successfully fabricated a QD-based light-emitting device with excellent long-term stability by incorporating hybrid QD/alumina/polymer film as a color conversion material on light-emitting diode chips.

DNA hybridization sensor based on pentacene thin film transistor.

PubMed

Kim, Jung-Min; Jha, Sandeep Kumar; Chand, Rohit; Lee, Dong-Hoon; Kim, Yong-Sang

2011-01-15

A DNA hybridization sensor using pentacene thin film transistors (TFTs) is an excellent candidate for disposable sensor applications due to their low-cost fabrication process and fast detection. We fabricated pentacene TFTs on glass substrate for the sensing of DNA hybridization. The ss-DNA (polyA/polyT) or ds-DNA (polyA/polyT hybrid) were immobilized directly on the surface of the pentacene, producing a dramatic change in the electrical properties of the devices. The electrical characteristics of devices were studied as a function of DNA immobilization, single-stranded vs. double-stranded DNA, DNA length and concentration. The TFT device was further tested for detection of λ-phage genomic DNA using probe hybridization. Based on these results, we propose that a "label-free" detection technique for DNA hybridization is possible through direct measurement of electrical properties of DNA-immobilized pentacene TFTs. Copyright © 2010 Elsevier B.V. All rights reserved.

Antibacterial potential of rutin conjugated with thioglycolic acid capped cadmium telluride quantum dots (TGA-CdTe QDs)

NASA Astrophysics Data System (ADS)

Ananth, Devanesan Arul; Rameshkumar, Angappan; Jeyadevi, Ramachandran; Jagadeeswari, Sivanadanam; Nagarajan, Natarajan; Renganathan, Rajalingam; Sivasudha, Thilagar

2015-03-01

Quantum dots not only act as nanocarrier but also act as stable and resistant natural fluorescent bio markers used in various in vitro and in vivo photolabelling and biological applications. In this study, the antimicrobial potential of TGA-CdTe QDs and commercial phenolics (rutin and caffeine) were investigated against Escherichiacoli. UV absorbance and fluorescence quenching study of TGA-CdTe QDs with rutin and caffeine complex was measured by spectroscopic technique. QDs-rutin conjugate exhibited excellent quenching property due to the -OH groups present in the rutin structure. But the same time caffeine has not conjugated with QDs because of lacking of -OH group in its structure. Photolabelling of E. coli with QDs-rutin and QDs-caffeine complex was analyzed by fluorescent microscopic method. Microbe E. coli cell membrane damage was assessed by atomic force (AFM) and confocal microscopy. Based on the results obtained, it is suggested that QDs-rutin conjugate enhance the antimicrobial activity more than the treatment with QDs, rutin and caffeine alone.

Structural, optical and photovoltaic properties of co-doped CdTe QDs for quantum dots sensitized solar cells

NASA Astrophysics Data System (ADS)

Ayyaswamy, Arivarasan; Ganapathy, Sasikala; Alsalme, Ali; Alghamdi, Abdulaziz; Ramasamy, Jayavel

2015-12-01

Zinc and sulfur alloyed CdTe quantum dots (QDs) sensitized TiO2 photoelectrodes have been fabricated for quantum dots sensitized solar cells. Alloyed CdTe QDs were prepared in aqueous phase using mercaptosuccinic acid (MSA) as a capping agent. The influence of co-doping on the structural property of CdTe QDs was studied by XRD analysis. The enhanced optical absorption of alloyed CdTe QDs was studied using UV-vis absorption and fluorescence emission spectra. The capping of MSA molecules over CdTe QDs was confirmed by the FTIR and XPS analyses. Thermogravimetric analysis confirms that the prepared QDs were thermally stable up to 600 °C. The photovoltaic performance of alloyed CdTe QDs sensitized TiO2 photoelectrodes were studied using J-V characteristics under the illumination of light with 1 Sun intensity. These results show the highest photo conversion efficiency of η = 1.21%-5% Zn & S alloyed CdTe QDs.

Shape changing thin films powered by DNA hybridization

NASA Astrophysics Data System (ADS)

Shim, Tae Soup; Estephan, Zaki G.; Qian, Zhaoxia; Prosser, Jacob H.; Lee, Su Yeon; Chenoweth, David M.; Lee, Daeyeon; Park, So-Jung; Crocker, John C.

2017-01-01

Active materials that respond to physical and chemical stimuli can be used to build dynamic micromachines that lie at the interface between biological systems and engineered devices. In principle, the specific hybridization of DNA can be used to form a library of independent, chemically driven actuators for use in such microrobotic applications and could lead to device capabilities that are not possible with polymer- or metal-layer-based approaches. Here, we report shape changing films that are powered by DNA strand exchange reactions with two different domains that can respond to distinct chemical signals. The films are formed from DNA-grafted gold nanoparticles using a layer-by-layer deposition process. Films consisting of an active and a passive layer show rapid, reversible curling in response to stimulus DNA strands added to solution. Films consisting of two independently addressable active layers display a complex suite of repeatable transformations, involving eight mechanochemical states and incorporating self-righting behaviour.

In situ self-assembly of polarizing chromogen nanofibers catalyzed with hybrid films of gold nanoparticles and cellulose

NASA Astrophysics Data System (ADS)

Liu, Zhiming; Wu, Wenjian

2017-09-01

Hybrid materials of metal nanoparticles and biopolymers with catalytic properties are very promising to be used as detectors in biochemical reactions. In this work, the catalytic properties and relevant in situ self-assembly abilities of hybrid films of gold nanoparticles (GNPs) and cellulose for the oxidation of benign chromogen 3,3‧,5,5‧-tetramethylbenzidine (TMB) with hydrogen peroxide (H2O2) are revealed for the first time. The peroxidase-like properties of hybrid films are inherited from those of colloidal GNPs and increase with their contents of GNPs. It is discovered that the oxidized products of TMB grow in situ and assemble into rod-like and tumbleweed-like nanofiber assemblies on hybrid films. The rod-like nanofibers show a magnificent polarizing phenomenon under polarized light because of polycrystalline globular nanoparticles inside. The in situ self-assembly of polarizing nanofibers of chromogen catalyzed with hybrid films creates an opportunity for the synthesis of novel organic nanomaterials and the enhanced detection of biochemical products under polarized light.

Paper-based solid-phase nucleic acid hybridization assay using immobilized quantum dots as donors in fluorescence resonance energy transfer.

PubMed

Noor, M Omair; Shahmuradyan, Anna; Krull, Ulrich J

2013-02-05

A paper-based solid-phase assay is presented for transduction of nucleic acid hybridization using immobilized quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET). The surface of paper was modified with imidazole groups to immobilize QD-probe oligonucleotide conjugates that were assembled in solution. Green-emitting QDs (gQDs) were FRET-paired with Cy3 acceptor. Hybridization of Cy3-labeled oligonucleotide targets provided the proximity required for FRET-sensitized emission from Cy3, which served as an analytical signal. The assay exhibited rapid transduction of nucleic acid hybridization within minutes. Without any amplification steps, the limit of detection of the assay was found to be 300 fmol with the upper limit of the dynamic range at 5 pmol. The implementation of glutathione-coated QDs for the development of nucleic acid hybridization assay integrated on a paper-based platform exhibited excellent resistance to nonspecific adsorption of oligonucleotides and showed no reduction in the performance of the assay in the presence of large quantities of noncomplementary DNA. The selectivity of nucleic acid hybridization was demonstrated by single-nucleotide polymorphism (SNP) detection at a contrast ratio of 19 to 1. The reuse of paper over multiple cycles of hybridization and dehybridization was possible, with less than 20% reduction in the performance of the assay in five cycles. This work provides an important framework for the development of paper-based solid-phase QD-FRET nucleic acid hybridization assays that make use of a ratiometric approach for detection and analysis.

Hybrid polymer/ZnO solar cells sensitized by PbS quantum dots

PubMed Central

2012-01-01

Poly[2-methoxy-5-(2-ethylhexyloxy-p-phenylenevinylene)]/ZnO nanorod hybrid solar cells consisting of PbS quantum dots [QDs] prepared by a chemical bath deposition method were fabricated. An optimum coating of the QDs on the ZnO nanorods could strongly improve the performance of the solar cells. A maximum power conversion efficiency of 0.42% was achieved for the PbS QDs' sensitive solar cell coated by 4 cycles, which was increased almost five times compared with the solar cell without using PbS QDs. The improved efficiency is attributed to the cascade structure formed by the PbS QD coating, which results in enhanced open-circuit voltage and exciton dissociation efficiency. PMID:22313746

Evaluation of the dielectric function of colloidal Cd1 - xHgxTe quantum dot films by spectroscopic ellipsometry

NASA Astrophysics Data System (ADS)

Bejaoui, A.; Alonso, M. I.; Garriga, M.; Campoy-Quiles, M.; Goñi, A. R.; Hetsch, F.; Kershaw, S. V.; Rogach, A. L.; To, C. H.; Foo, Y.; Zapien, J. A.

2017-11-01

We report on the investigation by spectroscopic ellipsometry of films containing Cd1 - xHgxTe alloy quantum dots (QDs). The alloy QDs were fabricated from colloidal CdTe QDs grown by an aqueous synthesis process followed by an ion-exchange step in which Hg2+ ions progressively replace Cd2+. For ellipsometric studies, several films were prepared on glass substrates using layer-by-layer (LBL) deposition. The contribution of the QDs to the measured ellipsometric spectra is extracted from a multi-sample, transmission and multi- angle-of-incidence ellipsometric data analysis fitted using standard multilayer and effective medium models that include surface roughness effects, modeled by an effective medium approximation. The relationship of the dielectric function of the QDs retrieved from these studies to that of the corresponding II-VI bulk material counterparts is presented and discussed.

Synthesis and characterization of organic/inorganic heterostructure films for hybrid light emitting diode

NASA Astrophysics Data System (ADS)

Toyama, Toshihiko; Ichihara, Tokuyuki; Yamaguchi, Daisuke; Okamoto, Hiroaki

2007-10-01

Thin-film light emitting devices based on organic materials have been gathering attentions for applying a flat-panel display and a solid-state lighting. Alternatively, inorganic technologies such as Si-based thin-film technology have been growing almost independently. It is then expected that combining the Si-based thin-film technology with the organic light emitting diode (OLED) technology will develop innovative devices. Here, we report syntheses of the hybrid light emitting diode (LED) with a heterostructure consisting of p-type SiC x and tris-(8-hydroxyquinoline) aluminum films and characterization for the hybrid LEDs. We present the energy diagram of the heterostructure, and describe that the use of high dark conductivities of the p-type SiC x as well as inserting wide-gap intrinsic a-SiC x at the p-type SiC x/Alq interface are effective for improving device performance.

Successive and large-scale synthesis of InP/ZnS quantum dots in a hybrid reactor and their application to white LEDs

NASA Astrophysics Data System (ADS)

Kim, Kyungnam; Jeong, Sohee; Woo, Ju Yeon; Han, Chang-Soo

2012-02-01

We report successive and large-scale synthesis of InP/ZnS core/shell nanocrystal quantum dots (QDs) using a customized hybrid flow reactor, which is based on serial combination of a batch-type mixer and a flow-type furnace. InP cores and InP/ZnS core/shell QDs were successively synthesized in the hybrid reactor in a simple one-step process. In this reactor, the flow rate of the solutions was typically 1 ml min-1, 100 times larger than that of conventional microfluidic reactors. In order to synthesize high-quality InP/ZnS QDs, we controlled both the flow rate and the crystal growth temperature. Finally, we obtained high-quality InP/ZnS QDs in colors from bluish green to red, and we demonstrated that these core/shell QDs could be incorporated into white-light-emitting diode (LED) devices to improve color rendering performance.

Successive and large-scale synthesis of InP/ZnS quantum dots in a hybrid reactor and their application to white LEDs.

PubMed

Kim, Kyungnam; Jeong, Sohee; Woo, Ju Yeon; Han, Chang-Soo

2012-02-17

We report successive and large-scale synthesis of InP/ZnS core/shell nanocrystal quantum dots (QDs) using a customized hybrid flow reactor, which is based on serial combination of a batch-type mixer and a flow-type furnace. InP cores and InP/ZnS core/shell QDs were successively synthesized in the hybrid reactor in a simple one-step process. In this reactor, the flow rate of the solutions was typically 1 ml min(-1), 100 times larger than that of conventional microfluidic reactors. In order to synthesize high-quality InP/ZnS QDs, we controlled both the flow rate and the crystal growth temperature. Finally, we obtained high-quality InP/ZnS QDs in colors from bluish green to red, and we demonstrated that these core/shell QDs could be incorporated into white-light-emitting diode (LED) devices to improve color rendering performance.

Photoluminescence Spectra From The Direct Energy Gap of a-SiQDs

NASA Astrophysics Data System (ADS)

Abdul-Ameer, Nidhal M.; Abdulrida, Moafak C.; Abdul-Hakeem, Shatha M.

2018-05-01

A theoretical model for radiative recombination in amorphous silicon quantum dots (a-SiQDs) was developed. In this model, for the first time, the coexistence of both spatial and quantum confinements were considered. Also, it is found that the photoluminescence exhibits significant size dependence in the range (1-4) nm of the quantum dots. a-SiQDs show visible light emission peak energies and high radiative quantum efficiency at room temperature,in contrast to bulk a-Si structures. The quantum efficiency is sensitive to any change in defect density (the volume nonradiative centers density and/or the surface nonradiative centers density) but, with small dots sizes, the quantum efficiency is insensitive to such defects. Our analysis shows that the photoluminescence intensity increases or decreases by the effect of radiative quantum efficiency. By controlling the size of a-SiQDs, we note that the energy of emission can be tuned. The blue shift is attributed to quantum confinement effect. Meanwhile, the spatial confinement effect is clearly observed in red shift in emission spectra. we found a good agreement with the experimental published data. Therefore, we assert that a-SiQDs material is a promising candidate for visible, tunable, and high performance devices of light emitting.

Paper-based solid-phase multiplexed nucleic acid hybridization assay with tunable dynamic range using immobilized quantum dots as donors in fluorescence resonance energy transfer.

PubMed

Noor, M Omair; Krull, Ulrich J

2013-08-06

A multiplexed solid-phase nucleic acid hybridization assay on a paper-based platform is presented using multicolor immobilized quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET). The surface of paper was modified with imidazole groups to immobilize two types of QD-probe oligonucleotide conjugates that were assembled in solution. Green-emitting QDs (gQDs) and red-emitting QDs (rQDs) served as donors with Cy3 and Alexa Fluor 647 (A647) acceptors. The gQD/Cy3 FRET pair served as an internal standard, while the rQD/A647 FRET pair served as a detection channel, combining the control and analytical test zones in one physical location. Hybridization of dye-labeled oligonucleotide targets provided the proximity for FRET sensitized emission from the acceptor dyes, which served as an analytical signal. Hybridization assays in the multicolor format provided a limit of detection of 90 fmol and an upper limit of dynamic range of 3.5 pmol. The use of an array of detection zones was designed to provide improved analytical figures of merit compared to that which could be achieved on one type of array design in terms of relative concentration of multicolor QDs. The hybridization assays showed excellent resistance to nonspecific adsorption of oligonucleotides. Selectivity of the two-plex hybridization assay was demonstrated by single nucleotide polymorphism (SNP) detection at a contrast ratio of 50:1. Additionally, it is shown that the use of preformed QD-probe oligonucleotide conjugates and consideration of the relative number density of the two types of QD-probe conjugates in the two-color assay format is advantageous to maximize assay sensitivity and the upper limit of dynamic range.

Fluorescent magnetic hybrid nanoprobe for multimodal bioimaging

PubMed Central

Bright, Vanessa

2011-01-01

A fluorescent magnetic hybrid imaging nanoprobe (HINP) was fabricated by conjugation of superparamagnetic Fe3O4 nanoparticles and visible light-emitting (~600 nm) fluorescent CdTe/CdS quantum dots (QDs). The assembly strategy used the covalent linking of the oxidized dextran shell of magnetic particles to the glutathione ligands of QDs. Synthesized HINP formed stable water-soluble colloidal dispersions. The structure and properties of the particles were characterized by transmission electron and atomic force microscopy, energy dispersive X-ray analysis and inductively coupled plasma optical emission spectroscopy, dynamic light scattering analysis, optical absorption and photoluminescence spectroscopy, and fluorescent imaging. The luminescence imaging region of the nanoprobe was extended to the near-infrared (NIR) (~800 nm) by conjugation of superparamagnetic nanoparticles with synthesized CdHgTe/CdS QDs. Cadmium, mercury based QDs in HINP can be easily replaced by novel water soluble glutathione stabilized AgInS2/ZnS QDs to present a new class of cadmium-free multimodal imaging agents. Observed NIR photoluminescence of fluorescent magnetic nanocomposites supports their use for bioimaging. The developed HINP provides dual-imaging channels for simultaneous optical and magnetic resonance imaging. PMID:21597146

Synthesis and characterization of ZnO/ZnSe NWs/PbS QDs solar cell

NASA Astrophysics Data System (ADS)

Kamruzzaman, M.; Zapien, J. A.

2017-04-01

The capture of solar energy has gained the attention for the next generation solar cell. ZnO/ZnSe NW arrays were synthesized on an FTO glass substrate using a simple and facile hydrothermal and ion-exchange approaches. The lead sulfide (PbS) QDs was infiltrated into ZnO/ZnSe NWs via SILAR method for making inorganic quantum dot sensitized ZnO/ZnSe/PbS QDs solar cell. The surface morphology, structural, optical, and J-V characteristics have been investigated. The ZnO/ZnSe NW is a core-shell like structure, and the absorption edge shifted from the UV region (ZnO NWs) to the near infrared region for ZnO/ZnSe NWs/PbS QDs. For PbS QDs-sensitized solar cell, the obtained value of η = 1.1%, J sc = 20.60 mA/cm2, V oc = 155 mV, and FF = 34.7%, respectively. The photovoltaic performance of the device in this study is still inferior. However, it is the first report regarding to ZnO/ZnZe NWs/PbS QDs solar cell. The achieving high absorption and large short circuit current density may interest in further improvement of the device performance by suppressing surface defects, optimizing the quality of ZnO/ZnSe NWs and PbS QDs.

Highly conductive and anticorrosion Ag/CNTs/NDs hybrid films on molecular-grafted PET substrate for flexible electrodes

NASA Astrophysics Data System (ADS)

Zhang, Yang; Kang, Zhixin

2018-01-01

We reported an approach of preparing highly conductive, anticorrosion, flexible Ag hybrid films enhanced by multi-walled carbon nanotubes (CNTs) and nanodaimonds (NDs) on molecular-grafted PET substrate by spin-spray for flexible electronics. we studied in this paper and found that even an outstanding enhancement on conductivity of Ag films, CNTs have a negative effect on anticorrosion property. Meanwhile, NDs decreased the conductivity of Ag/CNTs hybrids, but it remained a relatively high conductivity property and even was affirmed a distinctly boost improvement on anticorrosion, microhardness and tensile strength, which meant a better mechanical chemical stabilization and practicability in real flexible electronics. To obtain the strong adhesive strength of films/substrate, molecular-grafting technology was applied, which was affirmed by XPS and cross-cut test. What's more, we evaluated anticorrosion property by electrochemistry test, including Tafel measurements and electrochemical impedance spectroscopy measurements, proving the positive effect of NDs on Ag/CNTs hybrid films. For practical application, a flexible light-emitting diode (LED) circuit was successfully structured and remained steady under bending, folding and twisting. Besides, after 1000000 cycles inner/outer bending deformation, the hybrid films showed a mechanical compliance, fatigue stability and practicability in real flexible electronics.

Immobilization of carbon nanotubes on functionalized graphene film grown by chemical vapor deposition and characterization of the hybrid material.

PubMed

Adhikari, Prashanta Dhoj; Jeon, Seunghan; Cha, Myoung-Jun; Jung, Dae Sung; Kim, Yooseok; Park, Chong-Yun

2014-02-01

We report the surface functionalization of graphene films grown by chemical vapor deposition and fabrication of a hybrid material combining multi-walled carbon nanotubes and graphene (CNT-G). Amine-terminated self-assembled monolayers were prepared on graphene by the UV-modification of oxidized groups introduced onto the film surface. Amine-termination led to effective interaction with functionalized CNTs to assemble a CNT-G hybrid through covalent bonding. Characterization clearly showed no defects of the graphene film after the immobilization reaction with CNT. In addition, the hybrid graphene material revealed a distinctive CNT-G structure and p-n type electrical properties. The introduction of functional groups on the graphene film surface and fabrication of CNT-G hybrids with the present technique could provide an efficient, novel route to device fabrication.

Synthesis and characterizations of alginate-α-tricalcium phosphate microparticle hybrid film with flexibility and high mechanical property as a biomaterial.

PubMed

Das, Dipankar; Zhang, Shengmin; Noh, Insup

2018-01-24

A biocompatible hybrid film has been fabricated using alginate (Alg), α-tricalcium phosphate (α-TCP) microparticle and calcium chloride through ionic crosslinking as a biomaterial. The 'screeding method' (like a concrete finishing process) has been employed to develop the Alg-α-TCP film. For this method, the Alg/α-TCP blend has been prepared using an ultra-sonicator and then put on a glass slide. After that, the excess volume of blend has been cut off by skidding another slide along with the surface of the blend to achieve proper grade and flatness. The mechanical strength and flexibility of the film (Alg-α-TCP) has been controlled by changing its compositions. The crosslinking phenomenon has been confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), 13 C nuclear magnetic resonance (NMR), x-ray diffraction and thermogravimetric analyses. The ATR-FTIR and 13 C NMR analysis results suggest that carboxylate groups of the alginate are ionically cross-linked with Ca 2+ ions, while the α-TCP particles reside in the network by physical interaction. The micro-fatigue test results imply high tensile strength (up to 257 MPa) and flexibility (up to 13% elongation) of the Alg-α-TCP hybrid films. The SEM analysis suggests the α-TCP particles are homogeneously distributed on the surface of Alg-α-TCP films, whereas cross-sectional images confirmed the presence of α-TCP in the cross-linked network. TGA results demonstrated that thermal stability of the hybrid film was enhanced due to ionic crosslinking and interfacial interaction between alginate and α-TCP. The incorporation of α-TCP particles diminished the swelling ratio of the hybrid film. The in vitro bone cell (MC3T3) culture and cytotoxicity tests showed that the hybrid film is biocompatible. The hybrid film releases bovine serum albumin and dimethyloxaloylglycine in a controlled way at pH 7 and 7.4, and 37 °C. Overall, the biocompatible Alg-α-TCP hybrid film with

On hydrophilicity improvement of the porous anodic alumina film by hybrid nano/micro structuring

NASA Astrophysics Data System (ADS)

Wang, Weichao; Zhao, Wei; Wang, Kaige; Wang, Lei; Wang, Xuewen; Wang, Shuang; Zhang, Chen; Bai, Jintao

2017-09-01

In both, laboratory and industry, tremendous attention is paid to discover an effective technique to produce uniform, controllable and (super) hydrophilic surfaces over large areas that are useful in a wide range of applications. In this investigation, by combing porous anodic alumina (PAA) film with nano-structures and microarray of aluminum, the hydrophilicity of hybrid nano-micro structure has been significantly improved. It is found some factors can affect the hydrophilicity of film, such as the size and aspect ratio of microarray, the thickness of nano-PAA film etc. Comparing with pure nano-PAA films and microarray, the hybrid nano-micro structure can provide uniform surface with significantly better hydrophilicity. The improvement can be up to 84%. Also, this technique exhibits good stability and repeatability for industrial production. By optimizing the thickness of nano-PAA film and aspect ratio of micro-structures, super-hydrophilicity can be reached. This study has obvious prospect in the fields of chemical industry, biomedical engineering and lab-on-a-chip applications.

Hybrid structures based on gold nanoparticles and semiconductor quantum dots for biosensor applications.

PubMed

Kurochkina, Margarita; Konshina, Elena; Oseev, Aleksandr; Hirsch, Soeren

2018-01-01

The luminescence amplification of semiconductor quantum dots (QD) in the presence of self-assembled gold nanoparticles (Au NPs) is one of way for creating biosensors with highly efficient transduction. The objective of this study was to fabricate the hybrid structures based on semiconductor CdSe/ZnS QDs and Au NP arrays and to use them as biosensors of protein. In this paper, the hybrid structures based on CdSe/ZnS QDs and Au NP arrays were fabricated using spin coating processes. Au NP arrays deposited on a glass wafer were investigated by optical microscopy and absorption spectroscopy depending on numbers of spin coating layers and their baking temperature. Bovine serum albumin (BSA) was used as the target protein analyte in a phosphate buffer. A confocal laser scanning microscope was used to study the luminescent properties of Au NP/QD hybrid structures and to test BSA. The dimensions of Au NP aggregates increased and the space between them decreased with increasing processing temperature. At the same time, a blue shift of the plasmon resonance peak in the absorption spectra of Au NP arrays was observed. The deposition of CdSe/ZnS QDs with a core diameter of 5 nm on the surface of the Au NP arrays caused an increase in absorption and a red shift of the plasmon peak in the spectra. The exciton-plasmon enhancement of the QDs' photoluminescence intensity has been obtained at room temperature for hybrid structures with Au NPs array pretreated at temperatures of 100°C and 150°C. It has been found that an increase in the weight content of BSA increases the photoluminescence intensity of such hybrid structures. The ability of the qualitative and quantitative determination of protein content in solution using the Au NP/QD structures as an optical biosensor has been shown experimentally.

Optical properties of thin films of zinc oxide quantum dots and polydimethylsiloxane: UV-blocking and the effect of cross-linking.

PubMed

Eita, Mohamed; El Sayed, Ramy; Muhammed, Mamoun

2012-12-01

Thin films of polydimethylsiloxane (PDMS) and ZnO quantum dots (QDs) were built up as multilayers by spin-coating. The films are characterized by a UV-blocking ability that increases with increasing number of bilayers. Photoluminescence (PL) emission spectra of the thin films occur at 522 nm, which is the PL wavelength of the ZnO QDs dispersion, but with a lower intensity and a quantum yield (QY) less than 1% that of the dispersion. Cross-linking has introduced new features to the absorption spectra in that the absorption peak was absent. These changes were attributed to the morphological and structural changes revealed by transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR), respectively. TEM showed that the ZnO particle size in the film increased from 7 (±2.7) nm to 16 (±7.8) upon cross-linking. The FTIR spectra suggest that ZnO QDs are involved in the cross-linking of PDMS and that the surface of the ZnO QDs has been chemically modified. Copyright © 2012 Elsevier Inc. All rights reserved.

Electronic properties of hybrid Cu2S/Ru semiconductor/metallic-cage nanoparticles.

PubMed

Bekenstein, Yehonadav; Vinokurov, Kathy; Banin, Uri; Millo, Oded

2012-12-21

Hybrid inorganic nanoparticles, comprising a semiconducting Cu(2)S quantum-dot (QD) core encapsulated by a metallic Ru cage-like shell, and each of their individual components, are studied via scanning tunneling spectroscopy. Bare Cu(2)S QDs show nearly identical semiconducting-like I-V characteristics while the empty Ru cages exhibit single electron tunneling effects-the Coulomb blockade and staircase. Surprisingly, in some cases negative differential conductance features, with periodicity that correlates to the Coulomb staircase, were observed. The tunneling spectra measured on the hybrid QDs varies greatly along a single particle, manifesting synergetic electrical properties that originate from this unique semiconducting-metallic interface.

Multilevel organization in hybrid thin films for optoelectronic applications.

PubMed

Vohra, Varun; Bolognesi, Alberto; Calzaferri, Gion; Botta, Chiara

2009-10-20

In this work we report two simple approaches to prepare hybrid thin films displaying a high concentration of zeolite crystals that could be used as active layers in optoelectronic devices. In the first approach, in order to organize nanodimensional zeolite crystals of 40 nm diameter in an electroactive environment, we chemically modify their external surface and play on the hydrophilic/hydrophobic forces. We obtain inorganic nanocrystals that self-organize in honeycomb electroluminescent polymer structures obtained by breath figure formation. The different functionalizations of the zeolite surface result in different organizations inside the cavities of the polymeric structure. The second approach involving soft-litography techniques allows one to arrange single dye-loaded zeolite L crystals of 800 nm of length by mechanical loading into the nanocavities of a conjugated polymer. Both techniques result in the formation of thin hybrid films displaying three levels of organization: organization of the dye molecules inside the zeolite nanochannels, organization of the zeolite crystals inside the polymer cavities, and micro- or nanostructuration of the polymer.

Visualization of hormone binding proteins in vivo based on Mn-doped CdTe QDs

NASA Astrophysics Data System (ADS)

Liu, Fang fei; Yu, Ying; Lin, Bi xia; Hu, Xiao gang; Cao, Yu juan; Wu, Jian zhong

2014-10-01

Daminozide (B9) is a growth inhibitor with important regulatory roles in plant growth and development. Locating and quantifying B9-binding proteins in plant tissues will assist in investigating the mechanism behind the signal transduction of B9. In this study, red fluorescent Mn-doped CdTe quantum dots (CdTeMn QDs) were synthesized by a high-temperature hydrothermal process. Since CdTeMn QDs possess a maximum fluorescence emission peak at 610 nm, their fluorescence properties are more stable than those of CdTe QDs. A B9-CdTeMn probe was synthesized by coupling B9 with CdTeMn QDs. The fluorescence intensity of the probe is double that of CdTeMn QDs; its fluorescence stability is also superior under different ambient conditions. The probe retains the biological activity of B9 and is unaffected by interference from the green fluorescent protein present in plants. Therefore, we used this probe to label B9-binding proteins selectively in root tissue sections of mung bean seedlings. These proteins were observed predominantly on the surfaces of the cell membranes of the cortex and epidermal parenchyma.

Fluorescent CdSe QDs containing Bacillus licheniformis bioprobes for Copper (II) detection in water.

PubMed

Yan, Zheng-Yu; Du, Qing-Qing; Wan, Dong-Yu; Lv, Hang; Cao, Zhi-Ran; Wu, Sheng-Mei

2017-12-01

Quantum dots (QDs) are semiconductor nanoparticles (NPs) that offer valuable functionality for cellular labeling, drug delivery, solar cells and quantum computation. In this study, we reported that CdSe QDs could be bio-synthesized in Bacillus licheniformis. After optimization, the obtained CdSe QDs exhibited a uniform particle size of 3.71±0.04nm with a maximum fluorescence emission wavelength at 550nm and the synthetical positive ratio can reach up to 87%. Spectral properties, constitution, particle sizes and crystalline phases of the CdSe QDs were systematically and integrally investigated. The CdSe QD-containing Bacillus licheniformis cells were further used as whole fluorescent bio-probes to detect copper (II) (Cu 2+ ) in water, which demonstrated a low limit of detection (0.91μM). The assay also showed a good selectivity for Cu 2+ over other ions including Al 3+ , Cd 2+ , Mg 2+ , K + , Na + , NH 4 + , Zn 2+ , CH 3 COO + , Pb 2+ and I - . Our study suggests the fluorescent CdSe QDs-containing Bacillus licheniformis bio-probes as a promising approach for detection of Cu 2+ in complex solution environment. Copyright © 2017. Published by Elsevier Inc.

Hybrid Surface Acoustic Wave-Electrohydrodynamic Atomization (SAW-EHDA) For the Development of Functional Thin Films.

PubMed

Choi, Kyung Hyun; Kim, Hyun Bum; Ali, Kamran; Sajid, Memoon; Uddin Siddiqui, Ghayas; Chang, Dong Eui; Kim, Hyung Chan; Ko, Jeong Beom; Dang, Hyun Woo; Doh, Yang Hoi

2015-10-19

Conventional surface acoustic wave - electrostatic deposition (SAW-ED) technology is struggling to compete with other thin film fabrication technologies because of its limitation in atomizing high density solutions or solutions with strong inter-particle bonding that requires very high frequency (100 MHz) and power. In this study, a hybrid surface acoustic wave - electrohydrodynamic atomization (SAW-EHDA) system has been introduced to overcome this problem by integrating EHDA with SAW to achieve the deposition of different types of conductive inks at lower frequency (19.8 MHZ) and power. Three materials, Poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV), Zinc Oxide (ZnO), and Poly(3, 4-ethylenedioxythiophene):Polystyrene Sulfonate ( PSS) have been successfully deposited as thin films through the hybrid SAW-EHDA. The films showed good morphological, chemical, electrical, and optical characteristics. To further evaluate the characteristics of deposited films, a humidity sensor was fabricated with active layer of PSS deposited using the SAW-EHDA system. The response of sensor was outstanding and much better when compared to similar sensors fabricated using other manufacturing techniques. The results of the device and the films' characteristics suggest that the hybrid SAW-EHDA technology has high potential to efficiently produce wide variety of thin films and thus predict its promising future in certain areas of printed electronics.

InP/ZnS QDs exposure induces developmental toxicity in rare minnow (Gobiocypris rarus) embryos.

PubMed

Chen, Yao; Yang, Yang; Ou, Fang; Liu, Li; Liu, Xiao-Hong; Wang, Zhi-Jian; Jin, Li

2018-04-05

We investigated the in vivo toxicity of InP/ZnS quantum dots (QDs) in Chinese rare minnow (Gobiocypris rarus) embryos. The 72 h post-fertilization (hpf) LC 50 (median lethal concentration) was 1678.007 nmol/L. Rare minnows exposed to InP/ZnS QDs exhibited decreased spontaneous movement, decreased survival and hatchability rates, and an increased malformation rate. Pericardial edema, spinal curvature, bent tails and vitelline cysts were observed. Embryonic Wnt8a and Mstn mRNA levels were significantly up-regulated after InP/ZnS QDs treatment at 48 hpf (200 nmol/L) (p < 0.05). The superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels at 96 hpf (800 nmol/L) had an increasing trend. Hsp70 mRNA expression was significantly changed at 48 hpf (200 nmol/L), but compared with the blank control, the different InP/ZnS QDs treatments did not significantly change the Olive tail moments (p > 0.05). Thus, InP/ZnS QDs caused teratogenic effects and death during the development of Chinese rare minnow embryos, but InP/ZnS QDs did not cause significant genetic toxicity during Chinese rare minnow development. Copyright © 2018 Elsevier B.V. All rights reserved.

Angular distribution of hybridization in sputtered carbon thin film

NASA Astrophysics Data System (ADS)

Liu, Y.; Wang, H.; Wei, Z. C.

2017-08-01

The sp3/sp2 ratio of sputtered carbon thin film depends on the ion bombardment process and tailors the physical properties of carbon thin film. In present work, we report the angular distribution of hybridization in magnetron sputtered carbon thin film for the first time. By x-ray photoelectron spectra analyses, it is found that the sp3/sp2 ratio increases linearly with increasing the deposition angle from 0 to 90 degree, which could be attributed to the enhancement of direct knocking-out of near-surface target atoms. In addition, we also derive the sp3/sp2 ratio by simulation on complex permittivity in terahertz frequency using a modified percolation approximation tunneling model. Those derived data consist with the results from x-ray photoelectron spectroscopy.

Enhancement of the photovoltaic performance in P3HT: PbS hybrid solar cells using small size PbS quantum dots

NASA Astrophysics Data System (ADS)

Firdaus, Yuliar; Vandenplas, Erwin; Justo, Yolanda; Gehlhaar, Robert; Cheyns, David; Hens, Zeger; Van der Auweraer, Mark

2014-09-01

Different approaches of surface modification of the quantum dots (QDs), namely, solution-phase (octylamine, octanethiol) and post-deposition (acetic acid, 1,4-benzenedithiol) ligand exchange were used in the fabrication of hybrid bulk heterojunction solar cell containing poly (3-hexylthiophene) (P3HT) and small (2.4 nm) PbS QDs. We show that replacing oleic acid by shorter chain ligands improves the figures of merit of the solar cells. This can possibly be attributed to a combination of a reduced thickness of the barrier for electron transfer and an optimized phase separation. The best results were obtained for post-deposition ligand exchange by 1,4-benzenedithiol, which improves the power conversion efficiency of solar cells based on a bulk heterojunction of lead sulfide (PbS) QDs and P3HT up to two orders of magnitude over previously reported hybrid cells based on a bulk heterojunction of P3HT:PbS QDs, where the QDs are capped by acetic acid ligands. The optimal performance was obtained for solar cells with 69 wt. % PbS QDs. Besides the ligand effects, the improvement was attributed to the formation of an energetically favorable bulk heterojunction with P3HT, when small size (2.4 nm) PbS QDs were used. Dark current density-voltage (J-V) measurements carried out on the device provided insight into the working mechanism: the comparison between the dark J-V characteristics of the bench mark system P3HT:PCBM and the P3HT:PbS blends allows us to conclude that a larger leakage current and a more efficient recombination are the major factors responsible for the larger losses in the hybrid system.

Study on plasmon absorption of hybrid Au-GO-GNP films for SPR sensing application

NASA Astrophysics Data System (ADS)

Mukhtar, Wan Maisarah; Ahmad, Farah Hayati; Samsuri, Nurul Diyanah; Murat, Noor Faezah

2018-06-01

This study proposed the development of hybrid Au-GO-GNP films for the enhancement of plasmon absorption in SPR sensing. Several thicknesses of Au at t=40nm, t=50nm and t=300nm were sputtered on the glass substrate. The hybridization of bilayer and trilayer films were formed by depositing GO-GNP layers and GNP-GO layers on top of various thicknesses of Au coated substrates. UV-Vis spectra analysis was conducted to characterize the plasmon absorption for each configuration. The plasmon absorption was successfully amplified by employing hybrid trilayer Au-GO-GNP with the thickness of Au film was fixed at t=50nm. It is noteworthy to highlight that the employment of bilayer and trilayer configurations are the key success to enhance the SPP excitation. Au-GNP and Au-GNP-GO results no significant outcome in comparison with Au-GO and Au-GO-GNP. A redshift of the absorbance wavelength evinces the presence of GO on Au-GO sample and GNP on Au-GO-GNP sample due to the surface reconstruction. It is important to emphasize that not all bilayer and trilayer configurations able to enhance the plasmon absorption where no significant output was obtained with the hybridization order of Au-GNP and Au-GNP-GO.

The Enhanced Formaldehyde-Sensing Properties of P3HT-ZnO Hybrid Thin Film OTFT Sensor and Further Insight into Its Stability

PubMed Central

Tai, Huiling; Li, Xian; Jiang, Yadong; Xie, Guangzhong; Du, Xiaosong

2015-01-01

A thin-film transistor (TFT) having an organic–inorganic hybrid thin film combines the advantage of TFT sensors and the enhanced sensing performance of hybrid materials. In this work, poly(3-hexylthiophene) (P3HT)-zinc oxide (ZnO) nanoparticles' hybrid thin film was fabricated by a spraying process as the active layer of TFT for the employment of a room temperature operated formaldehyde (HCHO) gas sensor. The effects of ZnO nanoparticles on morphological and compositional features, electronic and HCHO-sensing properties of P3HT-ZnO thin film were systematically investigated. The results showed that P3HT-ZnO hybrid thin film sensor exhibited considerable improvement of sensing response (more than two times) and reversibility compared to the pristine P3HT film sensor. An accumulation p-n heterojunction mechanism model was developed to understand the mechanism of enhanced sensing properties by incorporation of ZnO nanoparticles. X-ray photoelectron spectroscope (XPS) and atomic force microscopy (AFM) characterizations were used to investigate the stability of the sensor in-depth, which reveals the performance deterioration was due to the changes of element composition and the chemical state of hybrid thin film surface induced by light and oxygen. Our study demonstrated that P3HT-ZnO hybrid thin film TFT sensor is beneficial in the advancement of novel room temperature HCHO sensing technology. PMID:25608214

The enhanced formaldehyde-sensing properties of P3HT-ZnO hybrid thin film OTFT sensor and further insight into its stability.

PubMed

Tai, Huiling; Li, Xian; Jiang, Yadong; Xie, Guangzhong; Du, Xiaosong

2015-01-19

A thin-film transistor (TFT) having an organic-inorganic hybrid thin film combines the advantage of TFT sensors and the enhanced sensing performance of hybrid materials. In this work, poly(3-hexylthiophene) (P3HT)-zinc oxide (ZnO) nanoparticles' hybrid thin film was fabricated by a spraying process as the active layer of TFT for the employment of a room temperature operated formaldehyde (HCHO) gas sensor. The effects of ZnO nanoparticles on morphological and compositional features, electronic and HCHO-sensing properties of P3HT-ZnO thin film were systematically investigated. The results showed that P3HT-ZnO hybrid thin film sensor exhibited considerable improvement of sensing response (more than two times) and reversibility compared to the pristine P3HT film sensor. An accumulation p-n heterojunction mechanism model was developed to understand the mechanism of enhanced sensing properties by incorporation of ZnO nanoparticles. X-ray photoelectron spectroscope (XPS) and atomic force microscopy (AFM) characterizations were used to investigate the stability of the sensor in-depth, which reveals the performance deterioration was due to the changes of element composition and the chemical state of hybrid thin film surface induced by light and oxygen. Our study demonstrated that P3HT-ZnO hybrid thin film TFT sensor is beneficial in the advancement of novel room temperature HCHO sensing technology.

Extraordinarily high conductivity of flexible adhesive films by hybrids of silver nanoparticle-nanowires

NASA Astrophysics Data System (ADS)

Muhammed Ajmal, C.; Mol Menamparambath, Mini; Ryeol Choi, Hyouk; Baik, Seunghyun

2016-06-01

Highly conductive flexible adhesive (CFA) film was developed using micro-sized silver flakes (primary fillers), hybrids of silver nanoparticle-nanowires (secondary fillers) and nitrile butadiene rubber. The hybrids of silver nanoparticle-nanowires were synthesized by decorating silver nanowires with silver nanoparticle clusters using bifunctional cysteamine as a linker. The dispersion in ethanol was excellent for several months. Silver nanowires constructed electrical networks between the micro-scale silver flakes. The low-temperature surface sintering of silver nanoparticles enabled effective joining of silver nanowires to silver flakes. The hybrids of silver nanoparticle-nanowires provided a greater maximum conductivity (54 390 S cm-1) than pure silver nanowires, pure multiwalled carbon nanotubes, and multiwalled carbon nanotubes decorated with silver nanoparticles in nitrile butadiene rubber matrix. The resistance change was smallest upon bending when the hybrids of silver nanoparticle-nanowires were employed. The adhesion of the film on polyethylene terephthalate substrate was excellent. Light emitting diodes were successfully wired to the CFA circuit patterned by the screen printing method for application demonstration.

A glucose biosensor based on Prussian blue/chitosan hybrid film.

PubMed

Wang, Xueying; Gu, Haifang; Yin, Fan; Tu, Yifeng

2009-01-01

Based on electrodeposition of Prussian blue (PB) and chitosan (CS) directly on gold electrode, a hybrid film of PB/CS has been prepared. PB in this film shows a good stability compared with pure PB film when it worked in neutral and weak alkalescent solution and can act as redox mediator. It provides the potential application of such film in biosensor fabrication. A glucose biosensor was fabricated by electrodepositing glucose oxidase (GOD)/CS film on this PB/CS modified electrode. The optimum experimental conditions of biosensor for the detection of glucose have been studied in detail. Under the optimal conditions, a linear dependence of the catalytic current upon glucose concentration was obtained in the range of 2x10(-6) to 4x10(-4)M with a detection limit of 3.97x10(-7)M. The resulting biosensor could be applied to detect the blood sugar in real samples without any pretreatment.

Ultrasensitive photoelectrochemical aptasensor for lead ion detection based on sensitization effect of CdTe QDs on MoS2-CdS:Mn nanocomposites by the formation of G-quadruplex structure.

PubMed

Shi, Jian-Jun; Zhu, Jing-Chun; Zhao, Ming; Wang, Yan; Yang, Ping; He, Jie

2018-06-01

An ultrasensitive photoelectrochemical (PEC) aptasensor for lead ion (Pb 2+ ) detection was fabricated based on MoS 2 -CdS:Mn nanocomposites and sensitization effect of CdTe quantum dots (QDs). MoS 2 -CdS:Mn modified electrode was used as the PEC matrix for the immobilization of probe DNA (pDNA) labeled with CdTe QDs. Target DNA (tDNA) were hybridized with pDNA to made the QDs locate away from the electrode surface by the rod-like double helix. The detection of Pb 2+ was based on the conformational change of the pDNA to G-quadruplex structure in the presence of Pb 2+ , which made the labeled QDs move close to the electrode surface, leading to the generation of sensitization effect and evident increase of the photocurrent intensity. The linear range was 50 fM to 100 nM with a detection limit of 16.7 fM. The recoveries of the determination of Pb 2+ in real samples were in the range of 102.5-108.0%. This proposed PEC aptasensor provides a new sensing strategy for various heavy metal ions at ultralow levels. Copyright © 2018 Elsevier B.V. All rights reserved.

Erythorbic acid promoted formation of CdS QDs in a tube-in-tube micro-channel reactor

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

Liang, Yan; Tan, Jiawei; Wang, Jiexin

2014-12-15

Erythorbic acid assistant synthesis of CdS quantum dots (QDs) was conducted by homogeneous mixing of two continuous liquids in a high-throughput microporous tube-in-tube micro-channel reactor (MTMCR) at room temperature. The effects of the micropore size of the MTMCR, liquid flow rate, mixing time and reactant concentration on the size and size distribution of CdS QDs were investigated. It was found that the size and size distribution of CdS QDs could be tuned in the MTMCR. A combination of erythorbic acid promoted formation technique with the MTMCR may be a promising pathway for controllable mass production of QDs.

NIR-Emitting Alloyed CdTeSe QDs and Organic Dye Assemblies: A Nontoxic, Stable, and Efficient FRET System.

PubMed

Ramírez-Herrera, Doris E; Rodríguez-Velázquez, Eustolia; Alatorre-Meda, Manuel; Paraguay-Delgado, Francisco; Tirado-Guízar, Antonio; Taboada, Pablo; Pina-Luis, Georgina

2018-04-11

In the present work, we synthesize Near Infrared (NIR)-emitting alloyed mercaptopropionic acid (MPA)-capped CdTeSe quantum dots (QDs) in a single-step one-hour process, without the use of an inert atmosphere or any pyrophoric ligands. The quantum dots are water soluble, non-toxic, and highly photostable and have high quantum yields (QYs) up to 84%. The alloyed MPA-capped CdTeSe QDs exhibit a red-shifted emission, whose color can be tuned between visible and NIR regions (608-750 nm) by controlling the Te:Se molar ratio in the precursor mixtures and/or changing the time reaction. The MPA-capped QDs were characterized by UV-visible absorption spectroscopy, fluorescence spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and zeta potential measurements. Photostability studies were performed by irradiating the QDs with a high-power xenon lamp. The ternary MPA-CdTeSe QDs showed greater photostability than the corresponding binary MPA-CdTe QDs. We report the Förster resonance energy transfer (FRET) from the MPA-capped CdTeSe QDs as energy donors and Cyanine5 NHS-ester (Cy5) dye as an energy acceptor with efficiency ( E ) up to 95%. The distance between the QDs and dye ( r ), the Förster distance ( R ₀), and the binding constant ( K ) are reported. Additionally, cytocompatibility and cell internalization experiments conducted on human cancer cells (HeLa) cells revealed that alloyed MPA-capped CdTeSe QDs are more cytocompatible than MPA-capped CdTe QDs and are capable of ordering homogeneously all over the cytoplasm, which allows their use as potential safe, green donors for biological FRET applications.

NIR-Emitting Alloyed CdTeSe QDs and Organic Dye Assemblies: A Nontoxic, Stable, and Efficient FRET System

PubMed Central

Ramírez-Herrera, Doris E.; Rodríguez-Velázquez, Eustolia; Alatorre-Meda, Manuel; Paraguay-Delgado, Francisco; Tirado-Guízar, Antonio; Taboada, Pablo; Pina-Luis, Georgina

2018-01-01

In the present work, we synthesize Near Infrared (NIR)-emitting alloyed mercaptopropionic acid (MPA)-capped CdTeSe quantum dots (QDs) in a single-step one-hour process, without the use of an inert atmosphere or any pyrophoric ligands. The quantum dots are water soluble, non-toxic, and highly photostable and have high quantum yields (QYs) up to 84%. The alloyed MPA-capped CdTeSe QDs exhibit a red-shifted emission, whose color can be tuned between visible and NIR regions (608–750 nm) by controlling the Te:Se molar ratio in the precursor mixtures and/or changing the time reaction. The MPA-capped QDs were characterized by UV-visible absorption spectroscopy, fluorescence spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and zeta potential measurements. Photostability studies were performed by irradiating the QDs with a high-power xenon lamp. The ternary MPA-CdTeSe QDs showed greater photostability than the corresponding binary MPA-CdTe QDs. We report the Förster resonance energy transfer (FRET) from the MPA-capped CdTeSe QDs as energy donors and Cyanine5 NHS-ester (Cy5) dye as an energy acceptor with efficiency (E) up to 95%. The distance between the QDs and dye (r), the Förster distance (R0), and the binding constant (K) are reported. Additionally, cytocompatibility and cell internalization experiments conducted on human cancer cells (HeLa) cells revealed that alloyed MPA-capped CdTeSe QDs are more cytocompatible than MPA-capped CdTe QDs and are capable of ordering homogeneously all over the cytoplasm, which allows their use as potential safe, green donors for biological FRET applications. PMID:29641435

New evidence for hybrid acrylic/TiO2 films inducing bacterial inactivation under low intensity simulated sunlight.

PubMed

Bonnefond, Audrey; González, Edurne; Asua, Jose María; Leiza, Jose Ramon; Kiwi, John; Pulgarin, Cesar; Rtimi, Sami

2015-11-01

This study addresses the preparation and characterization of hybrid films prepared from Titanium dioxide (TiO2) Pickering stabilized acrylic polymeric dispersion as well as their bacterial inactivation efficiency under sunlight irradiation. Complete bacterial inactivation under low intensity simulated solar light irradiation (55 mW/cm(2)) was observed within 240 min for the films containing 10 weight based on monomers (wbm) % of TiO2, whereas 360 min were needed for the films containing 20 wbm% of TiO2. The hybrid films showed repetitive Escherichia coli (E. coli) inactivation under light irradiation. TiO2 released from the films surfaces was measured by inductively coupled plasma mass spectrometry (IPC-MS), obtaining values of ∼ 0.5 and 1 ppb/cm(2) for the films containing 10 wbm% and 20 wbm% of TiO2, respectively, far below the allowed cytotoxicity level for TiO2 (200 ppb). Transmission electron microscopy (TEM) of the hybrid films showed that TiO2 nanoparticles (NPs) were located at the polymer particle's surface forming a continuous inorganic network inside the film matrix. Atomic force microscopy (AFM) images showed differences in the TiO2 dispersion between the air-film and film-substrate interfaces. Films containing 10 wbm% of TiO2 had higher roughness (Rg) at both interfaces than the one containing 20 wbm% of TiO2 inducing an increase in the bacterial adhesion as well as the bacterial inactivation kinetics. The highly oxidative OH-radicals participating in the bacterial inactivation were determined by fluorescence. Copyright © 2015 Elsevier B.V. All rights reserved.

Molecualr-scale multicoordinating ligands for coating luminescent QDs and gold nanoparticles

NASA Astrophysics Data System (ADS)

Zhan, Naiqian

Colloidal semiconductor quantum dots (QDs) are inorganic nanocrystals that possess several unique photophysical properties, including tunable narrow emission and remarkable photo- and chemical stability. They have large surface area, and thus can be decorated with large numbers and a variety of molecular vectors. These properties combined offer a potentially superior alternative to traditional organic fluorophore for advanced applications in bio-imaging and bio-sensing. Herein, our effort has centered on developing a series of metal coordinating ligands with controllable structures to modify the QD surfaces and construct biocompatible nanocrystals. The ligand architecture accounts for several factors: (i) variable coordination number, (ii) nature of the hydrophilic moiety, polyethylene glycol (PEG) or zwitterion, and (iii) versatility of end-reactive groups including amine, azide, carboxylic acid and aldehyde. The ligand design is combined with a newly developed photoligation strategy to promote the dispersion of luminescent QDs in buffer media. The dissertation is organized in six chapters: In chapter 1, we provide a brief introduction of the basic photophysical properties of QDs and the synthesis history for growing high quality semiconductor nanocrystals. We also present some of the most effective methods reported to date to prepare aqueous QD dispersions, discuss the effective chemical coupling strategies for conjugating biomolecules, and review the recent literatures that have used QD-bioconjugates for imaging and sensing purposes. In Chapter 2, we describe a novel photoligation strategy to promote the transfer of luminescent QDs from hydrophobic to hydrophilic media using lipic acid (LA)-based ligands. We also discusse the experimental conditions, mechanismfor in-situ ligand exchange and the generosity of the method towards the diverse functionality while maintaining the optical properties of the nanocrystals. In chapter 3, we present the design and synthesis

Optical Properties of Hybrid Inorganic/Organic Thin Film Encapsulation Layers for Flexible Top-Emission Organic Light-Emitting Diodes.

PubMed

An, Jae Seok; Jang, Ha Jun; Park, Cheol Young; Youn, Hongseok; Lee, Jong Ho; Heo, Gi-Seok; Choi, Bum Ho; Lee, Choong Hun

2015-10-01

Inorganic/organic hybrid thin film encapsulation layers consist of a thin Al2O3 layer together with polymer material. We have investigated optical properties of thin film encapsulation layers for top-emission flexible organic light-emitting diodes. The transmittance of hybrid thin film encapsulation layers and the electroluminescent spectrum of organic light-emitting diodes that were passivated by hybrid organic/inorganic thin film encapsulation layers were also examined as a function of the thickness of inorganic Al203 and monomer layers. The number of interference peaks, their intensity, and their positions in the visible range can be controlled by varying the thickness of inorganic Al2O3 layer. On the other hand, changing the thickness of monomer layer had a negligible effect on the optical properties. We also verified that there is a trade-off between transparency in the visible range and the permeation of water vapor in hybrid thin film encapsulation layers. As the number of dyads decreased, optical transparency improved while the water vapor permeation barrier was degraded. Our study suggests that, in top-emission organic light-emitting diodes, the thickness of each thin film encapsulation layer, in particular that of the inorganic layer, and the number of dyads should be controlled for highly efficient top-emission flexible organic light-emitting diodes.

Organic/hybrid thin films deposited by matrix-assisted pulsed laser evaporation (MAPLE)

NASA Astrophysics Data System (ADS)

Stiff-Roberts, Adrienne D.; Ge, Wangyao

2017-12-01

Some of the most exciting materials research in the 21st century attempts to resolve the challenge of simulating, synthesizing, and characterizing new materials with unique properties designed from first principles. Achievements in such development for organic and organic-inorganic hybrid materials make them important options for electronic and/or photonic devices because they can impart multi-functionality, flexibility, transparency, and sustainability to emerging systems, such as wearable electronics. Functional organic materials include small molecules, oligomers, and polymers, while hybrid materials include inorganic nanomaterials (such as zero-dimensional quantum dots, one-dimensional carbon nanotubes, or two-dimensional nanosheets) combined with organic matrices. A critically important step to implementing new electronic and photonic devices using such materials is the processing of thin films. While solution-based processing is the most common laboratory technique for organic and hybrid materials, vacuum-based deposition has been critical to the commercialization of organic light emitting diodes based on small molecules, for example. Therefore, it is desirable to explore vacuum-based deposition of organic and hybrid materials that include larger macromolecules, such as polymers. This review article motivates the need for physical vapor deposition of polymeric and hybrid thin films using matrix-assisted pulsed laser evaporation (MAPLE), which is a type of pulsed laser deposition. This review describes the development of variations in the MAPLE technique, discusses the current understanding of laser-target interactions and growth mechanisms for different MAPLE variations, surveys demonstrations of MAPLE-deposited organic and hybrid materials for electronic and photonic devices, and provides a future outlook for the technique.

Hybrid Surface Acoustic Wave- Electrohydrodynamic Atomization (SAW-EHDA) For the Development of Functional Thin Films

PubMed Central

Choi, Kyung Hyun; Kim, Hyun Bum; Ali, Kamran; Sajid, Memoon; Uddin Siddiqui, Ghayas; Chang, Dong Eui; Kim, Hyung Chan; Ko, Jeong Beom; Dang, Hyun Woo; Doh, Yang Hoi

2015-01-01

Conventional surface acoustic wave - electrostatic deposition (SAW-ED) technology is struggling to compete with other thin film fabrication technologies because of its limitation in atomizing high density solutions or solutions with strong inter-particle bonding that requires very high frequency (100 MHz) and power. In this study, a hybrid surface acoustic wave - electrohydrodynamic atomization (SAW-EHDA) system has been introduced to overcome this problem by integrating EHDA with SAW to achieve the deposition of different types of conductive inks at lower frequency (19.8 MHZ) and power. Three materials, Poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV), Zinc Oxide (ZnO), and Poly(3, 4-ethylenedioxythiophene):Polystyrene Sulfonate (PEDOT:PSS) have been successfully deposited as thin films through the hybrid SAW-EHDA. The films showed good morphological, chemical, electrical, and optical characteristics. To further evaluate the characteristics of deposited films, a humidity sensor was fabricated with active layer of PEDOT:PSS deposited using the SAW-EHDA system. The response of sensor was outstanding and much better when compared to similar sensors fabricated using other manufacturing techniques. The results of the device and the films’ characteristics suggest that the hybrid SAW-EHDA technology has high potential to efficiently produce wide variety of thin films and thus predict its promising future in certain areas of printed electronics. PMID:26478189

Hybrid Surface Acoustic Wave- Electrohydrodynamic Atomization (SAW-EHDA) For the Development of Functional Thin Films

NASA Astrophysics Data System (ADS)

Choi, Kyung Hyun; Kim, Hyun Bum; Ali, Kamran; Sajid, Memoon; Uddin Siddiqui, Ghayas; Chang, Dong Eui; Kim, Hyung Chan; Ko, Jeong Beom; Dang, Hyun Woo; Doh, Yang Hoi

2015-10-01

Conventional surface acoustic wave - electrostatic deposition (SAW-ED) technology is struggling to compete with other thin film fabrication technologies because of its limitation in atomizing high density solutions or solutions with strong inter-particle bonding that requires very high frequency (100 MHz) and power. In this study, a hybrid surface acoustic wave - electrohydrodynamic atomization (SAW-EHDA) system has been introduced to overcome this problem by integrating EHDA with SAW to achieve the deposition of different types of conductive inks at lower frequency (19.8 MHZ) and power. Three materials, Poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV), Zinc Oxide (ZnO), and Poly(3, 4-ethylenedioxythiophene):Polystyrene Sulfonate (PEDOT:PSS) have been successfully deposited as thin films through the hybrid SAW-EHDA. The films showed good morphological, chemical, electrical, and optical characteristics. To further evaluate the characteristics of deposited films, a humidity sensor was fabricated with active layer of PEDOT:PSS deposited using the SAW-EHDA system. The response of sensor was outstanding and much better when compared to similar sensors fabricated using other manufacturing techniques. The results of the device and the films’ characteristics suggest that the hybrid SAW-EHDA technology has high potential to efficiently produce wide variety of thin films and thus predict its promising future in certain areas of printed electronics.

Ultrastable Quantum Dot Composite Films under Severe Environments.

PubMed

Yang, Zunxian; Zhang, Yuxiang; Liu, Jiahui; Ai, Jingwei; Lai, Shouqiang; Zhao, Zhiwei; Ye, Bingqing; Ruan, Yushuai; Guo, Tailiang; Yu, Xuebin; Chen, Gengxu; Lin, Yuanyuan; Xu, Sheng

2018-05-09

Semiconductor quantum dots (QDs) have attracted extensive attention because of their remarkable optical and electrical characteristics. However, the practical application of QDs and further the QD composite films have greatly been hindered mainly owing to their essential drawbacks of extreme unstability under oxygen and water environments. Herein, one simple method has been employed to enhance enormously the stability of Cd x Zn 1- x Se y S 1- y QD composite films by a combination of Cd x Zn 1- x Se y S 1- y QDs and poly(vinylidene) fluoride (PVDF), which is characteristic of closely arranged molecular chains and strong hydrogen bonds. There are many particular advantages in using QD/PVDF composite films such as easy processing, low cost, large-area fabrication, and especially extreme stability even in the boiling water for more than 240 min. By employing K 2 SiF 6 :Mn 4+ as a red phosphor, a prototype white light-emitting diode (WLED) with color coordinates of (0.3307, 0.3387), T c of 5568 K, and color gamut 112.1NTSC(1931)% at 20 mA has been fabricated, and there is little variation under different excitation currents, indicating that the QD/PVDF composite films fabricated by this simple blade-coating process make them ideal candidates for liquid-crystal display backlight utilization via assembling a WLED on a large scale owing to its ultrahigh stability under severe environments.

Growth of strontium ruthenate films by hybrid molecular beam epitaxy

DOE PAGES

Marshall, Patrick B.; Kim, Honggyu; Ahadi, Kaveh; ...

2017-09-01

We report on the growth of epitaxial Sr 2RuO 4 films using a hybrid molecular beam epitaxy approach in which a volatile precursor containing RuO 4 is used to supply ruthenium and oxygen. The use of the precursor overcomes a number of issues encountered in traditional molecular beam epitaxy that uses elemental metal sources. Phase-pure, epitaxial thin films of Sr 2RuO 4 are obtained. At high substrate temperatures, growth proceeds in a layer-by-layer mode with intensity oscillations observed in reflection high-energy electron diffraction. Films are of high structural quality, as documented by x-ray diffraction, atomic force microscopy, and transmission electronmore » microscopy. In conclusion, the method should be suitable for the growth of other complex oxides containing ruthenium, opening up opportunities to investigate thin films that host rich exotic ground states.« less

Mildly reduced graphene oxide-Ag nanoparticle hybrid films for surface-enhanced Raman scattering

PubMed Central

2012-01-01

Large-area mildly reduced graphene oxide (MR-GO) monolayer films were self-assembled on SiO2/Si surfaces via an amidation reaction strategy. With the MR-GO as templates, MR-GO-Ag nanoparticle (MR-GO-Ag NP) hybrid films were synthesized by immersing the MR-GO monolayer into a silver salt solution with sodium citrate as a reducing agent under UV illumination. SEM image indicated that Ag NPs with small interparticle gap are uniformly distributed on the MR-GO monolayer. Raman spectra demonstrated that the MR-GO monolayer beneath the Ag NPs can effectively quench the fluorescence signal emitted from the Ag films and dye molecules under laser excitation, resulting in a chemical enhancement (CM). The Ag NPs with narrow gap provided numerous hot spots, which are closely related with electromagnetic mechanism (EM), and were believed to remarkably enhance the Raman signal of the molecules. Due to the co-contribution of the CM and EM effects as well as the coordination mechanism between the MR-GO and Ag NPs, the MR-GO-Ag NP hybrid films showed more excellent Raman signal enhancement performance than that of either Ag films or MR-GO monolayer alone. This will further enrich the application of surface-enhanced Raman scattering in molecule detection. PMID:22471923

Elaboration of ammonia gas sensors based on electrodeposited polypyrrole--cobalt phthalocyanine hybrid films.

PubMed

Patois, Tilia; Sanchez, Jean-Baptiste; Berger, Franck; Fievet, Patrick; Segut, Olivier; Moutarlier, Virginie; Bouvet, Marcel; Lakard, Boris

2013-12-15

The electrochemical incorporation of a sulfonated cobalt phthalocyanine (sCoPc) in conducting polypyrrole (PPy) was done, in the presence or absence of LiClO4, in order to use the resulting hybrid material for the sensing of ammonia. After electrochemical deposition, the morphological features and structural properties of polypyrrole/phthalocyanine hybrid films were investigated and compared to those of polypyrrole films. A gas sensor consisting in platinum microelectrodes arrays was fabricated using silicon microtechnologies, and the polypyrrole and polypyrrole/phthalocyanine films were electrochemically deposited on the platinum microelectrodes arrays of this gas sensor. When exposed to ammonia, polymer-based gas sensors exhibited a decrease in conductance due to the electron exchange between ammonia and sensitive polymer-based layer. The characteristics of the gas sensors (response time, response amplitude, reversibility) were studied for ammonia concentrations varying from 1 ppm to 100 ppm. Polypyrrole/phthalocyanine films exhibited a high sensitivity and low detection limit to ammonia as well as a fast and reproducible response at room temperature. The response to ammonia exposition of polypyrrole films was found to be strongly enhanced thanks to the incorporation of the phthalocyanine in the polypyrrole matrix. © 2013 Elsevier B.V. All rights reserved.

Preparation and characterization of flexible asymmetric supercapacitors based on transition-metal-oxide nanowire/single-walled carbon nanotube hybrid thin-film electrodes.

PubMed

Chen, Po-Chiang; Shen, Guozhen; Shi, Yi; Chen, Haitian; Zhou, Chongwu

2010-08-24

In the work described in this paper, we have successfully fabricated flexible asymmetric supercapacitors (ASCs) based on transition-metal-oxide nanowire/single-walled carbon nanotube (SWNT) hybrid thin-film electrodes. These hybrid nanostructured films, with advantages of mechanical flexibility, uniform layered structures, and mesoporous surface morphology, were produced by using a filtration method. Here, manganese dioxide nanowire/SWNT hybrid films worked as the positive electrode, and indium oxide nanowire/SWNT hybrid films served as the negative electrode in a designed ASC. In our design, charges can be stored not only via electrochemical double-layer capacitance from SWNT films but also through a reversible faradic process from transition-metal-oxide nanowires. In addition, to obtain stable electrochemical behavior during charging/discharging cycles in a 2 V potential window, the mass balance between two electrodes has been optimized. Our optimized hybrid nanostructured ASCs exhibited a superior device performance with specific capacitance of 184 F/g, energy density of 25.5 Wh/kg, and columbic efficiency of approximately 90%. In addition, our ASCs exhibited a power density of 50.3 kW/kg, which is 10-fold higher than obtained in early reported ASC work. The high-performance hybrid nanostructured ASCs can find applications in conformal electrics, portable electronics, and electrical vehicles.

Microstructure and optical properties of TiO2 nanocrystallites-CaTiO3:Pr3+ hybrid thick films

NASA Astrophysics Data System (ADS)

Xia, Chang-Kui; Gao, Xiang-Dong; Yu, Changjiang; Yu, Aimin; Li, Xiaomin; Gao, Dongsheng; Shi, Ying

Long afterglow CaTiO3:Pr3+ ceramic powders were integrated with hydrothermal TiO2 nanocrystallites via “doctor-blade” and TiO2-CaTiO3:Pr3+ hybrid thick films on FTO substrate were fabricated. Effects of the Pr3+ doping level (0.06%, 0.3%) and the CaTiO3:Pr3+/TiO2 weight ratio (0.23, 0.92) on the crystallinity, morphologies, optical transmittance and photoluminescence (PL) properties were investigated. Results showed that the crystallinity of the hybrid films originated from both TiO2 nanocrystallites and CaTiO3:Pr3+ ceramic particles, affected little by the integrating process. The film surface became denser and coarser due to the incorporation of CaTiO3:Pr3+ micron/submicron particles, and the film thickness varied little (˜2.2μm). The optical transmittance of the hybrid film decreased sharply (<20% for 0.92 incorporation level) due to the scattering effects of the CaTiO3:Pr3+ micron/submicron particles to the incident light. All the hybrid films exhibited strong PL at ˜613nm when excited with 332-335nm, and the film with the Ca0.997TiO3:Pr0.0033+/TiO2 weight ratio of 0.23 showed the highest emission. In addition, the film exhibited a photoresponce to a broad ultraviolet excitation ranging from 288-369nm and a long emission decay time up to 30min at 613nm, possible for use in the ultraviolet detectors, solar cells and other photoelectrical devices.

Stable and Flexible CuInS2/ZnS:Al-TiO2 Film for Solar-Light-Driven Photodegradation of Soil Fumigant.

PubMed

Yan, Lili; Li, Zhichun; Sun, Mingxing; Shen, Guoqing; Li, Liang

2016-08-10

Semiconductor quantum dots (QDs) are suitable light absorbers for photocatalysis because of their unique properties. However, QDs generally suffer from poor photochemical stability against air, limiting their applications in photocatalysis. In this study, a stable solar-light-driven QDs-containing photocatalytic film was developed to facilitate photocatalytic degradation of the soil fumigant 1,3-dichloropropene (1,3-D). Highly stable CuInS2/ZnS:Al core/shell QDs (CIS/ZnS:Al QDs) were synthesized by doping Al into the ZnS shell and controlling ZnS:Al shell thickness; the CIS/ZnS:Al QDs were subsequently combined with TiO2 to form a CIS/ZnS:Al-TiO2 photocatalyst. The optimized ZnS:Al shell thickness for 1,3-D photodegradation was approximately 1.3 nm, which guaranteed and balanced the good photocatalytic activity and stability of the CIS/ZnS:Al-TiO2 photocatalyst. The photodegradation efficiency of 1,3-D can be maintained up to more than 80% after five cycles during recycling experiment. When CIS/ZnS:Al-TiO2 was deposited as photocatalytic film on a flexible polyethylene terephthalate substrate, over 99% of cis-1,3-D and 98% of trans-1,3-D were depleted as they passed through the film during 15 h of irradiation under natural solar light. This study demonstrated that the stable CIS/ZnS:Al-TiO2 photocatalyst both in powder and film form is a promising agent for photodegradation and emission reduction of soil fumigants.

Ultralow refractive index optical films with enhanced mechanical performance obtained by hybrid glancing angle deposition.

PubMed

Trottier-Lapointe, W; Zabeida, O; Schmitt, T; Martinu, L

2016-11-01

Ultralow refractive index materials (n less than 1.38 at 550 nm) are of particular interest in the context of antireflective coatings, allowing one to enhance their overall optical performance. However, application of such materials is typically limited by their mechanical properties. In this study, we explore the characteristics of a new category of hybrid (organic/inorganic) SiOCH thin films prepared by glancing angle deposition (GLAD) using electron beam evaporation of SiO₂ in the presence of an organosilicon precursor. The resulting layers exhibited n as low as 1.2, showed high elastic rebound, and generally better mechanical properties than their inorganic counterparts. In addition, hybrid GLAD films were found to be highly hydrophobic. The performance of the films is discussed in terms of their hybridicity (organic/inorganic) ratio determined by infrared spectroscopic ellipsometry as well as the presence of anisotropy assessed by the nanostructure-based spectroscopic ellipsometry model. Finally, we demonstrate successful implementation of the ultralow-index material in a complete antireflective stack.

Angled injection: Hybrid fluid film bearings for cryogenic applications

NASA Technical Reports Server (NTRS)

SanAndres, Luis

1995-01-01

A computational bulk-flow analysis for prediction of the force coefficients of hybrid fluid film bearings with angled orifice injection is presented. Past measurements on water-lubricated hybrid bearings with angle orifice injection have demonstrated improved rotordynamic performance with virtual elimination of cross-coupled stiffness coefficients and nul or negative whirl frequency ratios. A simple analysis reveals that the fluid momentum exchange at the orifice discharge produces a pressure rise in the recess which retards the shear flow induced by journal rotation, and consequently, reduces cross-coupling forces. The predictions from the model correlate well with experimental measurements from a radial and 45 deg angled orifice injection, five recess water hybrid bearings (C = 125 microns) operating at 10.2, 17.4, and 24.6 krpm and with nominal supply pressures equal to 4, 5.5, and 7 MPa. An application example for a liquid oxygen six recess/pad hybrid journal bearing shows the advantages of tangential orifice injection on the rotordynamic force coefficients and stability indicator for forward whirl motions and without performance degradation on direct stiffness and damping coefficients. The computer program generated, 'hydrojet,' extends and complements previously developed codes.

Substrate effects on photoluminescence and low temperature phase transition of methylammonium lead iodide hybrid perovskite thin films

NASA Astrophysics Data System (ADS)

Shojaee, S. A.; Harriman, T. A.; Han, G. S.; Lee, J.-K.; Lucca, D. A.

2017-07-01

We examine the effects of substrates on the low temperature photoluminescence (PL) spectra and phase transition in methylammonium lead iodide hybrid perovskite (CH3NH3PbI3) thin films. Structural characterization at room temperature with X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy indicated that while the chemical structure of films deposited on glass and quartz was similar, the glass substrate induced strain in the perovskite films and suppressed the grain growth. The luminescence response and phase transition of the perovskite thin films were studied by PL spectroscopy. The induced strain was found to affect both the room temperature and low temperature PL spectra of the hybrid perovskite films. In addition, it was found that the effects of the glass substrate inhibited a tetragonal to orthorhombic phase transition such that it occurred at lower temperatures.

Microstructured Nickel-Titanium Thin Film Leaflets for Hybrid Tissue Engineered Heart Valves Fabricated by Magnetron Sputter Deposition.

PubMed

Loger, K; Engel, A; Haupt, J; Lima de Miranda, R; Lutter, G; Quandt, E

2016-03-01

Heart valves are constantly exposed to high dynamic loading and are prone to degeneration. Therefore, it is a challenge to develop a durable heart valve substitute. A promising approach in heart valve engineering is the development of hybrid scaffolds which are composed of a mechanically strong inorganic mesh enclosed by valvular tissue. In order to engineer an efficient, durable and very thin heart valve for transcatheter implantations, we developed a fabrication process for microstructured heart valve leaflets made from a nickel-titanium (NiTi) thin film shape memory alloy. To examine the capability of microstructured NiTi thin film as a matrix scaffold for tissue engineered hybrid heart valves, leaflets were successfully seeded with smooth muscle cells (SMCs). In vitro pulsatile hydrodynamic testing of the NiTi thin film valve leaflets demonstrated that the SMC layer significantly improved the diastolic sufficiency of the microstructured leaflets, without affecting the systolic efficiency. Compared to an established porcine reference valve model, magnetron sputtered NiTi thin film material demonstrated its suitability for hybrid tissue engineered heart valves.

Effects of ion irradiation on the surface mechanical behavior of hybrid sol-gel derived silicate thin films

NASA Astrophysics Data System (ADS)

Ghisleni, Rudy

A study on the effects of ion irradiation on the surface mechanical behavior of hybrid sol-gel derived thin films has been performed. Hybrid organic/inorganic modified silicate thin films were synthesized by sol-gel processing from tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) precursors and spin-coated onto (100) Si substrates. The synthesized films were investigated by nanoindentation, photoluminescence spectroscopy, and Raman spectroscopy. Hybrid TEOS/MTES sol-gel films modified by ion irradiation with deposited electronic energies of 1.87 x 1025 eV/cm3 or higher showed higher values of reduced elastic modulus and hardness than 800°C heat treated films. Thus, ion irradiation was found to be an effective means in converting the polymer sol into ceramic type coatings. The ions used in this study were Cu2+, N2+, Si+, O+, N+, He+, and H+, with incident energies ranging from 100 keV to 2 MeV, and fluences ranging from 1 x 1014 to 1 x 1017 ions/cm2. Both the reduced elastic modulus and hardness were seen to increase monotonically with the increase in ion fluence, with an observed maximum hardness of 7.7 GPa (an unirradiated film hardness was 0.4 GPa) and a maximum reduced elastic modulus of 84.0 GPa (an unirradiated film reduced elastic modulus was 7.1 GPa) for 250 keV N2+ irradiation with a 5 x 1016 ions/cm2 fluence. The electronic stopping power was found to be principally responsible for the film hardening, while the role of nuclear stopping power was minimal. A monotonic increase in hardness with increase in electronic energy deposited to the film surface was found. A model describing the hardening of ion irradiated films was developed. This model characterizes the hardening effectiveness of the ion species considered by two parameters: the constant hardening cross-section and the hardening coefficient. Where the hardening cross-section represents the cross-sectional area hardened by the interaction of an incident ion with the target, and the

Adsorption of quantum dots onto polymer and Gemini surfactant films: a quartz crystal microbalance study.

PubMed

Alejo, T; Merchán, M D; Velázquez, M M

2014-08-26

We used quartz crystal microbalance with dissipation to study the mechanical properties, the kinetics of adsorption, and the amount of CdSe quantum dots (QDs) adsorbed onto a SiO2 sensor, referred as bare sensor, onto the sensor modified with a film of the polymer poly(maleic anhydride-alt-1-octadecene), PMAO, or with a film of the Gemini surfactant ethyl-bis(dimethyl octadecyl ammonium bromide), abbreviated as 18-2-18. Results showed that when the sensor is coated with polymer or surfactant molecules, the coverage increases compared with that obtained for the bare sensor. On the other hand, rheological properties and kinetics of adsorption of QDs are driven by QD nanoparticles. Thus, the QD films present elastic behavior, and the elasticity values are independent of the molecule used as coating and similar to the elasticity value obtained for QDs films on the bare sensor. The QD adsorption is a two-step mechanism in which the fastest process is attributed to the QD adsorption onto the solid substrate and the slowest one is ascribed to rearrangement movements of the nanoparticles adsorbed at the surface.

Highly Luminescent Hybrid SiO2-Coated CdTe Quantum Dots Retained Initial Photoluminescence Efficiency in Sol-Gel SiO2 Film.

PubMed

Sun, Hongsheng; Xing, Yugui; Wu, Qinan; Yang, Ping

2015-02-01

A highly luminescent silica film was fabricated using tetraethyl orthosilicate (TEOS) and 3-aminopropyltrimethoxysilane (APS) through a controlled sol-gel reaction. The pre-hydrolysis of TEOS and APS which resulted in the mixture of TEOS and APS in a molecular level is a key for the formation of homogenous films. The aminopropyl groups in APS play an important role for obtaining homogeneous film with high photoluminescence (PL). Red-emitting hybrid SiO2-coated CdTe nano-crystals (NCs) were fabricated by a two-step synthesis including a thin SiO2 coating via a sol-gel process and a subsequent refluxing using green-emitting CdTe NCs. The hybrid SiO2-coated CdTe NCs were embedded in a functional SiO2 film via a two-step process including adding the NCs in SiO2 sol with a high viscosity and almost without ethanol and a subsequent spinning coating. The hybrid SiO2-coated CdTe NCs retained their initial PL efficiency (54%) in the film. Being encapsulated with the hybrid NCs in the film, no change on the absorption and PL spectra of red-emitting CdTe NCs (632 nm) was observed. This indicates the hybrid NCs is stable enough during preparation. This phenomenon is ascribed to the controlled sol-gel process and a hybrid SiO2 shell on CdTe NCs. Because these films exhibited high PL efficiency and stability, they will be utilizable for potential applications in many fields.

Functionalized magnetic-fluorescent hybrid nanoparticles for cell labelling.

PubMed

Lou, Lei; Yu, Ke; Zhang, Zhengli; Li, Bo; Zhu, Jianzhong; Wang, Yiting; Huang, Rong; Zhu, Ziqiang

2011-05-01

A facile method of synthesizing 60 nm magnetic-fluorescent core-shell bifunctional nanocomposites with the ability to label cells is presented. Hydrophobic trioctylphosphine oxide (TOPO)-capped CdSe@ZnS quantum dots (QDs) were assembled on polyethyleneimine (PEI)-coated Fe(3)O(4) nanoparticles (MNP). Polyethyleneimine was utilized for the realization of multifunction, including attaching 4 nm TOPO capped CdSe@ZnS quantum dots onto magnetite particles, altering the surface properties of quantum dots from hydrophobic to hydrophilic as well as preventing the formation of large aggregates. Results show that these water-soluble hybrid nanocomposites exhibit good colloidal stability and retain good magnetic and fluorescent properties. Because TOPO-capped QDs are assembled instead of their water-soluble equivalents, the nanocomposites are still highly luminescent with no shift in the PL peak position and present long-term fluorescence stability. Moreover, TAT peptide (GRKKRRQRRRPQ) functionalized hybrid nanoparticles were also studied due to their combined magnetic enrichment and optical detection for cell separation and rapid cell labelling. A cell viability assay revealed good biocompatibility of these hybrid nanoparticles. The potential application of the new magnetic-fluorescent nanocomposites in biological and medicine is demonstrated. © The Royal Society of Chemistry 2011

Photonic crystals on copolymer film for label-free detection of DNA hybridization.

PubMed

Su, Han; Cheng, Xin R; Endo, Tatsuro; Kerman, Kagan

2018-04-30

The presence of a single-nucleotide polymorphism in Apolipoprotein E4 gene is implicated with the increased risk of developing Alzheimer's disease (AD). In this study, detection of AD-related DNA oligonucleotide sequence associated with Apolipoprotein E4 gene sequence was achieved using localized-surface plasmon resonance (LSPR) on 2D-Photonic crystal (2D-PC) and Au-coated 2D-PC surfaces. 2D-PC surfaces were fabricated on a flexible copolymer film using nano-imprint lithography (NIL). The film surface was then coated with a dual-functionalized polymer to react with surface immobilized DNA probe. DNA hybridization was detected by monitoring the optical responses of either a Fresnel decrease in reflectance on 2D-PC surfaces or an increase in LSPR on Au-coated 2D-PC surfaces. The change in response due to DNA hybridization on the modified surfaces was also investigated using mismatched and non-complementary oligonucleotides sequences. The proof-of-concept results are promising towards the development of 2D-PC on copolymer film surfaces as miniaturized and wearable biosensors for various diagnostic and defense applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Exploitation of inimitable properties of CuInS2 quantum dots for energy conversion in bulk heterojunction hybrid solar cell

NASA Astrophysics Data System (ADS)

Jindal, Shikha; Giripunje, Sushama M.

2017-11-01

Quantum dots (QDs) are the suitable material for solar cell devices owing to its distinctive optical, electrical and electronic properties. Currently, the most efficient devices have employed the toxic QDs which cause destructive impact on environment. In the present article, we have used environment benign CuInS2 QDs as an acceptor material in bulk heterojunction device of P3HT and QDs. The energy level positions corroborated from UPS spectra substantiates the acceptor property of CuInS2. We scrutinized the hybrid solar cell by tailoring the acceptor content in active layer. The increased acceptor content intensifies the performance of device. The enhancement in photovoltaic parameters is mainly due to the fast dissociation and extraction of photogenerated excitons which occurs with the larger wt% of acceptor QDs. Current density-voltage characteristics describes the greater V oc and I sc in the 60 wt% CuInS2 QDs based solar cell as compared to the low wt% of QDs in the active layer.

Enhanced electrocatalytic activity of reduced graphene oxide-Os nanoparticle hybrid films obtained at a liquid/liquid interface

NASA Astrophysics Data System (ADS)

Bramhaiah, K.; Pandey, Indu; Singh, Vidya N.; Kavitha, C.; John, Neena S.

2018-03-01

Hybrid films of reduced graphene oxide-osmium nanoparticles (rGO-Os NPs) synthesized at a liquid/liquid interface are explored for their electrocatalytic activity towards the oxidation of rhodamine B (RhB), a popular colourant found in textile industry effluents and a non-permitted food colour. The free-standing nature of the films enables them to be lifted directly on to electrodes without the aid of any binders. The films consist of aggregates of ultra-small Os NPs interspersed with rGO layers. The hybrid film exhibits enhanced RhB oxidation when compared to its constituents arising from the synergic effect between rGO and Os NPs, Os contributing to electrocatalysis and rGO contributing to high surface area and conductance as well as stabilization of Os nanoparticles. The electrochemical sensor based on rGO-Os NP hybrid film on pencil graphite electrode shows a remarkable performance for the quantitative detection of RhB with a linear variation in a wide range of concentrations, 4-1300 ppb (8.3 nM-2.71 μM). The modified electrode presents good stability over more than 6 months, reproducibility and anti-interference capability. The use of developed sensor for adequate detection of RhB in real samples such as food samples and pen markers is also demonstrated.

TiN films fabricated by reactive gas pulse sputtering: A hybrid design of multilayered and compositionally graded structures

NASA Astrophysics Data System (ADS)

Yang, Jijun; Zhang, Feifei; Wan, Qiang; Lu, Chenyang; Peng, Mingjing; Liao, Jiali; Yang, Yuanyou; Wang, Lumin; Liu, Ning

2016-12-01

Reactive gas pulse (RGP) sputtering approach was used to prepare TiN thin films through periodically changing the N2/Ar gas flow ratio. The obtained RGPsbnd TiN film possessed a hybrid architecture containing compositionally graded and multilayered structures, composed of hcp Ti-phase and fcc TiN-phase sublayers. Meanwhile, the RGP-TiN film exhibited a composition-oscillation along the film thickness direction, where the Ti-phase sublayer had a compositional gradient and the TiN-phase retained a constant stoichiometric ratio of Ti:N ≈ 1. The film modulation ratio λ (the thicknesses ratio of the Ti and TiN-phase sublayer) can be effectively tuned by controlling the undulation behavior of the N2 partial flow rate. Detailed analysis showed that this hybrid structure originated from a periodic transition of the film growth mode during the reactive sputtering process.

Interpreting Neutron Reflectivity Profiles of Diblock Copolymer Nanocomposite Thin Films Using Hybrid Particle-Field Simulations

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

Mahalik, Jyoti P.; Dugger, Jason W.; Sides, Scott W.

Mixtures of block copolymers and nanoparticles (block copolymer nanocomposites) are known to microphase separate into a plethora of microstructures, depending on the composition, length scale and nature of interactions among its different constituents. Theoretical and experimental works on this class of nanocomposites have already high-lighted intricate relations among chemical details of the polymers, nanoparticles, and various microstructures. Confining these nanocomposites in thin films yields an even larger array of structures, which are not normally observed in the bulk. In contrast to the bulk, exploring various microstructures in thin films by the experimental route remains a challenging task. Here in thismore » work, we construct a model for the thin films of lamellar forming diblock copolymers containing spherical nanoparticles based on a hybrid particle-field approach. The model is benchmarked by comparison with the depth profiles obtained from the neutron reflectivity experiments for symmetric poly(deuterated styrene-b-n butyl methacrylate) copolymers blended with spherical magnetite nanoparticles covered with hydrogenated poly(styrene) corona. We show that the model based on a hybrid particle-field approach provides details of the underlying microphase separation in the presence of the nanoparticles through a direct comparison to the neutron reflectivity data. This work benchmarks the application of the hybrid particle-field model to extract the interaction parameters for exploring different microstructures in thin films containing block copolymers and nanocomposites.« less

Interpreting Neutron Reflectivity Profiles of Diblock Copolymer Nanocomposite Thin Films Using Hybrid Particle-Field Simulations

DOE PAGES

Mahalik, Jyoti P.; Dugger, Jason W.; Sides, Scott W.; ...

2018-04-10

Mixtures of block copolymers and nanoparticles (block copolymer nanocomposites) are known to microphase separate into a plethora of microstructures, depending on the composition, length scale and nature of interactions among its different constituents. Theoretical and experimental works on this class of nanocomposites have already high-lighted intricate relations among chemical details of the polymers, nanoparticles, and various microstructures. Confining these nanocomposites in thin films yields an even larger array of structures, which are not normally observed in the bulk. In contrast to the bulk, exploring various microstructures in thin films by the experimental route remains a challenging task. Here in thismore » work, we construct a model for the thin films of lamellar forming diblock copolymers containing spherical nanoparticles based on a hybrid particle-field approach. The model is benchmarked by comparison with the depth profiles obtained from the neutron reflectivity experiments for symmetric poly(deuterated styrene-b-n butyl methacrylate) copolymers blended with spherical magnetite nanoparticles covered with hydrogenated poly(styrene) corona. We show that the model based on a hybrid particle-field approach provides details of the underlying microphase separation in the presence of the nanoparticles through a direct comparison to the neutron reflectivity data. This work benchmarks the application of the hybrid particle-field model to extract the interaction parameters for exploring different microstructures in thin films containing block copolymers and nanocomposites.« less

11th International Conference "Correlation Optics": Propolis films for hybrid biomaterial-inorganic electronics and optoelectronics.

PubMed

Brus, Viktor V; Pidkamin, Leonid J; Ilashchuk, Maria I; Maryanchuk, Pavlo D

2014-04-01

We report on the analysis of optical, polarimetric, and electrical properties of propolis films and hybrid biomaterial-inorganic heterojunctions based on them. It was shown that the material of the propolis films belongs to wide-bandgap optically active substances with the light-scattering centers, which possess complex optical properties. The values of the specific resistance ρ(P)=1.9·10⁷ Ω·cm and dielectric constant ε(P)=19.5 of the propolis film were determined from the spectral distribution of the real and imaginary components of its impedance at room temperature, respectively. The dominating current transport mechanisms through the hybrid bioinorganic heterojunction propolis/p-CdTe were established to be the interface-states-assisted generation-recombination within the depletion region via deep energy levels at forward bias as well as the leakage current through the shunt resistance at reverse bias.

Photosensitization of CdSe/ZnS QDs and reliability of assays for reactive oxygen species production.

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

Cooper, D. R.; Dimitrijevic, N. M.; Nadeau, J. L.

CdSe/ZnS quantum dots (QDs) conjugated to biomolecules that can act as electron donors are said to be 'photosensitized': that is, they are able to oxidize or reduce molecules whose redox potential lies inside their band edges, in particular molecular oxygen and water. This leads to the formation of reactive oxygen species (ROS) and phototoxicity. In this work, we quantify the generation of different forms of ROS from as-synthesized QDs in toluene; water-solubilized, unconjugated QDs; QDs conjugated to the neurotransmitter dopamine; and dopamine alone. Results of indirect fluorescent ROS assays, both in solution and inside cells, are compared with those ofmore » spin-trap electron paramagentic resonance spectroscopy (EPR). The effect of these particles on the metabolism of mammalian cells is shown to be dependent upon light exposure and proportional to the amount of ROS generated.« less

Fabrication and electrocatalytic properties of chitosan and keplerate-type polyoxometalate {Mo72Fe30} hybrid films.

PubMed

Fan, Dawei; Hao, Jingcheng

2009-05-28

Hybrid films composed of chitosan and Keplerate-type polyoxometalate, {Mo72Fe30} (Mo72VIFe30IIIO252L102.ca.180H2O, L=H2O/CH3COO-/Mo2O8/9n-), were fabricated on quartz, silicon, and ITO substrates by layer-by-layer (LbL) method. The LbL films were characterized by UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and cyclic voltammetry (CV). UV-vis spectra show that the absorbance values at characteristic wavelengths of the multilayer films increase almost linearly with the number of chitosan/{Mo72Fe30} bilayers. XPS spectra confirm the incorporation of chitosan and {Mo72Fe30} into the films. The electrocatalytic reduction of ClO3-, BrO3-, and IO3- by chitosan/{Mo72Fe30} hybrid films in an acidic aqueous solution shows an electrocatalytic reduction activity of IO3->BrO3->ClO3-. In particular, the modified electrodes exhibited high electrocatalytic activity for reduction of IO3-.

Comprehensive study of interaction between biocompatible PEG-InP/ZnS QDs and bovine serum albumin.

PubMed

Sannaikar, M S; Inamdar, Laxmi S; Pujar, G H; Wari, M N; Balasinor, Nafisa H; Inamdar, S R

2018-05-01

Polyethylene glycol (PEG) surface modified biocompatible InP/ZnS quantum dots (QDs) act as a potential alternative for conventional carcinogenic cadmium-based quantum dots for in vivo and in vitro studies. Comprehensively, we studied the interaction between a model protein bovine serum albumin (BSA) and PEGylated toxic free InP/ZnS QDs using various spectroscopic tools such as absorption, fluorescence quenching, time resolved and synchronous fluorescence spectroscopic measurements. These studies principally show that tryptophan (Trp) residues of BSA have preferable binding affinity towards PEG-InP/ZnS QDs surface and a blue shift in Trp fluorescence emission is a signature of conformational changes in its hydrophobic microenvironment. Photoluminescence (PL) intensity of Trp is quenched by ground state complex formation (static quenching) at room temperature. However, InP/ZnS@BSA conjugates become unstable with increasing temperature and PL intensity of Trp is quenched via dynamic quenching by PEG-InP/ZnS QDs. Experimentally determined thermodynamic parameters for these conjugates have shown spontaneity, entropy driven and exothermic nature of bio-conjugation. The calculated binding affinity (n ≅ 1, Hill coefficient) suggest that the affinity of InP/ZnS QDs for a BSA protein is not dependent on whether or not other BSA proteins are already bound to the QD surface. Energy transfer efficiency (E), Trp residue to InP/ZnS QDs distances and energy transfer rate (k T ) were all obtained from FÖrster resonance energy. Copyright © 2017 John Wiley & Sons, Ltd.

Photothermally Activated Pyroelectric Polymer Films for Harvesting of Solar Heat with a Hybrid Energy Cell Structure.

PubMed

Park, Teahoon; Na, Jongbeom; Kim, Byeonggwan; Kim, Younghoon; Shin, Haijin; Kim, Eunkyoung

2015-12-22

Photothermal effects in poly(3,4-ethylenedioxythiophene)s (PEDOTs) were explored for pyroelectric conversion. A poled ferroelectric film was coated on both sides with PEDOT via solution casting polymerization of EDOT, to give highly conductive and effective photothermal thin films of PEDOT. The PEDOT films not only provided heat source upon light exposure but worked as electrodes for the output energy from the pyroelectric layer in an energy harvester hybridized with a thermoelectric layer. Compared to a bare thermoelectric system under NIR irradiation, the photothermal-pyro-thermoelectric device showed more than 6 times higher thermoelectric output with the additional pyroelectric output. The photothermally driven pyroelectric harvesting film provided a very fast electric output with a high voltage output (Vout) of 15 V. The pyroelectric effect was significant due to the transparent and high photothermal PEDOT film, which could also work as an electrode. A hybrid energy harvester was assembled to enhance photoconversion efficiency (PCE) of a solar cell with a thermoelectric device operated by the photothermally generated heat. The PCE was increased more than 20% under sunlight irradiation (AM 1.5G) utilizing the transmitted light through the photovoltaic cell as a heat source that was converted into pyroelectric and thermoelectric output simultaneously from the high photothermal PEDOT electrodes. Overall, this work provides a dynamic and static hybrid energy cell to harvest solar energy in full spectral range and thermal energy, to allow solar powered switching of an electrochromic display.

A study on the electrical, optical, and physicochemical properties of poly(MMA-co-MAA)/ poly(3,4-ethylenedioxythiophene) hybrid thin films.

PubMed

Han, Yong-Hyeon; Kim, Hyeong Eun; Hwangbo, Kyung-Hee; Yim, Jin-Heong; Cho, Kuk Young

2013-08-01

Poly(3,4-ethylenedioxythiophene) (PEDOT) has good properties as a conductive polymer such as high conductivity, optical transmittance, and chemical stability, while offering relatively weak physicochemical properties. The main purpose of this paper is to improve physicochemical properties such as solvent resistance and pencil hardness of PEDOT. Carboxyl groups in the poly(MMA-co-MAA) polymer chains can effectively crosslink each other in the presence of aziridine, resulting in physicochemically robust PEDOT/poly(MMA-co-MAA) hybrid conductive films. The electrical conductivity, optical properties, and physicochemical properties of the hybrid conductive film were compared by varying the solid content and poly(MMA-co-MAA) portion in the coating precursor solution. From the results, the transparency and surface resistance of the hybrid film show a tendency to decrease with increasing solid content in the coating precursor. Moreover, solvent resistance and hardness were dramatically enhanced by hybridization of PEDOT and crosslinked poly(MMA-co-MAA) due to curing reactions between carboxyl groups. The chemical composition of 30 wt-% of poly(MMA-co-MAA) (MMA:MAA mole ratio 9:1) and 3 wt-% - 5 wt-% of aziridine yields the best physicochemical properties of poly(MMA-co-MAA)/PEDOT hybrid thin films.

Polyhydroxyalkanoate-based natural synthetic hybrid copolymer films: A small-angle neutron scattering study

NASA Astrophysics Data System (ADS)

Foster, L. John R.; Knott, Robert; Sanguanchaipaiwong, Vorapat; Holden, Peter J.

2006-11-01

Polyhydroxyalkanoates have attracted attention as biodegradable alternatives to conventional thermoplastics and as biomaterials. Through modification of their biosynthesis using Pseudomonas oleovorans, we have manipulated the material properties of these biopolyesters and produced a natural-synthetic hybrid copolymer of polyhydroxyoctanoate- block-diethylene glycol (PHO- b-DEG). A mixture of PHO and PHO-DEG were solvent cast from analytical grade chloroform and analysed using small-angle neutron scattering. A scattering pattern, easily distinguished above the background, was displayed by the films with a diffraction ring at q∼0.12 Å -1. This narrow ring of intensity is suggestive of a highly ordered system. Analysis of the diffraction pattern supported this concept and showed a d-spacing of approximately 50 Å. In addition, conformation of the hybrid polymer chains can be manipulated to support their self-assembly into ordered microporous films.

Totally embedded hybrid thin films of carbon nanotubes and silver nanowires as flat homogenous flexible transparent conductors.

PubMed

Pillai, Suresh Kumar Raman; Wang, Jing; Wang, Yilei; Sk, Md Moniruzzaman; Prakoso, Ari Bimo; Rusli; Chan-Park, Mary B

2016-12-08

There is a great need for viable alternatives to today's transparent conductive film using largely indium tin oxide. We report the fabrication of a new type of flexible transparent conductive film using silver nanowires (AgNW) and single-walled carbon nanotube (SWCNT) networks which are fully embedded in a UV curable resin substrate. The hybrid SWCNTs-AgNWs film is relatively flat so that the RMS roughness of the top surface of the film is 3 nm. Addition of SWCNTs networks make the film resistance uniform; without SWCNTs, sheet resistance of the surface composed of just AgNWs in resin varies from 20 Ω/sq to 10 7  Ω/sq. With addition of SWCNTs embedded in the resin, sheet resistance of the hybrid film is 29 ± 5 Ω/sq and uniform across the 47 mm diameter film discs; further, the optimized film has 85% transparency. Our lamination-transfer UV process doesn't need solvent for sacrificial substrate removal and leads to good mechanical interlocking of the nano-material networks. Additionally, electrochemical study of the film for supercapacitors application showed an impressive 10 times higher current in cyclic voltammograms compared to the control without SWCNTs. Our fabrication method is simple, cost effective and enables the large-scale fabrication of flat and flexible transparent conductive films.

Totally embedded hybrid thin films of carbon nanotubes and silver nanowires as flat homogenous flexible transparent conductors

NASA Astrophysics Data System (ADS)

Pillai, Suresh Kumar Raman; Wang, Jing; Wang, Yilei; Sk, Md Moniruzzaman; Prakoso, Ari Bimo; Rusli; Chan-Park, Mary B.

2016-12-01

There is a great need for viable alternatives to today’s transparent conductive film using largely indium tin oxide. We report the fabrication of a new type of flexible transparent conductive film using silver nanowires (AgNW) and single-walled carbon nanotube (SWCNT) networks which are fully embedded in a UV curable resin substrate. The hybrid SWCNTs-AgNWs film is relatively flat so that the RMS roughness of the top surface of the film is 3 nm. Addition of SWCNTs networks make the film resistance uniform; without SWCNTs, sheet resistance of the surface composed of just AgNWs in resin varies from 20 Ω/sq to 107 Ω/sq. With addition of SWCNTs embedded in the resin, sheet resistance of the hybrid film is 29 ± 5 Ω/sq and uniform across the 47 mm diameter film discs; further, the optimized film has 85% transparency. Our lamination-transfer UV process doesn’t need solvent for sacrificial substrate removal and leads to good mechanical interlocking of the nano-material networks. Additionally, electrochemical study of the film for supercapacitors application showed an impressive 10 times higher current in cyclic voltammograms compared to the control without SWCNTs. Our fabrication method is simple, cost effective and enables the large-scale fabrication of flat and flexible transparent conductive films.

Totally embedded hybrid thin films of carbon nanotubes and silver nanowires as flat homogenous flexible transparent conductors

PubMed Central

Pillai, Suresh Kumar Raman; Wang, Jing; Wang, Yilei; Sk, Md Moniruzzaman; Prakoso, Ari Bimo; Rusli; Chan-Park, Mary B.

2016-01-01

There is a great need for viable alternatives to today’s transparent conductive film using largely indium tin oxide. We report the fabrication of a new type of flexible transparent conductive film using silver nanowires (AgNW) and single-walled carbon nanotube (SWCNT) networks which are fully embedded in a UV curable resin substrate. The hybrid SWCNTs-AgNWs film is relatively flat so that the RMS roughness of the top surface of the film is 3 nm. Addition of SWCNTs networks make the film resistance uniform; without SWCNTs, sheet resistance of the surface composed of just AgNWs in resin varies from 20 Ω/sq to 107 Ω/sq. With addition of SWCNTs embedded in the resin, sheet resistance of the hybrid film is 29 ± 5 Ω/sq and uniform across the 47 mm diameter film discs; further, the optimized film has 85% transparency. Our lamination-transfer UV process doesn’t need solvent for sacrificial substrate removal and leads to good mechanical interlocking of the nano-material networks. Additionally, electrochemical study of the film for supercapacitors application showed an impressive 10 times higher current in cyclic voltammograms compared to the control without SWCNTs. Our fabrication method is simple, cost effective and enables the large-scale fabrication of flat and flexible transparent conductive films. PMID:27929125

High-performance microsupercapacitors based on two-dimensional graphene/manganese dioxide/silver nanowire ternary hybrid film.

PubMed

Liu, Wenwen; Lu, Congxiang; Wang, Xingli; Tay, Roland Yingjie; Tay, Beng Kang

2015-02-24

Microsupercapacitors (MSCs), as one type of significant power source or energy storage unit in microelectronic devices, have attracted more and more attention. However, how to reasonably design electrode structures and exploit the active materials to endow the MSCs with excellent performances in a limited surface area still remains a challenge. Here, a reduced graphene oxide (RGO)/manganese dioxide (MnO2)/silver nanowire (AgNW) ternary hybrid film (RGMA ternary hybrid film) is successfully fabricated by a facile vacuum filtration and subsequent thermal reduction, and is used directly as a binder-free electrode for MSCs. Additionally, a flexible, transparent, all-solid state RMGA-MSC is also built, and its electrochemical performance in an ionic liquid gel electrolyte are investigated in depth. Notably, the RGMA-MSCs display superior electrochemical properties, including exceptionally high rate capability (up to 50000 mV·s(-1)), high frequency response (very short corresponding time constant τ0 = 0.14 ms), and excellent cycle stability (90.3% of the initial capacitance after 6000 cycles in ionic liquid gel electrolyte). Importantly, the electrochemical performance of RGMA-MSCs shows a strong dependence on the geometric parameters including the interspace between adjacent fingers and the width of the finger of MSCs. These encouraging results may not only provide important references for the design and fabrication of high-performance MSCs, but also make the RGMA ternary hybrid film promising for the next generation film lithium ion batteries and other energy storage devices.

Sensor Functionality of Conducting Polyaniline-Metal Oxide (TiO2/SnO2) Hybrid Materials Films toward Benzene and Toluene Vapors at Room Temperature

NASA Astrophysics Data System (ADS)

Subramanian, E.; Santhanamari, P.; Murugan, C.

2018-05-01

Polyaniline-metal oxide (TiO2/SnO2) organic-inorganic hybrid materials films were fabricated in situ on a printed circuit board (PCB) via drop coating technique. The mixture of aniline and metal oxide (TiO2/SnO2) dispersed in ethanol was applied along with an oxidant for the coating process. The formed material films were characterized by Fourier transform infra-red spectroscopy, x-ray diffraction and scanning electron microscopy techniques. The sensor functionality of the prepared films on PCB was investigated individually for the detection of benzene or toluene vapor at room temperature. The promptness of sensor response to analyte vapor and its recovery to air, as well as the concentration-dependent sensor functionality of the hybrid material films were investigated. The film form of hybrid materials has shown much improved sensor efficiency even at ambient air condition compared to the pellet form of the polyaniline-SnO2 hybrid material reported earlier, which sensed the same analytes only in nitrogen atmosphere.

Pure Cubic-Phase Hybrid Iodobismuthates AgBi2 I7 for Thin-Film Photovoltaics.

PubMed

Kim, Younghoon; Yang, Zhenyu; Jain, Ankit; Voznyy, Oleksandr; Kim, Gi-Hwan; Liu, Min; Quan, Li Na; García de Arquer, F Pelayo; Comin, Riccardo; Fan, James Z; Sargent, Edward H

2016-08-08

Bismuth-based hybrid perovskites are candidates for lead-free and air-stable photovoltaics, but poor surface morphologies and a high band-gap energy have previously limited these hybrid perovskites. A new materials processing strategy to produce enhanced bismuth-based thin-film photovoltaic absorbers by incorporation of monovalent silver cations into iodobismuthates is presented. Solution-processed AgBi2 I7 thin films are prepared by spin-coating silver and bismuth precursors dissolved in n-butylamine and annealing under an N2 atmosphere. X-ray diffraction analysis reveals the pure cubic structure (Fd3m) with lattice parameters of a=b=c=12.223 Å. The resultant AgBi2 I7 thin films exhibit dense and pinhole-free surface morphologies with grains ranging in size from 200-800 nm and a low band gap of 1.87 eV suitable for photovoltaic applications. Initial studies produce solar power conversion efficiencies of 1.22 % and excellent stability over at least 10 days under ambient conditions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Large-scale complementary macroelectronics using hybrid integration of carbon nanotubes and IGZO thin-film transistors.

PubMed

Chen, Haitian; Cao, Yu; Zhang, Jialu; Zhou, Chongwu

2014-06-13

Carbon nanotubes and metal oxide semiconductors have emerged as important materials for p-type and n-type thin-film transistors, respectively; however, realizing sophisticated macroelectronics operating in complementary mode has been challenging due to the difficulty in making n-type carbon nanotube transistors and p-type metal oxide transistors. Here we report a hybrid integration of p-type carbon nanotube and n-type indium-gallium-zinc-oxide thin-film transistors to achieve large-scale (>1,000 transistors for 501-stage ring oscillators) complementary macroelectronic circuits on both rigid and flexible substrates. This approach of hybrid integration allows us to combine the strength of p-type carbon nanotube and n-type indium-gallium-zinc-oxide thin-film transistors, and offers high device yield and low device variation. Based on this approach, we report the successful demonstration of various logic gates (inverter, NAND and NOR gates), ring oscillators (from 51 stages to 501 stages) and dynamic logic circuits (dynamic inverter, NAND and NOR gates).

Hybrid perovskite films approaching the radiative limit with over 90% photoluminescence quantum efficiency

NASA Astrophysics Data System (ADS)

Braly, Ian L.; deQuilettes, Dane W.; Pazos-Outón, Luis M.; Burke, Sven; Ziffer, Mark E.; Ginger, David S.; Hillhouse, Hugh W.

2018-06-01

Reducing non-radiative recombination in semiconducting materials is a prerequisite for achieving the highest performance in light-emitting and photovoltaic applications. Here, we characterize both external and internal photoluminescence quantum efficiency and quasi-Fermi-level splitting of surface-treated hybrid perovskite (CH3NH3PbI3) thin films. With respect to the material bandgap, these passivated films exhibit the highest quasi-Fermi-level splitting measured to date, reaching 97.1 ± 0.7% of the radiative limit, approaching that of the highest performing GaAs solar cells. We confirm these values with independent measurements of internal photoluminescence quantum efficiency of 91.9 ± 2.7% under 1 Sun illumination intensity, setting a new benchmark for these materials. These results suggest hybrid perovskite solar cells are inherently capable of further increases in power conversion efficiency if surface passivation can be combined with optimized charge carrier selective interfaces.

Particle-Film Plasmons on Periodic Silver Film over Nanosphere (AgFON): A Hybrid Plasmonic Nanoarchitecture for Surface-Enhanced Raman Spectroscopy.

PubMed

Lee, Jiwon; Zhang, Qianpeng; Park, Seungyoung; Choe, Ayoung; Fan, Zhiyong; Ko, Hyunhyub

2016-01-13

Plasmonic systems based on particle-film plasmonic couplings have recently attracted great attention because of the significantly enhanced electric field at the particle-film gaps. Here, we introduce a hybrid plasmonic architecture utilizing combined plasmonic effects of particle-film gap plasmons and silver film over nanosphere (AgFON) substrates. When gold nanoparticles (AuNPs) are assembled on AgFON substrates with controllable particle-film gap distances, the AuNP-AgFON system supports multiple plasmonic couplings from interparticle, particle-film, and crevice gaps, resulting in a huge surface-enhanced Raman spectroscopy (SERS) effect. We show that the periodicity of AgFON substrates and the particle-film gaps greatly affects the surface plasmon resonances, and thus, the SERS effects due to the interplay between multiple plasmonic couplings. The optimally designed AuNP-AgFON substrate shows a SERS enhancement of 233 times compared to the bare AgFON substrate. The ultrasensitive SERS sensing capability is also demonstrated by detecting glutathione, a neurochemical molecule that is an important antioxidant, down to the 10 pM level.

Hybrid Energy Cell with Hierarchical Nano/Micro-Architectured Polymer Film to Harvest Mechanical, Solar, and Wind Energies Individually/Simultaneously.

PubMed

Dudem, Bhaskar; Ko, Yeong Hwan; Leem, Jung Woo; Lim, Joo Ho; Yu, Jae Su

2016-11-09

We report the creation of hybrid energy cells based on hierarchical nano/micro-architectured polydimethylsiloxane (HNMA-PDMS) films with multifunctionality to simultaneously harvest mechanical, solar, and wind energies. These films consist of nano/micro dual-scale architectures (i.e., nanonipples on inverted micropyramidal arrays) on the PDMS surface. The HNMA-PDMS is replicable by facile and cost-effective soft imprint lithography using a nanoporous anodic alumina oxide film formed on the micropyramidal-structured silicon substrate. The HNMA-PDMS film plays multifunctional roles as a triboelectric layer in nanogenerators and an antireflection layer for dye-sensitized solar cells (DSSCs), as well as a self-cleaning surface. This film is employed in triboelectric nanogenerator (TENG) devices, fabricated by laminating it on indium-tin oxide-coated polyethylene terephthalate (ITO/PET) as a bottom electrode. The large effective contact area that emerged from the densely packed hierarchical nano/micro-architectures of the PDMS film leads to the enhancement of TENG device performance. Moreover, the HNMA-PDMS/ITO/PET, with a high transmittance of >90%, also results in highly transparent TENG devices. By placing the HNMA-PDMS/ITO/PET, where the ITO/PET is coated with zinc oxide nanowires, as the top glass substrate of DSSCs, the device is able to add the functionality of TENG devices, thus creating a hybrid energy cell. The hybrid energy cell can successfully convert mechanical, solar, and wind energies into electricity, simultaneously or independently. To specify the device performance, the effects of external pushing frequency and load resistance on the output of TENG devices are also analyzed, including the photovoltaic performance of the hybrid energy cells.

Multiplexed interfacial transduction of nucleic acid hybridization using a single color of immobilized quantum dot donor and two acceptors in fluorescence resonance energy transfer.

PubMed

Algar, W Russ; Krull, Ulrich J

2010-01-01

A multiplexed solid-phase assay for the detection of nucleic acid hybridization was developed on the basis of a single color of immobilized CdSe/ZnS quantum dot (QD) as a donor in fluorescence resonance energy transfer (FRET). This work demonstrated that two channels of detection did not necessitate two different QD donors. Two probe oligonucleotides were coimmobilized on optical fibers modified with QDs, and a sandwich assay was used to associate the acceptor dyes with interfacial hybridization events without target labeling. FRET-sensitized acceptor emission provided an analytical signal that was concentration dependent down to 10 nM. Changes in the ratio of coimmobilized probe oligonucleotides were found to yield linear changes in the relative amounts of acceptor emission. These changes were compared to previous studies that used mixed films of two QD donors for two detection channels. The analysis indicated that probe dilution effects were primarily driven by changes in acceptor number density and that QD dilution effects or changes in mean donor-acceptor distance were secondary. Hybridization kinetics were found to be consistent between different ratios of coimmobilized probes, suggesting that hybridization in this type of system occurred via the accepted model for solid-phase hybridization, where adsorption and then diffusion at the solid interface drove hybridization.

Cellulose acetate-based SiO2/TiO2 hybrid microsphere composite aerogel films for water-in-oil emulsion separation

NASA Astrophysics Data System (ADS)

Yang, Xue; Ma, Jianjun; Ling, Jing; Li, Na; Wang, Di; Yue, Fan; Xu, Shimei

2018-03-01

The cellulose acetate (CA)/SiO2-TiO2 hybrid microsphere composite aerogel films were successfully fabricated via water vapor-induced phase inversion of CA solution and simultaneous hydrolysis/condensation of 3-aminopropyltrimethoxysilane (APTMS) and tetrabutyl titanate (TBT) at room temperature. Micro-nano hierarchical structure was constructed on the surface of the film. The film could separate nano-sized surfactant-stabilized water-in-oil emulsions only under gravity. The flux of the film for the emulsion separation was up to 667 L m-2 h-1, while the separation efficiency was up to 99.99 wt%. Meanwhile, the film exhibited excellent stability during multiple cycles. Moreover, the film performed excellent photo-degradation performance under UV light due to the photocatalytic ability of TiO2. Facile preparation, good separation and potential biodegradation maked the CA/SiO2-TiO2 hybrid microsphere composite aerogel films a candidate in oil/water separation application.

Free-Standing and Self-Crosslinkable Hybrid Films by Core-Shell Particle Design and Processing.

PubMed

Vowinkel, Steffen; Paul, Stephen; Gutmann, Torsten; Gallei, Markus

2017-11-15

The utilization and preparation of functional hybrid films for optical sensing applications and membranes is of utmost importance. In this work, we report the convenient and scalable preparation of self-crosslinking particle-based films derived by directed self-assembly of alkoxysilane-based cross-linkers as part of a core-shell particle architecture. The synthesis of well-designed monodisperse core-shell particles by emulsion polymerization is the basic prerequisite for subsequent particle processing via the melt-shear organization technique. In more detail, the core particles consist of polystyrene (PS) or poly(methyl methacrylate) (PMMA), while the comparably soft particle shell consists of poly(ethyl acrylate) (PEA) and different alkoxysilane-based poly(methacrylate)s. For hybrid film formation and convenient self-cross-linking, different alkyl groups at the siloxane moieties were investigated in detail by solid-state Magic-Angle Spinning Nuclear Magnetic Resonance (MAS, NMR) spectroscopy revealing different crosslinking capabilities, which strongly influence the properties of the core or shell particle films with respect to transparency and iridescent reflection colors. Furthermore, solid-state NMR spectroscopy and investigation of the thermal properties by differential scanning calorimetry (DSC) measurements allow for insights into the cross-linking capabilities prior to and after synthesis, as well as after the thermally and pressure-induced processing steps. Subsequently, free-standing and self-crosslinked particle-based films featuring excellent particle order are obtained by application of the melt-shear organization technique, as shown by microscopy (TEM, SEM).

Dendritic Ni(Cu)-polypyrrole hybrid films for a pseudo-capacitor.

PubMed

Choi, Bit Na; Chun, Woo Won; Qian, Aniu; Lee, So Jeong; Chung, Chan-Hwa

2015-11-28

Dendritic Ni(Cu)-polypyrrole hybrid films are fabricated for a pseudo-capacitor in a unique morphology using two simple methods: electro-deposition and electrochemical de-alloying. Three-dimensional structures of porous dendrites are prepared by electro-deposition within the hydrogen evolution reaction (HER) at a high cathodic potential; the high-surface-area structure provides sufficient redox reactions between the electrodes and the electrolyte. The dependence of the active-layer thickness on the super-capacitor performance is also investigated, and the 60 μm-thick Ni(Cu)PPy hybrid electrode presents the highest performance of 659.52 F g(-1) at the scan rate of 5 mV s(-1). In the thicker layers, the specific capacitance became smaller due to the diffusion limitation of the ions in an electrolyte. The polypyrrole-hybridization on the porous dendritic Ni(Cu) electrode provides superior specific capacitance and excellent cycling stability due to the improvement in electric conductivity by the addition of conducting polypyrrole in the matrices of the dendritic nano-porous Ni(Cu) layer and the synergistic effect of composite materials.

Growth, characterization and post-processing of inorganic and hybrid organic-inorganic thin films deposited using atomic and molecular layer deposition techniques

NASA Astrophysics Data System (ADS)

Abdulagatov, Aziz Ilmutdinovich

Atomic layer deposition (ALD) and molecular layer deposition (MLD) are advanced thin film coating techniques developed for deposition of inorganic and hybrid organic-inorganic films respectively. Decreasing device dimensions and increasing aspect ratios in semiconductor processing has motivated developments in ALD. The beginning of this thesis will cover study of new ALD chemistry for high dielectric constant Y 2O3. In addition, the feasibility of conducting low temperature ALD of TiN and TiAlN is explored using highly reactive hydrazine as a new nitrogen source. Developments of these ALD processes are important for the electronics industry. As the search for new materials with more advanced properties continues, attention has shifted toward exploring the synthesis of hierarchically nanostructured thin films. Such complex architectures can provide novel functions important to the development of state of the art devices for the electronics industry, catalysis, energy conversion and memory storage as a few examples. Therefore, the main focus of this thesis is on the growth, characterization, and post-processing of ALD and MLD films for fabrication of novel composite (nanostructured) thin films. Novel composite materials are created by annealing amorphous ALD oxide alloys in air and by heat treatment of hybrid organic-inorganic MLD films in inert atmosphere (pyrolysis). The synthesis of porous TiO2 or Al2O3 supported V2O5 for enhanced surface area catalysis was achieved by the annealing of inorganic TiVxOy and AlV xOy ALD films in air. The interplay between phase separation, surface energy difference, crystallization, and melting temperature of individual oxides were studied for their control of film morphology. In other work, a class of novel metal oxide-graphitic carbon composite thin films was produced by pyrolysis of MLD hybrid organic-inorganic films. For example, annealing in argon of titania based hybrid films enabled fabrication of thin films of intimately

Coupling Two-Dimensional MoTe2 and InGaZnO Thin-Film Materials for Hybrid PN Junction and CMOS Inverters.

PubMed

Lee, Han Sol; Choi, Kyunghee; Kim, Jin Sung; Yu, Sanghyuck; Ko, Kyeong Rok; Im, Seongil

2017-05-10

We report the fabrication of hybrid PN junction diode and complementary (CMOS) inverters, where 2D p-type MoTe 2 and n-type thin film InGaZnO (IGZO) are coupled for each device process. IGZO thin film was initially patterned by conventional photolithography either for n-type material in a PN diode or for n-channel of top-gate field-effect transistors (FET) in CMOS inverter. The hybrid PN junction diode shows a good ideality factor of 1.57 and quite a high ON/OFF rectification ratio of ∼3 × 10 4 . Under photons, our hybrid PN diode appeared somewhat stable only responding to high-energy photons of blue and ultraviolet. Our 2D nanosheet-oxide film hybrid CMOS inverter exhibits voltage gains as high as ∼40 at 5 V, low power consumption less than around a few nW at 1 V, and ∼200 μs switching dynamics.

Electrocatalytic reaction of hydrogen peroxide and NADH based on poly(neutral red) and FAD hybrid film.

PubMed

Lin, Kuo Chiang; Lin, Yu Ching; Chen, Shen Ming

2012-01-07

A simple method to immobilize poly(neutral red) (PNR) and flavin adenine dinucleotide (FAD) hybrid film (PNR/FAD) by cyclic voltammetry is proposed. The PNR/FAD hybrid film can be easily prepared on an electrode surface involving electropolymerization of neutral red (NR) monomers and the electrostatic interaction between the positively charged PNR and the negatively charged FAD. It exhibits electroactive, stable, surface-confined, pH-dependent, nano-sized, and compatible properties. It provides good electrocatalytic properties to various species. It shows a sensitivity of 5.4 μA mM(-1) cm(-2) and 21.5 μA mM(-1) cm(-2) for hydrogen peroxide (H(2)O(2)) and nicotinamide adenine dinucleotide (NADH) with the linear range of 0.1 μM-39 mM and 5 × 10(-5) to 2.5 × 10(-4) M, respectively. It shows another linear range of 48.8-355.5 mM with the sensitivity of 12.3 μA mM(-1) cm(-2) for H(2)O(2). In particular, the PNR/FAD hybrid film has potential to replace some hemoproteins to be a cathode of biofuel cells and provide the biosensing system for glucose and ethanol. This journal is © The Royal Society of Chemistry 2012

Solid-phase supports for the in situ assembly of quantum dot-FRET hybridization assays in channel microfluidics.

PubMed

Tavares, Anthony J; Noor, M Omair; Uddayasankar, Uvaraj; Krull, Ulrich J; Vannoy, Charles H

2014-01-01

Semiconductor quantum dots (QDs) have long served as integral components in signal transduction modalities such as Förster resonance energy transfer (FRET). The majority of bioanalytical methods using QDs for FRET-based techniques simply monitor binding-induced conformational changes. In more recent work, QDs have been incorporated into solid-phase support systems, such as microfluidic chips, to serve as physical platforms in the development of functional biosensors and bioprobes. Herein, we describe a simple strategy for the transduction of nucleic acid hybridization that combines a novel design method based on FRET with an electrokinetically controlled microfluidic technology, and that offers further potential for amelioration of sample-handling issues and for simplification of dynamic stringency control.

Ultrasensitive FRET-based DNA sensor using PNA/DNA hybridization.

PubMed

Yang, Lan-Hee; Ahn, Dong June; Koo, Eunhae

2016-12-01

In the diagnosis of genetic diseases, rapid and highly sensitive DNA detection is crucial. Therefore, many strategies for detecting target DNA have been developed, including electrical, optical, and mechanical methods. Herein, a highly sensitive FRET based sensor was developed by using PNA (Peptide Nucleic Acid) probe and QD, in which red color QDs are hybridized with capture probes, reporter probes and target DNAs by EDC-NHS coupling. The hybridized probe with target DNA gives off fluorescent signal due to the energy transfer from QD to Cy5 dye in the reporter probe. Compared to the conventional DNA sensor using DNA probes, the DNA sensor using PNA probes shows higher FRET factor and efficiency due to the higher reactivity between PNA and target DNA. In addition, to elicit the effect of the distance between the donor and the acceptor, we have investigated two types of the reporter probes having Cy5 dyes attached at the different positions of the reporter probes. Results show that the shorter the distance between QDs and Cy5s, the stronger the signal intensity. Furthermore, based on the fluorescence microscopy images using microcapillary chips, the FRET signal is enhanced to be up to 276% times stronger than the signal obtained using the cuvette by the fluorescence spectrometer. These results suggest that the PNA probe system conjugated with QDs can be used as ultrasensitive DNA nanosensors. Copyright © 2016. Published by Elsevier B.V.

A sulphonated carbon dot-chitosan hybrid hydrogel nanocomposite as an efficient ion-exchange film for Ca2+ and Mg2+ removal

NASA Astrophysics Data System (ADS)

Baruah, Upama; Konwar, Achyut; Chowdhury, Devasish

2016-04-01

We have developed a hybrid hydrogel nanocomposite film via conjugation of oxidised carbon dots synthesized from 11-mercaptoundecanoic acid with chitosan. The potential applicability of the film was then successfully tested for the removal of Ca2+ and Mg2+ ions from solution.We have developed a hybrid hydrogel nanocomposite film via conjugation of oxidised carbon dots synthesized from 11-mercaptoundecanoic acid with chitosan. The potential applicability of the film was then successfully tested for the removal of Ca2+ and Mg2+ ions from solution. Electronic supplementary information (ESI) available: The ESI includes the detailed synthesis and characterization of carbon dots both before and after oxidation and of the carbon dot-chitosan nanocomposite films viz. DLS, SEM, UV-visible, FTIR, PL spectroscopy and TGA. See DOI: 10.1039/c6nr01129b

Detection of malachite green in fish based on magnetic fluorescent probe of CdTe QDs/nano-Fe3O4@MIPs

NASA Astrophysics Data System (ADS)

Wu, Le; Lin, Zheng-Zhong; Zeng, Jun; Zhong, Hui-Ping; Chen, Xiao-Mei; Huang, Zhi-Yong

2018-05-01

A magnetic fluorescent probe of CdTe QDs/nano-Fe3O4@MIPs was prepared using CdTe QDs and Fe3O4 nanoparticles as co-nucleus and molecularly imprinted polymers (MIPs) as specific recognition sites based on a reverse microemulsion method. With the specific enrichment and magnetic separation properties, the probe of CdTe QDs/nano-Fe3O4@MIPs was used to detect malachite green (MG) in fish samples. The TEM analysis showed that the particles of CdTe QDs/nano-Fe3O4@MIPs were spherical with average diameter around 53 nm, and a core-shell structure was well-shaped with several Fe3O4 nanoparticles and CdTe QDs embedded in each of the microsphere. Quick separation of the probes from solutions could be realized with a magnet, indicating the excellent magnetic property of CdTe QDs/nano-Fe3O4@MIPs. The probe exhibited high specific adsorption towards MG and excellent fluorescence emission at λem 598 nm. The fluorescence of CdTe QDs/nano-Fe3O4@MIPs could be linearly quenched by MG at the concentrations from 0.025 to 1.5 μmol L-1. The detection limit was 0.014 μmol L-1. The average recovery of spiked MG in fish samples was 105.2%. The result demonstrated that the as-prepared CdTe QDs/nano-Fe3O4@MIPs could be used as a probe to the detection of trace MG in fish samples.

Detection of malachite green in fish based on magnetic fluorescent probe of CdTe QDs/nano-Fe3O4@MIPs.

PubMed

Wu, Le; Lin, Zheng-Zhong; Zeng, Jun; Zhong, Hui-Ping; Chen, Xiao-Mei; Huang, Zhi-Yong

2018-05-05

A magnetic fluorescent probe of CdTe QDs/nano-Fe 3 O 4 @MIPs was prepared using CdTe QDs and Fe 3 O 4 nanoparticles as co-nucleus and molecularly imprinted polymers (MIPs) as specific recognition sites based on a reverse microemulsion method. With the specific enrichment and magnetic separation properties, the probe of CdTe QDs/nano-Fe 3 O 4 @MIPs was used to detect malachite green (MG) in fish samples. The TEM analysis showed that the particles of CdTe QDs/nano-Fe 3 O 4 @MIPs were spherical with average diameter around 53nm, and a core-shell structure was well-shaped with several Fe 3 O 4 nanoparticles and CdTe QDs embedded in each of the microsphere. Quick separation of the probes from solutions could be realized with a magnet, indicating the excellent magnetic property of CdTe QDs/nano-Fe 3 O 4 @MIPs. The probe exhibited high specific adsorption towards MG and excellent fluorescence emission at λ em 598nm. The fluorescence of CdTe QDs/nano-Fe 3 O 4 @MIPs could be linearly quenched by MG at the concentrations from 0.025 to 1.5μmolL -1 . The detection limit was 0.014μmolL -1 . The average recovery of spiked MG in fish samples was 105.2%. The result demonstrated that the as-prepared CdTe QDs/nano-Fe 3 O 4 @MIPs could be used as a probe to the detection of trace MG in fish samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Charge transport through exciton shelves in cadmium chalcogenide quantum dot-DNA nano-bioelectronic thin films

NASA Astrophysics Data System (ADS)

Goodman, Samuel M.; Noh, Hyunwoo; Singh, Vivek; Cha, Jennifer N.; Nagpal, Prashant

2015-02-01

Quantum dot (QD), or semiconductor nanocrystal, thin films are being explored for making solution-processable devices due to their size- and shape-tunable bandgap and discrete higher energy electronic states. While DNA has been extensively used for the self-assembly of nanocrystals, it has not been investigated for the simultaneous conduction of multiple energy charges or excitons via exciton shelves (ES) formed in QD-DNA nano-bioelectronic thin films. Here, we present studies on charge conduction through exciton shelves, which are formed via chemically coupled QDs and DNA, between electronic states of the QDs and the HOMO-LUMO levels in the complementary DNA nucleobases. While several challenges need to be addressed in optimizing the formation of devices using QD-DNA thin films, a higher charge collection efficiency for hot-carriers and our detailed investigations of charge transport mechanism in these thin films highlight their potential for applications in nano-bioelectronic devices and biological transducers.

Hybrid enabled thin film metrology using XPS and optical

NASA Astrophysics Data System (ADS)

Vaid, Alok; Iddawela, Givantha; Mahendrakar, Sridhar; Lenahan, Michael; Hossain, Mainul; Timoney, Padraig; Bello, Abner F.; Bozdog, Cornel; Pois, Heath; Lee, Wei Ti; Klare, Mark; Kwan, Michael; Kang, Byung Cheol; Isbester, Paul; Sendelbach, Matthew; Yellai, Naren; Dasari, Prasad; Larson, Tom

2016-03-01

Complexity of process steps integration and material systems for next-generation technology nodes is reaching unprecedented levels, the appetite for higher sampling rates is on the rise, while the process window continues to shrink. Current thickness metrology specifications reach as low as 0.1A for total error budget - breathing new life into an old paradigm with lower visibility for past few metrology nodes: accuracy. Furthermore, for advance nodes there is growing demand to measure film thickness and composition on devices/product instead of surrogate planar simpler pads. Here we extend our earlier work in Hybrid Metrology to the combination of X-Ray based reference technologies (high performance) with optical high volume manufacturing (HVM) workhorse metrology (high throughput). Our stated goal is: put more "eyes" on the wafer (higher sampling) and enable move to films on pattern structure (control what matters). Examples of 1X front-end applications are used to setup and validate the benefits.

Piezoelectric, Solar and Thermal Energy Harvesting for Hybrid Low-Power Generator Systems With Thin-Film Batteries

DTIC Science & Technology

2012-01-01

research has investigated simultaneous harvesting of vibration energy using the direct piezoelectric effect and harvesting of magnetic energy (alternating... Piezoelectric , solar and thermal energy harvesting for hybrid low-power generator systems with thin-film batteries This article has been downloaded...TYPE 3. DATES COVERED 00-00-2011 to 00-00-2011 4. TITLE AND SUBTITLE Piezoelectric , solar and thermal energy harvesting for hybrid low-power

The biocompatability of mesoporous inorganic-organic hybrid resin films with ionic and hydrophilic characteristics.

PubMed

Kim, Gahee; Hong, Lan Young; Jung, Jungwoon; Kim, Dong-Pyo; Kim, Heesoo; Kim, Ik Jung; Kim, Jung Ran; Ree, Moonhor

2010-03-01

New mesoporous silicate-titania resin systems hybridized with 4,5-dihydroxy-m-benzenedisulfonic acid and poly(ethylene glycol)-dimethacrylate component were developed. These inorganic-organic hybrid resins were found to reveal highly controlled ionic and hydrophilic surface with excellent durability and adhesion onto various substrates. The resin films revealed high resistance to nonspecific adsorption of fibrinogen and to adherence by several bacterial pathogens such as Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis. Furthermore, excellent biocompatibility of the developed resins was proved by both HEp-2 cell adhesion in vitro and subcutaneous implantation in mice. The inorganic-organic hybrid resins are strongly promising for biomedical applications including biomedical devices and biosensors. Copyright 2009 Elsevier Ltd. All rights reserved.

Plasmonic fluorescent CdSe/Cu2S hybrid nanocrystals for multichannel imaging and cancer directed photo-thermal therapy

NASA Astrophysics Data System (ADS)

Sheikh Mohamed, M.; Poulose, Aby Cheruvathoor; Veeranarayanan, Srivani; Romero Aburto, Rebecca; Mitcham, Trevor; Suzuki, Yuko; Sakamoto, Yasushi; Ajayan, Pulickel M.; Bouchard, Richard R.; Yoshida, Yasuhiko; Maekawa, Toru; Sakthi Kumar, D.

2016-04-01

A simple, crude Jatropha curcas (JC) oil-based synthesis approach, devoid of any toxic phosphine and pyrophoric ligands, to produce size and shape tuned CdSe QDs and a further copper sulfide (Cu2S) encasing is presented. The QDs exhibited excellent photoluminescent properties with narrow band gap emission. Furthermore, the Cu2S shell rendered additional cytocompatibility and stability to the hybrid nanomaterial, which are major factors for translational and clinical applications of QDs. The nanocomposites were PEGylated and folate conjugated to augment their cytoamiability and enhance their specificity towards cancer cells. The nanohybrids possess potentials for visible, near infrared (NIR), photoacoustic (PA) and computed tomography (μCT) imaging. The diverse functionality of the composite was derived from the multi-channel imaging abilities and thermal competence on NIR laser irradiation to specifically actuate the photo-thermal ablation of brain cancer cells.A simple, crude Jatropha curcas (JC) oil-based synthesis approach, devoid of any toxic phosphine and pyrophoric ligands, to produce size and shape tuned CdSe QDs and a further copper sulfide (Cu2S) encasing is presented. The QDs exhibited excellent photoluminescent properties with narrow band gap emission. Furthermore, the Cu2S shell rendered additional cytocompatibility and stability to the hybrid nanomaterial, which are major factors for translational and clinical applications of QDs. The nanocomposites were PEGylated and folate conjugated to augment their cytoamiability and enhance their specificity towards cancer cells. The nanohybrids possess potentials for visible, near infrared (NIR), photoacoustic (PA) and computed tomography (μCT) imaging. The diverse functionality of the composite was derived from the multi-channel imaging abilities and thermal competence on NIR laser irradiation to specifically actuate the photo-thermal ablation of brain cancer cells. Electronic supplementary information (ESI

Preparation of water soluble L-arginine capped CdSe/ZnS QDs and their interaction with synthetic DNA: Picosecond-resolved FRET study

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

Giri, Anupam; Goswami, Nirmal; Lemmens, Peter

2012-08-15

Graphical abstract: Förster resonance energy transfer (FRET) studies on the interaction of water soluble arginine-capped CdSe/ZnS QDs with ethidium bromide (EB) labeled synthetic dodecamer DNA. Highlights: ► We have solubilized CdSe/ZnS QD in water replacing their TOPO ligand by L-arginine. ► We have studied arginine@QD–DNA interaction using FRET technique. ► Arginine@QDs act as energy donor and ethidium bromide-DNA acts as energy acceptor. ► We have applied a kinetic model to understand the kinetics of energy transfer. ► Circular dichroism studies revealed negligible perturbation in the DNA B-form in the arg@QD-DNA complex. -- Abstract: We have exchanged TOPO (trioctylphosphine oxide) ligandmore » of CdSe/ZnS core/shell quantum dots (QDs) with an amino acid L-arginine (Arg) at the toluene/water interface and eventually rendered the QDs from toluene to aqueous phase. We have studied the interaction of the water soluble Arg-capped QDs (energy donor) with ethidium (EB) labeled synthetic dodecamer DNA (energy acceptor) using picoseconds resolved Förster resonance energy transfer (FRET) technique. Furthermore, we have applied a model developed by M. Tachiya to understand the kinetics of energy transfer and the distribution of acceptor (EB-DNA) molecules around the donor QDs. Circular dichroism (CD) studies revealed a negligible perturbation in the native B-form structure of the DNA upon interaction with Arg-capped QDs. The melting and the rehybridization pathways of the DNA attached to the QDs have been monitored by the CD which reveals hydrogen bonding is the associative mechanism for interaction between Arg-capped QDs and DNA.« less

Hybrid k .p tight-binding model for intersubband optics in atomically thin InSe films

NASA Astrophysics Data System (ADS)

Magorrian, S. J.; Ceferino, A.; Zólyomi, V.; Fal'ko, V. I.

2018-04-01

We propose atomic films of n -doped γ -InSe as a platform for intersubband optics in the infrared and far-infrared range, coupled to out-of-plane polarized light. Depending on the film thickness (number of layers) and the amount of n -doping of the InSe film, these transitions span from ˜0.7 eV for bilayer to ˜0.05 eV for 15-layer InSe. We use a hybrid k .p theory and tight-binding model, fully parametrized using density-functional theory, to predict their oscillator strengths and thermal linewidths at room temperature.

Hybrid films with phase-separated domains: A new class of functional materials

NASA Astrophysics Data System (ADS)

Kang, Minjee; Leal, Cecilia

The cell membrane is highly compartmentalized over micro-and nano scale. The compartmentalized domains play an important role in regulating the diffusion and distribution of species within and across the membrane. In this work, we introduced nanoscale heterogeneities into lipid films for the purpose of developing nature-mimicking phase-separated materials. The mixtures of phospholipids and amphiphilic block copolymers self-assemble into supported 1D multi-bilayers. We observed that in each lamella, mixtures of lipid and polymer phase-separate into domains that differ in their composition akin to sub-phases in cholesterol-containing lipid bilayers. Interestingly, we found evidence that like-domains are in registry across multilayers, making phase separation three-dimensional. To exploit such distinctive domain structure for surface-mediated drug delivery, we incorporated pharmaceutical molecules into the films. The drug release study revealed that the presence of domains in hybrid films modifies the diffusion pathways of drugs that become confined within phase-separated domains. A comprehensive domain structure coupled with drug diffusion pathways in films will be presented, offering new perspectives in designing a thin-film matrix system for controlled drug delivery. This work was supported by the National Science Foundation under Grant No. DMR-1554435.

Hybrid zinc oxide/graphene electrodes for depleted heterojunction colloidal quantum-dot solar cells.

PubMed

Tavakoli, Mohammad Mahdi; Aashuri, Hossein; Simchi, Abdolreza; Fan, Zhiyong

2015-10-07

Recently, hybrid nanocomposites consisting of graphene/nanomaterial heterostructures have emerged as promising candidates for the fabrication of optoelectronic devices. In this work, we have employed a facile and in situ solution-based process to prepare zinc oxide/graphene quantum dots (ZnO/G QDs) in a hybrid structure. The prepared hybrid dots are composed of a ZnO core, with an average size of 5 nm, warped with graphene nanosheets. Spectroscopic studies show that the graphene shell quenches the photoluminescence intensity of the ZnO nanocrystals by about 72%, primarily due to charge transfer reactions and static quenching. A red shift in the absorption peak is also observed. Raman spectroscopy determines G-band splitting of the graphene shell into two separated sub-bands (G(+), G(-)) caused by the strain induced symmetry breaking. It is shown that the hybrid ZnO/G QDs can be used as a counter-electrode for heterojunction colloidal quantum-dot solar cells for efficient charge-carrier collection, as evidenced by the external quantum efficiency measurement. Under the solar simulated spectrum (AM 1.5G), we report enhanced power conversion efficiency (35%) with higher short current circuit (80%) for lead sulfide-based solar cells as compared to devices prepared by pristine ZnO nanocrystals.

High color rendering index of remote-type white LEDs with multi-layered quantum dot-phosphor films and short-wavelength pass dichroic filters

NASA Astrophysics Data System (ADS)

Yoon, Hee Chang; Oh, Ji Hye; Do, Young Rag

2014-09-01

This paper introduces high color rendering index (CRI) white light-emitting diodes (W-LEDs) coated with red emitting (Sr,Ca)AlSiN3:Eu phosphors and yellowish-green emitting AgIn5S8/ZnS (AIS/ZS) quantum dots (QDs) on glass or a short-wavelength pass dichroic filter (SPDF), which transmit blue wavelength regions and reflect yellow wavelength regions. The red emitting (Sr,Ca)AlSiN3:Eu phosphor film is coated on glass and a SPDF using a screen printing method, and then the yellowish-green emitting AIS/ZS QDs are coated on the red phosphor (Sr,Ca)AlSiN3:Eu film-coated glass and SPDF using the electrospray (e-spray) method.To fabricate the red phosphor film, the optimum amount of phosphor is dispersed in a silicon binder to form a red phosphor paste. The AIS/ZS QDs are mixed with dimethylformamide (DMF), toluene, and poly(methyl methacrylate) (PMMA) for the e-spray coating. The substrates are spin-coated with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to fabricate a conductive surface. The CRI of the white LEDs is improved through inserting the red phosphor film between the QD layer and the glass substrate. Furthermore, the light intensities of the multi-layered phosphor films are enhanced through changing the glass substrate to the SPDF. The correlated color temperatures (CCTs) vary as a function of the phosphor concentration in the phosphor paste. The optical properties of the yellowish-green AIS/ZS QDs and red (Sr,Ca)AlSiN3:Eu phosphors are characterized using photoluminescence (PL), and the multi-layered QD-phosphor films are measured using electroluminescence (EL) with an InGaN blue LED (λmax = 450 nm) at 60 mA.

ZnO nanostructures as electron extraction layers for hybrid perovskite thin films

NASA Astrophysics Data System (ADS)

Nikolaidou, Katerina; Sarang, Som; Tung, Vincent; Lu, Jennifer; Ghosh, Sayantani

Optimum interaction between light harvesting media and electron transport layers is critical for the efficient operation of photovoltaic devices. In this work, ZnO layers of different morphologies are implemented as electron extraction and transport layers for hybrid perovskite CH3NH3PbI3 thin films. These include nanowires, nanoparticles, and single crystalline film. Charge transfer at the ZnO/perovskite interface is investigated and compared through ultra-fast characterization techniques, including temperature and power dependent spectroscopy, and time-resolved photoluminescence. The nanowires cause an enhancement in perovskite emission, which may be attributed to increased scattering and grain boundary formation. However, the ZnO layers with decreasing surface roughness exhibit better electron extraction, as inferred from photoluminescence quenching, reduction in the number of bound excitons, and reduced exciton lifetime in CH3NH3PbI3 samples. This systematic study is expected to provide an understanding of the fundamental processes occurring at the ZnO-CH3NH3PbI3 interface and ultimately, provide guidelines for the ideal configuration of ZnO-based hybrid Perovskite devices. This research was supported by National Aeronautics and Space administration (NASA) Grant No: NNX15AQ01A.

Hybrid films of chitosan, cellulose nanofibrils and boric acid: Flame retardancy, optical and thermo-mechanical properties.

PubMed

Uddin, Khan M A; Ago, Mariko; Rojas, Orlando J

2017-12-01

Chitosan (CS), cellulose nanofibrils (CNF) and boric acid, the latter of which was used as flame retardant, were combined in transparent, hybrid films that were produced by solvent casting. The flammability and the thermal stability of the films were studied with respect to the loading of the inorganic component. Chitosan films displayed fire retardancy properties, which were enhanced in the presence of boric acid. CNF films, in contrast to those from chitosan, were readily flammable; however, when combined with boric acid (30w%), they became self-extinguishing. Most remarkably, bicomponent films comprising CNF and chitosan, displayed better fire retardancy than that of neat CS films. Moreover, boric acid improved the thermal stability of the bicomponent films. The tensile strength and Young's modulus of CS, CNF and CS-CNF films improved at intermediate boric acid addition, although a negative effect on elongation was observed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hybrid nanostructures of well-organized arrays of colloidal quantum dots and a self-assembled monolayer of gold nanoparticles for enhanced fluorescence

NASA Astrophysics Data System (ADS)

Liu, Xiaoying; McBride, Sean P.; Jaeger, Heinrich M.; Nealey, Paul F.

2016-07-01

Hybrid nanomaterials comprised of well-organized arrays of colloidal semiconductor quantum dots (QDs) in close proximity to metal nanoparticles (NPs) represent an appealing system for high-performance, spectrum-tunable photon sources with controlled photoluminescence. Experimental realization of such materials requires well-defined QD arrays and precisely controlled QD-metal interspacing. This long-standing challenge is tackled through a strategy that synergistically combines lateral confinement and vertical stacking. Lithographically generated nanoscale patterns with tailored surface chemistry confine the QDs into well-organized arrays with high selectivity through chemical pattern directed assembly, while subsequent coating with a monolayer of close-packed Au NPs introduces the plasmonic component for fluorescence enhancement. The results show uniform fluorescence emission in large-area ordered arrays for the fabricated QD structures and demonstrate five-fold fluorescence amplification for red, yellow, and green QDs in the presence of the Au NP monolayer. Encapsulation of QDs with a silica shell is shown to extend the design space for reliable QD/metal coupling with stronger enhancement of 11 times through the tuning of QD-metal spatial separation. This approach provides new opportunities for designing hybrid nanomaterials with tailored array structures and multiple functionalities for applications such as multiplexed optical coding, color display, and quantum transduction.

On-chip multiplexed solid-phase nucleic acid hybridization assay using spatial profiles of immobilized quantum dots and fluorescence resonance energy transfer.

PubMed

Noor, M Omair; Tavares, Anthony J; Krull, Ulrich J

2013-07-25

A microfluidic based solid-phase assay for the multiplexed detection of nucleic acid hybridization using quantum dot (QD) mediated fluorescence resonance energy transfer (FRET) is described herein. The glass surface of hybrid glass-polydimethylsiloxane (PDMS) microfluidic channels was chemically modified to assemble the biorecognition interface. Multiplexing was demonstrated using a detection system that was comprised of two colors of immobilized semi-conductor QDs and two different oligonucleotide probe sequences. Green-emitting and red-emitting QDs were paired with Cy3 and Alexa Fluor 647 (A647) labeled oligonucleotides, respectively. The QDs served as energy donors for the transduction of dye labeled oligonucleotide targets. The in-channel assembly of the biorecognition interface and the subsequent introduction of oligonucleotide targets was accomplished within minutes using a combination of electroosmotic flow and electrophoretic force. The concurrent quantification of femtomole quantities of two target sequences was possible by measuring the spatial coverage of FRET sensitized emission along the length of the channel. In previous reports, multiplexed QD-FRET hybridization assays that employed a ratiometric method for quantification had challenges associated with lower analytical sensitivity arising from both donor and acceptor dilution that resulted in reduced energy transfer pathways as compared to single-color hybridization assays. Herein, a spatial method for quantification that is based on in-channel QD-FRET profiles provided higher analytical sensitivity in the multiplexed assay format as compared to single-color hybridization assays. The selectivity of the multiplexed hybridization assays was demonstrated by discrimination between a fully-complementary sequence and a 3 base pair sequence at a contrast ratio of 8 to 1. Copyright © 2013 Elsevier B.V. All rights reserved.

Enhanced Electroluminescence from Silicon Quantum Dots Embedded in Silicon Nitride Thin Films Coupled with Gold Nanoparticles in Light Emitting Devices

PubMed Central

Muñoz-Rosas, Ana Luz; Alonso-Huitrón, Juan Carlos

2018-01-01

Nowadays, the use of plasmonic metal layers to improve the photonic emission characteristics of several semiconductor quantum dots is a booming tool. In this work, we report the use of silicon quantum dots (SiQDs) embedded in a silicon nitride thin film coupled with an ultra-thin gold film (AuNPs) to fabricate light emitting devices. We used the remote plasma enhanced chemical vapor deposition technique (RPECVD) in order to grow two types of silicon nitride thin films. One with an almost stoichiometric composition, acting as non-radiative spacer; the other one, with a silicon excess in its chemical composition, which causes the formation of silicon quantum dots imbibed in the silicon nitride thin film. The ultra-thin gold film was deposited by the direct current (DC)-sputtering technique, and an aluminum doped zinc oxide thin film (AZO) which was deposited by means of ultrasonic spray pyrolysis, plays the role of the ohmic metal-like electrode. We found that there is a maximum electroluminescence (EL) enhancement when the appropriate AuNPs-spacer-SiQDs configuration is used. This EL is achieved at a moderate turn-on voltage of 11 V, and the EL enhancement is around four times bigger than the photoluminescence (PL) enhancement of the same AuNPs-spacer-SiQDs configuration. From our experimental results, we surmise that EL enhancement may indeed be due to a plasmonic coupling. This kind of silicon-based LEDs has the potential for technology transfer. PMID:29565267

Hybrid structures based on gold nanoparticles and semiconductor quantum dots for biosensor applications

PubMed Central

Kurochkina, Margarita; Konshina, Elena; Oseev, Aleksandr; Hirsch, Soeren

2018-01-01

Background The luminescence amplification of semiconductor quantum dots (QD) in the presence of self-assembled gold nanoparticles (Au NPs) is one of way for creating biosensors with highly efficient transduction. Aims The objective of this study was to fabricate the hybrid structures based on semiconductor CdSe/ZnS QDs and Au NP arrays and to use them as biosensors of protein. Methods In this paper, the hybrid structures based on CdSe/ZnS QDs and Au NP arrays were fabricated using spin coating processes. Au NP arrays deposited on a glass wafer were investigated by optical microscopy and absorption spectroscopy depending on numbers of spin coating layers and their baking temperature. Bovine serum albumin (BSA) was used as the target protein analyte in a phosphate buffer. A confocal laser scanning microscope was used to study the luminescent properties of Au NP/QD hybrid structures and to test BSA. Results The dimensions of Au NP aggregates increased and the space between them decreased with increasing processing temperature. At the same time, a blue shift of the plasmon resonance peak in the absorption spectra of Au NP arrays was observed. The deposition of CdSe/ZnS QDs with a core diameter of 5 nm on the surface of the Au NP arrays caused an increase in absorption and a red shift of the plasmon peak in the spectra. The exciton–plasmon enhancement of the QDs’ photoluminescence intensity has been obtained at room temperature for hybrid structures with Au NPs array pretreated at temperatures of 100°C and 150°C. It has been found that an increase in the weight content of BSA increases the photoluminescence intensity of such hybrid structures. Conclusion The ability of the qualitative and quantitative determination of protein content in solution using the Au NP/QD structures as an optical biosensor has been shown experimentally. PMID:29731613

Hybrid pulse anodization for the fabrication of porous anodic alumina films from commercial purity (99%) aluminum at room temperature.

PubMed

Chung, C K; Zhou, R X; Liu, T Y; Chang, W T

2009-02-04

Most porous anodic alumina (PAA) or anodic aluminum oxide (AAO) films are fabricated using the potentiostatic method from high-purity (99.999%) aluminum films at a low temperature of approximately 0-10 degrees C to avoid dissolution effects at room temperature (RT). In this study, we have demonstrated the fabrication of PAA film from commercial purity (99%) aluminum at RT using a hybrid pulse technique which combines pulse reverse and pulse voltages for the two-step anodization. The reaction mechanism is investigated by the real-time monitoring of current. A possible mechanism of hybrid pulse anodization is proposed for the formation of pronounced nanoporous film at RT. The structure and morphology of the anodic films were greatly influenced by the duration of anodization and the type of voltage. The best result was obtained by first applying pulse reverse voltage and then pulse voltage. The first pulse reverse anodization step was used to form new small cells and pre-texture concave aluminum as a self-assembled mask while the second pulse anodization step was for the resulting PAA film. The diameter of the nanopores in the arrays could reach 30-60 nm.

Strained hybrid perovskite thin films and their impact on the intrinsic stability of perovskite solar cells

PubMed Central

Zhao, Jingjing; Deng, Yehao; Wei, Haotong; Zheng, Xiaopeng; Yu, Zhenhua; Shao, Yuchuan; Shield, Jeffrey E.; Huang, Jinsong

2017-01-01

Organic-inorganic hybrid perovskite (OIHP) solar cells have achieved comparable efficiencies to those of commercial solar cells, although their instability hinders their commercialization. Although encapsulation techniques have been developed to protect OIHP solar cells from external stimuli such as moisture, oxygen, and ultraviolet light, understanding of the origin of the intrinsic instability of perovskite films is needed to improve their stability. We show that the OIHP films fabricated by existing methods are strained and that strain is caused by mismatched thermal expansion of perovskite films and substrates during the thermal annealing process. The polycrystalline films have compressive strain in the out-of-plane direction and in-plane tensile strain. The strain accelerates degradation of perovskite films under illumination, which can be explained by increased ion migration in strained OIHP films. This study points out an avenue to enhance the intrinsic stability of perovskite films and solar cells by reducing residual strain in perovskite films. PMID:29159287

Probing site-exclusive binding of aqueous QDs and their organelle-dependent dynamics in live cells by single molecule spectroscopy.

PubMed

Dong, Chaoqing; Chowdhury, Basudev; Irudayaraj, Joseph

2013-05-21

Understanding the biophysical and chemical interactions of nanoprobes and their fate upon entering live cells is critical for developing fundamental insights related to intracellular diagnostics, drug delivery and targeting. In this article we report herein a single molecule analysis procedure to quantitate site-specific exclusive membrane binding of N-acetyl-L-cysteine (NAC)-capped cadmium telluride (CdTe) quantum dots (QDs) in A-427 lung carcinoma cells (k(eq) = 0.075 ± 0.011 nM(-1)), its relative intracellular distribution and dynamics using fluorescence correlation spectroscopy (FCS) combined with scanning confocal fluorescence lifetime imaging (FLIM). In particular, we demonstrate that the binding efficacy of QDs to the cell membrane is directly related to their size and the targeting of QDs to specific membrane sites is exclusive. We also show that QDs are efficiently internalized by endocytosis and enclosed within the endosome and organelle-dependent diffusion dynamics can be monitored in live cells.

Thickness Dependent Nanostructural, Morphological, Optical and Impedometric Analyses of Zinc Oxide-Gold Hybrids: Nanoparticle to Thin Film

PubMed Central

Perumal, Veeradasan; Hashim, Uda; Gopinath, Subash C. B.; Haarindraprasad, R.; Liu, Wei-Wen; Poopalan, P.; Balakrishnan, S. R.; Thivina, V.; Ruslinda, A. R.

2015-01-01

The creation of an appropriate thin film is important for the development of novel sensing surfaces, which will ultimately enhance the properties and output of high-performance sensors. In this study, we have fabricated and characterized zinc oxide (ZnO) thin films on silicon substrates, which were hybridized with gold nanoparticles (AuNPs) to obtain ZnO-Aux (x = 10, 20, 30, 40 and 50 nm) hybrid structures with different thicknesses. Nanoscale imaging by field emission scanning electron microscopy revealed increasing film uniformity and coverage with the Au deposition thickness. Transmission electron microscopy analysis indicated that the AuNPs exhibit an increasing average diameter (5–10 nm). The face center cubic Au were found to co-exist with wurtzite ZnO nanostructure. Atomic force microscopy observations revealed that as the Au content increased, the overall crystallite size increased, which was supported by X-ray diffraction measurements. The structural characterizations indicated that the Au on the ZnO crystal lattice exists without any impurities in a preferred orientation (002). When the ZnO thickness increased from 10 to 40 nm, transmittance and an optical bandgap value decreased. Interestingly, with 50 nm thickness, the band gap value was increased, which might be due to the Burstein-Moss effect. Photoluminescence studies revealed that the overall structural defect (green emission) improved significantly as the Au deposition increased. The impedance measurements shows a decreasing value of impedance arc with increasing Au thicknesses (0 to 40 nm). In contrast, the 50 nm AuNP impedance arc shows an increased value compared to lower sputtering thicknesses, which indicated the presence of larger sized AuNPs that form a continuous film, and its ohmic characteristics changed to rectifying characteristics. This improved hybrid thin film (ZnO/Au) is suitable for a wide range of sensing applications. PMID:26694656

Thickness Dependent Nanostructural, Morphological, Optical and Impedometric Analyses of Zinc Oxide-Gold Hybrids: Nanoparticle to Thin Film.

PubMed

Perumal, Veeradasan; Hashim, Uda; Gopinath, Subash C B; Haarindraprasad, R; Liu, Wei-Wen; Poopalan, P; Balakrishnan, S R; Thivina, V; Ruslinda, A R

2015-01-01

The creation of an appropriate thin film is important for the development of novel sensing surfaces, which will ultimately enhance the properties and output of high-performance sensors. In this study, we have fabricated and characterized zinc oxide (ZnO) thin films on silicon substrates, which were hybridized with gold nanoparticles (AuNPs) to obtain ZnO-Aux (x = 10, 20, 30, 40 and 50 nm) hybrid structures with different thicknesses. Nanoscale imaging by field emission scanning electron microscopy revealed increasing film uniformity and coverage with the Au deposition thickness. Transmission electron microscopy analysis indicated that the AuNPs exhibit an increasing average diameter (5-10 nm). The face center cubic Au were found to co-exist with wurtzite ZnO nanostructure. Atomic force microscopy observations revealed that as the Au content increased, the overall crystallite size increased, which was supported by X-ray diffraction measurements. The structural characterizations indicated that the Au on the ZnO crystal lattice exists without any impurities in a preferred orientation (002). When the ZnO thickness increased from 10 to 40 nm, transmittance and an optical bandgap value decreased. Interestingly, with 50 nm thickness, the band gap value was increased, which might be due to the Burstein-Moss effect. Photoluminescence studies revealed that the overall structural defect (green emission) improved significantly as the Au deposition increased. The impedance measurements shows a decreasing value of impedance arc with increasing Au thicknesses (0 to 40 nm). In contrast, the 50 nm AuNP impedance arc shows an increased value compared to lower sputtering thicknesses, which indicated the presence of larger sized AuNPs that form a continuous film, and its ohmic characteristics changed to rectifying characteristics. This improved hybrid thin film (ZnO/Au) is suitable for a wide range of sensing applications.

Co-encapsulation of CdSe/ZnS and CeO2 nanoparticles in waterborne polymer dispersions: enhancement of fluorescence emission under sunlight.

PubMed

De San Luis, Alicia; Paulis, Maria; Leiza, Jose Ramon

2017-11-15

Hybrid core/shell polymer particles with co-encapsulated quantum dots (QDs) (CdSe/ZnS) and CeO 2 nanoparticles have been synthesized in a two stage semi-batch emulsion polymerization process. In the first stage, both inorganic nanoparticles are incorporated into cross-linked polystyrene (PS) particles by miniemulsion polymerization. This hybrid dispersion is then used as the seed to produce the core/shell particles by starved feeding of methyl methacrylate and divinylbenzene (MMA/DVB) monomers. The core/shell hybrid dispersions maintained in the dark exhibit stable fluorescence emission over time, and notably their fluorescence intensity increases under sunlight, likely due to the effect of the co-encapsulated CeO 2 nanoparticles that change the optical properties of the environment of the quantum dot particles. The fluorescence increase depends on the QD : CeO 2 ratio, with the 1 : 2 ratio resulting in the highest increase (280%). Furthermore, a film forming hybrid latex has been synthesized using the former core/shell PS/QD/CeO 2 /PMMA particles as seeds and feeding under semi-batch conditions methyl methacrylate, butyl acrylate and acrylic acid. Films cast from this core/shell/shell hybrid dispersion also exhibit fluorescence, and as for the core/shell latex the fluorescence increases under sunlight exposure. Interestingly, the increase in the film is at least two times higher than that in the latex, which is attributed to the additional effect of the neighboring coalesced particles containing CeO 2 affecting the environment of the QDs.

Förster resonance energy transfer in hybrid associates of colloidal Ag2S quantum dots with thionine molecules

NASA Astrophysics Data System (ADS)

Ovchinnikov, Oleg V.; Smirnov, Mikhail S.; Kondratenko, Tamara S.; Ambrosevich, Sergey A.; Metlin, Mikhail T.; Grevtseva, Irina G.; Perepelitsa, Aleksey S.

2017-12-01

Nonradiative resonance energy transfer in hydrophilic hybrid associates of thionine molecules (TH+) with colloidal Ag2S quantum dots (QDs) with average diameter of 3.5 nm was studied. Photoluminescence spectra and its decay shown that for these systems the supplemental photosensitization of recombination luminescence of Ag2S QDs (1200 nm) from the region of TH+ fluorescence (618 nm) is possible. It was found that the average lifetime of TH+ molecules luminescence is shortened during their association with Ag2S QDs. Approximation of luminescence decay by stretched exponent with value of parameter β = 0.5 indicates on the inductive-resonance dipole-dipole (Förster) mechanism of nonradiative energy transfer (FRET). The efficiency of FRET was 0.29-0.41.

CdS QDs-chitosan microcapsules with stimuli-responsive property generated by gas-liquid microfluidic technique.

PubMed

Chen, Yanjun; Yao, Rongyi; Wang, Yifeng; Chen, Ming; Qiu, Tong; Zhang, Chaocan

2015-01-01

This article describes a straightforward gas-liquid microfluidic approach to generate uniform-sized chitosan microcapsules containing CdS quantum dots (QDs). CdS QDs are encapsulated into the liquid-core of the microcapsules. The sizes of the microcapsules can be conveniently controlled by gas flow rate. QDs-chitosan microcapsules show good fluorescent stability in water, and exhibit fluorescent responses to chemical environmental stimuli. α-Cyclodextrin (α-CD) causes the microcapsules to deform and even collapse. More interestingly, α-CD induces obvious changes on the fluorescent color of the microcapsules. However, β-cyclodextrin (β-CD) has little influence on the shape and fluorescent color of the microcapsules. Based on the results of scanning electron microscopy, the possible mechanism about the effects of α-CD on the chitosan microcapsules is analyzed. These stimuli-responsive microcapsules are low-cost and easy to be prepared by gas-liquid microfluidic technique, and can be applied as a potential micro-detector to chemicals, such as CDs. Copyright © 2014 Elsevier B.V. All rights reserved.

In Situ Monitoring the Uptake of Moisture into Hybrid Perovskite Thin Films.

PubMed

Schlipf, Johannes; Bießmann, Lorenz; Oesinghaus, Lukas; Berger, Edith; Metwalli, Ezzeldin; Lercher, Johannes A; Porcar, Lionel; Müller-Buschbaum, Peter

2018-04-19

Solution-processed hybrid perovskites are of great interest for use in photovoltaics. However, polycrystalline perovskite thin films show strong degradation in humid atmospheres, which poses an important challenge for large-scale market introduction. With in situ grazing incidence neutron scattering (GISANS) we analyzed water content, degradation products, and morphological changes during prolonged exposure to several humidity levels. In high humidity, the formation of metastable hydrate phases is accompanied by domain swelling, which transforms the faceted crystals to a round-washed, pebble-like form. The films incorporate much more water than is integrated into the hydrates, with smaller crystals being more affected, making the degradation strongly dependent on film morphology. Even at low humidity, water is adsorbed on the crystal surfaces without the formation of crystalline degradation products. Thus, although production in an ambient atmosphere is of interest for industrial production it might lead to long-term degradation without appropriate countermeasures like postproduction drying below 30% RH.

Successful entrapment of carbon dots within flexible free-standing transparent mesoporous organic-inorganic silica hybrid films for photonic applications

NASA Astrophysics Data System (ADS)

Vassilakopoulou, Anastasia; Georgakilas, Vasilios; Vainos, Nikolaos; Koutselas, Ioannis

2017-04-01

The effective entrapment of Carbon dots (CDs) into a polymer-silica hybrid matrix, formed as free standing transparent flexible films, is presented. The composite's synthesis, characterization, device application and properties -mechanical, thermal and optical- are being provided and discussed. CDs of 3 nm mean size with strong photoluminescence are embedded into a silica matrix during the sol-gel procedure, using tetraethyl orthosilicate as the precursor and F127 triblock copolymer as the structure directing agent under acidic conditions. The final hybrid nanostructure forms free standing transparent films that show high flexibility and long term stable CDs luminescence indicating the protective character of the hybrid matrix. It is crucial that the photoluminescence of the hybrid's CDs is not seriously affected after thermal treatment at 550 °C for 30 min. Moreover, the herein reported hybrid is demonstrated to be suitable for the fabrication of advanced photonic structures using soft lithography processes due to its low shrinkage and distortion upon drying, both attributable to its porosity. Finally, it is reported that addition of F127 ethanolic solution in aqueous solution of CDs induces a blue-shift of their photoluminescence.

Chitosan-silane sol-gel hybrid thin films with controllable layer thickness and morphology.

PubMed

Spirk, Stefan; Findenig, Gerald; Doliska, Ales; Reichel, Victoria E; Swanson, Nicole L; Kargl, Rupert; Ribitsch, Volker; Stana-Kleinschek, Karin

2013-03-01

The preparation of thin films of chitosan-silane hybrid materials by combining sol-gel processing and spin coating is reported. A variety of silanes can be used as starting materials for the preparation of such thin films, namely tetraethoxysilane, tri-tert-butoxysilanol, trimethylethoxysilane, p-trifluoromethyltetra-fluorophenyltriethoxysilane, trivinylmethoxysilane, (methoxymethyl)trimethyl-silane, and hexamethoxydisilane. These silanes are subjected to a sol-gel process before they are added to acidic chitosan solutions. The chitosan:silane ratio is kept constant at 6:1 (w/w) and dilutions with ethanol are prepared and spin coated. Depending on the degree of dilution, film thickness can be controlled in a range between 5 and 70 nm. For the determination of additional surface properties, static water contact angle measurements and atomic force microscopy have been employed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Uniform thin films of CdSe and CdSe(ZnS) core(shell) quantum dots by sol-gel assembly: enabling photoelectrochemical characterization and electronic applications.

PubMed

Korala, Lasantha; Wang, Zhijie; Liu, Yi; Maldonado, Stephen; Brock, Stephanie L

2013-02-26

Optoelectronic properties of quantum dot (QD) films are limited by (1) poor interfacial chemistry and (2) nonradiative recombination due to surface traps. To address these performance issues, sol-gel methods are applied to fabricate thin films of CdSe and core(shell) CdSe(ZnS) QDs. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging with chemical analysis confirms that the surface of the QDs in the sol-gel thin films are chalcogen-rich, consistent with an oxidative-induced gelation mechanism in which connectivity is achieved by formation of dichalcogenide covalent linkages between particles. The ligand removal and assembly process is probed by thermogravimetric, spectroscopic, and microscopic studies. Further enhancement of interparticle coupling via mild thermal annealing, which removes residual ligands and reinforces QD connectivity, results in QD sol-gel thin films with superior charge transport properties, as shown by a dramatic enhancement of electrochemical photocurrent under white light illumination relative to thin films composed of ligand-capped QDs. A more than 2-fold enhancement in photocurrent, and a further increase in photovoltage can be achieved by passivation of surface defects via overcoating with a thin ZnS shell. The ability to tune interfacial and surface characteristics for the optimization of photophysical properties suggests that the sol-gel approach may enable formation of QD thin films suitable for a range of optoelectronic applications.

Uniform Thin Films of CdSe and CdSe(ZnS) Core(shell) Quantum Dots by Sol-Gel Assembly: Enabling Photoelectrochemical Characterization and Electronic Applications

PubMed Central

Korala, Lasantha; Wang, Zhijie; Liu, Yi; Maldonado, Stephen; Brock, Stephanie L.

2013-01-01

Optoelectronic properties of quantum dot (QD) films are limited by (1) poor interfacial chemistry and (2) non-radiative recombination due to surface traps. To address these performance issues, sol-gel methods are applied to fabricate thin films of CdSe and core(shell) CdSe(ZnS) QDs. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging with chemical analysis confirms that the surface of the QDs in the sol-gel thin films are chalcogen-rich, consistent with an oxidative-induced gelation mechanism in which connectivity is achieved by formation of dichalcogenide covalent linkages between particles. The ligand removal and assembly process is probed by thermogravimetric, spectroscopic and microscopic studies. Further enhancement of inter-particle coupling via mild thermal annealing, which removes residual ligands and reinforces QD connectivity, results in QD sol-gel thin films with superior charge transport properties, as shown by a dramatic enhancement of electrochemical photocurrent under white light illumination relative to thin films composed of ligand-capped QDs. A more than 2-fold enhancement in photocurrent, and a further increase in photovoltage can be achieved by passivation of surface defects via overcoating with a thin ZnS shell. The ability to tune interfacial and surface characteristics for the optimization of photophysical properties suggests that the sol-gel approach may enable formation of QD thin films suitable for a range of optoelectronic applications. PMID:23350924

Enhancement of durability of NIR emission of Ag2S@ZnS QDs in water

NASA Astrophysics Data System (ADS)

Karimipour, M.; Bagheri, M.; Molaei, M.

2017-11-01

Stability of Ag2S@ZnS QDs in water is a crucial concern for their application in biology. In this work, both physical sustainability and emission stability of Ag2S QDs were enhanced using parameter optimization of a pulsed microwave irradiation (MI) method up to 105 days after their preparation. UV-Vis and photoluminescence spectroscopies depicted an absorption and emission about 817 nm and 878 nm, respectively. X-ray diffraction (XRD) analysis showed a growth of Ag2S acanthite phase. Transmission Electron Microscopy (TEM) images revealed a clear formation of Ag2S@ZnS core-shell structure.

Direct synthesis of all-inorganic heterostructured CdSe/CdS QDs in aqueous solution for improved photocatalytic hydrogen generation

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

Li, Zhi-Jun; Fan, Xiang-Bing; Li, Xu-Bing

2017-01-01

Here we present a facile aqueous approach to synthesize heterostructured CdSe/CdS QDs with all-inorganic chalcogenide S2- ligands under mild conditions. High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and steady-state emission spectroscopy demonstrate that the heterostructured CdSe/CdS QDs with sulfur-rich surface composition are formed by heterogeneous nucleation of Cd2+ and S2- precursors on the CdSe QDs. After adsorption of small Ni(OH)(2) clusters over the surface in situ, the CdSe/CdS-Ni(OH)(2) photocatalyst enables H-2 production efficiently with an internal quantum yield of 52% under visible light irradiation at 455 nm, up to an 8-fold increase ofmore » activity to that of spherical CdSe QDs-Ni(OH)(2) under the same conditions. Femtosecond transient absorption spectroscopy, X-ray transient absorption (XTA) spectroscopy, steady-state and time-resolved emission spectroscopy show that the quasi-type-II band alignment in the CdSe/CdS heterostructure is responsible for the efficiency enhancement of light harvesting and surface/interfacial charge separation in solar energy conversion. The unprecedented results exemplify an easily accessible pattern of aqueous synthesis of all-inorganic heterostructured QDs for advanced photosynthetic H-2 evolution.« less

Layered Ni(OH)2-Co(OH)2 films prepared by electrodeposition as charge storage electrodes for hybrid supercapacitors

NASA Astrophysics Data System (ADS)

Nguyen, Tuyen; Boudard, Michel; Carmezim, M. João; Montemor, M. Fátima

2017-01-01

Consecutive layers of Ni(OH)2 and Co(OH)2 were electrodeposited on stainless steel current collectors for preparing charge storage electrodes of high specific capacity with potential application in hybrid supercapacitors. Different electrodes were prepared consisting on films of Ni(OH)2, Co(OH)2, Ni1/2Co1/2(OH)2 and layered films of Ni(OH)2 on Co(OH)2 and Co(OH)2 on Ni(OH)2 to highlight the advantages of the new architecture. The microscopy studies revealed the formation of nanosheets in the Co(OH)2 films and of particles agglomerates in the Ni(OH)2 films. Important morphological changes were observed in the double hydroxides films and layered films. Film growth by electrodeposition was governed by instantaneous nucleation mechanism. The new architecture composed of Ni(OH)2 on Co(OH)2 displayed a redox response characterized by the presence of two peaks in the cyclic voltammograms, arising from redox reactions of the metallic species present in the layered film. These electrodes revealed a specific capacity of 762 C g-1 at the specific current of 1 A g-1. The hybrid cell using Ni(OH)2 on Co(OH)2 as positive electrode and carbon nanofoam paper as negative electrode display specific energies of 101.3 W h g-1 and 37.8 W h g-1 at specific powers of 0.2 W g-1 and 2.45 W g-1, respectively.

Layered Ni(OH)2-Co(OH)2 films prepared by electrodeposition as charge storage electrodes for hybrid supercapacitors

PubMed Central

Nguyen, Tuyen; Boudard, Michel; Carmezim, M. João; Montemor, M. Fátima

2017-01-01

Consecutive layers of Ni(OH)2 and Co(OH)2 were electrodeposited on stainless steel current collectors for preparing charge storage electrodes of high specific capacity with potential application in hybrid supercapacitors. Different electrodes were prepared consisting on films of Ni(OH)2, Co(OH)2, Ni1/2Co1/2(OH)2 and layered films of Ni(OH)2 on Co(OH)2 and Co(OH)2 on Ni(OH)2 to highlight the advantages of the new architecture. The microscopy studies revealed the formation of nanosheets in the Co(OH)2 films and of particles agglomerates in the Ni(OH)2 films. Important morphological changes were observed in the double hydroxides films and layered films. Film growth by electrodeposition was governed by instantaneous nucleation mechanism. The new architecture composed of Ni(OH)2 on Co(OH)2 displayed a redox response characterized by the presence of two peaks in the cyclic voltammograms, arising from redox reactions of the metallic species present in the layered film. These electrodes revealed a specific capacity of 762 C g−1 at the specific current of 1 A g−1. The hybrid cell using Ni(OH)2 on Co(OH)2 as positive electrode and carbon nanofoam paper as negative electrode display specific energies of 101.3 W h g−1 and 37.8 W h g−1 at specific powers of 0.2 W g−1 and 2.45 W g−1, respectively. PMID:28051143

Layered Ni(OH)2-Co(OH)2 films prepared by electrodeposition as charge storage electrodes for hybrid supercapacitors.

PubMed

Nguyen, Tuyen; Boudard, Michel; Carmezim, M João; Montemor, M Fátima

2017-01-04

Consecutive layers of Ni(OH) 2 and Co(OH) 2 were electrodeposited on stainless steel current collectors for preparing charge storage electrodes of high specific capacity with potential application in hybrid supercapacitors. Different electrodes were prepared consisting on films of Ni(OH) 2 , Co(OH) 2 , Ni 1/2 Co 1/2 (OH) 2 and layered films of Ni(OH) 2 on Co(OH) 2 and Co(OH) 2 on Ni(OH) 2 to highlight the advantages of the new architecture. The microscopy studies revealed the formation of nanosheets in the Co(OH) 2 films and of particles agglomerates in the Ni(OH) 2 films. Important morphological changes were observed in the double hydroxides films and layered films. Film growth by electrodeposition was governed by instantaneous nucleation mechanism. The new architecture composed of Ni(OH) 2 on Co(OH) 2 displayed a redox response characterized by the presence of two peaks in the cyclic voltammograms, arising from redox reactions of the metallic species present in the layered film. These electrodes revealed a specific capacity of 762 C g -1 at the specific current of 1 A g -1 . The hybrid cell using Ni(OH) 2 on Co(OH) 2 as positive electrode and carbon nanofoam paper as negative electrode display specific energies of 101.3 W h g -1 and 37.8 W h g -1 at specific powers of 0.2 W g -1 and 2.45 W g -1 , respectively.

Ultrasensitive fluorescence immunoassay for detection of ochratoxin A using catalase-mediated fluorescence quenching of CdTe QDs

NASA Astrophysics Data System (ADS)

Huang, Xiaolin; Zhan, Shengnan; Xu, Hengyi; Meng, Xianwei; Xiong, Yonghua; Chen, Xiaoyuan

2016-04-01

Herein, for the first time we report an improved competitive fluorescent enzyme linked immunosorbent assay (ELISA) for the ultrasensitive detection of ochratoxin A (OTA) by using hydrogen peroxide (H2O2)-induced fluorescence quenching of mercaptopropionic acid-modified CdTe quantum dots (QDs). In this immunoassay, catalase (CAT) was labeled with OTA as a competitive antigen to connect the fluorescence signals of the QDs with the concentration of the target. Through the combinatorial use of H2O2-induced fluorescence quenching of CdTe QDs as a fluorescence signal output and the ultrahigh catalytic activity of CAT to H2O2, our proposed method could be used to perform a dynamic linear detection of OTA ranging from 0.05 pg mL-1 to 10 pg mL-1. The half maximal inhibitory concentration was 0.53 pg mL-1 and the limit of detection was 0.05 pg mL-1. These values were approximately 283- and 300-folds lower than those of horseradish peroxidase (HRP)-based conventional ELISA, respectively. The reported method is accurate, highly reproducible, and specific against other mycotoxins in agricultural products as well. In summary, the developed fluorescence immunoassay based on H2O2-induced fluorescence quenching of CdTe QDs can be used for the rapid and highly sensitive detection of mycotoxins or haptens in food safety monitoring.Herein, for the first time we report an improved competitive fluorescent enzyme linked immunosorbent assay (ELISA) for the ultrasensitive detection of ochratoxin A (OTA) by using hydrogen peroxide (H2O2)-induced fluorescence quenching of mercaptopropionic acid-modified CdTe quantum dots (QDs). In this immunoassay, catalase (CAT) was labeled with OTA as a competitive antigen to connect the fluorescence signals of the QDs with the concentration of the target. Through the combinatorial use of H2O2-induced fluorescence quenching of CdTe QDs as a fluorescence signal output and the ultrahigh catalytic activity of CAT to H2O2, our proposed method could be used to

Efficient double-quenching of electrochemiluminescence from CdS:Eu QDs by hemin-graphene-Au nanorods ternary composite for ultrasensitive immunoassay

PubMed Central

Liu, Jing; Cui, Meirong; Zhou, Hong; Zhang, Shusheng

2016-01-01

A novel ternary composite of hemin-graphene-Au nanorods (H-RGO-Au NRs) with high electrocatalytic activity was synthesized by a simple method. And this ternary composite was firstly used in construction of electrochemiluminescence (ECL) immunosensor due to its double-quenching effect of quantum dots (QDs). Based on the high electrocatalytic activity of ternary complexes for the reduction of H2O2 which acted as the coreactant of QDs-based ECL, as a result, the ECL intensity of QDs decreased. Besides, due to the ECL resonance energy transfer (ECL-RET) strategy between the large amount of Au nanorods (Au NRs) on the ternary composite surface and the CdS:Eu QDs, the ECL intensity of QDs was further quenched. Based on the double-quenching effect, a novel ultrasensitive ECL immunoassay method for detection of carcinoembryonic antigen (CEA) which is used as a model biomarker analyte was proposed. The designed immunoassay method showed a linear range from 0.01 pg mL−1 to 1.0 ng mL−1 with a detection limit of 0.01 pg mL−1. The method showing low detection limit, good stability and acceptable fabrication reproducibility, provided a new approach for ECL immunoassay sensing and significant prospect for practical application. PMID:27460868

Impact of magnetic fields on the morphology of hybrid perovskite films for solar cells

NASA Astrophysics Data System (ADS)

Corpus-Mendoza, Asiel N.; Moreno-Romero, Paola M.; Hu, Hailin

2018-05-01

The impact of magnetic fields on the morphology of hybrid perovskite films is assessed via scanning electron microscopy and X-ray diffraction. Small-grain non-uniform perovskite films are obtained when a large magnetic flux density is applied to the sample during reaction of PbI2 and methylammonium iodide (chloride). Similarly, X-ray diffraction reveals a change of preferential crystalline planes when large magnetic fields are applied. Furthermore, we experimentally demonstrate that the quality of the perovskite film is affected by the magnetic field induced by the magnetic stirring system of the hot plate where the samples are annealed. As a consequence, optimization of the perovskite layer varies with magnetic field and annealing temperature. Finally, we prove that uncontrolled magnetic fields on the environment of preparation can severely influence the reproducibility of results.

Thin Film Solar Cells: Organic, Inorganic and Hybrid

NASA Technical Reports Server (NTRS)

Dankovich, John

2004-01-01

Thin film solar cells are an important developing resource for hundreds of applications including space travel. In addition to being more cost effective than traditional single crystal silicon cells, thin film multi-crystaline cells are plastic and light weight. The plasticity of the cells allows for whole solar panels to be rolled out from reams. Organic layers are being investigated in order to increase the efficiency of the cells to create an organic / inorganic hybrid cell. The main focus of the group is a thin film inorganic cell made with the absorber CuInS2. So far the group has been successful in creating the layer from a single-source precursor. They also use a unique method of film deposition called chemical vapor deposition for this. The general makeup of the cell is a molybdenum back contact with the CuInS2 layer, then CdS, ZnO and aluminum top contacts. While working cells have been produced, the efficiency so far has been low. Along with quantum dot fabrication the side project of this that is currently being studied is adding a polymer layer to increase efficiency. The polymer that we are using is P3OT (Poly(3-octylthiopene-2,5-diyll), retroregular). Before (and if) it is added to the cell, it must be understood in itself. To do this simple diodes are being constructed to begin to look at its behavior. The P3OT is spin coated onto indium tin oxide and silver or aluminum contacts are added. This method is being studied in order to find the optimal thickness of the layer as well as other important considerations that may later affect the composition of the finished solar cell. Because the sun is the most abundant renewable, energy source that we have, it is important to learn how to harness that energy and begin to move away from our other depleted non-renewable energy sources. While traditional silicon cells currently create electricity at relatively high efficiencies, they have drawbacks such as weight and rigidness that make them unattractive

On-chip transduction of nucleic acid hybridization using spatial profiles of immobilized quantum dots and fluorescence resonance energy transfer.

PubMed

Tavares, Anthony J; Noor, M Omair; Vannoy, Charles H; Algar, W Russ; Krull, Ulrich J

2012-01-03

The glass surface of a glass-polydimethylsiloxane (PDMS) microfluidic channel was modified to develop a solid-phase assay for quantitative determination of nucleic acids. Electroosmotic flow (EOF) within channels was used to deliver and immobilize semiconductor quantum dots (QDs), and electrophoresis was used to decorate the QDs with oligonucleotide probe sequences. These processes took only minutes to complete. The QDs served as energy donors in fluorescence resonance energy transfer (FRET) for transduction of nucleic acid hybridization. Electrokinetic injection of fluorescent dye (Cy3) labeled oligonucleotide target into a microfluidic channel and subsequent hybridization (within minutes) provided the proximity for FRET, with emission from Cy3 being the analytical signal. The quantification of target concentration was achieved by measurement of the spatial length of coverage by target along a channel. Detection of femtomole quantities of target was possible with a dynamic range spanning an order of magnitude. The assay provided excellent resistance to nonspecific interactions of DNA. Further selectivity of the assay was achieved using 20% formamide, which allowed discrimination between a fully complementary target and a 3 base pair mismatch target at a contrast ratio of 4:1. © 2011 American Chemical Society

Few-Layer MoS2-Organic Thin-Film Hybrid Complementary Inverter Pixel Fabricated on a Glass Substrate.

PubMed

Lee, Hee Sung; Shin, Jae Min; Jeon, Pyo Jin; Lee, Junyeong; Kim, Jin Sung; Hwang, Hyun Chul; Park, Eunyoung; Yoon, Woojin; Ju, Sang-Yong; Im, Seongil

2015-05-13

Few-layer MoS2-organic thin-film hybrid complementary inverters demonstrate a great deal of device performance with a decent voltage gain of ≈12, a few hundred pW power consumption, and 480 Hz switching speed. As fabricated on glass, this hybrid CMOS inverter operates as a light-detecting pixel as well, using a thin MoS2 channel. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Amorphous indium-gallium-zinc-oxide thin-film transistors using organic-inorganic hybrid films deposited by low-temperature plasma-enhanced chemical vapor deposition for all dielectric layers

NASA Astrophysics Data System (ADS)

Hsu, Chao-Jui; Chang, Ching-Hsiang; Chang, Kuei-Ming; Wu, Chung-Chih

2017-01-01

We investigated the deposition of high-performance organic-inorganic hybrid dielectric films by low-temperature (close to room temperature) inductively coupled plasma chemical vapor deposition (ICP-CVD) with hexamethyldisiloxane (HMDSO)/O2 precursor gas. The hybrid films exhibited low leakage currents and high breakdown fields, suitable for thin-film transistor (TFT) applications. They were successfully integrated into the gate insulator, the etch-stop layer, and the passivation layer for bottom-gate staggered amorphous In-Ga-Zn-O (a-IGZO) TFTs having the etch-stop configuration. With the double-active-layer configuration having a buffer a-IGZO back-channel layer grown in oxygen-rich atmosphere for better immunity against plasma damage, the etch-stop-type bottom-gate staggered a-IGZO TFTs with good TFT characteristics were successfully demonstrated. The TFTs showed good field-effect mobility (μFE), threshold voltage (V th), subthreshold swing (SS), and on/off ratio (I on/off) of 7.5 cm2 V-1 s-1, 2.38 V, 0.38 V/decade, and 2.2 × 108, respectively, manifesting their usefulness for a-IGZO TFTs.

Low temperature excitonic spectroscopy and dynamics as a probe of quality in hybrid perovskite thin films.

PubMed

Sarang, Som; Ishihara, Hidetaka; Chen, Yen-Chang; Lin, Oliver; Gopinathan, Ajay; Tung, Vincent C; Ghosh, Sayantani

2016-10-19

We have developed a framework for using temperature dependent static and dynamic photoluminescence (PL) of hybrid organic-inorganic perovskites (PVSKs) to characterize lattice defects in thin films, based on the presence of nanodomains at low temperature. Our high-stability PVSK films are fabricated using a novel continuous liquid interface propagation technique, and in the tetragonal phase (T > 120 K), they exhibit bi-exponential recombination from free charge carriers with an average PL lifetime of ∼200 ns. Below 120 K, the emergence of the orthorhombic phase is accompanied by a reduction in lifetimes by an order of magnitude, which we establish to be the result of a crossover from free carrier to exciton-dominated radiative recombination. Analysis of the PL as a function of excitation power at different temperatures provides direct evidence that the exciton binding energy is different in the two phases, and using these results, we present a theoretical approach to estimate this variable binding energy. Our findings explain this anomalous low temperature behavior for the first time, attributing it to an inherent fundamental property of the hybrid PVSKs that can be used as an effective probe of thin film quality.

Supercapacitive properties of hybrid films of manganese dioxide and polyaniline based on active carbon in organic electrolyte

NASA Astrophysics Data System (ADS)

Zou, Wu-yuan; Wang, Wei; He, Ben-lin; Sun, Ming-liang; Yin, Yan-sheng

This is the first report about supercapacitive performance of hybrid film of manganese dioxide (MnO 2) and polyaniline (PANI) in an organic electrolyte (1.0 M LiClO 4 in acetonitrile). In this work, a high surface area and conductivity of active carbon (AC) electrode is used as a substrate for PANI/MnO 2 film electro-codeposition. The redox properties of the coated PANI/MnO 2 thin film exhibit ideal capacitive behaviour in 1 M LiClO 4/AN. The specific capacitance (SC) of PANI/MnO 2 hybrid film is as high as 1292 F g -1 and maintains about 82% of the initial capacitance after 1500 cycles at a current density of 4.0 mA cm -2, and the coulombic efficiency (η) is higher than 95%. An asymmetric capacitor has been developed with the PANI/MnO 2/AC positive and pure AC negative electrodes, which is able to deliver a specific energy as high as 61 Wh kg -1 at a specific power of 172 W kg -1 in the range of 0-2.0 V. These results indicate that the organic electrolyte is a promising candidate for PANI/MnO 2 material application in supercapacitors.

Fabrication of Stretchable Organic-Inorganic Hybrid Thin-Film Transistors on Polyimide Stiff-Island Structures.

PubMed

Jung, Soon-Won; Koo, Jae Bon; Park, Chan Woo; Na, Bock Soon; Oh, Ji-Young; Lee, Sang Seok

2015-10-01

In this study, stretchable organic-inorganic hybrid thin-film transistors (TFTs) are fabricated on a polyimide (PI) stiff-island/elastomer substrate using blends of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] and poly(methyl methacrylate) (PMMA) and oxide semiconductor In-Ga-Zn-O as the gate dielectric and semiconducting layer, respectively. Carrier mobility, Ion/Ioff ratio, and subthreshold swing (SS) values of 6.1 cm2 V(-1) s(-1), 10(7), and 0.2 V/decade, respectively, were achieved. For the hybrid TFTs, the endurable maximum strain without degradation of electrical properties was approximately 49%. These results correspond to those obtained in the first study on fabrication of stretchable hybrid-type TFTs on elastomer substrate using an organic gate insulator and oxide semiconducting active channel structure, thus indicating the feasibility of a promising device for stretchable electronic systems.

Effect of clay in controlling the non-fluorescence H-dimeric states of a cationic dye Nile Blue Chloride (NBC) in hybrid Langmuir-Blodgett (LB) film

NASA Astrophysics Data System (ADS)

Debnath, Chandan; Shil, Ashis; Hussain, S. A.; Bhattacharjee, D.

2018-01-01

Present communication reports the effect of amphiphilic matrices and nano-clay platelets on the aggregation properties of a water soluble cationic fluorescent dye Nile Blue Chloride (NBC) in Langmuir-Blodgett (LB) films. In-situ Brewster Angle Microscopic (BAM) studies showed distinct domain structures of complex and hybrid Langmuir monolayer at the air-water interface. UV-vis absorption spectra showed non-fluorescent H-dimeric band in concentrated aqueous solution of NBC and in complex LB film of NBC with stearic acid. By changing various parameters, a great control over H-dimeric states has been achieved in clay incorporated hybrid LB films. These films can act as efficient fluorescence probe.

Ambipolar Graphene-Quantum Dot Hybrid Vertical Photodetector with a Graphene Electrode.

PubMed

Che, Yongli; Zhang, Yating; Cao, Xiaolong; Zhang, Haiting; Song, Xiaoxian; Cao, Mingxuan; Yu, Yu; Dai, Haitao; Yang, Junbo; Zhang, Guizhong; Yao, Jianquan

2017-09-20

A strategy to fabricate an ambipolar near-infrared vertical photodetector (VPD) by sandwiching a photoactive material as a channel film between the bottom graphene and top metal electrodes was developed. The channel length in the vertical architecture was determined by the channel layer thickness, which can provide an ultrashort channel length without the need for a high-precision manufacturing process. The performance of VPDs with two types of semiconductor layers, a graphene-PbS quantum dot hybrid (GQDH) and PbS quantum dots (QDs), was measured. The GQDH VPD showed better photoelectric properties than the QD VPD because of the high mobility of graphene doped in the channel. The GQDH VPD exhibited excellent photoresponse properties with a responsivity of 1.6 × 10 4 A/W in the p-type regime and a fast response speed with a rise time of 8 ms. The simple manufacture and the promising photoresponse of the GQDH VPDs reveal that an easy and effective way to fabricate high-performance ambipolar photodetectors was developed.

Three-dimensional structures of graphene/polyaniline hybrid films constructed by steamed water for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Zhang, Liling; Huang, Da; Hu, Nantao; Yang, Chao; Li, Ming; Wei, Hao; Yang, Zhi; Su, Yanjie; Zhang, Yafei

2017-02-01

A novel three-dimensional (3D) structure of reduced graphene oxide/polyaniline (rGO/PANI) hybrid films has been demonstrated for high-performance supercapacitors. Steamed water in closed vessels with high pressure and moderately high temperature is applied to facilely construct this structure. The as-designed rGO/PANI hybrid films exhibit a highest gravimetric specific capacitance of 1182 F g-1 at 1 A g-1 in the three-electrode test. The assembled symmetric device based on this structure shows both a high capacitance of 808 F g-1 at 1 A g-1 and a high gravimetric energy density (28.06 Wh kg-1 at a power density of 0.25 kW kg-1). Above all, this novel 3D structure constructed by steamed water regulation techniques shows excellent capacitance performance and holds a great promise for high-performance energy storage applications.

Immobilization effects on the photocatalytic activity of CdS quantum Dots-Horseradish peroxidase hybrid nanomaterials.

PubMed

Iñarritu, Iker; Torres, Eduardo; Topete, Antonio; Campos-Terán, José

2017-11-15

The potential use of hybrid nanomaterials based on inorganic optically active nanoparticles known as quantum dots (QDs) and horseradish peroxidase (HRP) has been proposed by several authors as light-controllable nanocatalyzers, moreover, the immobilization within or over silica based supports represents an advantage over bulk-dispersed systems. However, the implications of the immobilization of such hybrid photoactivatable catalyzing systems have not been clarified with detail. Here, we present a thorough study of the functional photoactive efficiency and recycling of immobilized CdS QDs and HRP systems with different configurations, immobilized over silanized silica quartz crystal microbalance (QCM) sensors, allowing an accurate measure of the immobilized mass of each component and its correlation with the initial reaction rate of conversion of Amplex Red (AR) to resorufin. As well, the conversion efficiency is compared between the different systems and also to non-immobilized QD-HRP complexed systems. Copyright © 2017 Elsevier Inc. All rights reserved.

Interaction and energy transfer studies between bovine serum albumin and CdTe quantum dots conjugates: CdTe QDs as energy acceptor probes.

PubMed

Kotresh, M G; Inamdar, L S; Shivkumar, M A; Adarsh, K S; Jagatap, B N; Mulimani, B G; Advirao, G M; Inamdar, S R

2017-06-01

In this paper, a systematic investigation of the interaction of bovine serum albumin (BSA) with water-soluble CdTe quantum dots (QDs) of two different sizes capped with carboxylic thiols is presented based on steady-state and time-resolved fluorescence measurements. Efficient Förster resonance energy transfer (FRET) was observed to occur from BSA donor to CdTe acceptor as noted from reduction in the fluorescence of BSA and enhanced fluorescence from CdTe QDs. FRET parameters such as Förster distance, spectral overlap integral, FRET rate constant and efficiency were determined. The quenching of BSA fluorescence in aqueous solution observed in the presence of CdTe QDs infers that fluorescence resonance energy transfer is primarily responsible for the quenching phenomenon. Bimolecular quenching constant (k q ) determined at different temperatures and the time-resolved fluorescence data provide additional evidence for this. The binding stoichiometry and various thermodynamic parameters are evaluated by using the van 't Hoff equation. The analysis of the results suggests that the interaction between BSA and CdTe QDs is entropy driven and hydrophobic forces play a key role in the interaction. Binding of QDs significantly shortened the fluorescence lifetime of BSA which is one of the hallmarks of FRET. The effect of size of the QDs on the FRET parameters are discussed in the light of FRET parameters obtained. Copyright © 2016 John Wiley & Sons, Ltd.

Photo-Patternable ZnO Thin Films Based on Cross-Linked Zinc Acrylate for Organic/Inorganic Hybrid Complementary Inverters.

PubMed

Jeong, Yong Jin; An, Tae Kyu; Yun, Dong-Jin; Kim, Lae Ho; Park, Seonuk; Kim, Yebyeol; Nam, Sooji; Lee, Keun Hyung; Kim, Se Hyun; Jang, Jaeyoung; Park, Chan Eon

2016-03-02

Complementary inverters consisting of p-type organic and n-type metal oxide semiconductors have received considerable attention as key elements for realizing low-cost and large-area future electronics. Solution-processed ZnO thin-film transistors (TFTs) have great potential for use in hybrid complementary inverters as n-type load transistors because of the low cost of their fabrication process and natural abundance of active materials. The integration of a single ZnO TFT into an inverter requires the development of a simple patterning method as an alternative to conventional time-consuming and complicated photolithography techniques. In this study, we used a photocurable polymer precursor, zinc acrylate (or zinc diacrylate, ZDA), to conveniently fabricate photopatternable ZnO thin films for use as the active layers of n-type ZnO TFTs. UV-irradiated ZDA thin films became insoluble in developing solvent as the acrylate moiety photo-cross-linked; therefore, we were able to successfully photopattern solution-processed ZDA thin films using UV light. We studied the effects of addition of a tiny amount of indium dopant on the transistor characteristics of the photopatterned ZnO thin films and demonstrated low-voltage operation of the ZnO TFTs within ±3 V by utilizing Al2O3/TiO2 laminate thin films or ion-gels as gate dielectrics. By combining the ZnO TFTs with p-type pentacene TFTs, we successfully fabricated organic/inorganic hybrid complementary inverters using solution-processed and photopatterned ZnO TFTs.

Self-Assembled Core-Shell CdTe/Poly(3-hexylthiophene) Nanoensembles as Novel Donor-Acceptor Light-Harvesting Systems.

PubMed

Istif, Emin; Kagkoura, Antonia; Hernandez-Ferrer, Javier; Stergiou, Anastasios; Skaltsas, Theodosis; Arenal, Raul; Benito, Ana M; Maser, Wolfgang K; Tagmatarchis, Nikos

2017-12-27

The self-assembly of novel core-shell nanoensembles consisting of regioregular poly(3-hexylthiophene) nanoparticles (P3HT NPs ) of 100 nm as core and semiconducting CdTe quantum dots (CdTe QDs ) as shell with a thickness of a few tens of nanometers was accomplished by employing a reprecipitation approach. The structure, morphology, and composition of CdTe QDs /P3HT NPs nanoensembles were confirmed by high-resolution scanning transmission microscopy and dynamic light-scattering studies. Intimate interface contact between the CdTe QDs shell and the P3HT NPs core leads to the stabilization of the CdTe QDs /P3HT NPs nanoensemble as probed by the steady-state absorption spectroscopy. Effective quenching of the characteristic photoluminescence of CdTe QDs at 555 nm, accompanied by simultaneous increase in emission of P3HT NPs at 660 and 720 nm, reveals photoinduced charge-transfer processes. Probing the redox properties of films of CdTe QDs /P3HT NPs further proves the formation of a stabilized core-shell system in the solid state. Photoelectrochemical assays on CdTe QDs /P3HT NPs films show a reversible on-off photoresponse at a bias voltage of +0.8 V with a 3 times increased photocurrent compared to CdTe QDs . The improved charge separation is directly related to the unique core-shell configuration, in which the outer CdTe QDs shell forces the P3HT NPs core to effectively act as electron acceptor. The creation of novel donor-acceptor core-shell hybrid materials via self-assembly is transferable to other types of conjugated polymers and semiconducting nanoparticles. This work, therefore, opens new pathways for the design of improved optoelectronic devices.

A paper-based resonance energy transfer nucleic acid hybridization assay using upconversion nanoparticles as donors and quantum dots as acceptors.

PubMed

Doughan, Samer; Uddayasankar, Uvaraj; Krull, Ulrich J

2015-06-09

Monodisperse aqueous upconverting nanoparticles (UCNPs) were covalently immobilized on aldehyde modified cellulose paper via reduction amination to develop a luminescence resonance energy transfer (LRET)-based nucleic acid hybridization assay. This first account of covalent immobilization of UCNPs on paper for a bioassay reports an optically responsive method that is sensitive, reproducible and robust. The immobilized UCNPs were decorated with oligonucleotide probes to capture HPRT1 housekeeping gene fragments, which in turn brought reporter conjugated quantum dots (QDs) in close proximity to the UCNPs for LRET. This sandwich assay could detect unlabeled oligonucleotide target, and had a limit of detection of 13 fmol and a dynamic range spanning nearly 3 orders of magnitude. The use of QDs, which are excellent LRET acceptors, demonstrated improved sensitivity, limit of detection, dynamic range and selectivity compared to similar assays that have used molecular fluorophores as acceptors. The selectivity of the assay was attributed to the decoration of the QDs with polyethylene glycol to eliminate non-specific adsorption. The kinetics of hybridization were determined to be diffusion limited and full signal development occurred within 3 min. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis and electrochemical properties of Ti-doped DLC films by a hybrid PVD/PECVD process

NASA Astrophysics Data System (ADS)

Jo, Yeong Ju; Zhang, Teng Fei; Son, Myoung Jun; Kim, Kwang Ho

2018-03-01

Low electrical conductivity and poor adhesion to metallic substrates are the main drawbacks of diamond-like carbon (DLC) films when used in electrode applications. In this study, Ti-doped DLC films with various Ti contents were synthesized on metal Ti substrates by a hybrid PVD/PECVD process, where PECVD was used for deposition of DLC films and PVD was used for Ti doping. The effects of the Ti doping ratio on the microstructure, adhesion strength, and electrical and electrochemical properties of the DLC films were systematically investigated. An increase in the Ti content led to increased surface roughness and a higher sp2/sp3 ratio of the Ti-DLC films. Ti atoms existed as amorphous-phase Ti carbide when the Ti doping ratio was less than 2.8 at.%, while the nanocrystalline TiC phase was formed in DLC films when the Ti doping ratio was exceeded 4.0 at.%. The adhesion strength, electrical resistivity, electrochemical activity and reversibility of the DLC films were greatly improved by Ti doping. The influence of Ti doping ratio on the electrical and electrochemical properties of the DLC films were also investigated and the best performance was obtained at a Ti content of 2.8 at.%.

Unusual dynamic dewetting behavior of smooth perfluorinated hybrid films: potential advantages over conventional textured and liquid-infused perfluorinated surfaces.

PubMed

Urata, Chihiro; Masheder, Benjamin; Cheng, Dalton F; Hozumi, Atsushi

2013-10-08

From a viewpoint of reducing the burden on the environment and human health, an alternative method for preparing liquid-repellent surfaces without relying on the long perfluorocarbons (C((X-1)/2)F(X), X ≥ 17) has been strongly demanded lately. In this study, we have successfully demonstrated that dynamic dewettability toward various probe liquids (polar and nonpolar liquids with high or low surface tension) can be tuned by not only controlling surface chemistries (surface energies) but also the physical (solid-like or liquid-like) nature of the surface. We prepared smooth and transparent organic-inorganic hybrid films exhibiting unusual dynamic dewetting behavior toward various probe liquids using a simple sol-gel reaction based on the co-hydrolysis and co-condensation of a mixture including a range of perfluoroalkylsilanes (FASX, C((X-1)/2)F(X)CH2CH2Si(OR)3, where X = 3, 9, 13, and 17) and tetramethoxysilane (Si(OCH3)4, TMOS). Dynamic contact angle (CA) and substrate tilt angle (TA) measurements confirmed that our FASX-hybrid films exhibited excellent dynamic dewetting properties and were mostly independent of the length of perfluoroalkyl (Rf) groups. For example, 10 μL droplets of ultralow surface tension liquids (e.g., diethyl ether (γ = 16.26 dyn/cm) and n-pentane (γ = 15.51 dyn/cm)) could move easily on our FAS9-, FAS13-, and FAS17-hybrid film surfaces at low substrate TAs (<4°) without pinning. This is comparable or superior to the best perfluorinated textured and flat surfaces reported so far. This exceptional dynamic dewetting behavior appeared only when TMOS molecules were added to the precursor solutions; we assume this is due to co-condensed TMOS-derived silica species working as spacers between the neighboring Rf chains, enabling them to rotate freely and in doing so provide a surface with liquid-like properties. This led to the distinguished dynamic dewettability of our hybrid films, regardless of the small static CAs. Our FASX-hybrid films also

Quantum-dot size and thin-film dielectric constant: precision measurement and disparity with simple models.

PubMed

Grinolds, Darcy D W; Brown, Patrick R; Harris, Daniel K; Bulovic, Vladimir; Bawendi, Moungi G

2015-01-14

We study the dielectric constant of lead sulfide quantum dot (QD) films as a function of the volume fraction of QDs by varying the QD size and keeping the ligand constant. We create a reliable QD sizing curve using small-angle X-ray scattering (SAXS), thin-film SAXS to extract a pair-distribution function for QD spacing, and a stacked-capacitor geometry to measure the capacitance of the thin film. Our data support a reduced dielectric constant in nanoparticles.

Oxide Semiconductor-Based Flexible Organic/Inorganic Hybrid Thin-Film Transistors Fabricated on Polydimethylsiloxane Elastomer.

PubMed

Jung, Soon-Won; Choi, Jeong-Seon; Park, Jung Ho; Koo, Jae Bon; Park, Chan Woo; Na, Bock Soon; Oh, Ji-Young; Lim, Sang Chul; Lee, Sang Seok; Chu, Hye Yong

2016-03-01

We demonstrate flexible organic/inorganic hybrid thin-film transistors (TFTs) on a polydimethysilox- ane (PDMS) elastomer substrate. The active channel and gate insulator of the hybrid TFT are composed of In-Ga-Zn-O (IGZO) and blends of poly(vinylidene fluoride-trifluoroethylene) [P(VDF- TrFE)] with poly(methyl methacrylate) (PMMA), respectively. It has been confirmed that the fabri- cated TFT display excellent characteristics: the recorded field-effect mobility, sub-threshold voltage swing, and I(on)/I(off) ratio were approximately 0.35 cm2 V(-1) s(-1), 1.5 V/decade, and 10(4), respectively. These characteristics did not experience any degradation at a bending radius of 15 mm. These results correspond to the first demonstration of a hybrid-type TFT using an organic gate insulator/oxide semiconducting active channel structure fabricated on PDMS elastomer, and demonstrate the feasibility of a promising device in a flexible electronic system.

Hybrid Physical-Chemical Vapor Deposition of Bi2Se3 Thin films on Sapphire

NASA Astrophysics Data System (ADS)

Brom, Joseph; Ke, Yue; Du, Renzhong; Gagnon, Jarod; Li, Qi; Redwing, Joan

2012-02-01

High quality thin films of topological insulators continue to garner much interest. We report on the growth of highly-oriented thin films of Bi2Se3 on c-plane sapphire using hybrid physical-chemical vapor deposition (HPCVD). The HPCVD process utilizes the thermal decomposition of trimethyl bismuth (TMBi) and evaporation of elemental selenium in a hydrogen ambient to deposit Bi2Se3. Growth parameters including TMBi flow rate and decomposition temperature and selenium evaporation temperature were optimized, effectively changing the Bi:Se ratio, to produce high quality films. Glancing angle x- ray diffraction measurements revealed that the films were c-axis oriented on sapphire. Trigonal crystal planes were observed in atomic force microscopy images with an RMS surface roughness of 1.24 nm over an area of 2μmx2μm. Variable temperature Hall effect measurements were also carried out on films that were nominally 50-70 nm thick. Over the temperature range from 300K down to 4.2K, the carrier concentration remained constant at approximately 6x10^18 cm-3 while the mobility increased from 480 cm^2/Vs to 900 cm^2/Vs. These results demonstrate that the HPCVD technique can be used to deposit Bi2Se3 films with structural and electrical properties comparable to films produced by molecular beam epitaxy.

Nanoscale observation of organic thin film by atomic force microscopy

NASA Astrophysics Data System (ADS)

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

2017-08-01

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

Scanning electrochemical microscopy of graphene/polymer hybrid thin films as supercapacitors: Physical-chemical interfacial processes

NASA Astrophysics Data System (ADS)

Gupta, Sanju; Price, Carson

2015-10-01

Hybrid electrode comprising an electric double-layer capacitor of graphene nanosheets and a pseudocapacitor of the electrically conducting polymers namely, polyaniline; PAni and polypyrrole; PPy are constructed that exhibited synergistic effect with excellent electrochemical performance as thin film supercapacitors for alternative energy. The hybrid supercapacitors were prepared by layer-by-layer (LbL) assembly based on controlled electrochemical polymerization followed by reduction of graphene oxide electrochemically producing ErGO, for establishing intimate electronic contact through nanoscale architecture and chemical stability, producing a single bilayer of (PAni/ErGO)1, (PPy/ErGO)1, (PAni/GO)1 and (PPy/GO)1. The rationale design is to create thin films that possess interconnected graphene nanosheets (GNS) with polymer nanostructures forming well-defined tailored interfaces allowing sufficient surface adsorption and faster ion transport due to short diffusion distances. We investigated their electrochemical properties and performance in terms of gravimetric specific capacitance, Cs, from cyclic voltammograms. The LbL-assembled bilayer films exhibited an excellent Cs of ≥350 F g-1 as compared with constituents (˜70 F g-1) at discharge current density of 0.3 A g-1 that outperformed many other hybrid supercapacitors. To gain deeper insights into the physical-chemical interfacial processes occurring at the electrode/electrolyte interface that govern their operation, we have used scanning electrochemical microscopy (SECM) technique in feedback and probe approach modes. We present our findings from viewpoint of reinforcing the role played by heterogeneous electrode surface composed of nanoscale graphene sheets (conducting) and conducting polymers (semiconducting) backbone with ordered polymer chains via higher/lower probe current distribution maps. Also targeted is SECM imaging that allowed to determine electrochemical (re)activity of surface ion adsorption sites

Scanning electrochemical microscopy of graphene/polymer hybrid thin films as supercapacitors: Physical-chemical interfacial processes

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

Gupta, Sanju, E-mail: sanju.gupta@wku.edu; Price, Carson

2015-10-15

Hybrid electrode comprising an electric double-layer capacitor of graphene nanosheets and a pseudocapacitor of the electrically conducting polymers namely, polyaniline; PAni and polypyrrole; PPy are constructed that exhibited synergistic effect with excellent electrochemical performance as thin film supercapacitors for alternative energy. The hybrid supercapacitors were prepared by layer-by-layer (LbL) assembly based on controlled electrochemical polymerization followed by reduction of graphene oxide electrochemically producing ErGO, for establishing intimate electronic contact through nanoscale architecture and chemical stability, producing a single bilayer of (PAni/ErGO){sub 1}, (PPy/ErGO){sub 1}, (PAni/GO){sub 1} and (PPy/GO){sub 1}. The rationale design is to create thin films that possess interconnectedmore » graphene nanosheets (GNS) with polymer nanostructures forming well-defined tailored interfaces allowing sufficient surface adsorption and faster ion transport due to short diffusion distances. We investigated their electrochemical properties and performance in terms of gravimetric specific capacitance, C{sub s}, from cyclic voltammograms. The LbL-assembled bilayer films exhibited an excellent C{sub s} of ≥350 F g{sup −1} as compared with constituents (∼70 F g{sup −1}) at discharge current density of 0.3 A g{sup −1} that outperformed many other hybrid supercapacitors. To gain deeper insights into the physical-chemical interfacial processes occurring at the electrode/electrolyte interface that govern their operation, we have used scanning electrochemical microscopy (SECM) technique in feedback and probe approach modes. We present our findings from viewpoint of reinforcing the role played by heterogeneous electrode surface composed of nanoscale graphene sheets (conducting) and conducting polymers (semiconducting) backbone with ordered polymer chains via higher/lower probe current distribution maps. Also targeted is SECM imaging that allowed to

Single molecule localization imaging of telomeres and centromeres using fluorescence in situ hybridization and semiconductor quantum dots.

PubMed

Wang, Le; Zong, Shenfei; Wang, Zhuyuan; Lu, Ju; Chen, Chen; Zhang, Ruohu; Cui, Yiping

2018-07-13

Single molecule localization microscopy (SMLM) is a powerful tool for imaging biological targets at the nanoscale. In this report, we present SMLM imaging of telomeres and centromeres using fluorescence in situ hybridization (FISH). The FISH probes were fabricated by decorating CdSSe/ZnS quantum dots (QDs) with telomere or centromere complementary DNA strands. SMLM imaging experiments using commercially available peptide nucleic acid (PNA) probes labeled with organic fluorophores were also conducted to demonstrate the advantages of using QDs FISH probes. Compared with the PNA probes, the QDs probes have the following merits. First, the fluorescence blinking of QDs can be realized in aqueous solution or PBS buffer without thiol, which is a key buffer component for organic fluorophores' blinking. Second, fluorescence blinking of the QDs probe needs only one excitation light (i.e. 405 nm). While fluorescence blinking of the organic fluorophores usually requires two illumination lights, that is, the activation light (i.e. 405 nm) and the imaging light. Third, the high quantum yield, multiple switching times and a good optical stability make the QDs more suitable for long-term imaging. The localization precision achieved in telomeres and centromeres imaging experiments is about 30 nm, which is far beyond the diffraction limit. SMLM has enabled new insights into telomeres or centromeres on the molecular level, and it is even possible to determine the length of telomere and become a potential technique for telomere-related investigation.

Single molecule localization imaging of telomeres and centromeres using fluorescence in situ hybridization and semiconductor quantum dots

NASA Astrophysics Data System (ADS)

Wang, Le; Zong, Shenfei; Wang, Zhuyuan; Lu, Ju; Chen, Chen; Zhang, Ruohu; Cui, Yiping

2018-07-01

Single molecule localization microscopy (SMLM) is a powerful tool for imaging biological targets at the nanoscale. In this report, we present SMLM imaging of telomeres and centromeres using fluorescence in situ hybridization (FISH). The FISH probes were fabricated by decorating CdSSe/ZnS quantum dots (QDs) with telomere or centromere complementary DNA strands. SMLM imaging experiments using commercially available peptide nucleic acid (PNA) probes labeled with organic fluorophores were also conducted to demonstrate the advantages of using QDs FISH probes. Compared with the PNA probes, the QDs probes have the following merits. First, the fluorescence blinking of QDs can be realized in aqueous solution or PBS buffer without thiol, which is a key buffer component for organic fluorophores’ blinking. Second, fluorescence blinking of the QDs probe needs only one excitation light (i.e. 405 nm). While fluorescence blinking of the organic fluorophores usually requires two illumination lights, that is, the activation light (i.e. 405 nm) and the imaging light. Third, the high quantum yield, multiple switching times and a good optical stability make the QDs more suitable for long-term imaging. The localization precision achieved in telomeres and centromeres imaging experiments is about 30 nm, which is far beyond the diffraction limit. SMLM has enabled new insights into telomeres or centromeres on the molecular level, and it is even possible to determine the length of telomere and become a potential technique for telomere-related investigation.

A turn-on chemiluminescence biosensor for selective and sensitive detection of adenosine based on HKUST-1 and QDs-luminol-aptamer conjugates.

PubMed

Lin, Yanna; Dai, Yuxue; Sun, Yuanling; Ding, Chaofan; Sun, Weiyan; Zhu, Xiaodong; Liu, Hao; Luo, Chuannan

2018-05-15

In this work, HKUST-1 and QDs-luminol-aptamer conjugates were prepared. The QDs-luminol-aptamer conjugates can be adsorbed by graphene oxide through π-π conjugation. When the adenosine was added, the QDs-luminol-aptamer conjugates were released from magnetic graphene oxide (MGO), the chemiluminescent switch was turned on. It was reported that HKUST-1 can catalyze the chemiluminescence reaction of luminol-H 2 O 2 system in an alkaline medium, and improve the chemiluminescence resonance energy transfer (CRET) between chemiluminescence and QDs indirectly. Thus, the adenosine can be detected sensitively. Based on this phenomenon, the excellent platform for detection of adenosine was established. Under the optimized conditions, the linear detection range for adenosine was 1.0 × 10 -12 -2.2 × 10 -10 mol/L with a detection limit of 2.1 × 10 -13 mol/L. The proposed method was successfully used for adenosine detection in biological samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Solution-Processed Ag Nanowires + PEDOT:PSS Hybrid Electrode for Cu(In,Ga)Se₂ Thin-Film Solar Cells.

PubMed

Shin, Donghyeop; Kim, Taegeon; Ahn, Byung Tae; Han, Seung Min

2015-06-24

To reduce the cost of the Cu(In,Ga)Se2 (CIGS) solar cells while maximizing the efficiency, we report the use of an Ag nanowires (NWs) + poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) ( PSS) hybrid transparent electrode, which was deposited using all-solution-processed, low-cost, scalable methods. This is the first demonstration of an Ag NWs + PSS transparent electrode applied to CIGS solar cells. The spin-coated 10-nm-thick PSS conducting polymer layer in our hybrid electrode functioned as a filler of empty space of an electrostatically sprayed Ag NW network. Coating of PSS on the Ag NW network resulted in an increase in the short-circuit current from 15.4 to 26.5 mA/cm(2), but the open-circuit voltage and shunt resistance still needed to be improved. The limited open-circuit voltage was found to be due to interfacial recombination that is due to the ineffective hole-blocking ability of the CdS film. To suppress the interfacial recombination between Ag NWs and the CdS film, a Zn(S,O,OH) film was introduced as a hole-blocking layer between the CdS film and Ag NW network. The open-circuit voltage of the cell sharply improved from 0.35 to 0.6 V, which resulted in the best cell efficiency of 11.6%.

Influence of Hybrid Perovskite Fabrication Methods on Film Formation, Electronic Structure, and Solar Cell Performance

PubMed Central

Schnier, Tobias; Emara, Jennifer; Olthof, Selina; Meerholz, Klaus

2017-01-01

Hybrid organic/inorganic halide perovskites have lately been a topic of great interest in the field of solar cell applications, with the potential to achieve device efficiencies exceeding other thin film device technologies. Yet, large variations in device efficiency and basic physical properties are reported. This is due to unintentional variations during film processing, which have not been sufficiently investigated so far. We therefore conducted an extensive study of the morphology and electronic structure of a large number of CH3NH3PbI3 perovskite where we show how the preparation method as well as the mixing ratio of educts methylammonium iodide and lead(II) iodide impact properties like film formation, crystal structure, density of states, energy levels, and ultimately the solar cell performance. PMID:28287555

Patterning and photoluminescent properties of perovskite-type organic/inorganic hybrid luminescent films by soft lithography

NASA Astrophysics Data System (ADS)

Cheng, Z. Y.; Wang, Z.; Xing, R. B.; Han, Y. C.; Lin, J.

2003-07-01

Perovskite-type organic/inorganic hybrid layered compound (C 6H 5C 2H 4NH 3) 2PbI 4 was synthesized. The patterning of (C 6H 5C 2H 4NH 3) 2PbI 4 thin films on silicon substrate was realized by the micromolding in capillaries (MIMIC) process, a kind of soft lithography. Bright green luminescent stripes with different widths (50, 15, 0.8 μm) have been obtained. The structure and optical properties of (C 6H 5C 2H 4NH 3) 2PbI 4 films were characterized by X-ray diffraction (XRD), UV/Vis absorption and photoluminescence excitation and emission spectra, respectively. It is shown that the organic-inorganic layered (C 6H 5C 2H 4NH 3) 2PbI 4 film was c-axis oriented, paralleling to the substrate plane. Green exciton emission at 525 nm was observed in the film, and the explanations for it were given.

Toward a solid-phase nucleic acid hybridization assay within microfluidic channels using immobilized quantum dots as donors in fluorescence resonance energy transfer.

PubMed

Chen, Lu; Algar, W Russ; Tavares, Anthony J; Krull, Ulrich J

2011-01-01

The optical properties and surface area of quantum dots (QDs) have made them an attractive platform for the development of nucleic acid biosensors based on fluorescence resonance energy transfer (FRET). Solid-phase assays based on FRET using mixtures of immobilized QD-oligonucleotide conjugates (QD biosensors) have been developed. The typical challenges associated with solid-phase detection strategies include non-specific adsorption, slow kinetics of hybridization, and sample manipulation. The new work herein has considered the immobilization of QD biosensors onto the surfaces of microfluidic channels in order to address these challenges. Microfluidic flow can be used to dynamically control stringency by adjustment of the potential in an electrokinetic-based microfluidics environment. The shearing force, Joule heating, and the competition between electroosmotic and electrophoretic mobilities allow the optimization of hybridization conditions, convective delivery of target to the channel surface to speed hybridization, amelioration of adsorption, and regeneration of the sensing surface. Microfluidic flow can also be used to deliver (for immobilization) and remove QD biosensors. QDs that were conjugated with two different oligonucleotide sequences were used to demonstrate feasibility. One oligonucleotide sequence on the QD was available as a linker for immobilization via hybridization with complementary oligonucleotides located on a glass surface within a microfluidic channel. A second oligonucleotide sequence on the QD served as a probe to transduce hybridization with target nucleic acid in a sample solution. A Cy3 label on the target was excited by FRET using green-emitting CdSe/ZnS QD donors and provided an analytical signal to explore this detection strategy. The immobilized QDs could be removed under denaturing conditions by disrupting the duplex that was used as the surface linker and thus allowed a new layer of QD biosensors to be re-coated within the channel

Enhancement of conduction noise absorption by hybrid absorbers composed of indium-tin-oxide thin film and magnetic composite sheet on a microstrip line

NASA Astrophysics Data System (ADS)

Kim, Sun-Hong; Kim, Sung-Soo

2014-05-01

In order to develop wide-band noise absorbers with a focused design for low frequency performance, this study investigates hybrid absorbers that are composed of conductive indium-tin-oxide (ITO) thin film and magnetic composite sheets. The ITO films prepared via reactive sputtering exhibit a typical value of electrical resistivity of ≃10-4 Ω m. Rubber composites with flaky Fe-Si-Al particles are used as the magnetic sheet with a high permeability and high permittivity. For the ITO film with a low surface resistance and covered by the magnetic sheet, approximately 90% power absorption can be obtained at 1 GHz, which is significantly higher than that of the original magnetic sheet or ITO film. The high power absorption of the hybrid absorber is attributed to the enhanced ohmic loss of the ITO film through increased electric field strength bounded by the upper magnetic composite sheet. However, for the reverse layering sequence of the ITO film, the electric field experienced by ITO film is very weak due to the electromagnetic shielding by the under layer of magnetic sheet, which does not result in enhanced power absorption.

Hybrid quantum dot-tin disulfide field-effect transistors with improved photocurrent and spectral responsivity

DOE PAGES

Cotlet, Mircea; Huang, Yuan Zang; Chen, Jia -Shiang; ...

2016-03-24

We report an improved photosensitivity in few-layer tin disulfide (SnS 2) field-effect transistors(FETs) following doping with CdSe/ZnS core/shell quantum dots(QDs). The hybrid QD-SnS 2 FET devices achieve more than 500% increase in the photocurrent response compared with the starting SnS 2-only FET device and a spectral responsivity reaching over 650 A/W at 400 nm wavelength. The negligible electrical conductance in a control QD-only FET device suggests that the energy transfer between QDs and SnS 2 is the main mechanism responsible for the sensitization effect, which is consistent with the strong spectral overlap between QDphotoluminescence and SnS 2 optical absorption asmore » well as the large nominal donor-acceptor interspacing between QD core and SnS 2. Furthermore, we also find enhanced charge carrier mobility in hybrid QD-SnS 2 FETs which we attribute to a reduced contact Schottky barrier width due to an elevated background charge carrier density.« less

SnO{sub 2} films: In-situ template-sacrificial growth and photovoltaic property based on SnO{sub 2}/poly(3-hexyl-thiophene) for hybrid solar cell

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

Zhang, Yange, E-mail: zhangygzhang@163.com; Li, Pinjiang; Xu, Xiaoyun

2015-10-15

Highlights: • SnO{sub 2} nanocrystals/thin films were fabricated on ITO glass substrate from preformed SnS thin film as sacrificial template. • The SnO{sub 2} film and SnO{sub 2}/P3HT was characterized by several techniques. • The new hybrid solar cell device was based on the hybrid thin film of SnO{sub 2} NCs and P3HT composites. - Abstract: we described a facile in-situ wet chemical method to prepare SnO{sub 2} thin film on ITO glass substrate from preformed SnS thin film as sacrificial template. The chemical conversion process of SnS to SnO{sub 2} was studied. The SnO{sub 2} film and SnO{sub 2}/P3HTmore » was characterized by several techniques, such as powder X-ray diffract meter (XRD), Raman spectrometer, scanning electron microscope (SEM), atomic force microscope (AFM) and UV–vis spectrophotometer in detail. The new SnO{sub 2}/P3HT hybrid solar cell device showed an open-circuit voltage of 0.185 V, a short-circuit current density of 0.366 mA/cm{sup 2} and a fill factor of 0.247, corresponding to a power conversion efficiency of 0.0167%.« less

Enhancement of carrier lifetimes in type-II quantum dot/quantum well hybrid structures

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

Couto, O. D. D., E-mail: odilon@ifi.unicamp.br; Almeida, P. T. de; Santos, G. E. dos

We investigate optical transitions and carrier dynamics in hybrid structures containing type-I GaAs/AlGaAs quantum wells (QWs) and type-II GaSb/AlGaAs quantum dots (QDs). We show that the optical recombination of photocreated electrons confined in the QWs with holes in the QDs and wetting layer can be modified according to the QW/QD spatial separation. In particular, for low spacer thicknesses, the QW optical emission can be suppressed due to the transference of holes from the QW to the GaSb layer, favoring the optical recombination of spatially separated carriers, which can be useful for optical memory and solar cell applications. Time-resolved photoluminescence (PL)more » measurements reveal non-exponential recombination dynamics. We demonstrate that the PL transients can only be quantitatively described by considering both linear and quadratic terms of the carrier density in the bimolecular recombination approximation for type-II semiconductor nanostructures. We extract long exciton lifetimes from 700 ns to 5 μs for QDs depending on the spacer layer thickness.« less

Bio-hybridization of nanobactericides with cellulose films for effective treatment against members of ESKAPE multi-drug-resistant pathogens

NASA Astrophysics Data System (ADS)

Baker, Syed; Volova, Tatiana; Prudnikova, Svetlana V.; Shumilova, Anna A.; Perianova, Olga V.; Zharkov, Sergey M.; Kuzmin, Andrey; Olga, Kondratenka; Bogdan, Kiryukhin; Shidlovskiy, Ivan P.; Potkina, Zoya K.; Khohlova, Olga Y.; Lobova, Tatiana I.

2018-03-01

The rapid expansion of drug-resistant pathogens has created huge global impact and development of novel antimicrobial leads is one of the top priority studies in the current scenario. The present study aims to develop bio-hybridized nanocellulose films which comprise of phytogenic silver nanobactericides. The nanobactericides were synthesized by treating 1 mM silver nitrate with aqueous extract of Chamerion angustifolium which reduced the metal salt to produce polydispersed nanobactericides which were tested against the members of ESKAPE drug-resistant communities. The synthesized silver nanobactericides were subjected to characterization with UV-visible spectra which displayed maximum absorbance at 408 nm. The bio-molecular interaction of phyto-constituents to mediate synthesis and stabilization of nanobactericides was studied with Fourier-transform infrared spectroscopy (FTIR) which depicted functional groups associated with nanobactericides. The crystalline nature was studied with X-ray diffraction (XRD) which showed Bragg's intensities at 2θ angle which denoted (111), (200), (220), and (311) planes. The morphological characteristics of silver nanobactericides were defined with transmission electron Microscopy (TEM) image which displayed polydispersity of silver nanobactericides with size ranging from 2 to 40 nm. The synthesized nanobactericides showed a significant activity against MRSA strain with 21 mm zone of inhibition. The minimal inhibitory concentration of silver nanobactericides to inhibit the growth of test pathogens was also determined which ranged between 0.625 and 1.25 μg/ml. The silver nanobactericides were bio-hybridized onto nanocellulose films produced by Komagataeibacter xylinus B-12068 culture strain. The films were dried to determine the mechanical properties which showed increased in Young's modulus and tensile strength in comparison with control bacterial cellulose films. Overall, the results obtained in the present investigation are

Microbial detection in microfluidic devices through dual staining of quantum dots-labeled immunoassay and RNA hybridization.

PubMed

Zhang, Qing; Zhu, Liang; Feng, Hanhua; Ang, Simon; Chau, Fook Siong; Liu, Wen-Tso

2006-01-18

This paper reported the development of a microfludic device for the rapid detection of viable and nonviable microbial cells through dual labeling by fluorescent in situ hybridization (FISH) and quantum dots (QDs)-labeled immunofluorescent assay (IFA). The coin sized device consists of a microchannel and filtering pillars (gap=1-2 microm) and was demonstrated to effectively trap and concentrate microbial cells (i.e. Giardia lamblia). After sample injection, FISH probe solution and QDs-labeled antibody solution were sequentially pumped into the device to accelerate the fluorescent labeling reactions at optimized flow rates (i.e. 1 and 20 microL/min, respectively). After 2 min washing for each assay, the whole process could be finished within 30 min, with minimum consumption of labeling reagents and superior fluorescent signal intensity. The choice of QDs 525 for IFA resulted in bright and stable fluorescent signal, with minimum interference with the Cy3 signal from FISH detection.

Ultrasensitive electrochemical detection of nucleic acids by template enhanced hybridization followed with rolling circle amplification.

PubMed

Ji, Hanxu; Yan, Feng; Lei, Jianping; Ju, Huangxian

2012-08-21

An ultrasensitive protocol for electrochemical detection of DNA is designed with quantum dots (QDs) as a signal tag by combining the template enhanced hybridization process (TEHP) and rolling circle amplification (RCA). Upon the recognition of the molecular beacon (MB) to target DNA, the MB hybridizes with assistants and target DNA to form a ternary ''Y-junction''. The target DNA can be dissociated from the structure under the reaction of nicking endonuclease to initiate the next hybridization process. The template enhanced MB fragments further act as the primers of the RCA reaction to produce thousands of repeated oligonucleotide sequences, which can bind with oligonucleotide functionalized QDs. The attached signal tags can be easily read out by square-wave voltammetry after dissolving with acid. Because of the cascade signal amplification and the specific TEHP and RCA reaction, this newly designed protocol provides an ultrasensitive electrochemical detection of DNA down to the attomolar level (11 aM) with a linear range of 6 orders of magnitude (from 1 × 10(-17) to 1 × 10(-11) M) and can discriminate mismatched DNA from perfect matched target DNA with high selectivity. The high sensitivity and specificity make this method a great potential for early diagnosis in gene-related diseases.

Single step deposition of an interacting layer of a perovskite matrix with embedded quantum dots

NASA Astrophysics Data System (ADS)

Ngo, Thi Tuyen; Suarez, Isaac; Sanchez, Rafael S.; Martinez-Pastor, Juan P.; Mora-Sero, Ivan

2016-07-01

Hybrid lead halide perovskite (PS) derivatives have emerged as very promising materials for the development of optoelectronic devices in the last few years. At the same time, inorganic nanocrystals with quantum confinement (QDs) possess unique properties that make them suitable materials for the development of photovoltaics, imaging and lighting applications, among others. In this work, we report on a new methodology for the deposition of high quality, large grain size and pinhole free PS films (CH3NH3PbI3) with embedded PbS and PbS/CdS core/shell Quantum Dots (QDs). The strong interaction between both semiconductors is revealed by the formation of an exciplex state, which is monitored by photoluminescence and electroluminescence experiments. The radiative exciplex relaxation is centered in the near infrared region (NIR), ~1200 nm, which corresponds to lower energies than the corresponding band gap of both perovskite (PS) and QDs. Our approach allows the fabrication of multi-wavelength light emitting diodes (LEDs) based on a PS matrix with embedded QDs, which show considerably low turn-on potentials. The presence of the exciplex state of PS and QDs opens up a broad range of possibilities with important implications in both LEDs and solar cells.Hybrid lead halide perovskite (PS) derivatives have emerged as very promising materials for the development of optoelectronic devices in the last few years. At the same time, inorganic nanocrystals with quantum confinement (QDs) possess unique properties that make them suitable materials for the development of photovoltaics, imaging and lighting applications, among others. In this work, we report on a new methodology for the deposition of high quality, large grain size and pinhole free PS films (CH3NH3PbI3) with embedded PbS and PbS/CdS core/shell Quantum Dots (QDs). The strong interaction between both semiconductors is revealed by the formation of an exciplex state, which is monitored by photoluminescence and

Coffee-Ring-Free Quantum Dot Thin Film Using Inkjet Printing from a Mixed-Solvent System on Modified ZnO Transport Layer for Light-Emitting Devices.

PubMed

Jiang, Congbiao; Zhong, Zhiming; Liu, Baiquan; He, Zhiwei; Zou, Jianhua; Wang, Lei; Wang, Jian; Peng, JunBiao; Cao, Yong

2016-10-05

Inkjet printing has been considered an available way to achieve large size full-color RGB quantum dots LED display, and the key point is to obtain printed film with uniform and flat surface profile. In this work, mixed solvent of 20 vol % 1,2-dichlorobenzene (oDCB) with cyclohexylbenzene (CHB) was used to dissolve green quantum dots (QDs) with CdSe@ZnS/ZnS core/shell structure. Then, by inkjet printing, a flat dotlike QDs film without the coffee ring was successfully obtained on polyetherimide (PEI)-modified ZnO layer, and the printed dots array exhibited great stability and repeatability. Here, adding oDCB into CHB solutions was used to reduce surface tension, and employing ZnO nanoparticle layer with PEI-modified was used to increase the surface free energy. As a result, a small contact angle is formed, which leads to the enhancement of evaporation rate, and then the coffee ring effect was suppressed. The printed dots with flat surface profile were eventually realized. Moreover, inverted green QD-LEDs with PEI-modified ZnO film as electron transport layer (ETL) and printed green QDs film as emission layer were successfully fabricated. The QD-LEDs exhibited the maximum luminance of 12 000 cd/m 2 and the peak current efficiency of 4.5 cd/A at luminance of 1500 cd/m 2 .

Electrochemiluminescence sensors for scavengers of hydroxyl radical based on its annihilation in CdSe quantum dots film/peroxide system.

PubMed

Jiang, Hui; Ju, Huangxian

2007-09-01

This work elucidated the detailed electrochemiluminescence (ECL) process of the thioglycolic acid-capped CdSe quantum dots (QDs) film/peroxide aqueous system. The QDs were first electrochemically reduced to form electrons-injected QDs approximately -1.1 V, which then reduced hydrogen peroxide to produce OH* radical. The intermediate OH* radical was a key species for producing holes-injected QDs. The ECL emission with a peak at -1.114 V was demonstrated to come from the 1Se-1Sh transition emission. Using thiol compounds as the model molecules to annihilate the OH* radical, their quenching effects on ECL emission were studied. This effect led to a novel strategy for ECL sensing of the scavengers of hydroxyl radical. The detection results of thiol compounds showed high sensitivity, good precision, and acceptable accuracy, suggesting the promising application of the proposed method for quick detection of both scavengers and generators of hydroxyl radical in different fields.

Hierarchical hybrid film of MnO2 nanoparticles/multi-walled fullerene nanotubes-graphene for highly selective sensing of hydrogen peroxide.

PubMed

Pan, Yang; Hou, Zhaohui; Yi, Wei; Zhu, Wei; Zeng, Fanyan; Liu, You-Nian

2015-08-15

Hierarchical hybrid films of MnO2 nanoparticles/multi-walled fullerene nanotubes-graphene (MNPs/MWFNTs-GS) have been prepared via a simple wet-chemical method. For this purpose, MWFNTs (~300nm in length) are fabricated from tailoring multi-walled carbon nanotubes (MWCNTs), and then inserted into GS to pile up into a hierarchical hybrid film with the in situ formative MNPs. Scanning electron microscope, transmission electron microscope and X-ray diffraction are used to confirm the morphology and structure of the as-obtained film. The electrochemical studies reveal that MNPs/MWFNTs-GS exhibit significantly enhanced electrocatalytic activity compared with MNPs/GS, and show a rapid response to H2O2 over a wide linear range of 2.0μM-8.44mM with a high sensitivity of 206.3μA mM(-1)cm(-2) and an excellent selectivity. These favorable electrochemical detection properties may be mainly attributed to the introduction of MWFNTs, which helps to promote the electron/ion transport between MNPs and GS and form the hierarchical film structure. Copyright © 2015 Elsevier B.V. All rights reserved.

Organic-inorganic hybrid perovskite quantum dots with high PLQY and enhanced carrier mobility through crystallinity control by solvent engineering and solid-state ligand exchange.

PubMed

Woo Choi, Jin; Woo, Hee Chul; Huang, Xiaoguang; Jung, Wan-Gil; Kim, Bong-Joong; Jeon, Sie-Wook; Yim, Sang-Youp; Lee, Jae-Suk; Lee, Chang-Lyoul

2018-05-22

The photoluminescence quantum yield (PLQY) and charge carrier mobility of organic-inorganic perovskite QDs were enhanced by the optimization of crystallinity and surface passivation as well as solid-state ligand exchange. The crystallinity of perovskite QDs was determined by the Effective solvent field (Esol) of various solvents for precipitation. The solvent with high Esol could more quickly countervail the localized field generated by the polar solvent, and it causes fast crystallization of the dissolved precursor, which results in poor crystallinity. The post-ligand adding process (PLAP) and post-ligand exchange process (PLEP) increase the PLQY of perovskite QDs by reducing non-radiative recombination and the density of surface defect states through surface passivation. Particularly, the post ligand exchange process (PLEP) in the solid-state improved the charge carrier mobility of perovskite QDs in addition to the PLQY enhancement. The ligand exchange with short alkyl chain length ligands could improve the packing density of perovskite QDs in films by reducing the inter-particle distance between perovskite QDs. The maximum hole mobility of 6.2 × 10-3 cm2 V-1 s-1, one order higher than that of pristine QDs without the PLEP, is obtained at perovskite QDs with hexyl ligands. By using PLEP treatment, compared to the pristine device, a 2.5 times higher current efficiency in perovskite QD-LEDs was achieved due to the improved charge carrier mobility and PLQY.

XPS-nanocharacterization of organic layers electrochemically grafted on the surface of SnO2 thin films to produce a new hybrid material coating

NASA Astrophysics Data System (ADS)

Drevet, R.; Dragoé, D.; Barthés-Labrousse, M. G.; Chaussé, A.; Andrieux, M.

2016-10-01

This work presents the synthesis and the characterization of hybrid material thin films obtained by the combination of two processes. The electrochemical grafting of organic layers made of carboxyphenyl moieties is carried out from the reduction of a diazonium salt on tin dioxide (SnO2) thin films previously deposited on Si substrates by metal organic chemical vapor deposition (MOCVD). Since the MOCVD experimental parameters impact the crystal growth of the SnO2 layer (i.e. its morphology and its texturation), various electrochemical grafting models can occur, producing different hybrid materials. In order to evidence the efficiency of the electrochemical grafting of the carboxyphenyl moieties, X-ray Photoelectron Spectroscopy (XPS) is used to characterize the first nanometers in depth of the synthesized hybrid material layer. Then three electrochemical grafting models are proposed.

Quantum-dot light-emitting diodes utilizing CdSe /ZnS nanocrystals embedded in TiO2 thin film

NASA Astrophysics Data System (ADS)

Kang, Seung-Hee; Kumar, Ch. Kiran; Lee, Zonghoon; Kim, Kyung-Hyun; Huh, Chul; Kim, Eui-Tae

2008-11-01

Quantum-dot (QD) light-emitting diodes (LEDs) are demonstrated on Si wafers by embedding core-shell CdSe /ZnS nanocrystals in TiO2 thin films via plasma-enhanced metallorganic chemical vapor deposition. The n-TiO2/QDs /p-Si LED devices show typical p-n diode current-voltage and efficient electroluminescence characteristics, which are critically affected by the removal of QD surface ligands. The TiO2/QDs /Si system we presented can offer promising Si-based optoelectronic and electronic device applications utilizing numerous nanocrystals synthesized by colloidal solution chemistry.

Resonance Energy Transfer-Based Nucleic Acid Hybridization Assays on Paper-Based Platforms Using Emissive Nanoparticles as Donors.

PubMed

Doughan, Samer; Noor, M Omair; Han, Yi; Krull, Ulrich J

2017-01-01

Quantum dots (QDs) and upconverting nanoparticles (UCNPs) are luminescent nanoparticles (NPs) commonly used in bioassays and biosensors as resonance energy transfer (RET) donors. The narrow and tunable emissions of both QDs and UCNPs make them versatile RET donors that can be paired with a wide range of acceptors. Ratiometric signal processing that compares donor and acceptor emission in RET-based transduction offers improved precision, as it accounts for fluctuations in the absolute photoluminescence (PL) intensities of the donor and acceptor that can result from experimental and instrumental variations. Immobilizing NPs on a solid support avoids problems such as those that can arise with their aggregation in solution, and allows for facile layer-by-layer assembly of the interfacial chemistry. Paper is an attractive solid support for the development of point-of-care diagnostic assays given its ubiquity, low-cost, and intrinsic fluid transport by capillary action. Integration of nanomaterials with paper-based analytical devices (PADs) provides avenues to augment the analytical performance of PADs, given the unique optoelectronic properties of nanomaterials. Herein, we describe methodology for the development of PADs using QDs and UCNPs as RET donors for optical transduction of nucleic acid hybridization. Immobilization of green-emitting QDs (gQDs) on imidazole functionalized cellulose paper is described for use as RET donors with Cy3 molecular dye as acceptors for the detection of SMN1 gene fragment. We also describe the covalent immobilization of blue-emitting UCNPs on aldehyde modified cellulose paper for use as RET donors with orange-emitting QDs (oQDs) as acceptors for the detection of HPRT1 gene fragment. The data described herein is acquired using an epifluorescence microscope, and can also be collected using technology such as a typical electronic camera.

High-response hybrid quantum dots- 2D conductor phototransistors: recent progress and perspectives

NASA Astrophysics Data System (ADS)

Sablon, Kimberly A.; Sergeev, Andrei; Najmaei, Sina; Dubey, Madan

2017-03-01

Having been inspired by the tremendous progress in material nanoscience and device nanoengineering, hybrid phototransistors combine solution processed colloidal semiconductor quantum dots (QDs) with graphene or two-dimensional (2D) semiconductor materials. Novel detectors demonstrate ultrahigh photoconductive gain, high and selective photoresponse, low noise, and very high responsivity in visible- and near-infrared ranges. The outstanding performance of phototransistors is primarily due to the strong, selective, and size tunable absorption of QDs and fast charge transfer in 2D high mobility conductors. However, the relatively small mobility of QD nanomaterials was a technological barrier, which limited the operating rate of devices. Very recent innovations in detector design and significant progress in QD ligand engineering provide effective tools for further qualitative improvements. This article reviews the recent progress in material science, nanophysics, and device engineering related to hybrid phototransistors. Detectors based on various QD nanomaterials and several 2D conductors are compared, and advantages and disadvantages of various nanomaterials for applications in hybrid phototransistors are identified. We also benchmark the experimental characteristics with model results that establish interrelations and tradeoffs between detector characteristics, such as responsivity, dark and noise currents, the photocarrier lifetime, response, and noise bandwidths. We have shown that the most recent phototransistors demonstrate performance limited by the fundamental generation recombination noise in high gain devices. Interrelation between the dynamic range of the detector and the detector sensitivity is discussed. The review is concluded with a brief discussion of the remaining challenges and possible significant improvements in the performance of hybrid phototransistors.

Charge carrier dynamics investigation of CuInS2 quantum dots films using injected charge extraction by linearly increasing voltage (i-CELIV): the role of ZnS Shell

NASA Astrophysics Data System (ADS)

Bi, Ke; Sui, Ning; Zhang, Liquan; Wang, Yinghui; Liu, Qinghui; Tan, Mingrui; Zhou, Qiang; Zhang, Hanzhuang

2016-12-01

The role of ZnS shell on the photo-physical properties within CuInS2/ZnS quantum dots (QDs) is carefully studied in optoelectronic devices. Linearly increasing voltage technique has been employed to investigate the charge carrier dynamics of both CuInS2 and CuInS2/ZnS QDs films. This study shows that charge carriers follow a similar behavior of monomolecular recombination in this film, with their charge transfer rate correlates to the increase of applied voltage. It turns out that the ZnS shell could affect the carrier diffusion process through depressing the trapping states and would build up a potential barrier.

Highly luminescent InP/GaP/ZnS QDs emitting in the entire color range via a heating up process.

PubMed

Park, Joong Pill; Lee, Jae-Joon; Kim, Sang-Wook

2016-07-20

InP-based quantum dots (QDs) have attracted much attention for use in optical applications, and several types of QDs such as InP/ZnS, InP/ZnSeS, and InP/GaP/ZnS have been developed. However, early synthetic methods that involved rapid injection at high temperatures have not been able to reproducibly produce the required optical properties. They were also not able to support commercialization efforts successfully. Herein, we introduce a simple synthetic method for InP/GaP/ZnS core/shell/shell QDs via a heating process. The reaction was completed within 0.5 h and a full color range from blue to red was achieved. For emitting blue color, t-DDT was applied to prevent particle growth. From green to orange, color variation was achieved by adjusting the quantity of myristic acid. Utilizing large quantities of gallium chloride led to red color. With this method, we produced high-quality InP/GaP/ZnS QDs (blue QY: ~40%, FWHM: 50 nm; green QY: ~85%, FWHM: 41 nm; red QY: ~60%, FWHM: 65 nm). We utilized t-DDT as a new sulfur source. Compared with n-DDT, t-DDT was more reactive, which allowed for the formation of a thicker shell.

Highly luminescent InP/GaP/ZnS QDs emitting in the entire color range via a heating up process

PubMed Central

Park, Joong Pill; Lee, Jae-Joon; Kim, Sang-Wook

2016-01-01

InP-based quantum dots (QDs) have attracted much attention for use in optical applications, and several types of QDs such as InP/ZnS, InP/ZnSeS, and InP/GaP/ZnS have been developed. However, early synthetic methods that involved rapid injection at high temperatures have not been able to reproducibly produce the required optical properties. They were also not able to support commercialization efforts successfully. Herein, we introduce a simple synthetic method for InP/GaP/ZnS core/shell/shell QDs via a heating process. The reaction was completed within 0.5 h and a full color range from blue to red was achieved. For emitting blue color, t-DDT was applied to prevent particle growth. From green to orange, color variation was achieved by adjusting the quantity of myristic acid. Utilizing large quantities of gallium chloride led to red color. With this method, we produced high-quality InP/GaP/ZnS QDs (blue QY: ~40%, FWHM: 50 nm; green QY: ~85%, FWHM: 41 nm; red QY: ~60%, FWHM: 65 nm). We utilized t-DDT as a new sulfur source. Compared with n-DDT, t-DDT was more reactive, which allowed for the formation of a thicker shell. PMID:27435428

Highly luminescent InP/GaP/ZnS QDs emitting in the entire color range via a heating up process

NASA Astrophysics Data System (ADS)

Park, Joong Pill; Lee, Jae-Joon; Kim, Sang-Wook

2016-07-01

InP-based quantum dots (QDs) have attracted much attention for use in optical applications, and several types of QDs such as InP/ZnS, InP/ZnSeS, and InP/GaP/ZnS have been developed. However, early synthetic methods that involved rapid injection at high temperatures have not been able to reproducibly produce the required optical properties. They were also not able to support commercialization efforts successfully. Herein, we introduce a simple synthetic method for InP/GaP/ZnS core/shell/shell QDs via a heating process. The reaction was completed within 0.5 h and a full color range from blue to red was achieved. For emitting blue color, t-DDT was applied to prevent particle growth. From green to orange, color variation was achieved by adjusting the quantity of myristic acid. Utilizing large quantities of gallium chloride led to red color. With this method, we produced high-quality InP/GaP/ZnS QDs (blue QY: ~40%, FWHM: 50 nm green QY: ~85%, FWHM: 41 nm red QY: ~60%, FWHM: 65 nm). We utilized t-DDT as a new sulfur source. Compared with n-DDT, t-DDT was more reactive, which allowed for the formation of a thicker shell.

Fabrication of a Quartz-Crystal-Microbalance/Optical-Waveguide Hybrid Sensor and In situ Evaluation of Vacuum-Evaporated Lead Phthalocyanine Thin Film

NASA Astrophysics Data System (ADS)

Shinbo, Kazunari; Uno, Akihiro; Hirakawa, Ryo; Baba, Akira; Ohdaira, Yasuo; Kato, Keizo; Kaneko, Futao

2013-05-01

In this study, we fabricated a novel quartz-crystal-microbalance (QCM)/optical-waveguide hybrid sensor. An in situ observation of a lead phthalocyanine (PbPc) thin-film deposition was conducted during vacuum evaporation, and the effectiveness of the sensor was demonstrated. The film thickness was obtained from the QCM frequency, and the optical absorption of the film was observed by optical waveguide spectroscopy using part of the QCM substrate without the electrode. The film absorption depends on the polarization direction, substrate temperature and deposition rate, owing to aggregate formation. The thickness dependence of the absorption property was also investigated.

Dewetting-Induced Photoluminescent Enhancement of Poly(lauryl methacrylate)/Quantum Dot Thin Films.

PubMed

Geldmeier, Jeffrey; Rile, Lexy; Yoon, Young Jun; Jung, Jaehan; Lin, Zhiqun; Tsukruk, Vladimir V

2017-12-19

A new method for enhancing photoluminescence from quantum dot (QD)/polymer nanocomposite films is proposed. Poly(lauryl methacrylate) (PLMA) thin films containing embedded QDs are intentionally allowed to undergo dewetting on substrates by exposure to a nonsolvent vapor. After controlled dewetting, films exhibited typical dewetting morphologies with increased amounts of scattering that served to outcouple photoluminescence from the film and reduce internal light propagation within the film. Up to a 5-fold enhancement of the film emission was achieved depending on material factors such as the initial film thickness and QD concentration within the film. An increase in initial film thickness was shown to increase the dewetted maximum feature size and its characteristic length until a critical thickness was reached where dewetting became inhibited. A unique light exposure-based photopatterning method is also presented for the creation of high contrast emissive patterns as guided by spatially controlled dewetting.

Spontaneous formation of linearly arranged microcraters on sol-gel-derived silica-poly(vinylpyrrolidone) hybrid films induced by Bénard-Marangoni convection.

PubMed

Uchiyama, Hiroaki; Mantani, Yuto; Kozuka, Hiromitsu

2012-07-10

Complex, sophisticated surface patterns on micrometer and nanometer scales are obtained when solvent evaporates from solutions containing nonvolatile solutes dropped on a solid substrate. Such evaporation-driven pattern formation has been utilized as a fabrication process of highly ordered patterns in thin films. Here, we suggested the spontaneous pattern formation induced by Bénard-Marangoni convection triggered by solvent evaporation as a novel patterning process of sol-gel-derived organic-inorganic hybrid films. Microcraters of 1.0-1.5 μm in height and of 100-200 μm in width were spontaneously formed on the surface of silica-poly(vinylpyrrolidone) hybrid films prepared via temperature-controlled dip-coating process, where the surface patterns were linearly arranged parallel to the substrate withdrawal direction. Such highly ordered micropatterns were achieved by Bénard-Marangoni convection activated at high temperatures and the unidirectional flow of the coating solution on the substrate during dip-coating.

Organic/Inorganic Hybrid Nanocomposite Infrared Photodetection by Intraband Absorption

NASA Astrophysics Data System (ADS)

Lantz, Kevin Richard

The ability to detect infrared radiation is vital for a host of applications that include optical communication, medical diagnosis, thermal imaging, atmospheric monitoring, and space science. The need to actively cool infrared photon detectors increases their operation cost and weight, and the focus of much recent research has been to limit the dark current and create room-temperature infrared photodetectors appropriate for mid-to-long-wave infrared detection. Quantum dot infrared photodetectors (QDIPs) provide electron quantum confinement in three dimensions and have been shown to demonstrate high temperature operation (T>150 K) due to lower dark currents. However, these inorganic devices have not achieved sensitivity comparable to state-of-the-art photon detectors, due in large part to the inability to control the uniformity (size and shape) of QDs during strained-layer epitaxy. The purpose of this dissertation research was to investigate the feasibility of room-temperature infrared photodetection that could overcome the shortfalls of QDIPs by using chemically synthesized inorganic colloidal quantum dots (CQDs). CQDs are coated with organic molecules known as surface ligands that prevent the agglomeration of dots while in solution. When CQDs are suspended in a semiconducting organic polymer, these materials are known as organic/inorganic hybrid nanocomposites. The novel approach investigated in this work was to use intraband transitions in the conduction band of the polymer-embedded CQD for room-temperature photodetection in the mid-wave, and possibly long-wave, infrared ranges. Hybrid nanocomposite materials promise room-temperature operation due to: (i) large bandgaps of the inorganic CQDs and the semiconducting polymer that reduce thermionic emission; and (ii) low dark current due to the three-dimensional electron confinement in the CQD and low carrier mobility in the semiconducting polymer. The primary material system investigated in this research was Cd

Formation mechanism of photo-induced nested wrinkles on siloxane-photomonomer hybrid film

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

Suzuki, Kazumasa; International Laboratory of Materials Science and Nanotechnology; Laboratorio di Scienz

Nested wrinkle structures, hierarchical surface wrinkles of different periodicities of sub-μm and tens-μm, have been fabricated on a siloxane-photomonomer hybrid film via a photo-induced surface polymerization of acrylamide. The formation mechanism of the nested wrinkle structures is examined based on a time-dependent structure observation and chemical composition analyses. In-situ observation of the evolving surface structure showed that sub-μm scale wrinkles first formed, subsequently the tens-μm scale ones did. In-situ FT-IR analysis indicated that the nested wrinkles formation took place along with the development of siloxane network of under layer. A cross sectional observation of the film revealed that the filmmore » was composed of three layers. FT-IR spectra of the film revealed that the surface and interior layers were polyacrylamide rich layer and siloxane-polymer rich layer, respectively. The intermediate layer formed as a diffusion layer by migration of acrylamide from interior to the surface. These three layers have different chemical compositions and therefore different mechanical characteristics, which allows the wrinkle formation. Shrinkage of siloxane-polymer interior layers, as a result of polycondensation of siloxane network, induced mechanical instabilities at interlayers, to form the nested wrinkle structures.« less

Modification of Light Emission in Si-Rich Silicon Nitride Films Versus Stoichiometry and Excitation Light Energy

NASA Astrophysics Data System (ADS)

Torchynska, T.; Khomenkova, L.; Slaoui, A.

2018-04-01

Si-rich SiN x films with different stoichiometry were grown on Si substrate by plasma-enhanced chemical vapor deposition. The Si content was varied by changing the NH3/SiH4 gas flow ratio from 0.45 up to 1.0. Conventional furnace annealing at 1100°C for 30 min was applied to produce the Si quantum dots (QDs) in the SiN x films. Spectroscopic ellipsometry was used to determine the refractive index of the SiN x films that allowed estimating the film's stoichiometry. Fourier transform infrared spectroscopy has been also used to confirm the stoichiometry and microstructure. Photoluminescence (PL) spectra of Si-rich SiN x films are complex. A non-monotonous variation of the different PL peaks versus Si excess contents testifies to the competition of different radiative channels. The analysis of PL spectra, measured at the different excitation light energies and variable temperatures, has revealed that the PL bands with the peaks within the range 2.1-3.0 eV are related to the carrier recombination via radiative native defects in the SiN x host. Simultaneously, the PL bands with the peaks at 1.5-2.0 eV are caused by the exciton recombination in the Si QDs of different sizes. The way to control the SiN x emission is discussed.

Modification of Light Emission in Si-Rich Silicon Nitride Films Versus Stoichiometry and Excitation Light Energy

NASA Astrophysics Data System (ADS)

Torchynska, T.; Khomenkova, L.; Slaoui, A.

2018-07-01

Si-rich SiN x films with different stoichiometry were grown on Si substrate by plasma-enhanced chemical vapor deposition. The Si content was varied by changing the NH3/SiH4 gas flow ratio from 0.45 up to 1.0. Conventional furnace annealing at 1100°C for 30 min was applied to produce the Si quantum dots (QDs) in the SiN x films. Spectroscopic ellipsometry was used to determine the refractive index of the SiN x films that allowed estimating the film's stoichiometry. Fourier transform infrared spectroscopy has been also used to confirm the stoichiometry and microstructure. Photoluminescence (PL) spectra of Si-rich SiN x films are complex. A non-monotonous variation of the different PL peaks versus Si excess contents testifies to the competition of different radiative channels. The analysis of PL spectra, measured at the different excitation light energies and variable temperatures, has revealed that the PL bands with the peaks within the range 2.1-3.0 eV are related to the carrier recombination via radiative native defects in the SiN x host. Simultaneously, the PL bands with the peaks at 1.5-2.0 eV are caused by the exciton recombination in the Si QDs of different sizes. The way to control the SiN x emission is discussed.

Hybrid phototransistors based on bulk heterojunction films of poly(3-hexylthiophene) and zinc oxide nanoparticle.

PubMed

Nam, Sungho; Seo, Jooyeok; Park, Soohyeong; Lee, Sooyong; Jeong, Jaehoon; Lee, Hyena; Kim, Hwajeong; Kim, Youngkyoo

2013-02-01

Hybrid phototransistors (HPTRs) were fabricated on glass substrates using organic/inorganic hybrid bulk heterojunction films of p-type poly(3-hexylthiophene) (P3HT) and n-type zinc oxide nanoparticles (ZnO(NP)). The content of ZnO(NP) was varied up to 50 wt % in order to understand the composition effect of ZnO(NP) on the performance of HPTRs. The morphology and nanostructure of the P3HT:ZnO(NP) films was examined by employing high resolution electron microscopes and synchrotron radiation grazing angle X-ray diffraction system. The incident light intensity (P(IN)) was varied up to 43.6 μW/cm², whereas three major wavelengths (525 nm, 555 nm, 605 nm) corresponded to the optical absorption of P3HT were applied. Results showed that the present HPTRs showed typical p-type transistor performance even though the n-type ZnO(NP) content increased up to 50 wt %. The highest transistor performance was obtained at 50 wt %, whereas the lowest performance was measured at 23 wt % because of the immature bulk heterojunction morphology. The drain current (I(D)) was proportionally increased with P(IN) due to the photocurrent generation in addition to the field-effect current. The highest apparent and corrected responsivities (R(A) = 4.7 A/W and R(C) = 2.07 A/W) were achieved for the HPTR with the P3HT:ZnO(NP) film (50 wt % ZnO(NP)) at P(IN) = 0.27 μW/cm² (555 nm).

Construction of optical glucose nanobiosensor with high sensitivity and selectivity at physiological pH on the basis of organic-inorganic hybrid microgels.

PubMed

Wu, Weitai; Zhou, Ting; Aiello, Michael; Zhou, Shuiqin

2010-08-15

A new class of optical glucose nanobiosensors with high sensitivity and selectivity at physiological pH is described. To construct these glucose nanobiosensors, the fluorescent CdS quantum dots (QDs), serving as the optical code, were incorporated into the glucose-sensitive poly(N-isopropylacrylamide-acrylamide-2-acrylamidomethyl-5-fluorophenylboronic acid) copolymer microgels, via both in situ growth method and "breathing in" method, respectively. The polymeric gel can adapt to surrounding glucose concentrations, and regulate the fluorescence of the embedded QDs, converting biochemical signals into optical signals. The gradual swelling of the gel would lead to the quenching of the fluorescence at the elevated glucose concentrations. The hybrid microgels displayed high selectivity to glucose over the potential primary interferents of lactate and human serum albumin in the physiologically important glucose concentration range. The stability, reversibility, and sensitivity of the organic-inorganic hybrid microgel-based biosensors were also systematically studied. These general properties of our nanobiosensors are well tunable under appropriate tailor on the hybrid microgels, in particular, simply through the change in the crosslinking degree of the microgels. The optical glucose nanobiosensors based on the organic-inorganic hybrid microgels have shown the potential for a third generation fluorescent biosensor. Copyright 2010 Elsevier B.V. All rights reserved.

Solid state microelectronics tolerant to radiation and high temperature. [JFET thick film hybrids

NASA Technical Reports Server (NTRS)

Draper, B. L.; Palmer, D. W.

1981-01-01

The 300 C electronics technology based on JFET thick film hybrids was tested up to 10 to the 9th power rad gamma (Si) and 10 to the 15th power neutrons/sq cm. Circuits and individual components from this technology all survived this total dose although some devices required 1 hour of annealing at 200 or 300 C to regain functionality. This technology used with real time annealing should function to levels greater than 10 to the 10th power rad gamma and 10 to the 16th power n/sq cm.

Developing a fluorescence-coupled capillary electrophoresis based method to probe interactions between QDs and colorectal cancer targeting peptides.

PubMed

Liu, Feifei; Wang, Jianhao; Yang, Li; Liu, Li; Ding, Shumin; Fu, Minli; Deng, Linhong; Gao, Li-Qian

2016-08-01

As is well known, quantum dots (QDs) have become valuable probes for cancer imaging. In particular, QD-labeled targeting peptides are capable of identifying cancer or tumors cells. A new colorectal cancer targeting peptide, cyclo(1, 9)-CTPSPFSHC, has strong targeting ability and also shows great potential in the identification and treatment of colon cancer. Herein, we synthesized a dual functional polypeptide, cyclo(1, 9)-CTPSPFSHCD2 G2 DP9 G3 H6 (H6 -TCP), to investigate its interaction with QDs inside the capillary. Fluorescence-coupled CE was adopted and applied to characterize the self-assembly of H6 -TCP onto QDs. It was indicated that the formation of the assembly was affected by H6 -TCP/QD molar ratio and sampling time. This novel in-capillary assay greatly reduced the sample consumption and the detection time, which was beneficial for the environment. It is expected that this kind of detection method could find more applications to provide more useful information for cancer diagnosis and detection of harm and hazardous substances/organisms in the environment in the future. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Camera-based ratiometric fluorescence transduction of nucleic acid hybridization with reagentless signal amplification on a paper-based platform using immobilized quantum dots as donors.

PubMed

Noor, M Omair; Krull, Ulrich J

2014-10-21

Paper-based diagnostic assays are gaining increasing popularity for their potential application in resource-limited settings and for point-of-care screening. Achievement of high sensitivity with precision and accuracy can be challenging when using paper substrates. Herein, we implement the red-green-blue color palette of a digital camera for quantitative ratiometric transduction of nucleic acid hybridization on a paper-based platform using immobilized quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET). A nonenzymatic and reagentless means of signal enhancement for QD-FRET assays on paper substrates is based on the use of dry paper substrates for data acquisition. This approach offered at least a 10-fold higher assay sensitivity and at least a 10-fold lower limit of detection (LOD) as compared to hydrated paper substrates. The surface of paper was modified with imidazole groups to assemble a transduction interface that consisted of immobilized QD-probe oligonucleotide conjugates. Green-emitting QDs (gQDs) served as donors with Cy3 as an acceptor. A hybridization event that brought the Cy3 acceptor dye in close proximity to the surface of immobilized gQDs was responsible for a FRET-sensitized emission from the acceptor dye, which served as an analytical signal. A hand-held UV lamp was used as an excitation source and ratiometric analysis using an iPad camera was possible by a relative intensity analysis of the red (Cy3 photoluminescence (PL)) and green (gQD PL) color channels of the digital camera. For digital imaging using an iPad camera, the LOD of the assay in a sandwich format was 450 fmol with a dynamic range spanning 2 orders of magnitude, while an epifluorescence microscope detection platform offered a LOD of 30 fmol and a dynamic range spanning 3 orders of magnitude. The selectivity of the hybridization assay was demonstrated by detection of a single nucleotide polymorphism at a contrast ratio of 60:1. This work provides an

Hybridized boron-carbon nitride fibrous nanostructures on Ni substrates

NASA Astrophysics Data System (ADS)

Yap, Yoke Khin; Yoshimura, Masashi; Mori, Yusuke; Sasaki, Takatomo

2002-04-01

Stoichiometric BC2N films can be deposited on Si (100) at 800 °C, however, they are phase separated as pure carbon and BN phases. Likewise, hybridized boron-carbon nitride (BCN) films can be synthesized on Ni substrates. On Ni, the carbon and BN phases are hybridized through carbon nitride and boron carbide bonds. These films appeared as fibrous nanostructures. Evidence indicates that the Ni substrate acts as a sink for the carbon and forces the carbon composites to grow on top of the B and N atoms. However, as these films are grown thicker, phase separation occurs again. These results indicate that hybridized BCN phases should now be regarded as semiconducting or superhard nanostructures. High-temperature deposition on Ni substrates might be a solution to the obstacle of preparing hybridized BCN phases.

Fabrication of white light-emitting diodes based on UV light-emitting diodes with conjugated polymers-(CdSe/ZnS) quantum dots as hybrid phosphors.

PubMed

Jung, Hyunchul; Chung, Wonkeun; Lee, Chang Hun; Kim, Sung Hyun

2012-07-01

White light-emitting diodes (LEDs) were fabricated using GaN-based 380-nm UV LEDs precoated with the composite of blue-emitting polymer (poly[(9,9-dihexylfluorenyl-2,7-diyl)-alt-co-(2-methoxy-5-{2-ethylhexyloxy)-1 ,4-phenylene)]), yellow green-emitting polymer (poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1',3}-thiadiazole)]), and 605-nm red-emitting quantum dots (QDs). CdSe cores were obtained by solvothermal route using CdO, Se precursors and ZnS shells were synthesized by using diethylzinc, and hexamethyldisilathiane precursors. The optical properties of CdSe/ZnS QDs were characterized by UV-visible and photoluminescence (PL) spectra. The structural data and composition of the QDs were transmission electron microscopy (TEM), and EDX technique. The quantum yield and size of the QDs were 58.7% and about 6.7 nm, respectively. Three-band white light was generated by hybridizing blue (430 nm), green (535 nm), and red (605 nm) emission. The color-rendering index (CRI) of the device was extremely improved by introducing the QDs. The CIE-1931 chromaticity coordinate, color temperature, and CRI of a white LED at 20 mA were (0.379, 0.368), 3969 K, and 90, respectively.

Tuning of the Morphology and Optoelectronic Properties of ZnO/P3HT/P3HT- b-PEO Hybrid Films via Spray Deposition Method.

PubMed

Wang, Kun; Bießmann, Lorenz; Schwartzkopf, Matthias; Roth, Stephan V; Müller-Buschbaum, Peter

2018-06-20

The self-assembly of amphiphilic diblock copolymers yields the possibility of using them as a template for tailoring the film morphologies of sol-gel chemistry-derived inorganic electron transport materials, such as mesoporous ZnO and TiO 2 . However, additional steps including etching and backfilling are required for the common bulk heterojunction fabrication process when using insulating diblock copolymers. Here, we use the conducting diblock copolymer poly(3-hexylthiophene)- block-poly(ethylene oxide) (P3HT- b-PEO) in which P3HT acts as charge carrier transport material and light absorber, whereas PEO serves as a template for ZnO synthesis. The initial solution is subsequently spray-coated to obtain the hybrid film. Scanning electron microscopy and grazing-incidence small-angle X-ray scattering measurements reveal a significant change in the morphology of the hybrid films during deposition. Optoelectronic properties illustrate the improved charge separation and charge transfer process. Both the amount of the diblock copolymer and the annealing temperature play an important role in tuning the morphology and the optoelectronic properties. Hybrid films being sprayed from a solution with the ratio of ω ZnO , ω P3HT , and ω P3HT- b-PEO of 2:1:1 and subsequent annealing at 80 °C show the most promising morphology combined with an optimal photoluminescence quenching. Thus, the presented simple, reagent- and energy-saving fabrication method provides a promising approach for a large-scale preparation of bulk heterojunction P3HT/ZnO films on flexible substrates.

Strain-tuning of the optical properties of semiconductor nanomaterials by integration onto piezoelectric actuators

NASA Astrophysics Data System (ADS)

Martín-Sánchez, Javier; Trotta, Rinaldo; Mariscal, Antonio; Serna, Rosalía; Piredda, Giovanni; Stroj, Sandra; Edlinger, Johannes; Schimpf, Christian; Aberl, Johannes; Lettner, Thomas; Wildmann, Johannes; Huang, Huiying; Yuan, Xueyong; Ziss, Dorian; Stangl, Julian; Rastelli, Armando

2018-01-01

The tailoring of the physical properties of semiconductor nanomaterials by strain has been gaining increasing attention over the last years for a wide range of applications such as electronics, optoelectronics and photonics. The ability to introduce deliberate strain fields with controlled magnitude and in a reversible manner is essential for fundamental studies of novel materials and may lead to the realization of advanced multi-functional devices. A prominent approach consists in the integration of active nanomaterials, in thin epitaxial films or embedded within carrier nanomembranes, onto Pb(Mg1/3Nb2/3)O3-PbTiO3-based piezoelectric actuators, which convert electrical signals into mechanical deformation (strain). In this review, we mainly focus on recent advances in strain-tunable properties of self-assembled InAs quantum dots (QDs) embedded in semiconductor nanomembranes and photonic structures. Additionally, recent works on other nanomaterials like rare-earth and metal-ion doped thin films, graphene and MoS2 or WSe2 semiconductor two-dimensional materials are also reviewed. For the sake of completeness, a comprehensive comparison between different procedures employed throughout the literature to fabricate such hybrid piezoelectric-semiconductor devices is presented. It is shown that unprocessed piezoelectric substrates (monolithic actuators) allow to obtain a certain degree of control over the nanomaterials’ emission properties such as their emission energy, fine-structure-splitting in self-assembled InAs QDs and semiconductor 2D materials, upconversion phenomena in BaTiO3 thin films or piezotronic effects in ZnS:Mn films and InAs QDs. Very recently, a novel class of micro-machined piezoelectric actuators have been demonstrated for a full control of in-plane stress fields in nanomembranes, which enables producing energy-tunable sources of polarization-entangled photons in arbitrary QDs. Future research directions and prospects are discussed.

Bioelectrochemistry of heme peptide at seamless three-dimensional carbon nanotubes/graphene hybrid films for highly sensitive electrochemical biosensing.

PubMed

Komori, Kikuo; Terse-Thakoor, Trupti; Mulchandani, Ashok

2015-02-18

A seamless three-dimensional hybrid film consisting of carbon nanotubes grown at the graphene surface (CNTs/G) is a promising material for the application to highly sensitive enzyme-based electrochemical biosensors. The CNTs/G film was used as a conductive nanoscaffold for enzymes. The heme peptide (HP) was immobilized on the surface of the CNTs/G film for amperometric sensing of H2O2. Compared with flat graphene electrodes modified with HP, the catalytic current for H2O2 reduction at the HP-modified CNTs/G electrode increased due to the increase in the surface coverage of HP. In addition, microvoids in the CNTs/G film contributed to diffusion of H2O2 to modified HP, resulting in the enhancement of the catalytic cathodic currents. The kinetics of the direct electron transfer from the CNTs/G electrode to compound I and II of modified HP was also analyzed.

Enhanced photoelectrochemical DNA sensor based on TiO2/Au hybrid structure.

PubMed

Liu, Xing-Pei; Chen, Jing-Shuai; Mao, Chang-Jie; Niu, He-Lin; Song, Ji-Ming; Jin, Bao-Kang

2018-05-23

A novel enhanced photoelectrochemical DNA sensor, based on a TiO 2 /Au hybrid electrode structure, was developed to detect target DNA. The sensor was developed by successively modifying fluorine-tin oxide (FTO) electrodes with TiO 2 nanoparticles, gold (Au) nanoparticles, hairpin DNA (DNA1), and CdSe-COOH quantum dots (QDs), which acted as signal amplification factors. In the absence of target DNA, the incubated DNA1 hairpin and the CdSe-COOH QDs were in close contact with the TiO 2 /Au electrode surface, leading to an enhanced photocurrent intensity due to the sensitization effect. After incubation of the modified electrode with the target DNA, the hairpin DNA changed into a double helix structure, and the CdSe QDs moved away from the TiO 2 /Au electrode surface, leading to a decreased sensitization effect and photoelectrochemical signal intensity. This novel DNA sensor exhibited stable, sensitive and reproducible detection of DNA from 0.1 μM to 10 fM, with a lower detection limit of 3 fM. It provided good specificity, reproducibility, stability and is a promising strategy for the detection of a variety of other DNA targets, for early clinical diagnosis of various diseases. Copyright © 2018 Elsevier B.V. All rights reserved.

Connecting quantum dots and bionanoparticles in hybrid nanoscale ultra-thin films

NASA Astrophysics Data System (ADS)

Tangirala, Ravisubhash; Hu, Yunxia; Zhang, Qingling; He, Jinbo; Russell, Thomas; Emrick, Todd

2008-03-01

Aldehyde-functionalized CdSe quantum dots and nanorods, and horse spleen ferritin bionanoparticles, were co-assembled at an oil-water interface. Reaction of the aldehydes with the surface-available amines on the ferritin particles enabled cross-linking at the interface, converting the assembled nanoparticles into robust ultra-thin films. The cross-linked capsules and sheets thus made by aldehyde-amine conjugation could be disrupted by addition of acid. Reductive amination chemistry could be performed to convert these degradable capsules and sheets into structures with irreversible cross-linking. Fluorescence confocal microscopy, scanning force microscopy and pendant drop tensiometry were used to characterize these hybrid nanoparticle-based materials, and transmission electron microscopy (TEM) confirmed the presence of both the synthetic and naturally derived nanoparticles.

Interfacial transduction of nucleic acid hybridization using immobilized quantum dots as donors in fluorescence resonance energy transfer.

PubMed

Algar, W Russ; Krull, Ulrich J

2009-01-06

Fluorescence resonance energy transfer (FRET) using immobilized quantum dots (QDs) as energy donors was explored as a transduction method for the detection of nucleic acid hybridization at an interface. This research was motivated by the success of the QD-FRET-based transduction of nucleic acid hybridization in solution-phase assays. This new work represents a fundamental step toward the assembly of a biosensor, where immobilization of the selective chemistry on a surface is desired. After immobilizing QD-probe oligonucleotide conjugates on optical fibers, a demonstration of the retention of selectivity was achieved by the introduction of acceptor (Cy3)-labeled single-stranded target oligonucleotides. Hybridization generated the proximity required for FRET, and the resulting fluorescence spectra provided an analytical signal proportional to the amount of target. This research provides an important framework for the future development of nucleic acid biosensors based on QDs and FRET. The most important findings of this work are that (1) a QD-FRET solid-phase hybridization assay is viable and (2) a passivating layer of denatured bovine serum albumin alleviates nonspecific adsorption, ultimately resulting in (3) the potential for a reusable assay format and mismatch discrimination. In this, the first incarnation of a solid-phase QD-FRET hybridization assay, the limit of detection was found to be 5 nM, and the dynamic range was almost 2 orders of magnitude. Selective discrimination of the target was shown using a three-base-pairs mismatch from a fully complementary sequence. Despite a gradual loss of signal, reuse of the optical fibers over multiple cycles of hybridization and dehybridization was possible. Directions for further improvement of the analytical performance by optimizing the design of the QD-probe oligonucleotide interface are identified.

Photovoltaic Conversion Enhancement of a Carbon Quantum Dots/p-Type CuAlO2/n-Type ZnO Photoelectric Device.

PubMed

Pan, Jiaqi; Sheng, Yingzhuo; Zhang, Jingxiang; Huang, Peng; Zhang, Xin; Feng, Boxue

2015-04-22

Carbon quantum dots (C QDs)/p-type CuAlO2/n-type ZnO photoelectric bilayer film composites were prepared by a simple route, through which ZnO films were sputtered on crystal quartz substrates and CuAlO2 films were prepared by sol-gel on ZnO films and then these bilayer films were composited with C QDs on their surface. The characterization results indicated that C QDs were well combined with the surface of the CuAlO2 films. The photovoltage and photocurrent of these bilayer film composites were investigated under illumination and darkness switching, which demonstrated to be significantly enhanced compared with those of the CuAlO2/ZnO bilayer films. Through analysis, this enhancement of the photoconductivity was mainly attributed to C QDs with unique up-converted photoluminescence behavior.

Sub-micron Polymer–Zeolitic Imidazolate Framework Layered Hybrids via Controlled Chemical Transformation of Naked ZnO Nanocrystal Films

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

Meckler, Stephen M.; Li, Changyi; Queen, Wendy L.

2015-11-02

Here we show that sub-micron coatings of zeolitic imidazolate frameworks (ZIFs) and even ZIF–ZIF bilayers can be grown directly on polymers of intrinsic microporosity from zinc oxide (ZnO) nanocrystal precursor films, yielding a new class of all-microporous layered hybrids. The ZnO-to-ZIF chemical transformation proceeded in less than 30 min under microwave conditions using a solution of the imidazole ligand in N,N-dimethylformamide (DMF), water, or mixtures thereof. By varying the ratio of DMF to water, it was possible to control the morphology of the ZIF-on-polymer from isolated crystallites to continuous films. Grazing incidence X-ray diffraction was used to confirm the presencemore » of crystalline ZIF in the thin films, and X-ray absorption spectroscopy was used to quantify film purity, revealing films with little to no residual ZnO. The role solvent plays in the transformation mechanism is discussed in light of these findings, which suggest the ZnO nanocrystals may be necessary to localize heterogeneous nucleation of the ZIF to the polymer surface.« less

Sub-micron Polymer–Zeolitic Imidazolate Framework Layered Hybrids via Controlled Chemical Transformation of Naked ZnO Nanocrystal Films

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

Meckler, Stephen M.; Li, Changyi; Queen, Wendy L.

Here we show that sub-micron coatings of zeolitic imidazolate frameworks (ZIFs) and even ZIF–ZIF bilayers can be grown directly on polymers of intrinsic microporosity from zinc oxide (ZnO) nanocrystal precursor films, yielding a new class of all-microporous layered hybrids. The ZnO-to-ZIF chemical transformation proceeded in less than 30 min under microwave conditions using a solution of the imidazole ligand in N,N-dimethylformamide (DMF), water, or mixtures thereof. By varying the ratio of DMF to water, it was possible to control the morphology of the ZIF-on-polymer from isolated crystallites to continuous films. Grazing incidence X-ray diffraction was used to confirm the presencemore » of crystalline ZIF in the thin films, and X-ray absorption spectroscopy was used to quantify film purity, revealing films with little to no residual ZnO. The role solvent plays in the transformation mechanism is discussed in light of these findings, which suggest the ZnO nanocrystals may be necessary to localize heterogeneous nucleation of the ZIF to the polymer surface.« less

Flexible room-temperature formaldehyde sensors based on rGO film and rGo/MoS2 hybrid film

NASA Astrophysics Data System (ADS)

Li, Xian; Wang, Jing; Xie, Dan; Xu, Jianlong; Xia, Yi; Li, Weiwei; Xiang, Lan; Li, Zhemin; Xu, Shiwei; Komarneni, Sridhar

2017-08-01

Gas sensors based on reduced graphene oxide (rGO) films and rGO/MoS2 hybrid films were fabricated on polyethylene naphthalate substrates by a simple self-assembly method, which yielded flexible devices for detection of formaldehyde (HCHO) at room temperature. The sensing test results indicated that the rGO and rGO/MoS2 sensors were highly sensitive and fully recoverable to a ppm-level of HCHO. The bending and fatigue test results revealed that the sensors were also mechanically robust, durable and effective for long-term use. The rGO/MoS2 sensors showed higher sensitivities than rGO sensors, which was attributed to the enhanced HCHO adsorption and electron transfer mediated by MoS2. Furthermore, two kinds of MoS2 nanosheets were prepared by either hydrothermal synthesis or chemical exfoliation and were compared for their detection of HCHO, which revealed that the hydrothermally produced MoS2 nanosheets with rich defects led to enhanced sensitivity of the rGO/MoS2 sensors. Moreover, these fabricated flexible sensors can be applied for the HCHO detection in food packaging.

Flexible room-temperature formaldehyde sensors based on rGO film and rGo/MoS2 hybrid film.

PubMed

Li, Xian; Wang, Jing; Xie, Dan; Xu, Jianlong; Xia, Yi; Li, Weiwei; Xiang, Lan; Li, Zhemin; Xu, Shiwei; Komarneni, Sridhar

2017-08-11

Gas sensors based on reduced graphene oxide (rGO) films and rGO/MoS 2 hybrid films were fabricated on polyethylene naphthalate substrates by a simple self-assembly method, which yielded flexible devices for detection of formaldehyde (HCHO) at room temperature. The sensing test results indicated that the rGO and rGO/MoS 2 sensors were highly sensitive and fully recoverable to a ppm-level of HCHO. The bending and fatigue test results revealed that the sensors were also mechanically robust, durable and effective for long-term use. The rGO/MoS 2 sensors showed higher sensitivities than rGO sensors, which was attributed to the enhanced HCHO adsorption and electron transfer mediated by MoS 2 . Furthermore, two kinds of MoS 2 nanosheets were prepared by either hydrothermal synthesis or chemical exfoliation and were compared for their detection of HCHO, which revealed that the hydrothermally produced MoS 2 nanosheets with rich defects led to enhanced sensitivity of the rGO/MoS 2 sensors. Moreover, these fabricated flexible sensors can be applied for the HCHO detection in food packaging.

Structure and optical properties of Ge/Si quantum dots formed by driving the evolution of Ge thin films via thermal annealing

NASA Astrophysics Data System (ADS)

Shu, Qijiang; Yang, Jie; Chi, Qingbin; Sun, Tao; Wang, Chong; Yang, Yu

2018-04-01

Ge/Si quantum dots (QDs) are fabricated by driving the transformation of a Ge thin film-deposited using the direct current (DC) magnetron sputtering technique by controlling the subsequent in situ annealing processes. The experimental results indicate that, with the increase in annealing temperature, the volume of Ge QDs increases monotonically, while the QD density initially increases then decreases. The maximal QD density can reach 1.1 × 1011 cm‑2 after a 10 min annealing at 650 °C. The Ge–Ge peak of Ge QDs obtained by Raman spectroscopy initially undergoes a blue shift and then a red shift with increasing annealing temperature. This behavior results from the competition between the dislocation and the strain relaxation in QDs. Concurrently, a series of photoelectric detectors are fabricated to evaluate the photoelectric performance of these annealed Ge QD samples. A high-photoelectricity response is demonstrated in the QD sample annealed at 650 °C. Our results pave a promising way for whole-silicon-material optical-electronic integration based on a simple and practicable fabrication method.

Graphene and PbS quantum dot hybrid vertical phototransistor

NASA Astrophysics Data System (ADS)

Song, Xiaoxian; Zhang, Yating; Zhang, Haiting; Yu, Yu; Cao, Mingxuan; Che, Yongli; Dai, Haitao; Yang, Junbo; Ding, Xin; Yao, Jianquan

2017-04-01

A field-effect phototransistor based on a graphene and lead sulfide quantum dot (PbS QD) hybrid in which PbS QDs are embedded in a graphene matrix has been fabricated with a vertical architecture through a solution process. The n-type Si/SiO2 substrate (gate), Au/Ag nanowire transparent source electrode, active layer and Au drain electrode are vertically stacked in the device, which has a downscaled channel length of 250 nm. Photoinduced electrons in the PbS QDs leap into the conduction band and fill in the trap states, while the photoinduced holes left in the valence band transfer to the graphene and form the photocurrent under biases from which the photoconductive gain is evaluated. The graphene/QD-based vertical phototransistor shows a photoresponsivity of 2 × 103 A W-1, and specific detectivity up to 7 × 1012 Jones under 808 nm laser illumination with a light irradiance of 12 mW cm-2. The solution-processed vertical phototransistor provides a new facile method for optoelectronic device applications.

Use of CdS quantum dot-functionalized cellulose nanocrystal films for anti-counterfeiting applications

NASA Astrophysics Data System (ADS)

Chen, L.; Lai, C.; Marchewka, R.; Berry, R. M.; Tam, K. C.

2016-07-01

Structural colors and photoluminescence have been widely used for anti-counterfeiting and security applications. We report for the first time the use of CdS quantum dot (QD)-functionalized cellulose nanocrystals (CNCs) as building blocks to fabricate nanothin films via layer-by-layer (LBL) self-assembly for anti-counterfeiting applications. Both negatively- and positively-charged CNC/QD nanohybrids with a high colloidal stability and a narrow particle size distribution were prepared. The controllable LBL coating process was characterized by scanning electron microscopy and ellipsometry. The rigid structure of CNCs leads to nanoporous structured films on poly(ethylene terephthalate) (PET) substrates with high transmittance (above 70%) over the entire range of visible light and also resulted in increased hydrophilicity (contact angles of ~40 degrees). Nanothin films on PET substrates showed good flexibility and enhanced stability in both water and ethanol. The modified PET films with structural colors from thin-film interference and photoluminescence from QDs can be used in anti-counterfeiting applications.Structural colors and photoluminescence have been widely used for anti-counterfeiting and security applications. We report for the first time the use of CdS quantum dot (QD)-functionalized cellulose nanocrystals (CNCs) as building blocks to fabricate nanothin films via layer-by-layer (LBL) self-assembly for anti-counterfeiting applications. Both negatively- and positively-charged CNC/QD nanohybrids with a high colloidal stability and a narrow particle size distribution were prepared. The controllable LBL coating process was characterized by scanning electron microscopy and ellipsometry. The rigid structure of CNCs leads to nanoporous structured films on poly(ethylene terephthalate) (PET) substrates with high transmittance (above 70%) over the entire range of visible light and also resulted in increased hydrophilicity (contact angles of ~40 degrees). Nanothin films

Enhancement of electroluminescence from embedded Si quantum dots/SiO2multilayers film by localized-surface-plasmon and surface roughening.

PubMed

Li, Wei; Wang, Shaolei; Hu, Mingyue; He, Sufeng; Ge, Pengpeng; Wang, Jing; Guo, Yan Yan; Zhaowei, Liu

2015-07-03

In this paper, we prepared a novel structure to enhance the electroluminescence intensity from Si quantum dots/SiO2multilayers. An amorphous Si/SiO2 multilayer film was fabricated by plasma-enhanced chemical vapor deposition on a Pt nanoparticle (NP)-coated Si nanopillar array substrate. By thermal annealing, an embedded Si quantum dot (QDs)/SiO2 multilayer film was obtained. The result shows that electroluminescence intensity was significantly enhanced. And, the turn-on voltage of the luminescent device was reduced to 3 V. The enhancement of the light emission is due to the resonance coupling between the localized-surface-plasmon (LSP) of Pt NPs and the band-gap emission of Si QDs/SiO2 multilayers. The other factors were the improved absorption of excitation light and the increase of light extraction ratio by surface roughening structures. These excellent characteristics are promising for silicon-based light-emitting applications.

High performance novel gadolinium doped ceria/yttria stabilized zirconia/nickel layered and hybrid thin film anodes for application in solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Garcia-Garcia, F. J.; Beltrán, A. M.; Yubero, F.; González-Elipe, A. R.; Lambert, R. M.

2017-09-01

Magnetron sputtering under oblique angle deposition was used to produce Ni-containing ultra thin film anodes comprising alternating layers of gadolinium doped ceria (GDC) and yttria stabilized zirconia (YSZ) of either 200 nm or 1000 nm thickness. The evolution of film structure from initial deposition, through calcination and final reduction was examined by XRD, SEM, TEM and TOF-SIMS. After subsequent fuel cell usage, the porous columnar architecture of the two-component layered thin film anodes was maintained and their resistance to delamination from the underlying YSZ electrolyte was superior to that of corresponding single component Ni-YSZ and Ni-GDC thin films. Moreover, the fuel cell performance of the 200 nm layered anodes compared favorably with conventional commercially available thick anodes. The observed dependence of fuel cell performance on individual layer thicknesses prompted study of equivalent but more easily fabricated hybrid anodes consisting of simultaneously deposited Ni-GDC and Ni-YSZ, which procedure resulted in exceptionally intimate mixing and interaction of the components. The hybrids exhibited very unusual and favorable Isbnd V characteristics, along with exceptionally high power densities at high currents. Their discovery is the principal contribution of the present work.

Multifunctional quantum dot-polypeptide hybrid nanogel for targeted imaging and drug delivery

NASA Astrophysics Data System (ADS)

Yang, Jie; Yao, Ming-Hao; Wen, Lang; Song, Ji-Tao; Zhang, Ming-Zhen; Zhao, Yuan-Di; Liu, Bo

2014-09-01

A new type of multifunctional quantum dot (QD)-polypeptide hybrid nanogel with targeted imaging and drug delivery properties has been developed by metal-affinity driven self-assembly between artificial polypeptides and CdSe-ZnS core-shell QDs. On the surface of QDs, a tunable sandwich-like microstructure consisting of two hydrophobic layers and one hydrophilic layer between them was verified by capillary electrophoresis, transmission electron microscopy, and dynamic light scattering measurements. Hydrophobic and hydrophilic drugs can be simultaneously loaded in a QD-polypeptide nanogel. In vitro drug release of drug-loaded QD-polypeptide nanogels varies strongly with temperature, pH, and competitors. A drug-loaded QD-polypeptide nanogel with an arginine-glycine-aspartic acid (RGD) motif exhibited efficient receptor-mediated endocytosis in αvβ3 overexpressing HeLa cells but not in the control MCF-7 cells as analyzed by confocal microscopy and flow cytometry. In contrast, non-targeted QD-polypeptide nanogels revealed minimal binding and uptake in HeLa cells. Compared with the original QDs, the QD-polypeptide nanogels showed lower in vitro cytotoxicity for both HeLa cells and NIH 3T3 cells. Furthermore, the cytotoxicity of the targeted QD-polypeptide nanogel was lower for normal NIH 3T3 cells than that for HeLa cancer cells. These results demonstrate that the integration of imaging and drug delivery functions in a single QD-polypeptide nanogel has the potential for application in cancer diagnosis, imaging, and therapy.A new type of multifunctional quantum dot (QD)-polypeptide hybrid nanogel with targeted imaging and drug delivery properties has been developed by metal-affinity driven self-assembly between artificial polypeptides and CdSe-ZnS core-shell QDs. On the surface of QDs, a tunable sandwich-like microstructure consisting of two hydrophobic layers and one hydrophilic layer between them was verified by capillary electrophoresis, transmission electron

Constructing a MoS₂ QDs/CdS Core/Shell Flowerlike Nanosphere Hierarchical Heterostructure for the Enhanced Stability and Photocatalytic Activity.

PubMed

Liang, Shijing; Zhou, Zhouming; Wu, Xiuqin; Zhu, Shuying; Bi, Jinhong; Zhou, Limin; Liu, Minghua; Wu, Ling

2016-02-15

MoS₂ quantum dots (QDs)/CdS core/shell nanospheres with a hierarchical heterostructure have been prepared by a simple microwave hydrothermal method. The as-prepared samples are characterized by XRD, TEM, SEM, UV-VIS diffuse reflectance spectra (DRS) and N₂-sorption in detail. The photocatalytic activities of the samples are evaluated by water splitting into hydrogen. Results show that the as-prepared MoS₂ QDs/CdS core/shell nanospheres with a diameter of about 300 nm are composed of the shell of CdS nanorods and the core of MoS₂ QDs. For the photocatalytic reaction, the samples exhibit a high stability of the photocatalytic activity and a much higher hydrogen evolution rate than the pure CdS, the composite prepared by a physical mixture, and the Pt-loaded CdS sample. In addition, the stability of CdS has also been greatly enhanced. The effect of the reaction time on the formations of nanospheres, the photoelectric properties and the photocatalytic activities of the samples has been investigated. Finally, a possible photocatalytic reaction process has also been proposed.

Small temperature coefficient of resistivity of graphene/graphene oxide hybrid membranes.

PubMed

Sun, Pengzhan; Zhu, Miao; Wang, Kunlin; Zhong, Minlin; Wei, Jinquan; Wu, Dehai; Zhu, Hongwei

2013-10-09

Materials with low temperature coefficient of resistivity (TCR) are of great importance in some areas, for example, highly accurate electronic measurement instruments and microelectronic integrated circuits. In this work, we demonstrated the ultrathin graphene-graphene oxide (GO) hybrid films prepared by layer-by-layer assembly with very small TCR (30-100 °C) in the air. Electrical response of the hybrid films to temperature variation was investigated along with the progressive reduction of GO sheets. The mechanism of electrical response to temperature variation of the hybrid film was discussed, which revealed that the interaction between graphene and GO and the chemical doping effect were responsible for the tunable control of its electrical response to temperature variation. The unique properties of graphene-GO hybrid film made it a promising candidate in many areas, such as high-end film electronic device and sensor applications.

Poster — Thur Eve — 39: Feasibility of Commissioning HybridArc with the Delta 4 two plane diode phantom: comparisons with Gafchromic Film

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

Bojechko, C.; Ploquin, N.; University of Calgary, Department of Oncology, Tom Baker Cancer Center, Calgary AB

2014-08-15

HybridArc is a relatively novel radiation therapy technique which combines optimized dynamic conformai arcs (DCA) and intensity modulated radiation therapy (IMRT). HybridArc has possible dosimetry and efficiency advantages over stand alone DCA and IMRT treatments and can be readily implemented on any linac capable of DCA and IMRT, giving strong motivation to commission the modality. The Delta4 phantom (Scandidos, Uppsala, Sweden) has been used for IMRT and VMAT clinical dosimetric verification making it a candidate for HybridArc commissioning. However the HybridArc modality makes use of several non co-planar arcs which creates setup issues due to the geometry of the Delta4,more » resulting in possible phantom gantry collisions for plans with non-zero couch angles. An analysis was done determining the feasibility of using the Delta4 fixed at 0° couch angle compared with results obtained using Gafchromic ETB2 film (Ashland, Covington Kentucky) in an anthropomorphic phantom at the planned couch angles. A gamma index analysis of the measured and planned dose distributions was done using Delta4 and DoseLab Pro (Mobius Medical Systems, Houston Texas) software. For both arc and IMRT sub-fields there is reasonable correlation between the gamma index found from the Delta4 and Gafchromic film. All results show the feasibility of using the Delta4 for HybridArc commissioning.« less

Hybrid absorbers composed of Fe3O4 thin film and magnetic composite sheet and enhancement of conduction noise absorption on a microstrip line

NASA Astrophysics Data System (ADS)

Kim, Sung-Soo

2015-05-01

In response to develop wide-band noise absorbers with an improved low-frequency performance, this study investigates hybrid absorbers that are composed of conductive Fe3O4 thin film and magnetic composite sheets. The Fe3O4 films prepared via reactive sputtering exhibit a typical value of electrical resistivity of ≃10-4 Ωm. Rubber composites with flaky Fe-Si-Al particles of a high permeability and high permittivity are used as the magnetic sheet functioning as an electromagnetic shield barrier. Microstrip lines with a characteristic impedance of 50 Ω are used to measure the noise absorbing properties. For the Fe3O4 film with a low surface resistance and covered by the magnetic sheet, approximately 80% power absorption can be obtained at 1 GHz, which is significantly higher than that of the original magnetic sheet or Fe3O4 film. The high power absorption of the hybrid absorber is attributed to the enhanced ohmic loss of the Fe3O4 film through increased electric field strength bounded by the upper magnetic composite sheet. The noise absorption is further enhanced through increasing the electrical conductivity of the film containing more conductive phase (Fe3O4 + Fe), which can be prepared in a reduced oxygen partial pressure during reactive sputtering.

Hybrid colloidal plasmonic-photonic crystals.

PubMed

Romanov, Sergei G; Korovin, Alexander V; Regensburger, Alois; Peschel, Ulf

2011-06-17

We review the recently emerged class of hybrid metal-dielectric colloidal photonic crystals. The hybrid approach is understood as the combination of a dielectric photonic crystal with a continuous metal film. It allows to achieve a strong modification of the optical properties of photonic crystals by involving the light scattering at electronic excitations in the metal component into moulding of the light flow in series to the diffraction resonances occurring in the body of the photonic crystal. We consider different realizations of hybrid plasmonic-photonic crystals based on two- and three-dimensional colloidal photonic crystals in association with flat and corrugated metal films. In agreement with model calculations, different resonance phenomena determine the optical response of hybrid crystals leading to a broadly tuneable functionality of these crystals. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced efficiency of hybrid amorphous silicon solar cells based on single-walled carbon nanotubes/polymer composite thin film.

PubMed

Rajanna, Pramod Mulbagal; Gilshteyn, Evgenia; Yagafarov, Timur; Alekseeva, Alena; Anisimov, Anton; Sergeev, Oleg; Neumueller, Alex; Bereznev, Sergei; Maricheva, Jelena; Nasibulin, Albert

2018-01-09

We report a simple approach to fabricate hybrid solar cells (HSCs) based on a single-walled carbon nanotube (SWCNT) film and a thin film hydrogenated amorphous silicon (a-Si:H). Randomly oriented high quality SWCNTs with an enhanced conductivity by means of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate are used as a window layer and a front electrode. A series of HSCs are fabricated in ambient conditions with different SWCNT film thicknesses. The polymethylmethacrylate layer drop-casted on fabricated HSCs reduces the reflection fourfold and enhances the short-circuit Jsc, open-circuit Voc, and efficiency by nearly 10%. A state-of-the-art J-V performance is shown for SWCNT/a-Si HSC with an open-circuit voltage of 900 mV and efficiency of 3.4% under simulated one-sun AM 1.5G direct illumination. © 2018 IOP Publishing Ltd.

Two-dimensional photonic crystal bandedge laser with hybrid perovskite thin film for optical gain

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

Cha, Hyungrae; Inter-University Semiconductor Research Center, Seoul National University, Seoul 08826; Bae, Seunghwan

2016-05-02

We report optically pumped room temperature single mode laser that contains a thin film of hybrid perovskite, an emerging photonic material, as gain medium. Two-dimensional square lattice photonic crystal (PhC) backbone structure enables single mode laser operation via a photonic bandedge mode, while a thin film of methyl-ammonium lead iodide (CH{sub 3}NH{sub 3}PbI{sub 3}) spin-coated atop provides optical gain for lasing. Two kinds of bandedge modes, Γ and M, are employed, and both devices laser in single mode at similar laser thresholds of ∼200 μJ/cm{sup 2} in pulse energy density. Polarization dependence measurements reveal a clear difference between the two kindsmore » of bandedge lasers: isotropic for the Γ-point laser and highly anisotropic for the M-point laser. These observations are consistent with expected modal properties, confirming that the lasing actions indeed originate from the corresponding PhC bandedge modes.« less

Dual-Band Modulation of Visible and Near-Infrared Light Transmittance in an All-Solution-Processed Hybrid Micro-Nano Composite Film.

PubMed

Liang, Xiao; Chen, Mei; Guo, Shumeng; Zhang, Lanying; Li, Fasheng; Yang, Huai

2017-11-22

Smart windows with controllable visible and near-infrared light transmittance can significantly improve the building's energy efficiency and inhabitant comfort. However, most of the current smart window technology cannot achieve the target of ideal solar control. Herein, we present a novel all-solution-processed hybrid micronano composite smart material that have four optical states to separately modulate the visible and NIR light transmittance through voltage and temperature, respectively. This dual-band optical modulation was achieved by constructing a phase-separated polymer framework, which contains the microsized liquid crystals domains with a negative dielectric constant and tungsten-doped vanadium dioxide (W-VO 2 ) nanocrystals (NCs). The film with 2.5 wt % W-VO 2 NCs exhibits transparency at normal condition, and the passage of visible light can be reversibly and actively regulated between 60.8% and 1.3% by external applied voltage. Also, the transmittance of NIR light can be reversibly and passively modulated between 59.4% and 41.2% by temperature. Besides, the film also features easy all-solution processability, fast electro-optical (E-O) response time, high mechanical strength, and long-term stability. The as-prepared film provides new opportunities for next-generation smart window technology, and the proposed strategy is conductive to engineering novel hybrid inorganic-organic functional matters.

Light trapping in thin-film solar cells with randomly rough and hybrid textures.

PubMed

Kowalczewski, Piotr; Liscidini, Marco; Andreani, Lucio Claudio

2013-09-09

We study light-trapping in thin-film silicon solar cells with rough interfaces. We consider solar cells made of different materials (c-Si and μc-Si) to investigate the role of size and nature (direct/indirect) of the energy band gap in light trapping. By means of rigorous calculations we demonstrate that the Lambertian Limit of absorption can be obtained in a structure with an optimized rough interface. We gain insight into the light trapping mechanisms by analysing the optical properties of rough interfaces in terms of Angular Intensity Distribution (AID) and haze. Finally, we show the benefits of merging ordered and disordered photonic structures for light trapping by studying a hybrid interface, which is a combination of a rough interface and a diffraction grating. This approach gives a significant absorption enhancement for a roughness with a modest size of spatial features, assuring good electrical properties of the interface. All the structures presented in this work are compatible with present-day technologies, giving recent progress in fabrication of thin monocrystalline silicon films and nanoimprint lithography.

Understanding charge transfer dynamics in QDs-TiO2 nanorod array photoanodes for solar fuel generation

NASA Astrophysics Data System (ADS)

Li, Jiangtian; McClure, Joshua P.; Fu, Richard; Jiang, Rongzhong; Chu, Deryn

2018-01-01

Harvesting light to drive water splitting for hydrogen generation is an attractive approach to satisfy the urgent energy demands. The design and fabrication of photoelectrode materials that are able to harvest sunlight is an important scientific undertaking. In this study, a two-quantum-dot (QD) layer is developed to decorate one-dimensional TiO2 nanorod arrays, which are subsequently utilized as photoanodes to harvest the wide-spectrum sunlight for water splitting. The QD-coated TiO2 nanorod arrays extend the light absorption range from the UV into the visible region yielding increased solar-to-hydrogen efficiencies. Transient photocurrent decay measurements demonstrate that the multi-layer CdSe-CdS QDs deposited onto the TiO2 nanorod arrays result in a stepwise band alignment that not only improves the hole extraction but also facilitates electron injection from the QDs to TiO2 rods. Moreover, the multi-heterojunction photoanode introduces interfacial states that act as recombination centers to trap the photogenerated electrons.

Electroluminescence from ZnCuInS/ZnS quantum dots/poly(9-vinylcarbazole) multilayer films with different thicknesses of quantum dot layer

NASA Astrophysics Data System (ADS)

Dong, Xiaofei; Xu, Jianping; Shi, Shaobo; Zhang, Xiaosong; Li, Lan; Yin, Shougen

2017-05-01

We report tunable electroluminescence (EL) from solution-processed ZnCuInS/ZnS (ZCIS/ZnS) quantum dots (QDs)/poly(9-vinlycarbazole) multilayer films. The EL spectra exhibit a red shift as the QD layer thickness increases. By analyzing the dependence of the applied voltage and the ZCIS/ZnS QD layer thickness on the EL spectra, the origin of the red shift is associated with the increased trap density of QDs that induces the injected electrons to be trapped in the deep donor level. The current conduction mechanism based on the current density-voltage curves at different voltage regions was discussed.

Intrinsically Labeled Fluorescent Oligonucleotide Probes on Quantum Dots for Transduction of Nucleic Acid Hybridization.

PubMed

Shahmuradyan, Anna; Krull, Ulrich J

2016-03-15

Quantum dots (QDs) have been widely used in chemical and biosensing due to their unique photoelectrical properties and are well suited as donors in fluorescence resonance energy transfer (FRET). Selective hybridization interactions of oligonucleotides on QDs have been determined by FRET. Typically, the QD-FRET constructs have made use of labeled targets or have implemented labeled sandwich format assays to introduce dyes in proximity to the QDs for the FRET process. The intention of this new work is to explore a method to incorporate the acceptor dye into the probe molecule. Thiazole orange (TO) derivatives are fluorescent intercalating dyes that have been used for detection of double-stranded nucleic acids. One such dye system has been reported in which single-stranded oligonucleotide probes were doubly labeled with adjacent thiazole orange derivatives. In the absence of the fully complementary (FC) oligonucleotide target, the dyes form an H-aggregate, which results in quenching of fluorescence emission due to excitonic interactions between the dyes. The hybridization of the FC target to the probe provides for dissociation of the aggregate as the dyes intercalate into the double stranded duplex, resulting in increased fluorescence. This work reports investigation of the dependence of the ratiometric signal on the type of linkage used to conjugate the dyes to the probe, the location of the dye along the length of the probe, and the distance between adjacent dye molecules. The limit of detection for 34mer and 90mer targets was found to be identical and was 10 nM (2 pmol), similar to analogous QD-FRET using labeled oligonucleotide target. The detection system could discriminate a one base pair mismatch (1BPM) target and was functional without substantial compromise of the signal in 75% serum. The 1BPM was found to reduce background signal, indicating that the structure of the mismatch affected the environment of the intercalating dyes.

Organic–Inorganic Eu3+/Tb3+ codoped hybrid films for temperature mapping in integrated circuits

PubMed Central

Brites, Carlos D. S.; Lima, Patrícia P.; Silva, Nuno J. O.; Millán, Angel; Amaral, Vitor S.; Palacio, Fernando; Carlos, Luís D.

2013-01-01

The continuous decrease on the geometric size of electronic devices and integrated circuits generates higher local power densities and localized heating problems that cannot be characterized by conventional thermographic techniques. Here, a self-referencing intensity-based molecular thermometer involving a di-ureasil organic-inorganic hybrid thin film co-doped with Eu3+ and Tb3+ tris (β-diketonate) chelates is used to obtain the temperature map of a FR4 printed wiring board with spatio-temporal resolutions of 0.42 μm/4.8 ms. PMID:24790938

Copper Phthalocyanine Functionalized Single-Walled Carbon Nanotubes: Thin Films for Optical Detection.

PubMed

Banimuslem, Hikmat; Hassan, Aseel; Basova, Tamara; Durmuş, Mahmut; Tuncel, Sinem; Esenpinar, Aliye Asli; Gürek, Ayşe Gül; Ahsen, Vefa

2015-03-01

Thin films of non-covalently hybridized single-walled carbon nanotubes (SWCNT) and tetra-substituted copper phthalocyanine (CuPcR4) molecules have been produced from their solutions in dimethylformamide (DMF). FTIR spectra revealed the 7π-7π interaction between SWCNTs and CuPcR4 molecules. DC conductivity of films of acid-treated SWCNT/CuPcR4 hybrid has increased by more than three orders of.magnitude in comparison with conductivity of CuPcR4 films. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements have shown that films obtained from the acid-treated SWCNTs/CuPcR4 hybrids demonstrated more homogenous surface which is ascribed to the highly improved solubility of the hybrid powder in DMF Using total internal reflection ellipsometry spectroscopy (TIRE), thin films of the new hybrid have been examined as an optical sensing membrane for the detection of benzo[a]pyrene in water to demonstrate the sensing properties of the hybrid.

An All-Solution-Based Hybrid CMOS-Like Quantum Dot/Carbon Nanotube Inverter.

PubMed

Shulga, Artem G; Derenskyi, Vladimir; Salazar-Rios, Jorge Mario; Dirin, Dmitry N; Fritsch, Martin; Kovalenko, Maksym V; Scherf, Ullrich; Loi, Maria A

2017-09-01

The development of low-cost, flexible electronic devices is subordinated to the advancement in solution-based and low-temperature-processable semiconducting materials, such as colloidal quantum dots (QDs) and single-walled carbon nanotubes (SWCNTs). Here, excellent compatibility of QDs and SWCNTs as a complementary pair of semiconducting materials for fabrication of high-performance complementary metal-oxide-semiconductor (CMOS)-like inverters is demonstrated. The n-type field effect transistors (FETs) based on I - capped PbS QDs (V th = 0.2 V, on/off = 10 5 , S S-th = 114 mV dec -1 , µ e = 0.22 cm 2 V -1 s -1 ) and the p-type FETs with tailored parameters based on low-density random network of SWCNTs (V th = -0.2 V, on/off > 10 5 , S S-th = 63 mV dec -1 , µ h = 0.04 cm 2 V -1 s -1 ) are integrated on the same substrate in order to obtain high-performance hybrid inverters. The inverters operate in the sub-1 V range (0.9 V) and have high gain (76 V/V), large maximum-equal-criteria noise margins (80%), and peak power consumption of 3 nW, in combination with low hysteresis (10 mV). © 2017 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhancement of electroluminescence from embedded Si quantum dots/SiO2multilayers film by localized-surface-plasmon and surface roughening

PubMed Central

Li, Wei; Wang, Shaolei; Hu, Mingyue; He, Sufeng; Ge, Pengpeng; Wang, Jing; Guo, Yan Yan; Zhaowei, Liu

2015-01-01

In this paper, we prepared a novel structure to enhance the electroluminescence intensity from Si quantum dots/SiO2multilayers. An amorphous Si/SiO2 multilayer film was fabricated by plasma-enhanced chemical vapor deposition on a Pt nanoparticle (NP)-coated Si nanopillar array substrate. By thermal annealing, an embedded Si quantum dot (QDs)/SiO2 multilayer film was obtained. The result shows that electroluminescence intensity was significantly enhanced. And, the turn-on voltage of the luminescent device was reduced to 3 V. The enhancement of the light emission is due to the resonance coupling between the localized-surface-plasmon (LSP) of Pt NPs and the band-gap emission of Si QDs/SiO2 multilayers. The other factors were the improved absorption of excitation light and the increase of light extraction ratio by surface roughening structures. These excellent characteristics are promising for silicon-based light-emitting applications. PMID:26138830

Integrated fast assembly of free-standing lithium titanate/carbon nanotube/cellulose nanofiber hybrid network film as flexible paper-electrode for lithium-ion batteries.

PubMed

Cao, Shaomei; Feng, Xin; Song, Yuanyuan; Xue, Xin; Liu, Hongjiang; Miao, Miao; Fang, Jianhui; Shi, Liyi

2015-05-27

A free-standing lithium titanate (Li4Ti5O12)/carbon nanotube/cellulose nanofiber hybrid network film is successfully assembled by using a pressure-controlled aqueous extrusion process, which is highly efficient and easily to scale up from the perspective of disposable and recyclable device production. This hybrid network film used as a lithium-ion battery (LIB) electrode has a dual-layer structure consisting of Li4Ti5O12/carbon nanotube/cellulose nanofiber composites (hereinafter referred to as LTO/CNT/CNF), and carbon nanotube/cellulose nanofiber composites (hereinafter referred to as CNT/CNF). In the heterogeneous fibrous network of the hybrid film, CNF serves simultaneously as building skeleton and a biosourced binder, which substitutes traditional toxic solvents and synthetic polymer binders. Of importance here is that the CNT/CNF layer is used as a lightweight current collector to replace traditional heavy metal foils, which therefore reduces the total mass of the electrode while keeping the same areal loading of active materials. The free-standing network film with high flexibility is easy to handle, and has extremely good conductivity, up to 15.0 S cm(-1). The flexible paper-electrode for LIBs shows very good high rate cycling performance, and the specific charge/discharge capacity values are up to 142 mAh g(-1) even at a current rate of 10 C. On the basis of the mild condition and fast assembly process, a CNF template fulfills multiple functions in the fabrication of paper-electrode for LIBs, which would offer an ever increasing potential for high energy density, low cost, and environmentally friendly flexible electronics.

Following glucose oxidase activity by chemiluminescence and chemiluminescence resonance energy transfer (CRET) processes involving enzyme-DNAzyme conjugates.

PubMed

Niazov, Angelica; Freeman, Ronit; Girsh, Julia; Willner, Itamar

2011-01-01

A hybrid consisting of glucose oxidase-functionalized with hemin/G-quadruplex units is used for the chemiluminescence detection of glucose. The glucose oxidase-mediated oxidation of glucose yields gluconic acid and H(2)O(2). The latter in the presence of luminol acts as substrate for the hemin/G-quadruplex-catalyzed generation of chemiluminescence. The glucose oxidase/hemin G-quadruplex hybrid was immobilized on CdSe/ZnS quantum dots (QDs). The light generated by the hybrid, in the presence of glucose, activated a chemiluminescence resonance energy transfer process to the QDs, resulting in the luminescence of the QDs. The intensities of the luminescence of the QDs at different concentrations of glucose provided an optical means to detect glucose.

Phase and electrical properties of PZT thin films embedded with CuO nano-particles by a hybrid sol-gel route

NASA Astrophysics Data System (ADS)

Sreesattabud, Tharathip; Gibbons, Brady J.; Watcharapasorn, Anucha; Jiansirisomboon, Sukanda

2013-07-01

Pb(Zr0.52Ti0.48)O3 or PZT thin films embedded with CuO nano-particles were successfully prepared by a hybrid sol-gel process. In this process, CuO (0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1 wt. %) nanopowder was suspended in an organometallic solution of PZT, and then coated on platinised silicon substrate using a spin-coating technique. The influence of CuO nano-particles' dispersion on the phase of PZT thin films was investigated. XRD results showed a perovskite phase in all films. At the CuO concentration of 0.4-1 wt. %, a second phase was observed. The addition of CuO nano-particles affected the orientation of PZT thin films. The addition was also found to reduce the ferroelectric properties of PZT thin films. However, at 0.2 wt. % CuO concentration, the film exhibited good ferroelectric properties similar to those of PZT films. In addition, the fatigue retention properties of the PZT/CuO system was observed, and it showed 14% fatigue at 108 switching bipolar pulse cycles while the fatigue in PZT thin films was found to be 17% at the same switching bipolar pulse cycles.

Distinct Optoelectronic Signatures for Charge Transfer and Energy Transfer in Quantum Dot-MoS 2 Hybrid Photodetectors Revealed by Photocurrent Imaging Microscopy

DOE PAGES

Li, Mingxing; Chen, Jia-Shiang; Routh, Prahlad K.; ...

2018-05-17

Atomically thin transition metal dichalcogenides (TMDCs) have intriguing nanoscale properties like high charge mobility, photosensitivity, layer-thickness-dependent bandgap, and mechanical flexibility, which are all appealing for the development of next generation optoelectronic, catalytic, and sensory devices. Their atomically thin thickness, however, renders TMDCs poor absorptivity. For this study, bilayer MoS 2 is combined with core-only CdSe QDs and core/shell CdSe/ZnS QDs to obtain hybrids with increased light harvesting and exhibiting interfacial charge transfer (CT) and nonradiative energy transfer (NET), respectively. Field-effect transistors based on these hybrids and their responses to varying laser power and applied gate voltage are investigated with scanningmore » photocurrent microscopy (SPCM) in view of their potential utilization in light harvesting and photodetector applications. CdSe–MoS 2 hybrids are found to exhibit encouraging properties for photodetectors, like high responsivity and fast on/off response under low light exposure while CdSe/ZnS–MoS 2 hybrids show enhanced charge carrier generation with increased light exposure, thus suitable for photovoltaics. While distinguishing optically between CT and NET in QD–TMDCs is nontrivial, it is found that they can be differentiated by SPCM as these two processes exhibit distinctive light-intensity dependencies: CT causes a photogating effect, decreasing the photocurrent response with increasing light power while NET increases the photocurrent response with increasing light power, opposite to CT case.« less

Distinct Optoelectronic Signatures for Charge Transfer and Energy Transfer in Quantum Dot-MoS 2 Hybrid Photodetectors Revealed by Photocurrent Imaging Microscopy

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

Li, Mingxing; Chen, Jia-Shiang; Routh, Prahlad K.

Atomically thin transition metal dichalcogenides (TMDCs) have intriguing nanoscale properties like high charge mobility, photosensitivity, layer-thickness-dependent bandgap, and mechanical flexibility, which are all appealing for the development of next generation optoelectronic, catalytic, and sensory devices. Their atomically thin thickness, however, renders TMDCs poor absorptivity. For this study, bilayer MoS 2 is combined with core-only CdSe QDs and core/shell CdSe/ZnS QDs to obtain hybrids with increased light harvesting and exhibiting interfacial charge transfer (CT) and nonradiative energy transfer (NET), respectively. Field-effect transistors based on these hybrids and their responses to varying laser power and applied gate voltage are investigated with scanningmore » photocurrent microscopy (SPCM) in view of their potential utilization in light harvesting and photodetector applications. CdSe–MoS 2 hybrids are found to exhibit encouraging properties for photodetectors, like high responsivity and fast on/off response under low light exposure while CdSe/ZnS–MoS 2 hybrids show enhanced charge carrier generation with increased light exposure, thus suitable for photovoltaics. While distinguishing optically between CT and NET in QD–TMDCs is nontrivial, it is found that they can be differentiated by SPCM as these two processes exhibit distinctive light-intensity dependencies: CT causes a photogating effect, decreasing the photocurrent response with increasing light power while NET increases the photocurrent response with increasing light power, opposite to CT case.« less

Hyaluronan functionalizing QDs as turn-on fluorescent probe for targeted recognition CD44 receptor

NASA Astrophysics Data System (ADS)

Zhou, Shang; Huo, Danqun; Hou, Changjun; Yang, Mei; Fa, Huanbao

2017-09-01

The recognition of tumor markers in living cancer cells has attracted increasing interest. In the present study, the turn-on fluorescence probe was designed based on the fluorescence of thiolated chitosan-coated CdTe QDs (CdTe/TCS QDs) quenched by hyaluronan, which could provide the low background signal for sensitive cellular imaging. This system is expected to offer specific recognition of CD44 receptor over other substances owing to the specific affinity of hyaluronan and CD44 receptor ( 8-9 kcal/mol). The probe is stable in aqueous and has little toxicity to living cells; thus, it can be utilized for targeted cancer cell imaging. The living lung cancer cell imaging experiments further demonstrate its value in recognizing cell-surface CD44 receptor with turn-on mode. In addition, the probe can be used to recognize and differentiate the subtypes of lung cancer cells based on the difference of CD44 expression on the surface of lung cancer cells. And, the western blot test further confirmed that the expression level of the CD44 receptor in lung cancer cells is different. Therefore, this probe may be potentially applied in recognizing lung cancer cells with higher contrast and sensitivity and provide new tools for cancer prognosis and therapy. [Figure not available: see fulltext.

Fabrication of a Quartz-Crystal-Microbalance/Surface-Plasmon-Resonance Hybrid Sensor and Its Use for Detection of Polymer Thin-Film Deposition and Evaluation of Moisture Sorption Phenomena

NASA Astrophysics Data System (ADS)

Shinbo, Kazunari; Ishikawa, Hiroshi; Baba, Akira; Ohdaira, Yasuo; Kato, Keizo; Kaneko, Futao

2012-03-01

We fabricated a hybrid sensor utilizing quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) spectroscopy. We confirmed its effectiveness by observing QCM frequency shifts and SPR wavelength changes for two processes: deposition of various transparent polymer thin films and moisture sorption. For thin-film deposition, the relationship between the QCM frequency and SPR wavelength was found to depend on the refractive index of the film material. For moisture sorption, the direction of SPR wavelength shift depended on the film thickness. This was estimated to be caused by film swelling and decrease in refractive index induced by moisture.

Resonant coupling into hybrid 3D micro-resonator devices on organic/biomolecular film/glass photonic structures

NASA Astrophysics Data System (ADS)

Bêche, Bruno; Potel, Arnaud; Barbe, Jérémy; Vié, Véronique; Zyss, Joseph; Godet, Christian; Huby, Nolwenn; Pluchon, David; Gaviot, Etienne

2010-01-01

We have designed and realized an integrated photonic family of micro-resonators (MR) on multilayer SU8/lipidic film/glass materials. Such a family involves hybrid 3D-MR structures composed of spherical glass-MR arranged upon organic pair-SU8-waveguides, an efficient coupling being ensured with a Langmuir-Blodgett Dipalmitoylphosphatidylcholine (DPPC-lipid from Avanti Polar ®) film whose thickness is ranging from 12 to 48 nm. We have characterized such add/drop filters, respectively, in intensity and spectral measurements, and experimentally achieved an evanescent resonant-photonic-coupling between the 3D-MR and the 4-ports structure through the DPPC-gap. Spectral resonances have been measured for 4-whispering gallery-modes (WGM) into such 3D-structures, respectively, characterized with a 0.97 nm free spectral range (FSR) and a high quality Q-factor up to 4.10 4.

Enhanced efficiency of hybrid amorphous silicon solar cells based on single-walled carbon nanotubes and polymer composite thin film.

PubMed

Rajanna, Pramod M; Gilshteyn, Evgenia P; Yagafarov, Timur; Aleekseeva, Alena K; Anisimov, Anton S; Neumüller, Alex; Sergeev, Oleg; Bereznev, Sergei; Maricheva, Jelena; Nasibulin, Albert G

2018-01-31

We report a simple approach to fabricate hybrid solar cells (HSCs) based on a single-walled carbon nanotube (SWCNT) film and thin film hydrogenated amorphous silicon (a-Si:H). Randomly oriented high-quality SWCNTs with conductivity enhanced by means of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate are used as a window layer and a front electrode. A series of HSCs are fabricated in ambient conditions with varying SWCNT film thicknesses. The polymethylmethacrylate layer drop-casted on fabricated HSCs reduces the reflection fourfold and enhances the short-circuit J sc , open-circuit V oc , and efficiency by nearly 10%. A state-of-the-art J-V performance is shown for SWCNT/a-Si HSC with an open-circuit voltage of 900 mV and an efficiency of 3.4% under simulated one-sun AM 1.5 G direct illumination.

Enhanced efficiency of hybrid amorphous silicon solar cells based on single-walled carbon nanotubes and polymer composite thin film

NASA Astrophysics Data System (ADS)

Rajanna, Pramod M.; Gilshteyn, Evgenia P.; Yagafarov, Timur; Aleekseeva, Alena K.; Anisimov, Anton S.; Neumüller, Alex; Sergeev, Oleg; Bereznev, Sergei; Maricheva, Jelena; Nasibulin, Albert G.

2018-03-01

We report a simple approach to fabricate hybrid solar cells (HSCs) based on a single-walled carbon nanotube (SWCNT) film and thin film hydrogenated amorphous silicon (a-Si:H). Randomly oriented high-quality SWCNTs with conductivity enhanced by means of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate are used as a window layer and a front electrode. A series of HSCs are fabricated in ambient conditions with varying SWCNT film thicknesses. The polymethylmethacrylate layer drop-casted on fabricated HSCs reduces the reflection fourfold and enhances the short-circuit J sc , open-circuit V oc , and efficiency by nearly 10%. A state-of-the-art J-V performance is shown for SWCNT/a-Si HSC with an open-circuit voltage of 900 mV and an efficiency of 3.4% under simulated one-sun AM 1.5 G direct illumination.

Highly reliable photosensitive organic-inorganic hybrid passivation layers for a-InGaZnO thin-film transistors

NASA Astrophysics Data System (ADS)

Bermundo, Juan Paolo; Ishikawa, Yasuaki; Yamazaki, Haruka; Nonaka, Toshiaki; Fujii, Mami N.; Uraoka, Yukiharu

2015-07-01

We report the fabrication of a photosensitive hybrid passivation material on amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) that greatly enhance its stability and improve its electrical characteristics. The hybrid passivation based on polysilsesquioxane is transparent and fabricated using a simple solution process. Because the passivation is photosensitive, dry etching was never performed during TFT fabrication. TFTs passivated with this material had a small threshold voltage shift of 0.5 V during positive bias stress, 0.5 V during negative bias stress, and -2.5 V during negative bias illumination stress. Furthermore, TFTs passivated by this layer were stable after being subjected to high relative humidity stress — confirming the superb barrier ability of the passivation. Analysis of secondary ion mass spectrometry showed that a large amount of hydrogen, carbon, and fluorine can be found in the channel region. We show that both hydrogen and fluorine reduced oxygen vacancies and that fluorine stabilized weak oxygen and hydroxide bonds. These results demonstrate the large potential of photosensitive hybrid passivation layers as effective passivation materials.

Graphene-carbon nanotube hybrid materials and use as electrodes

DOEpatents

Tour, James M.; Zhu, Yu; Li, Lei; Yan, Zheng; Lin, Jian

2016-09-27

Provided are methods of making graphene-carbon nanotube hybrid materials. Such methods generally include: (1) associating a graphene film with a substrate; (2) applying a catalyst and a carbon source to the graphene film; and (3) growing carbon nanotubes on the graphene film. The grown carbon nanotubes become covalently linked to the graphene film through carbon-carbon bonds that are located at one or more junctions between the carbon nanotubes and the graphene film. In addition, the grown carbon nanotubes are in ohmic contact with the graphene film through the carbon-carbon bonds at the one or more junctions. The one or more junctions may include seven-membered carbon rings. Also provided are the formed graphene-carbon nanotube hybrid materials.

Toward highly stable solid-state unconventional thin-film battery-supercapacitor hybrid devices: Interfacing vertical core-shell array electrodes with a gel polymer electrolyte

NASA Astrophysics Data System (ADS)

Pandey, Gaind P.; Klankowski, Steven A.; Liu, Tao; Wu, Judy; Li, Jun

2017-02-01

A novel solid-state battery-supercapacitor hybrid device is fabricated for high-performance electrical energy storage using a Si anode and a TiO2 cathode in conjunction with a flexible, solid-like gel polymer electrolyte film as the electrolyte and separator. The electrodes were fabricated as three-dimensional nanostructured vertical arrays by sputtering active materials as conformal shells on vertically aligned carbon nanofibers (VACNFs) which serve as the current collector and structural template. Such nanostructured vertical core-shell array-electrodes enable short Li-ion diffusion path and large pseudocapacitive contribution by fast surface reactions, leading to the hybrid features of batteries and supercapacitors that can provide high specific energy over a wide range of power rates. Due to the improved mechanical stability of the infiltrated composite structure, the hybrid cell shows excellent cycling stability and is able to retain more than 95% of the original capacity after 3500 cycles. More importantly, this solid-state device can stably operate in a temperature range from -20 to 60 °C with a very low self-discharge rate and an excellent shelf life. This solid-state architecture is promising for the development of highly stable thin-film hybrid energy storage devices for unconventional applications requiring largely varied power, wider operation temperature, long shelf-life and higher safety standards.

Mechanistic study of the electrodeposition of nanoporous self-assembled ZnO/Eosin Y hybrid thin films: effect of eosin concentration.

PubMed

Goux, Aurélie; Pauporté, Thierry; Yoshida, Tsukasa; Lincot, Daniel

2006-12-05

ZnO films prepared by one-step electrodeposition in the presence of dissolved eosin molecules present an internal nanoporous hybrid structure resulting from self-assembling processes occurring in solution between ZnO and eosin components. This study aims to better understand the underlying growth mechanism, which is still unexplained. The films were deposited by cathodic electrodeposition from an oxygen-saturated aqueous zinc chloride solution. The effects of the addition of 10 to 100 micromol.L(-1) eosin Y, as a sodium salt, on the growth rate and film properties, were systematically studied while all other parameters remained constant (concentrations of zinc salt and supporting electrolyte, applied potential of -1.4 V versus the mercurous sulfate electrode (MSE), temperature of 70 degrees C, rotating disk electrode at 300 rotations per min, and a glass-coated tin oxide electrode). It is shown that the addition of eosin provokes the formation of a nanoporous "cauliflower" structure whose nodule size and composition depend on the eosin concentration in the bath. The growth rate of the hybrid films increases markedly with the eosin concentration. The ZnO and eosin contents of the films are determined for each concentration by chemical analysis. Comparing with thickness determinations, it is shown that the total porosity increases up to 60-65% in volume fraction toward an eosin concentration of 100 micromol.L(-1). The empty pore volume fraction increases up to about 30% at an eosin concentration of about 20 micromol.L(-1) and then decreases. These correlations have been precisely established for the first time. It is shown that the global composition is fixed by the relative rate of deposition for zinc oxide, which is constant, and for the relative rate of eosin inclusion, which is proportional to the concentration in solution. This is explained on the basis of different steps in the growth mechanism, in particular, a diffusion effect limitation for both oxygen and

Electrochemically formed 3D hierarchical thin films of cobalt-manganese (Co-Mn) hexacyanoferrate hybrids for electrochemical applications

NASA Astrophysics Data System (ADS)

Alam Venugopal, Narendra Kumar; Joseph, James

2016-02-01

Here we report the feasibility of forming 3D nanostructured hexacyanoferates of Cobalt and Manganese (Co-MnHCF) on GC surface by a facile electrochemical method. This 3D architecture on glassy carbon electrode characterised systematically by voltammetry and other physical characterisation techniques like Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Fourier transform Infrared spectroscopy (FTIR) etc,. Electrochemical Quartz crystal microbalance (EQCM) studies helped out to calculate the total mass change during Co-MnHCF formation. Electrochemical studies reveal that the formal redox potentials of both Co and MnHCF films remained close to that of newly formed Co-MnHCF hybrid films. These 3D modified films were successfully applied for two different electrochemical applications i) For pseudocapacitor studies in KNO3 medium ii) Investigated the electrocatalytic behaviour of redox film towards water oxidation reaction in alkaline medium. Electrochemical performances of newly formed Co-MnHCF are compared with their individual transition metal (Co, Mn) hexacyanoferrates. The resulting material shows a specific capacitance of 350 F g-1 through its fast reversible redox reaction of electrochemically formed Co-MnHCF modified film. Interestingly we showed the overpotential of 450 mV (from its thermodynamic voltage 1.2 V) to attain its optimum current density of 10 mA cm-2 for O2 evolution in alkaline medium.

Tumor invasion unit in gastric cancer revealed by QDs-based in situ molecular imaging and multispectral analysis.

PubMed

Hu, Wen-Qing; Fang, Min; Zhao, Hao-Liang; Yan, Shu-Guang; Yuan, Jing-Ping; Peng, Chun-Wei; Yang, Gui-Fang; Li, Yan; Li, Jian-Ding

2014-04-01

In tumor tissues, cancer cells, tumor infiltrating macrophages and tumor neo-vessels in close spatial vicinity with one another form tumor invasion unit, which is a biologically important tumor microenvironment of metastasis to facilitate cancer invasion and metastasis. Establishing an in situ molecular imaging technology to simultaneously reveal these three components is essential for the in-depth investigation of tumor invasion unit. In this report, we have developed a computer-aided algorithm by quantum dots (QDs)-based multiplexed molecular imaging technique for such purpose. A series of studies on gastric cancer tumor tissues demonstrated that the tumor invasion unit was correlated with major unfavorable pathological features and worse clinical outcomes, which illustrated the significantly negative impacts and predictive power of tumor invasion unit on patient overall survival. This study confirmed the technical advantages of QDs-based in situ and simultaneous molecular imaging of key cancer molecules to gain deeper insights into the biology of cancer invasion. Copyright © 2014 Elsevier Ltd. All rights reserved.

White lighting device from composite films embedded with hydrophilic Cu(In, Ga)S2/ZnS and hydrophobic InP/ZnS quantum dots

NASA Astrophysics Data System (ADS)

Kim, Jong-Hoon; Yang, Heesun

2014-06-01

Two types of non-Cd quantum dots (QDs)—In/Ga ratio-varied, green-to-greenish-yellow fluorescence-tuned Cu-In-Ga-S (CIGS) alloy ones, and red-emitting InP ones—are synthesized for use as down-converters in conjunction with a blue light-emitting diode (LED). Among a series of Ga-rich CI1-xGxS/ZnS core/shell QDs (x = 0.7, 0.8, and 0.9), CI0.2G0.8S/ZnS QD is chosen for the hydrophobic-to-hydrophilic surface modification via an in-situ ligand exchange and then embedded in a water-soluble polyvinyl alcohol (PVA). This free-standing composite film is utilized as a down-converter for the fabrication of a remote-type white QD-LED, but the resulting bi-colored device exhibits a cool white light with a limited color rendering index property. To improve white light qualities, another QD-polymer film of hydrophobic red InP/ZnS QD-embedding polyvinylpyrrolidone is sequentially stacked onto the CI0.2G0.8S/ZnS QD-PVA film, producing a unique dual color-emitting, flexible and transparent bilayered composite film. Tri-colored white QD-LED integrated with the bilayered QD film possesses an exceptional color rendering property through reinforcing a red spectral component and balancing a white spectral distribution.

White lighting device from composite films embedded with hydrophilic Cu(In, Ga)S2/ZnS and hydrophobic InP/ZnS quantum dots.

PubMed

Kim, Jong-Hoon; Yang, Heesun

2014-06-06

Two types of non-Cd quantum dots (QDs)-In/Ga ratio-varied, green-to-greenish-yellow fluorescence-tuned Cu-In-Ga-S (CIGS) alloy ones, and red-emitting InP ones-are synthesized for use as down-converters in conjunction with a blue light-emitting diode (LED). Among a series of Ga-rich CI1-xGxS/ZnS core/shell QDs (x = 0.7, 0.8, and 0.9), CI0.2G0.8S/ZnS QD is chosen for the hydrophobic-to-hydrophilic surface modification via an in-situ ligand exchange and then embedded in a water-soluble polyvinyl alcohol (PVA). This free-standing composite film is utilized as a down-converter for the fabrication of a remote-type white QD-LED, but the resulting bi-colored device exhibits a cool white light with a limited color rendering index property. To improve white light qualities, another QD-polymer film of hydrophobic red InP/ZnS QD-embedding polyvinylpyrrolidone is sequentially stacked onto the CI0.2G0.8S/ZnS QD-PVA film, producing a unique dual color-emitting, flexible and transparent bilayered composite film. Tri-colored white QD-LED integrated with the bilayered QD film possesses an exceptional color rendering property through reinforcing a red spectral component and balancing a white spectral distribution.

Following Glucose Oxidase Activity by Chemiluminescence and Chemiluminescence Resonance Energy Transfer (CRET) Processes Involving Enzyme-DNAzyme Conjugates

PubMed Central

Niazov, Angelica; Freeman, Ronit; Girsh, Julia; Willner, Itamar

2011-01-01

A hybrid consisting of glucose oxidase-functionalized with hemin/G-quadruplex units is used for the chemiluminescence detection of glucose. The glucose oxidase-mediated oxidation of glucose yields gluconic acid and H2O2. The latter in the presence of luminol acts as substrate for the hemin/G-quadruplex-catalyzed generation of chemiluminescence. The glucose oxidase/hemin G-quadruplex hybrid was immobilized on CdSe/ZnS quantum dots (QDs). The light generated by the hybrid, in the presence of glucose, activated a chemiluminescence resonance energy transfer process to the QDs, resulting in the luminescence of the QDs. The intensities of the luminescence of the QDs at different concentrations of glucose provided an optical means to detect glucose. PMID:22346648

Hybrid thin-film amplifier

NASA Technical Reports Server (NTRS)

Cleveland, G.

1977-01-01

Miniature amplifier for bioelectronic instrumentation consumes only about 100 mW and has frequency response flat to within 0.5 dB from 0.14 to 450 Hz. Device consists of five thin film substrates, which contain eight operational amplifiers and seven field-effect transistor dice.

Thermostability of Hybrid Thermoelectric Materials Consisting of Poly(Ni-ethenetetrathiolate), Polyimide and Carbon Nanotubes

PubMed Central

Oshima, Keisuke; Sadakata, Shifumi; Shiraishi, Yukihide; Toshima, Naoki

2017-01-01

Three-component organic/inorganic hybrid films were fabricated by drop-casting the mixed dispersion of nanodispersed-poly(nickel 1,1,2,2-ethenetetrathiolate) (nano-PETT), polyimide (PI) and super growth carbon nanotubes (SG-CNTs) in N-methylpyrrolidone (NMP) at the designed ratio on a substrate. The dried nano-PETT/PI/SG-CNT hybrid films were prepared by the stepwise cleaning of NMP and methanol, and were dried once more. The thermoelectric properties of Seebeck coefficient S and electrical conductivity σ were measured by a thin-film thermoelectric measurement system ADVANCE RIKO ZEM-3M8 at 330–380 K. The electrical conductivity of nano-PETT/PI/SG-CNT hybrid films increased by 1.9 times for solvent treatment by clearing insulated of polymer. In addition, the density of nano-PETT/PI/SG-CNT hybrid films decreased 1.31 to 0.85 g·cm−3 with a decrease in thermal conductivity from 0.18 to 0.12 W·m−1·K−1. To evaluate the thermostability of nano-PETT/PI/SG-CNT hybrid films, the samples were kept at high temperature and the temporal change of thermoelectric properties was measured. The nano-PETT/PI/SG-CNT hybrid films were rather stable at 353 K and kept their power factor even after 4 weeks. PMID:28773182

Novel organic–inorganic amorphous photoactive hybrid films with rare earth (Eu{sup 3+}, Tb{sup 3+}) covalently embedded into silicon–oxygen network via sol–gel process

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

Zhang, Qiang; Sheng, Ye; Zheng, Keyan

2015-10-15

Highlights: • The hybrids are prepared through the hydrolysis and condensation process. • The hybrids are amorphous and heat stabilized. • The hybrids containing Eu{sup 3+} and Tb{sup 3+} show the typical red and green emissions. - Abstract: Novel organic–inorganic hybrid amorphous thin films were synthesized by linking lanthanide (Tb{sup 3+}, Eu{sup 3+}) complexes through 3,4-bis(3-(triethoxysilyl)propylcarbamoyloxy)benzoic acid using sol–gel method. These inorganic–organic hybrids were characterized in detail by Fourier transform infrared spectroscopy, wide angle X-ray diffraction, themogravimetric analysis, scanning electron microscope, and fluorescence spectra. The above research results indicate that the hybrids possess high thermal-stability, amorphous structure features and especiallymore » favorable luminescent performances, such as long luminescent decay lifetime, high quantum yield etc.« less

High-performance solar cells with induced crystallization of perovskite by an evenly distributed CdSe quantum dots seed-mediated underlayer

NASA Astrophysics Data System (ADS)

Qi, Jiabin; Xiong, Hao; Wang, Gang; Xie, Huaqing; Jia, Wei; Zhang, Qinghong; Li, Yaogang; Wang, Hongzhi

2018-02-01

Crystallization and interface engineering of perovskite are the most important factors in achieving high-performance perovskite solar cells (PSCs). Herein, we construct an ultrathin CdSe quantum dots (QDs) underlayer via a solution-processable method, which acts as a seed-mediated layer for perfect perovskite film, with both uniform morphology and better absorption capacity. In addition, CdSe QDs and perovskites form a fully crystalline heterojunction, which is beneficial to minimizing the defect and trap densities. Then, an Ostwald ripening process is adopted to fabricate large-grain, pinhole-free perovskite thin film, by a simple methylammonium bromide treatment. Besides, the first principle is applied in calculating organic/inorganic hybrid perovskite, confirming that electrons can move even quicker and more effectively, as a result of our work. Due to these treatments, representing a very simple method to simultaneously control perovskite crystallization and optimize the interfaces in PSCs, a maximum power conversion efficiency of 15.68% is achieved, 35% higher than the PSC both without CdSe and MABr treatment (11.57%), indicating better performance.

Novel Flexible Transparent Conductive Films with Enhanced Chemical and Electromechanical Sustainability: TiO2 Nanosheet-Ag Nanowire Hybrid.

PubMed

Sohn, Hiesang; Kim, Seyun; Shin, Weonho; Lee, Jong Min; Lee, Hyangsook; Yun, Dong-Jin; Moon, Kyoung-Seok; Han, In Taek; Kwak, Chan; Hwang, Seong-Ju

2018-01-24

Flexible transparent conductive films (TCFs) of TiO 2 nanosheet (TiO 2 NS) and silver nanowire (Ag NW) network hybrid were prepared through a simple and scalable solution-based process. The as-formed TiO 2 NS-Ag NW hybrid TCF shows a high optical transmittance (TT: 97% (90.2% including plastic substrate)) and low sheet resistance (R s : 40 Ω/sq). In addition, the TiO 2 NS-Ag NW hybrid TCF exhibits a long-time chemical/aging and electromechanical stability. As for the chemical/aging stability, the hybrid TCF of Ag NW and TiO 2 NS reveals a retained initial conductivity (ΔR s /R s < 1%) under ambient oxidant gas over a month, superior to that of bare Ag NW (ΔR s /R s > 4000%) or RuO 2 NS-Ag NW hybrid (ΔR s /R s > 200%). As corroborated by the density functional theory simulation, the superb chemical stability of TiO 2 NS-Ag NW hybrid is attributable to the unique role of TiO 2 NS as a barrier, which prevents Ag NW's chemical corrosion via the attenuated adsorption of sulfidation molecules (H 2 S) on TiO 2 NS. With respect to the electromechanical stability, in contrast to Ag NWs (ΔR/R 0 ∼ 152.9%), our hybrid TCF shows a limited increment of fractional resistivity (ΔR/R 0 ∼ 14.4%) after 200 000 cycles of the 1R bending test (strain: 6.7%) owing to mechanically welded Ag NW networks by TiO 2 NS. Overall, our unique hybrid of TiO 2 NS and Ag NW exhibits excellent electrical/optical properties and reliable chemical/electromechanical stabilities.

Preparation and properties of CVD-graphene/AgNWs hybrid transparent electrodes for the application of flexible optoelectronic devices

NASA Astrophysics Data System (ADS)

Wang, Xue-yan; Bao, Jun; Li, Lu; Cui, Shao-li; Du, Xiao-qing

2017-10-01

The flexible electrodes based on CVD-graphene/ AgNWs hybrid transparent films were prepared by the vacuum filtration and substrate transferring method, and several performances of the films including sheet resistance, optical transmittance, work function, surface roughness and flexibility were further researched. The results suggested that the hybrid films which were obtained by vacuum filtration and substrate transferring method have the advantages such as uniform distribution of AgNWs, high work function, low roughness and small sheet resistance and good flexibility. The sheet resistance of the hybrid films would decrease with the increasing of the concentration of AgNWs, while the surface roughness would increase and the optical transmittance at 550nm of the films decrease linearly. Organic light emitting devices (OLED) devices based on CVD-graphene/AgNWs hybrid films were fabricated, and characteristics of voltage-current density, luminance, current efficiency were tested. It's found that CVD-graphene/AgNWs hybrid films were better than CVD-graphene films when they were used as anodes for organic light emitting devices. It can be seen that CVD-graphene/AgNWs hybrid transparent films have great potential in applications of flexible electrodes, and are of great significance for promoting the development of organic light emitting devices.

Synthesis of superhydrophobic PTFE-like thin films by self-nanostructuration in a hybrid plasma process

NASA Astrophysics Data System (ADS)

Henry, Frédéric; Renaux, Fabian; Coppée, Séverine; Lazzaroni, Roberto; Vandencasteele, Nicolas; Reniers, François; Snyders, Rony

2012-12-01

Superhydrophobic poly(tetrafluoro-ethylene) (PTFE) like thin films were grown on silicon wafers using a plasma-based hybrid process consisting on sputtering a carbon target in an Ar/CF4 atmosphere. The influence of the bias voltage applied to the substrate (VBias) as well as of the gas mixture composition (%CF4) on the chemical composition, the wettability and the morphology of the deposited thin films were evaluated. The chemical composition measured by X-ray Photoelectron Spectroscopy (XPS) has revealed that the F/C atomic ratio is always lower than for conventional PTFE (F/C = 2) and that it decreases when VBias increases (from F/C = 1 for VBias = - 100 V to F/C = 0.75 for VBias = - 200 V). This behavior is associated with the preferential sputtering of the fluorine atoms during the plasma-assisted growth of the films. Consecutively, a self-nanostructuration enhanced when increasing VBias is observed. As a consequence, the water contact angle (WCA) measurements range from 70° up to 150° depending on (i) the fluorine concentration and (ii) on the magnitude of the nanostructuration. In addition, for the films presenting the highest WCAs, a small hysteresis between the advancing and receding WCAs is observed (< 10°) allowing these films to fulfill completely the requirements of superhydrophobicity. The nanostructuration is probably due to the chemical etching by fluorine atoms of the fluorinated group. In order to get more understanding on the wettability mechanisms of these surfaces, the topography of the films has been evaluated by atomic force microscopy (AFM). The data have revealed, for all films, a dense and regular structure composed by conic objects (AvH is their average height and AvD is the average distance between them) for which the dimensions increase with VBias. A correlation between AvH/AvD, defined as the "morphological ratio", with the WCA was established. Theoretical evaluations of the WCA using the Wenzel and Cassie equations with, as inputs

Application of quantum-dots for analysis of nanosystems by either utilizing or preventing FRET

NASA Astrophysics Data System (ADS)

Kim, Joong H.; Chaudhary, Sumit; Stephens, Jared P.; Singh, Krishna V.; Ozkan, Mihrimah

2005-04-01

We have developed conjugates with quantum-dots (QDs) for the purpose of analysis of nanosystems that are organic or inorganic in nature such as DNA and carbon nanotubes. First, by employing Florescence Resonant Energy Transfer (FRET) principles, a hybrid molecular beacon conjugates are synthesized. For water- solubilization of QDs, we modified the surface of CdSe-ZnS core-shell QD by using mercaptoacetic acid ligand. This modification does not affect the size of QDs from that of unmodified QDs. After linking molecular beacons to the carboxyl groups of the modified QDs using 1-Ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, hybrid molecular beacons are prepared as a DNA probe. After hybridization with specific target DNA and non-specific target DNA, the hybrid conjugates show high specificity to the target DNA with 5-fold increase in the intensity of fluorescence. By developing atomic model of the conjugates, we calculated with 8 numbers of molecular beacons on a single quantum dots, we could increase the efficiency of FRET up to 90%. In other hands, for application of quantum dots to the carbon nanotubes, FRET is a barrier. Thus, after employing 1 % sodium-dodecyl-sulfonate (SDS), single-walled carbon nanotubes are decorated with QDs at their outer surface. This enables fluorescent microscopy imaging of single-walled carbon nanotubes which is a more common technique than electron microscopy. In summary, QDs can be used for analysis or detection of both organic and inorganic based nanosystems.

Explanation of the photocurrent generation of Cu2O quantum dots (QDs) sensitized p-CuSCN stable photoelectrochemical cells

NASA Astrophysics Data System (ADS)

Karunarathna, P. G. D. C. K.; Samarakoon, S. P. A. U. K.; Fernando, C. A. N.

2018-01-01

Fabrication of Cu2O quantum dots (QDs) sensitized p-CuSCN photoelectrode provides a significant photocurrent enhancement in photoelectrochemical medium for the first time. The variation of photocurrent quantum efficiency (Ф%) with Cu2O amount formed on p-CuSCN was presented. Here, two maxima of photocurrent could be observed in Cu/p-CuSCN/Cu2O photoelectrodes. The first photocurrent peak was due to the Cu2O QDs sensitization on p-CuSCN layer, and the second photocurrent peak was due to the formation of p-n junction. Time development of the photocurrent for Cu/p-CuSCN/n-Cu2O photoelectrodes and material characterization from Fourier transform infrared (FTIR) spectra, scanning electron microscope (SEM) images, energy dispersive x-ray spectroscopy (EDX) and x-ray diffraction (XRD) were done in this study in detailed.

Designing hybrid gate dielectric for fully printing high-performance carbon nanotube thin film transistors

NASA Astrophysics Data System (ADS)

Li, Qian; Li, Shilong; Yang, Dehua; Su, Wei; Wang, Yanchun; Zhou, Weiya; Liu, Huaping; Xie, Sishen

2017-10-01

The electrical characteristics of carbon nanotube (CNT) thin-film transistors (TFTs) strongly depend on the properties of the gate dielectric that is in direct contact with the semiconducting CNT channel materials. Here, we systematically investigated the dielectric effects on the electrical characteristics of fully printed semiconducting CNT-TFTs by introducing the organic dielectrics of poly(methyl methacrylate) (PMMA) and octadecyltrichlorosilane (OTS) to modify SiO2 dielectric. The results showed that the organic-modified SiO2 dielectric formed a favorable interface for the efficient charge transport in s-SWCNT-TFTs. Compared to single-layer SiO2 dielectric, the use of organic-inorganic hybrid bilayer dielectrics dramatically improved the performances of SWCNT-TFTs such as mobility, threshold voltage, hysteresis and on/off ratio due to the suppress of charge scattering, gate leakage current and charge trapping. The transport mechanism is related that the dielectric with few charge trapping provided efficient percolation pathways for charge carriers, while reduced the charge scattering. High density of charge traps which could directly act as physical transport barriers and significantly restrict the charge carrier transport and, thus, result in decreased mobile carriers and low device performance. Moreover, the gate leakage phenomenon is caused by conduction through charge traps. So, as a component of TFTs, the gate dielectric is of crucial importance to the manufacture of high quality TFTs from the aspects of affecting the gate leakage current and device operation voltage, as well as the charge carrier transport. Interestingly, the OTS-modified SiO2 allows to directly print horizontally aligned CNT film, and the corresponding devices exhibited a higher mobility than that of the devices with the hybrid PMMA/SiO2 dielectric although the thickness of OTS layer is only ˜2.5 nm. Our present result may provide key guidance for the further development of printed

Laser synthesis of hybrid nanoparticles for biomedicine

NASA Astrophysics Data System (ADS)

Avetissian, H. K.; Lalayan, A. A.

2018-04-01

The extraordinary properties of size-tunable nanoparticles (NPs) have given rise to their widespread applications in Nanophotonics, Biomedicine, Plasmonics etc. Semiconductor and metal NPs have found a number of significant applications in the modern biomedicine due to ultrasmall sizes (1-10 nm) and the size-dependent flexibility of their optical properties. In the present work passive Q-switched Nd:YAG pulsed laser was used to synthesize NPs by method of laser ablation in different liquids. For cases of hybrid metal NPs we have demonstrated that plasmon resonance can be modified and tuned from the plasmon resonances of pure metal NPs. The shifted plasmon resonance frequency at 437 nm for Au-Ag hybrid NPs, and 545 nm for Au-Cu hybrid NPs have been observed. Effectiveness of biotissue ablation in the case of the tissue sample that colored with metal NPs was approximately on 4-5 times larger than for the sample with non-colored area. Laser welding for deep-located biotissue layers colored by metal NPs has been realized. The luminescence properties of the colloidal hybrid Si-Ni nanoparticles' system fabricated by pulsed laser ablation are also considered. The red-shifted photoluminescence of this system has been registered in the blue range of the spectrum because of the Stark effect in the Coulomb field of the charged Ni nanoparticles. Summarizing, the knowledge of peculiarities of optical properties of hybrid NPs is very important for biomedical applications. More complex nanoassemblies can be easily constructed by the presented technique of laser synthesis of colloidal QDs including complexes of NPs of different materials.

Bacterial self-defense antibiotics release from organic-inorganic hybrid multilayer films for long-term anti-adhesion and biofilm inhibition properties.

PubMed

Xu, Qingwen; Li, Xi; Jin, Yingying; Sun, Lin; Ding, Xiaoxu; Liang, Lin; Wang, Lei; Nan, Kaihui; Ji, Jian; Chen, Hao; Wang, Bailiang

2017-12-14

Implant-associated bacterial infections pose serious medical and financial issues due to the colonization and proliferation of pathogens on the surface of the implant. The as-prepared traditional antibacterial surfaces can neither resist bacterial adhesion nor inhibit the development of biofilm over the long term. Herein, novel (montmorillonite/poly-l-lysine-gentamicin sulfate) 8 ((MMT/PLL-GS) 8 ) organic-inorganic hybrid multilayer films were developed to combine enzymatic degradation PLL for on-demand self-defense antibiotics release. Small molecule GS was loaded into the multilayer films during self-assembly and the multilayer films showed pH-dependent and linear growth behavior. The chymotrypsin- (CMS) and bacterial infections-responsive film degradation led to the peeling of the films and GS release. Enzyme-responsive GS release exhibited CMS concentration dependence as measured by the size of the inhibition zone and SEM images. Notably, the obtained antibacterial films showed highly efficient bactericidal activity which killed more than 99.9% of S. aureus in 12 h. Even after 3 d of incubation in S. aureus, E. coli or S. epidermidis solutions, the multilayer films exhibited inhibition zones of more than 1.5 mm in size. Both in vitro and in vivo antibacterial tests indicated good cell compatibility, and anti-inflammatory, and long-term bacterial anti-adhesion and biofilm inhibition properties.

Use of CdS quantum dot-functionalized cellulose nanocrystal films for anti-counterfeiting applications.

PubMed

Chen, L; Lai, C; Marchewka, R; Berry, R M; Tam, K C

2016-07-21

Structural colors and photoluminescence have been widely used for anti-counterfeiting and security applications. We report for the first time the use of CdS quantum dot (QD)-functionalized cellulose nanocrystals (CNCs) as building blocks to fabricate nanothin films via layer-by-layer (LBL) self-assembly for anti-counterfeiting applications. Both negatively- and positively-charged CNC/QD nanohybrids with a high colloidal stability and a narrow particle size distribution were prepared. The controllable LBL coating process was characterized by scanning electron microscopy and ellipsometry. The rigid structure of CNCs leads to nanoporous structured films on poly(ethylene terephthalate) (PET) substrates with high transmittance (above 70%) over the entire range of visible light and also resulted in increased hydrophilicity (contact angles of ∼40 degrees). Nanothin films on PET substrates showed good flexibility and enhanced stability in both water and ethanol. The modified PET films with structural colors from thin-film interference and photoluminescence from QDs can be used in anti-counterfeiting applications.

Sandwiched confinement of quantum dots in graphene matrix for efficient electron transfer and photocurrent production

PubMed Central

Zhu, Nan; Zheng, Kaibo; Karki, Khadga J.; Abdellah, Mohamed; Zhu, Qiushi; Carlson, Stefan; Haase, Dörthe; Žídek, Karel; Ulstrup, Jens; Canton, Sophie E.; Pullerits, Tõnu; Chi, Qijin

2015-01-01

Quantum dots (QDs) and graphene are both promising materials for the development of new-generation optoelectronic devices. Towards this end, synergic assembly of these two building blocks is a key step but remains a challenge. Here, we show a one-step strategy for organizing QDs in a graphene matrix via interfacial self-assembly, leading to the formation of sandwiched hybrid QD-graphene nanofilms. We have explored structural features, electron transfer kinetics and photocurrent generation capacity of such hybrid nanofilms using a wide variety of advanced techniques. Graphene nanosheets interlink QDs and significantly improve electronic coupling, resulting in fast electron transfer from photoexcited QDs to graphene with a rate constant of 1.3 × 109 s−1. Efficient electron transfer dramatically enhances photocurrent generation in a liquid-junction QD-sensitized solar cell where the hybrid nanofilm acts as a photoanode. We thereby demonstrate a cost-effective method to construct large-area QD-graphene hybrid nanofilms with straightforward scale-up potential for optoelectronic applications. PMID:25996307

Sandwiched confinement of quantum dots in graphene matrix for efficient electron transfer and photocurrent production

NASA Astrophysics Data System (ADS)

Zhu, Nan; Zheng, Kaibo; Karki, Khadga J.; Abdellah, Mohamed; Zhu, Qiushi; Carlson, Stefan; Haase, Dörthe; Žídek, Karel; Ulstrup, Jens; Canton, Sophie E.; Pullerits, Tõnu; Chi, Qijin

2015-05-01

Quantum dots (QDs) and graphene are both promising materials for the development of new-generation optoelectronic devices. Towards this end, synergic assembly of these two building blocks is a key step but remains a challenge. Here, we show a one-step strategy for organizing QDs in a graphene matrix via interfacial self-assembly, leading to the formation of sandwiched hybrid QD-graphene nanofilms. We have explored structural features, electron transfer kinetics and photocurrent generation capacity of such hybrid nanofilms using a wide variety of advanced techniques. Graphene nanosheets interlink QDs and significantly improve electronic coupling, resulting in fast electron transfer from photoexcited QDs to graphene with a rate constant of 1.3 × 109 s-1. Efficient electron transfer dramatically enhances photocurrent generation in a liquid-junction QD-sensitized solar cell where the hybrid nanofilm acts as a photoanode. We thereby demonstrate a cost-effective method to construct large-area QD-graphene hybrid nanofilms with straightforward scale-up potential for optoelectronic applications.

Hybrid Black Phosphorus/Zero-Dimensional Quantum Dot Phototransistors: Tunable Photodoping and Enhanced Photoresponsivity.

PubMed

Lee, A-Young; Ra, Hyun-Soo; Kwak, Do-Hyun; Jeong, Min-Hye; Park, Jeong-Hyun; Kang, Yeon-Su; Chae, Weon-Sik; Lee, Jong-Soo

2018-05-09

Recently, black phosphorus (BP) with direct band gap exhibited excellent potential for optoelectronic applications because of its high charge carrier mobility and low dark current as well as the variable band gap of 0.3-1.5 eV depending on the number of layers. However, few-layer BP-based phototransistors (photo-FETs) have been limited in sensitivity and wavelength selectivity. To overcome the drawback of these photo-FETs, we studied hybrid photo-FETs combined with the novel properties of the two materials between the channel and sensitizer layers. By combining a strong absorbance of a quantum dot (QD) layer and a two-dimensional layer material with high carrier mobility, the hybrid photo-FETs are expected to produce high-performance photodetectors that can effectively control the responsivity, detectivity, and response time. In this study, we demonstrate that the photogenerated carriers formed from QD sensitizer layers migrate to the BP transport layer with high charge mobility and not only improve the photodetector performance but also enhance the photodoping effect of the BP transport layer with an ambipolar characteristic by electrons transferred from n-type CdSe QDs or holes injected from p-type PbS QDs. The responsivity and detectivity of hybrid BP/0D photo-FETs exhibit 1.16 × 10 9 A W -1 and 7.53 × 10 16 Jones for the BP/CdSe QD photo-FET and 5.36 × 10 8 A W -1 and 1.89 × 10 16 Jones for the BP/PbS QD photo-FET, respectively. The photocurrent rise (τ rise ) and decay (τ decay ) times were τ rise = 0.406 s and τ decay = 0.815 s for BP/CdSe QD photo-FET and τ rise = 0.576 s and τ decay = 0.773 s for BP/PbS QD photo-FET, respectively.

Acetylcholinesterase-reduced graphene oxide hybrid films for organophosphorus neurotoxin sensing via quartz crystal microbalance

NASA Astrophysics Data System (ADS)

Tang, Shi; Ma, Wenying; Xie, Guangzhong; Su, Yuanjie; Jiang, Yadong

2016-09-01

An acetylcholinesterase (AChE)-reduced graphene oxide (RGO) hybrid films based biosensor enabled by quartz crystal microbalance (QCM) has been developed for the detection of organophosphorus neurotoxin in gas phase at room temperature. To improve the sensing performance, RGO was used to immobilize large quantities of enzyme and provide a favorable microenvironment to maintain the enzyme activity. The experimental results reveal that the response of AChE-RGO/glutaraldehyde based sensors is about 8 times larger than that of the AChE with the sensitivity of 1.583 Hz/mg/m3. 1.0 mg amount of RGO, 5% concentration of glutaraldehyde and pH 6.8 is the optimal condition of this biosensor.

Design and evaluation of a 3 million DN series-hybrid thrust bearing

NASA Technical Reports Server (NTRS)

Scibbe, H. W.; Winn, L. W.; Eusepi, M.

1976-01-01

The design and experimental evaluation of a series-hybrid thrust bearing, consisting of a 150-mm ball bearing and a centrifugally actuated, conical, fluid-film bearing, is presented. Tests were conducted up to 16,000 rpm and at this speed an axial load of 15,600 N (3500 lb) was safely supported by the hybrid bearing system. Through the series-hybrid bearing principle, the effective ball bearing speed was reduced to approximately one-half of the shaft speed. A speed reduction of this magnitude would result in a tenfold increase in the ball bearing fatigue life. A successful evaluation of fluid-film bearing lubricant supply failure was performed repeatedly at an operating speed of 10,000 rpm. A complete and smooth changeover to full-scale ball bearing operation was effected when the oil supply to the fluid-film bearing was cut off. Reactivation of the fluid-film oil supply system produced a flawless return to the original mode of hybrid operation.

Novel hybrid structure silica/CdTe/molecularly imprinted polymer: synthesis, specific recognition, and quantitative fluorescence detection of bovine hemoglobin.

PubMed

Li, Dong-Yan; He, Xi-Wen; Chen, Yang; Li, Wen-You; Zhang, Yu-Kui

2013-12-11

This work presented a novel strategy for the synthesis of the hybrid structure silica/CdTe/molecularly imprinted polymer (Si-NP/CdTe/MIP) to recognize and detect the template bovine hemoglobin (BHb). First, amino-functionalized silica nanoparticles (Si-NP) and carboxyl-terminated CdTe quantum dots (QDs) were assembled into composite nanoparticles (Si-NP/CdTe) using the EDC (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride) chemistry. Next, Si-NP/CdTe/MIP was synthesized by anchoring molecularly imprinted polymer (MIP) layer on the surface of Si-NP/CdTe through the sol-gel technique and surface imprinting technique. The hybrid structure possessed the selectivity of molecular imprinting technique and the sensitivity of CdTe QDs as well as well-defined morphology. The binding experiment and fluorescence method demonstrated its special recognition performance toward the template BHb. Under the optimized conditions, the fluorescence intensity of the Si-NP/CdTe/MIP decreased linearly with the increase of BHb in the concentration range 0.02-2.1 μM, and the detection limit was 9.4 nM. Moreover, the reusability and reproducibility and the successful applications in practical samples indicated the synthesis of Si-NP/CdTe/MIP provided an alternative solution for special recognition and determination of protein from real samples.

Tunneling conductance in superconductor-hybrid double quantum dots Josephson junction

NASA Astrophysics Data System (ADS)

Chamoli, Tanuj; Ajay

2018-05-01

The present work deals with the theoretical model study to analyse the tunneling conductance across a superconductor hybrid double quantum dots tunnel junction (S-DQD-S). Recently, there are many experimental works where the Josephson current across such nanoscopic junction is found to be dependent on nature of the superconducting electrodes, coupling of the hybrid double quantum dot's electronic states with the electronic states of the superconductors and nature of electronic structure of the coupled dots. For this, we have attempted a theoretical model containing contributions of BCS superconducting leads, magnetic coupled quantum dot states and coupling of superconducting leads with QDs. In order to include magnetic coupled QDs the contributions of competitive Kondo and Ruderman-Kittel- Kasuya-Yosida (RKKY) interaction terms are also introduced through many body effects in the model Hamiltonian at low temperatures (where Kondo temperature TK < superconducting transition temperature TC). Employing non-equilibrium Green's function approach within mean field approximation, we have obtained expressions for density of states (DOS) and analysed the same using numerical computation to underline the nature of DOS close to Fermi level in S-DQD-S junctions. On the basis of numerical computation, it is pointed out that indirect exchange interaction between impurities (QD) i.e. RKKY interaction suppresses the screening of magnetic QD due to Cooper pair electrons i.e. Kondo effect in the form of reduction in the magnitude of sharp DOS peak close to Fermi level which is in qualitative agreement with the experimental observations in such tunnel junctions. Tunneling conductance is proportional to DOS, hence we can analyse it's behaviour with the help of DOS.

Design automation for complex CMOS/SOS LSI hybrid substrates

NASA Technical Reports Server (NTRS)

Ramondetta, P. W.; Smiley, J. W.

1976-01-01

A design automated approach used to develop thick-film hybrid packages is described. The hybrid packages produced combine thick-film and silicon on sapphire (SOS) laser surface interaction technologies to bring the on-chip performance level of SOS to the subsystem level. Packing densities are improved by a factor of eight over ceramic dual in-line packing; interchip wiring capacitance is low. Due to significant time savings, the design automated approach presented can be expected to yield a 3:1 reduction in cost over the use of manual methods for the initial design of a hybrid.

Three-Dimensional Microphase Separation and Synergistic Permeability in Stacked Lipid–Polymer Hybrid Membranes

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

Kang, Minjee; Lee, Byeongdu; Leal, Cecilia

Here, we present new structures of soft-material thin films that augment the functionality of substrate-mediated delivery systems. A hybrid material composed of phospholipids and block copolymers adopts a multilayered membrane structure supported on a solid surface. The hybrid films comprise intentional intramembrane heterogeneities that register across multilayers. These stacked domains convey unprecedented enhancement and control of permeability of solutes across micrometer-thick films. Using grazing incidence X-ray scattering, phase contrast atomic force microscopy, and confocal microscopy, we observed that in each lamella, lipid and polymers partition unevenly within the membrane plane segregating into lipid- or polymer-rich domains. Interestingly, we found evidencemore » that like-domains align in registry across multilayers, thereby making phase separation three-dimensional. Phase boundaries exist over extended length scales to compensate the height mismatch between lipid and polymer molecules. We show that microphase separation in hybrid films can be exploited to augment the capability of drug-eluting substrates. Lipid–polymer hybrid films loaded with paclitaxel show synergistic permeability of drug compared to single-component counterparts. We present a thorough structural study of stacked lipid–polymer hybrid membranes and propose that the presence of registered domains and domain boundaries impart enhanced drug release functionality. This work offers new perspectives in designing thin films for controlled delivery applications« less

Three-Dimensional Microphase Separation and Synergistic Permeability in Stacked Lipid–Polymer Hybrid Membranes

DOE PAGES

Kang, Minjee; Lee, Byeongdu; Leal, Cecilia

2017-10-20

Here, we present new structures of soft-material thin films that augment the functionality of substrate-mediated delivery systems. A hybrid material composed of phospholipids and block copolymers adopts a multilayered membrane structure supported on a solid surface. The hybrid films comprise intentional intramembrane heterogeneities that register across multilayers. These stacked domains convey unprecedented enhancement and control of permeability of solutes across micrometer-thick films. Using grazing incidence X-ray scattering, phase contrast atomic force microscopy, and confocal microscopy, we observed that in each lamella, lipid and polymers partition unevenly within the membrane plane segregating into lipid- or polymer-rich domains. Interestingly, we found evidencemore » that like-domains align in registry across multilayers, thereby making phase separation three-dimensional. Phase boundaries exist over extended length scales to compensate the height mismatch between lipid and polymer molecules. We show that microphase separation in hybrid films can be exploited to augment the capability of drug-eluting substrates. Lipid–polymer hybrid films loaded with paclitaxel show synergistic permeability of drug compared to single-component counterparts. We present a thorough structural study of stacked lipid–polymer hybrid membranes and propose that the presence of registered domains and domain boundaries impart enhanced drug release functionality. This work offers new perspectives in designing thin films for controlled delivery applications« less

Growth of magnesium diboride thin films on boron buffered Si and silicon-on-insulator substrates by hybrid physical chemical vapor deposition

NASA Astrophysics Data System (ADS)

Withanage, Wenura K.; Penmatsa, Sashank V.; Acharya, Narendra; Melbourne, Thomas; Cunnane, D.; Karasik, B. S.; Xi, X. X.

2018-07-01

We report on the growth of high quality MgB2 thin films on silicon and silicon-on-insulator substrates by hybrid physical chemical vapor deposition. A boron buffer layer was deposited on all sides of the Si substrate to prevent the reaction of Mg vapor and Si. Ar ion milling at a low angle of 1° was used to reduce the roughness of the boron buffer layer before the MgB2 growth. An Ar ion milling at low angle of 1° was also applied to the MgB2 surface to reduce its roughness. The resultant MgB2 films showed excellent superconducting properties and a smooth surface. The process produces thin MgB2 films suitable for waveguide-based superconducting hot electron bolometers and other MgB2-based electronic devices.

In situ intercalation strategies for device-quality hybrid inorganic-organic self-assembled quantum wells

NASA Astrophysics Data System (ADS)

Pradeesh, K.; Baumberg, J. J.; Prakash, G. Vijaya

2009-07-01

Thin films of self-organized quantum wells of inorganic-organic hybrid perovskites of (C6H9C2H4NH3)2PbI4 are formed from a simple intercalation strategy to yield well-ordered uniform films over centimeter-size scales. These films compare favorably with traditional solution-chemistry-synthesized thin films. The hybrid films show strong room-temperature exciton-related absorption and photoluminescence, which shift with fabrication protocol. We demonstrate the potential of this method for electronic and photonic device applications.

Multifunctional Hybrid Multilayer Gate Dielectrics with Tunable Surface Energy for Ultralow-Power Organic and Amorphous Oxide Thin-Film Transistors.

PubMed

Byun, Hye-Ran; You, Eun-Ah; Ha, Young-Geun

2017-03-01

For large-area, printable, and flexible electronic applications using advanced semiconductors, novel dielectric materials with excellent capacitance, insulating property, thermal stability, and mechanical flexibility need to be developed to achieve high-performance, ultralow-voltage operation of thin-film transistors (TFTs). In this work, we first report on the facile fabrication of multifunctional hybrid multilayer gate dielectrics with tunable surface energy via a low-temperature solution-process to produce ultralow-voltage organic and amorphous oxide TFTs. The hybrid multilayer dielectric materials are constructed by iteratively stacking bifunctional phosphonic acid-based self-assembled monolayers combined with ultrathin high-k oxide layers. The nanoscopic thickness-controllable hybrid dielectrics exhibit the superior capacitance (up to 970 nF/cm 2 ), insulating property (leakage current densities <10 -7 A/cm 2 ), and thermal stability (up to 300 °C) as well as smooth surfaces (root-mean-square roughness <0.35 nm). In addition, the surface energy of the hybrid multilayer dielectrics are easily changed by switching between mono- and bifunctional phosphonic acid-based self-assembled monolayers for compatible fabrication with both organic and amorphous oxide semiconductors. Consequently, the hybrid multilayer dielectrics integrated into TFTs reveal their excellent dielectric functions to achieve high-performance, ultralow-voltage operation (< ± 2 V) for both organic and amorphous oxide TFTs. Because of the easily tunable surface energy, the multifunctional hybrid multilayer dielectrics can also be adapted for various organic and inorganic semiconductors, and metal gates in other device configurations, thus allowing diverse advanced electronic applications including ultralow-power and large-area electronic devices.

Microstructure and property of diamond-like carbon films with Al and Cr co-doping deposited using a hybrid beams system

NASA Astrophysics Data System (ADS)

Dai, Wei; Liu, Jingmao; Geng, Dongsen; Guo, Peng; Zheng, Jun; Wang, Qimin

2016-12-01

DLC films with weak carbide former Al and carbide former Cr co-doping (Al:Cr-DLC) were deposited by a hybrid beams system comprising an anode-layer linear ion beam source (LIS) and high power impulse magnetron sputtering using a gas mixture of C2H2 and Ar as the precursor. The doped Al and Cr contents were controlled via adjusting the C2H2 fraction in the gas mixture. The composition, microstructure, compressive stress, mechanical properties and tribological behaviors of the Al:Cr-DLC films were researched carefully using X-ray photoelectron spectroscopy, transmission electron microscopy, Raman spectroscopy, stress-tester, nanoindentation and ball-on-plate tribometer as function of the C2H2 fraction. The results show that the Al and Cr contents in the films increased continuously as the C2H2 fraction decreased. The doped Cr atoms preferred to bond with the carbon while the Al atoms mainly existed in metallic state. Structure modulation with alternate multilayer consisted of Al-poor DLC layer and Al-rich DLC layer was found in the films. Those periodic Al-rich DLC layers can effectively release the residual stress of the films. On the other hand, the formation of the carbide component due to Cr incorporation can help to increase the film hardness. Accordingly, the residual stress of the DLC films can be reduced without sacrificing the film hardness though co-doping Al and Cr atoms. Furthermore, it was found that the periodic Al-rich layer can greatly improve the elastic resilience of the DLC films and thus decreases the film friction coefficient and wear rate significantly. However, the existence of the carbide component would cause abrasive wear and thus deteriorate the wear performance of the films.

Surface-plasmon-polariton hybridized cavity modes in submicrometer slits in a thin Au film

NASA Astrophysics Data System (ADS)

Walther, R.; Fritz, S.; Müller, E.; Schneider, R.; Maniv, T.; Cohen, H.; Matyssek, C.; Busch, K.; Gerthsen, D.

2016-06-01

The excitation of cavity standing waves in double-slit structures in thin gold films, with slit lengths between 400 and 2560 nm, was probed with a strongly focused electron beam in a transmission electron microscope. The energies and wavelengths of cavity modes up to the 11 th mode order were measured with electron energy loss spectroscopy to derive the corresponding dispersion relation. For all orders, a significant redshift of mode energies accompanied by a wavelength elongation relative to the expected resonator energies and wavelengths is observed. The resultant dispersion relation is found to closely follow the well-known dispersion law of surface-plasmon polaritons (SPPs) propagating on a gold/air interface, thus providing direct evidence for the hybridized nature of the detected cavity modes with SPPs.

Efficient cold cathode emission in crystalline-amorphous hybrid: Study on carbon nanotube-cadmium selenide system

NASA Astrophysics Data System (ADS)

Sarkar, S.; Banerjee, D.; Das, N. S.; Ghorai, U. K.; Sen, D.; Chattopadhyay, K. K.

2018-03-01

Cadmium Selenide (CdSe) quantum dot (QD) decorated amorphous carbon nanotubes (a-CNTs) hybrids have been synthesized by simple chemical process. The samples were characterized by field emission scanning and transmission electron microscopy, Fourier transformed infrared spectroscopy, Raman and UV-Vis spectroscopy. Lattice image obtained from transmission electron microscopic study confirms the successful attachment of CdSe QDs. It is seen that hybrid samples show an enhanced cold emission properties with good stability. The results have been explained in terms of increased roughness, more numbers of emitting sites and favorable band bending induced electron transport. ANSYS software based calculation has also supported the result. Also a first principle based study has been done which shows that due to the formation of hybrid structure there is a profound upward shift in the Fermi level, i.e. a decrease of work function, which is believed to be another key reason for the observed improved field emission performance.

Secondary treatment of films of colloidal quantum dots for optoelectronics and devices produced thereby

DOEpatents

Semonin, Octavi Escala; Luther, Joseph M; Beard, Matthew C; Chen, Hsiang-Yu

2014-04-01

A method of forming an optoelectronic device. The method includes providing a deposition surface and contacting the deposition surface with a ligand exchange chemical and contacting the deposition surface with a quantum dot (QD) colloid. This initial process is repeated over one or more cycles to form an initial QD film on the deposition surface. The method further includes subsequently contacting the QD film with a secondary treatment chemical and optionally contacting the surface with additional QDs to form an enhanced QD layer exhibiting multiple exciton generation (MEG) upon absorption of high energy photons by the QD active layer. Devices having an enhanced QD active layer as described above are also disclosed.

Highly Transparent, Visible-Light Photodetector Based on Oxide Semiconductors and Quantum Dots.

PubMed

Shin, Seung Won; Lee, Kwang-Ho; Park, Jin-Seong; Kang, Seong Jun

2015-09-09

Highly transparent phototransistors that can detect visible light have been fabricated by combining indium-gallium-zinc oxide (IGZO) and quantum dots (QDs). A wide-band-gap IGZO film was used as a transparent semiconducting channel, while small-band-gap QDs were adopted to absorb and convert visible light to an electrical signal. Typical IGZO thin-film transistors (TFTs) did not show a photocurrent with illumination of visible light. However, IGZO TFTs decorated with QDs showed enhanced photocurrent upon exposure to visible light. The device showed a responsivity of 1.35×10(4) A/W and an external quantum efficiency of 2.59×10(4) under illumination by a 635 nm laser. The origin of the increased photocurrent in the visible light was the small band gap of the QDs combined with the transparent IGZO films. Therefore, transparent phototransistors based on IGZO and QDs were fabricated and characterized in detail. The result is relevant for the development of highly transparent photodetectors that can detect visible light.

Hybrid Thin Film Organosilica Sol-Gel Coatings To Support Neuronal Growth and Limit Astrocyte Growth.

PubMed

Capeletti, Larissa Brentano; Cardoso, Mateus Borba; Dos Santos, João Henrique Zimnoch; He, Wei

2016-10-07

Thin films of silica prepared by a sol-gel process are becoming a feasible coating option for surface modification of implantable neural sensors without imposing adverse effects on the devices' electrical properties. In order to advance the application of such silica-based coatings in the context of neural interfacing, the characteristics of silica sol-gel are further tailored to gain active control of interactions between cells and the coating materials. By incorporating various readily available organotrialkoxysilanes carrying distinct organic functional groups during the sol-gel process, a library of hybrid organosilica coatings is developed and investigated. In vitro neural cultures using PC12 cells and primary cortical neurons both reveal that, among these different types of hybrid organosilica, the introduction of aminopropyl groups drastically transforms the silica into robust neural permissive substrate, supporting neuron adhesion and neurite outgrowth. Moreover, when this organosilica is cultured with astrocytes, a key type of glial cells responsible for glial scar response toward neural implants, such cell growth promoting effect is not observed. These findings highlight the potential of organo-group-bearing silica sol-gel to function as advanced coating materials to selectively modulate cell response and promote neural integration with implantable sensing devices.

Charge Transport between Coupling Colloidal Perovskite Quantum Dots Assisted by Functional Conjugated Ligands.

PubMed

Dai, Jinfei; Xi, Jun; Li, Lu; Zhao, JingFeng; Shi, Yifei; Zhang, Wenwen; Ran, Chenxin; Jiao, Bo; Hou, Xun; Duan, Xinhua; Wu, Zhaoxin

2018-05-14

Long alkyl-chain capping ligands are indispensable for preparing stable colloidal quantum dots. However, its insulating feature blocks efficient carrier transport among QDs, leading to inferior performance in light-emitting diodes (LEDs). The trade-off between conductivity and colloidal stability of QDs has now been overcome. Methylamine lead bromide (MAPbBr 3 ) QDs with a conjugated alkyl-amine, 3-phenyl-2-propen-1-amine (PPA), as ligands were prepared. Owing to electron cloud overlapping and the delocalization effect of conjugated molecules, the conductivity and carrier mobility of PPA-QDs films increased almost 22 times over that of OA-QD films without compromising colloidal stability and photoluminescence. PPA-QDs LEDs exhibit a maximum current efficiency of 9.08 cd A -1 , which is 8 times of that of OA-QDs LEDs (1.14 cd A -1 ). This work provides critical solution for the poor conductivity of QDs in applications of energy-related devices. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hybrid gas-to-particle conversion and chemical vapor deposition for production of high-surface area films

NASA Astrophysics Data System (ADS)

Nguyen, Quynh Tan

A hybrid process, based upon gas-to-particle conversion and chemical vapor deposition, is presented as an alternative technique for producing porous films with the main advantages of solvent-free, low-substrate temperature operation. Starting from solid precursors, nanoparticles were produced in the vapor phase. Downstream of this reaction zone, these nanoparticles were collected via thermophoresis onto a cooled substrate forming a porous film. Initially, alumina (Al2O3) films were produced. Later, multi-component processing was explored by incorporating platinum (Pt) nanoparticles into the Al2O3 matrix leading to the production of Pt/Al 2O3 films by two routes: simultaneous precursor injection processing or by a layer-by-layer approach. In single component processing, the formation of nanoparticle aggregates was evident within the amorphous Al2O3 films. Aggregates, composed of these particles, are likely held together by relatively weak van der Waals forces leading to the observed poor physical cohesion. In multi-component processing, reasonable control of composition and distribution of species is possible with Pt nanoparticles appearing to be co-agglomerated with alumina. Deposited crystalline Pt nanoparticles may encourage the crystallization of the amorphous Al2O3. Finally, from chemisorption results, the produced sample appears to have potentially greater catalytic activity than a commercially available standard. A model is in development to study nanoparticle interactions with a gas and deposition occurring in stagnation flow onto the cooled horizontal substrate within the tubular reactor. Using velocity and temperature fields generated from numerical solutions to the Navier-Stokes and energy equations, particle trajectories were calculated from the summation of drag, gravitational, thermophoretic, and Brownian forces. In rectangular coordinates, cooling stage width to reactor diameter ratio, deposition stage temperature, and initial velocity were the

Spatial localization of excitons and charge carriers in hybrid perovskite thin films

DOE PAGES

Simpson, Mary Jane; Doughty, Benjamin; Yang, Bin; ...

2015-07-21

The fundamental photophysics underlying the remarkably high power conversion efficiency of organic-inorganic hybrid perovskite-based solar cells has been increasingly studied using complementary spectroscopic techniques. The spatially heterogeneous polycrystalline morphology of the photoactive layers owing to the presence of distinct crystalline grains has been generally neglected in optical measurements and therefore the reported results are typically averaged over hundreds or even thousands of such grains. Here, we apply femtosecond transient absorption microscopy to spatially and temporally probe ultrafast electronic excited-state dynamics in pristine methylammonium lead tri-iodide (CH 3NH 3PbI 3) thin films and composite structures. We found that the electronic excited-statemore » relaxation kinetics are extremely sensitive to the sample location probed, which was manifested by position-dependent decay timescales and transient signals. As a result, analysis of transient absorption kinetics acquired at distinct spatial positions enabled us to identify contributions of excitons and free charge carriers.« less

Development of near-infrared ratiometric fluorescent probe based on cationic conjugated polymer and CdTe/CdS QDs for label-free determination of glucose in human body fluids.

PubMed

Yu, Mengze; Zhao, Kunli; Zhu, Xiaohua; Tang, Shiyun; Nie, Zhou; Huang, Yan; Zhao, Peng; Yao, Shouzhuo

2017-09-15

Quantum dots (QDs) have attracted extensive attention in biomedical applications， because of their broad excitation spectra, narrow and symmetric emission peaks etc. Furthermore, near-infrared (NIR) QDs have further advantages including low autofluorescence, good tissue penetration and low phototoxicity. In this work, the electrostatic interaction and fluorescence resonance energy transfer (FRET) between NIR CdTe/CdS QDs and cationic conjugated polymer (CCP) was studied for the first time. Based on the newly discovered phenomena and the result that hydrogen peroxide (H 2 O 2 ) can efficiently quench the fluorescence of NIR CdTe/CdS QDs, a novel NIR ratiometric fluorescent probe for determination of H 2 O 2 and glucose was developed. Under the optimized conditions, the detection limit of H 2 O 2 and glucose assay were 0.1mM and 0.05mM (S/N=3), with a linear range of 0.2-4mM and 0.1-5mM, respectively. Because of the NIR spectrum, this ratiometric probe can be also applied for the determination of glucose in whole blood samples directly, providing a valuable platform for glucose sensing in clinic diagnostic and drug screening. Copyright © 2017. Published by Elsevier B.V.

Planar structured perovskite solar cells by hybrid physical chemical vapor deposition with optimized perovskite film thickness

NASA Astrophysics Data System (ADS)

Wei, Xiangyang; Peng, Yanke; Jing, Gaoshan; Cui, Tianhong

2018-05-01

The thickness of perovskite absorber layer is a critical parameter to determine a planar structured perovskite solar cell’s performance. By modifying the spin coating speed and PbI2/N,N-dimethylformamide (DMF) solution concentration, the thickness of perovskite absorber layer was optimized to obtain high-performance solar cells. Using a PbI2/DMF solution of 1.3 mol/L, maximum power conversion efficiency (PCE) of a perovskite solar cell is 15.5% with a perovskite film of 413 nm at 5000 rpm, and PCE of 14.3% was also obtained for a solar cell with a perovskite film of 182 nm thick. It is derived that higher concentration of PbI2/DMF will result in better perovskite solar cells. Additionally, these perovskite solar cells are highly uniform. In 14 sets of solar cells, standard deviations of 11 sets of solar cells were less than 0.50% and the smallest standard deviation was 0.25%, which demonstrates the reliability and effectiveness of hybrid physical chemical vapor deposition (HPCVD) method.

Electrochemical control over photoinduced electron transfer and trapping in CdSe-CdTe quantum-dot solids.

PubMed

Boehme, Simon C; Walvis, T Ardaan; Infante, Ivan; Grozema, Ferdinand C; Vanmaekelbergh, Daniël; Siebbeles, Laurens D A; Houtepen, Arjan J

2014-07-22

Understanding and controlling charge transfer between different kinds of colloidal quantum dots (QDs) is important for devices such as light-emitting diodes and solar cells and for thermoelectric applications. Here we study photoinduced electron transfer between CdTe and CdSe QDs in a QD film. We find that very efficient electron trapping in CdTe QDs obstructs electron transfer to CdSe QDs under most conditions. Only the use of thiol ligands results in somewhat slower electron trapping; in this case the competition between trapping and electron transfer results in a small fraction of electrons being transferred to CdSe. However, we demonstrate that electron trapping can be controlled and even avoided altogether by using the unique combination of electrochemistry and transient absorption spectroscopy. When the Fermi level is raised electrochemically, traps are filled with electrons and electron transfer from CdTe to CdSe QDs occurs with unity efficiency. These results show the great importance of knowing and controlling the Fermi level in QD films and open up the possibility of studying the density of trap states in QD films as well as the systematic investigation of the intrinsic electron transfer rates in donor-acceptor films.

Exciton Recombination, Energy-, and Charge Transfer in Single- and Multilayer Quantum-Dot Films on Silver Plasmonic Resonators.

PubMed

Shin, Taeho; Cho, Kyung-Sang; Yun, Dong-Jin; Kim, Jinwoo; Li, Xiang-Shu; Moon, Eui-Seong; Baik, Chan-Wook; Il Kim, Sun; Kim, Miyoung; Choi, Jun Hee; Park, Gyeong-Su; Shin, Jai-Kwang; Hwang, Sungwoo; Jung, Tae-Sung

2016-05-17

We examine exciton recombination, energy-, and charge transfer in multilayer CdS/ZnS quantum dots (QDs) on silver plasmonic resonators using photoluminescence (PL) and excitation spectroscopy along with kinetic modeling and simulations. The exciton dynamics including all the processes are strongly affected by the separation distance between QDs and silver resonators, excitation wavelength, and QD film thickness. For a direct contact or very small distance, interfacial charge transfer and tunneling dominate over intrinsic radiative recombination and exciton energy transfer to surface plasmons (SPs), resulting in PL suppression. With increasing distance, however, tunneling diminishes dramatically, while long-range exciton-SP coupling takes place much faster (>6.5 ns) than intrinsic recombination (~200 ns) causing considerable PL enhancement. The exciton-SP coupling strength shows a strong dependence on excitation wavelengths, suggesting the state-specific dynamics of excitons and the down-conversion of surface plasmons involved. The overlayers as well as the bottom monolayer of QD multilayers exhibit significant PL enhancement mainly through long-range exciton-SP coupling. The overall emission behaviors from single- and multilayer QD films on silver resonators are described quantitatively by a photophysical kinetic model and simulations. The present experimental and simulation results provide important and useful design rules for QD-based light harvesting applications using the exciton-surface plasmon coupling.

A molecularly imprinted dual-emission carbon dot-quantum dot mesoporous hybrid for ratiometric determination of anti-inflammatory drug celecoxib

NASA Astrophysics Data System (ADS)

Amjadi, Mohammad; Jalili, Roghayeh

2018-02-01

We report on a ratiometric fluorescent sensor based on dual-emission molecularly imprinted mesoporous silica embedded with carbon dots and CdTe quantum dots (mMIP@CDs/QDs) for celecoxib (CLX) as target molecule. The fluorescence of the embedded CDs is insensitive to the analyte while the green emissive QDs are selectively quenched by it. This effect is much stronger for the MIP than for the non-imprinted polymer, which indicates a good recognition ability of the mesoporous MIP. The hybrid sensor also exhibited good selectivity to CLX over other substances. The ratio of the intensity at two wavelengths (F550/F440) proportionally decreased with the increasing of CLX concentration in the range of 0.08-0.90 μM. A detection limit as low as 57 nM was achieved. Experimental results testified that this sensor was highly sensitive and selective for the detection of CLX in human serum samples.

Fabrication of transparent conductive tri-composite film for electrochromic application

NASA Astrophysics Data System (ADS)

Choi, Dahyun; Lee, Minji; Kim, Hyungsub; Chu, Won-shik; Chun, Doo-man; Ahn, Sung-Hoon; Lee, Caroline Sunyong

2017-12-01

A transparent conductive electrode (TCE) based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was developed using a dry deposition method for application as an electrochromic (EC) device. To improve its electrical conductivity and stable EC performance, AgNW and TiO2 nanoparticles were included in the TCE film. The resulting TiO2/AgNW/PEDOT:PSS hybrid film showed electrical sheet resistivity of 23 Ω/sq., similar to that of a commercial TCE film. When +2.0 V was applied to the hybrid film, the response current was stable, maintaining a value of 2.0 mA. We found that the hybrid film could be used as an EC device, without using commercial TCE film. Antimony-doped tin oxide on indium-doped tin oxide-glass as an ion-storage layer was combined with the hybrid film, with 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI) injected into the EC device as an ionic liquid electrolyte. The optical transmittance difference between the colored and bleached states was 23% at 630 nm; under applied voltages of -2.0 V and +2.0 V, the coloration efficiency was 127.83 cm2/C. Moreover, cyclic transmittance with switching voltage for 3 h showed stable optical transmittance of 31% at 630 nm. Cyclic voltammetry measurements indicated stable behavior over 50 cycles. Thus, the proposed TCE configuration (TiO2/AgNW/PEDOT:PSS) shows great potential as a substitute for commercial TCEs, the cost of which depends on the availability of rare-earth materials.

Octahedral rotation patterns in strained EuFeO 3 and other Pbnm perovskite films: Implications for hybrid improper ferroelectricity

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

Choquette, A. K.; Smith, C. R.; Sichel-Tissot, R. J.

2016-07-01

We report the relationship between epitaxial strain and the crystallographic orientation of the in-phase rotation axis and A-site displacements in Pbnm-type perovskite films. Synchrotron diffraction measurements of EuFeO3 films under strain states ranging from 2% compressive to 0.9% tensile on cubic or rhombohedral substrates exhibit a combination of a(-)a(+)c(-) and a(+)a(-)c(-) rotational patterns. We compare the EuFeO3 behavior with previously reported experimental and theoretical work on strained Pbnm-type films on nonorthorhombic substrates, as well as additional measurements from LaGaO3, LaFeO3, and Eu0.7Sr0.3MnO3 films on SrTiO3. Compiling the results from various material systems reveals a general strain dependence in which compressivemore » strain strongly favors a(-)a(+)c(-) and a(+)a(-)c(-) rotation patterns and tensile strain weakly favors a(-)a(-)c(+) structures. In contrast, EuFeO3 films grown on Pbnm-type GdScO3 under 2.3% tensile strain take on a uniform a(-)a(+)c(-) rotation pattern imprinted from the substrate, despite strain considerations that favor the a(-)a(-)c(+) pattern. These results point to the use of substrate imprinting as a more robust route than strain for tuning the crystallographic orientations of the octahedral rotations and A-site displacements needed to realize rotation-induced hybrid improper ferroelectricity in oxide heterostructures.« less

Octahedral rotation patterns in strained EuFeO 3 and other Pbnm perovskite films: Implications for hybrid improper ferroelectricity

DOE PAGES

Choquette, A. K.; Smith, C. R.; Sichel-Tissot, R. J.; ...

2016-07-07

Here, we report the relationship between epitaxial strain and the crystallographic orientation of the in-phase rotation axis and A -site displacements in Pbnm-type perovskite films. Synchrotron diffraction measurements of EuFeO 3 films under strain states ranging from 2% compressive to 0.9% tensile on cubic or rhombohedral substrates exhibit a combination of a - a + c - and a + a - c - rotational patterns. We compare the EuFeO 3 behavior with previously reported experimental and theoretical work on strained Pbnm-type films on nonorthorhombic substrates, as well as additional measurements from LaGaO 3 ,more » LaFeO 3 , and Eu 0.7Sr 0.3 MnO 3 films on SrTiO 3 . Compiling the results from various material systems reveals a general strain dependence in which compressive strain strongly favors a - a + c - and a + a - c - rotation patterns and tensile strain weakly favors a - a - c + structures. In contrast, EuFeO 3 films grown on Pbnm-type GdScO 3 under 2.3% tensile strain take on a uniform a - a + c - rotation pattern imprinted from the substrate, despite strain considerations that favor the a - a - c + pattern. Our results point to the use of substrate imprinting as a more robust route than strain for tuning the crystallographic orientations of the octahedral rotations and A -site displacements needed to realize rotation-induced hybrid improper ferroelectricity in oxide heterostructures.« less

Separating Bulk and Surface Contributions to Electronic Excited-State Processes in Hybrid Mixed Perovskite Thin Films via Multimodal All-Optical Imaging.

PubMed

Simpson, Mary Jane; Doughty, Benjamin; Das, Sanjib; Xiao, Kai; Ma, Ying-Zhong

2017-07-20

A comprehensive understanding of electronic excited-state phenomena underlying the impressive performance of solution-processed hybrid halide perovskite solar cells requires access to both spatially resolved electronic processes and corresponding sample morphological characteristics. Here, we demonstrate an all-optical multimodal imaging approach that enables us to obtain both electronic excited-state and morphological information on a single optical microscope platform with simultaneous high temporal and spatial resolution. Specifically, images were acquired for the same region of interest in thin films of chloride containing mixed lead halide perovskites (CH 3 NH 3 PbI 3-x Cl x ) using femtosecond transient absorption, time-integrated photoluminescence, confocal reflectance, and transmission microscopies. Comprehensive image analysis revealed the presence of surface- and bulk-dominated contributions to the various images, which describe either spatially dependent electronic excited-state properties or morphological variations across the probed region of the thin films. These results show that PL probes effectively the species near or at the film surface.

Quantitative determination of Escherichia coli based on the electrochemical measurement of bacterial catalase activity using H2O2-selective organic/inorganic-hybrid sol-gel film-modified Pt electrode.

PubMed

Hasebe, Yasushi; Fukuzawa, Michiru; Matsuhisa, Hironori

2009-01-01

Quantitative determination of Escherichia coli (E. coli) concentration was achieved by measuring the intrinsic catalase activity of E. coli using novel H2O2-selective organic/inorganic-hybrid sol-gel film-modified platinum (Pt) wire electrode. This hybrid sol-gel film is composed of three kinds of organosilanes and two biopolymers (i.e., chitosan and bovine serum albumin), and exhibited an excellent permselectivity toward H2O2 based on a size-exclusive mechanism. The steady-state anodic current for 100 [xmol/L H2O2 at +0.6 V (vs. Ag/AgCl) in 0.1 mol/L phosphate buffer (pH 6.5) solution was apparently diminished by the addition of E. coli samples, due to the decomposition of H2O2 by intrinsic catalase activity of E. coli. The time-dependent decrease in current (-AI/At) was significantly dependent on the E. coli concentration. The -AI/At was enhanced by the permeabilization pretreatment of E. coli samples with the mixed solution of polymyxin B and lysozyme. This H2O2-selective organic/inorganic-hybrid sol-gel film-modified platinum (Pt) wire electrode allowed quantitative determination of E. coli concentration ranging from 10(6) to 10(9) CFU/mL within 30 min. This method required no label and complicated procedure, and allowed rapid, simple and cost-effective quantitative electrochemical determination of catalase-positive bacteria.

Hybridization regulated metal penetration at transition metal-organic semiconductor contacts

NASA Astrophysics Data System (ADS)

Chuang, Tzu-Hung; Lu, Kun-Ta; Lu, Chun-I.; Hsu, Yao-Jane; Wei, Der-Hsin

2018-02-01

Metal-organic contacts are keys to define the functionalities of hybrid structures, but orbital hybridization at interfaces has made rationalizing their behavior a challenging task. Here, we examined Fe/C60 and Ni/C60 bilayers with X-ray absorption spectra to study the nature of orbital hybridization and the possible correlation with metal penetration. Depositing Fe or Ni on C60 films of sub-nanometer thickness to emulate interfaces, we found that both bilayers show evidence of not only d-π hybridization and metal penetration but also a deeper Ni penetration. The carbon K-edge spectra recorded from C60 films indicate that the deeper Ni penetration is accompanied by a larger donation of electrons from Ni to C60. This finding of hybridization-modulated metal penetration is somewhat counterintuitive but is consistent with a scenario of metal-C60 hybridization competing with metal-metal aggregation. A stronger Ni-C60 hybridization could result in smaller Ni clusters and a greater probability of penetration through the interstitial space between C60 molecules. We conclude that metal penetration can be regulated with orbital hybridization between metal and C60.

Hole-Accepting-Ligand-Modified CdSe QDs for Dramatic Enhancement of Photocatalytic and Photoelectrochemical Hydrogen Evolution by Solar Energy.

PubMed

Li, Xu-Bing; Liu, Bin; Wen, Min; Gao, Yu-Ji; Wu, Hao-Lin; Huang, Mao-Yong; Li, Zhi-Jun; Chen, Bin; Tung, Chen-Ho; Wu, Li-Zhu

2016-04-01

Solar H 2 evolution of CdSe QDs can be significantly enhanced simply by introducing a suitable hole-accepting-ligand for achieving efficient hole extraction and transfer at the nanoscale interfaces, which opens an effective pathway for dissociation of excitons to generate long-lived charge separation, thus improving the solar-to-fuel conversion efficiency.

Direct growth of Ge quantum dots on a graphene/SiO2/Si structure using ion beam sputtering deposition.

PubMed

Zhang, Z; Wang, R F; Zhang, J; Li, H S; Zhang, J; Qiu, F; Yang, J; Wang, C; Yang, Y

2016-07-29

The growth of Ge quantum dots (QDs) using the ion beam sputtering deposition technique has been successfully conducted directly on single-layer graphene supported by SiO2/Si substrate. The results show that the morphology and size of Ge QDs on graphene can be modulated by tuning the Ge coverage. Charge transfer behavior, i.e. doping effect in graphene has been demonstrated at the interface of Ge/graphene. Compared with that of traditional Ge dots grown on Si substrate, the positions of both corresponding photoluminescence (PL) peaks of Ge QDs/graphene hybrid structure undergo a large red-shift, which can probably be attributed to the lack of atomic intermixing and the existence of surface states in this hybrid material. According to first-principles calculations, the Ge growth on the graphene should follow the so-called Volmer-Weber mode instead of the Stranski-Krastanow one which is observed generally in the traditional Ge QDs/Si system. The calculations also suggest that the interaction between Ge and graphene layer can be enhanced with the decrease of the Ge coverage. Our results may supply a prototype for fabricating novel optoelectronic devices based on a QDs/graphene hybrid nanostructure.

New insights into the nanostructure of innovative thin film solar cells gained by positron annihilation spectroscopy

NASA Astrophysics Data System (ADS)

Eijt, S. W. H.; Shi, W.; Mannheim, A.; Butterling, M.; Schut, H.; Egger, W.; Dickmann, M.; Hugenschmidt, C.; Shakeri, B.; Meulenberg, R. W.; Callewaert, V.; Saniz, R.; Partoens, B.; Barbiellini, B.; Bansil, A.; Melskens, J.; Zeman, M.; Smets, A. H. M.; Kulbak, M.; Hodes, G.; Cahen, D.; Brück, E.

2017-01-01

Recent studies showed that positron annihilation methods can provide key insights into the nanostructure and electronic structure of thin film solar cells. In this study, positron annihilation lifetime spectroscopy (PALS) is applied to investigate CdSe quantum dot (QD) light absorbing layers, providing evidence of positron trapping at the surfaces of the QDs. This enables one to monitor their surface composition and electronic structure. Further, 2D-Angular Correlation of Annihilation Radiation (2D-ACAR) is used to investigate the nanostructure of divacancies in photovoltaic-high-quality a-Si:H films. The collected momentum distributions were converted by Fourier transformation to the direct space representation of the electron-positron autocorrelation function. The evolution of the size of the divacancies as a function of hydrogen dilution during deposition of a-Si:H thin films was examined. Finally, we present a first positron Doppler Broadening of Annihilation Radiation (DBAR) study of the emerging class of highly efficient thin film solar cells based on perovskites.

Flexible Pb(Zr0.52Ti0.48)O3 Films for a Hybrid Piezoelectric-Pyroelectric Nanogenerator under Harsh Environments.

PubMed

Ko, Young Joon; Kim, Dong Yeong; Won, Sung Sik; Ahn, Chang Won; Kim, Ill Won; Kingon, Angus I; Kim, Seung-Hyun; Ko, Jae-Hyeon; Jung, Jong Hoon

2016-03-01

In spite of extremely high piezoelectric and pyroelectric coefficients, there are few reports on flexible ferroelectric perovskite film based nanogenerators (NGs). Here, we report the successful growth of a flexible Pb(Zr0.52Ti0.48)O3 (PZT) film and its application to hybrid piezoelectric-pyroelectric NG. A highly flexible Ni-Cr metal foil substrate with a conductive LaNiO3 bottom electrode enables the growth of flexible PZT film having high piezoelectric (140 pC/N) and pyroelectric (50 nC/cm(2)K) coefficients at room temperature. The flexible PZT-based NG effectively scavenges mechanical vibration and thermal fluctuation from sources ranging from the human body to the surroundings such as wind. Furthermore, it stably generates electric current even at elevated temperatures of 100 °C, relative humidity of 70%, and pH of 13 by virtue of its high Curie temperature and strong resistance for water and base. As proof of power generation under harsh environments, we demonstrate the generation of extremely high current at the exhaust pipe of a car, where hot CO and CO2 gases are rapidly expelled to air. This work expands the application of flexible PZT film-based NG for the scavenging mechanical vibration and thermal fluctuation energies even at extreme conditions.

Optical orientation in ferromagnet/semiconductor hybrids

NASA Astrophysics Data System (ADS)

Korenev, V. L.

2008-11-01

The physics of optical pumping of semiconductor electrons in ferromagnet/semiconductor hybrids is discussed. Optically oriented semiconductor electrons detect the magnetic state of a ferromagnetic film. In turn, the ferromagnetism of the hybrid can be controlled optically with the help of a semiconductor. Spin-spin interactions near the ferromagnet/semiconductor interface play a crucial role in the optical readout and the manipulation of ferromagnetism.

Scale-Up of the Electrodeposition of ZnO/Eosin Y Hybrid Thin Films for the Fabrication of Flexible Dye-Sensitized Solar Cell Modules.

PubMed

Bittner, Florian; Oekermann, Torsten; Wark, Michael

2018-02-02

The low-temperature fabrication of flexible ZnO photo-anodes for dye-sensitized solar cells (DSSCs) by templated electrochemical deposition of films was performed in an enlarged and technical simplified deposition setup to demonstrate the feasibility of the scale-up of the deposition process. After extraction of eosin Y (EY) from the initially deposited ZnO/EY hybrid films, mesoporous ZnO films with an area of about 40 cm² were reproducibly obtained on fluorine doped tin oxide (FTO)-glass as well as flexible indium tin oxide (ITO)-polyethylenterephthalate (PET) substrates. With a film thickness of up to 9 µm and a high specific surface area of up to about 77 m²·cm -3 the ZnO films on the flexible substrates show suitable properties for DSSCs. Operative flexible DSSC modules proved the suitability of the ZnO films for use as DSSC photo-anodes. Under a low light intensity of about 0.007 sun these modules achieved decent performance parameters with conversion efficiencies of up to 2.58%. With rising light intensity the performance parameters deteriorated, leading to conversion efficiencies below 1% at light intensities above 0.5 sun. The poor performance of the modules under high light intensities can be attributed to their high series resistances.

Scale-Up of the Electrodeposition of ZnO/Eosin Y Hybrid Thin Films for the Fabrication of Flexible Dye-Sensitized Solar Cell Modules

PubMed Central

Oekermann, Torsten

2018-01-01

The low-temperature fabrication of flexible ZnO photo-anodes for dye-sensitized solar cells (DSSCs) by templated electrochemical deposition of films was performed in an enlarged and technical simplified deposition setup to demonstrate the feasibility of the scale-up of the deposition process. After extraction of eosin Y (EY) from the initially deposited ZnO/EY hybrid films, mesoporous ZnO films with an area of about 40 cm2 were reproducibly obtained on fluorine doped tin oxide (FTO)-glass as well as flexible indium tin oxide (ITO)–polyethylenterephthalate (PET) substrates. With a film thickness of up to 9 µm and a high specific surface area of up to about 77 m2·cm−3 the ZnO films on the flexible substrates show suitable properties for DSSCs. Operative flexible DSSC modules proved the suitability of the ZnO films for use as DSSC photo-anodes. Under a low light intensity of about 0.007 sun these modules achieved decent performance parameters with conversion efficiencies of up to 2.58%. With rising light intensity the performance parameters deteriorated, leading to conversion efficiencies below 1% at light intensities above 0.5 sun. The poor performance of the modules under high light intensities can be attributed to their high series resistances. PMID:29393910

Resonant silicon nanoparticles for enhancement of light absorption and photoluminescence from hybrid perovskite films and metasurfaces.

PubMed

Tiguntseva, E; Chebykin, A; Ishteev, A; Haroldson, R; Balachandran, B; Ushakova, E; Komissarenko, F; Wang, H; Milichko, V; Tsypkin, A; Zuev, D; Hu, W; Makarov, S; Zakhidov, A

2017-08-31

Recently, hybrid halide perovskites have emerged as one of the most promising types of materials for thin-film photovoltaic and light-emitting devices because of their low-cost and potential for high efficiency. Further boosting their performance without detrimentally increasing the complexity of the architecture is critically important for commercialization. Despite a number of plasmonic nanoparticle based designs having been proposed for solar cell improvement, inherent optical losses of the nanoparticles reduce photoluminescence from perovskites. Here we use low-loss high-refractive-index dielectric (silicon) nanoparticles for improving the optical properties of organo-metallic perovskite (MAPbI 3 ) films and metasurfaces to achieve strong enhancement of photoluminescence as well as useful light absorption. As a result, we observed experimentally a 50% enhancement of photoluminescence intensity from a perovskite layer with silicon nanoparticles and 200% enhancement for a nanoimprinted metasurface with silicon nanoparticles on top. Strong increase in light absorption is also demonstrated and described by theoretical calculations. Since both silicon nanoparticle fabrication/deposition and metasurface nanoimprinting techniques are low-cost, we believe that the developed all-dielectric approach paves the way to novel scalable and highly effective designs of perovskite based metadevices.

Sunlight-charged electrochromic battery based on hybrid film of tungsten oxide and polyaniline

NASA Astrophysics Data System (ADS)

Chang, Xueting; Hu, Ruirui; Sun, Shibin; Liu, Jingrong; Lei, Yanhua; Liu, Tao; Dong, Lihua; Yin, Yansheng

2018-05-01

Electrochromic (EC) energy storage devices that could realize the multifunctional integration of energy storage and electrochromism have gained much recent attention. Herein, an EC battery based on the hybrid film of W18O49 and polyaniline (PANI) is developed and assembled, which integrates energy storage and EC functions in one device. The W18O49/PANI-EC battery delivers a discharging capacity of 52.96 mA h g-1, which is about two times higher than that of the W18O49-EC battery. Sunlight irradiation could greatly promote the oxidation reactions of both W18O49 and PANI during the charging process of the W18O49/PANI-EC battery, thus effectively accelerating the charging rate. This work provides a green, convenient, environmentally friendly, and cost-free charging strategy for the EC energy systems and could further advance the development of the multifunctional EC devices based on the organic/inorganic composites.

Analysis of temporal evolution of quantum dot surface chemistry by surface-enhanced Raman scattering.

PubMed

Doğan, İlker; Gresback, Ryan; Nozaki, Tomohiro; van de Sanden, Mauritius C M

2016-07-08

Temporal evolution of surface chemistry during oxidation of silicon quantum dot (Si-QD) surfaces were probed using surface-enhanced Raman scattering (SERS). A monolayer of hydrogen and chlorine terminated plasma-synthesized Si-QDs were spin-coated on silver oxide thin films. A clearly enhanced signal of surface modes, including Si-Clx and Si-Hx modes were observed from as-synthesized Si-QDs as a result of the plasmonic enhancement of the Raman signal at Si-QD/silver oxide interface. Upon oxidation, a gradual decrease of Si-Clx and Si-Hx modes, and an emergence of Si-Ox and Si-O-Hx modes have been observed. In addition, first, second and third transverse optical modes of Si-QDs were also observed in the SERS spectra, revealing information on the crystalline morphology of Si-QDs. An absence of any of the abovementioned spectral features, but only the first transverse optical mode of Si-QDs from thick Si-QD films validated that the spectral features observed from Si-QDs on silver oxide thin films are originated from the SERS effect. These results indicate that real-time SERS is a powerful diagnostic tool and a novel approach to probe the dynamic surface/interface chemistry of quantum dots, especially when they involve in oxidative, catalytic, and electrochemical surface/interface reactions.

Separating Bulk and Surface Contributions to Electronic Excited-State Processes in Hybrid Mixed Perovskite Thin Films via Multimodal All-Optical Imaging

DOE PAGES

Simpson, Mary Jane; Doughty, Benjamin; Das, Sanjib; ...

2017-07-04

A comprehensive understanding of electronic excited-state phenomena underlying the impressive performance of solution-processed hybrid halide perovskite solar cells requires access to both spatially resolved electronic processes and corresponding sample morphological characteristics. In this paper, we demonstrate an all-optical multimodal imaging approach that enables us to obtain both electronic excited-state and morphological information on a single optical microscope platform with simultaneous high temporal and spatial resolution. Specifically, images were acquired for the same region of interest in thin films of chloride containing mixed lead halide perovskites (CH 3NH 3PbI 3–xCl x) using femtosecond transient absorption, time-integrated photoluminescence, confocal reflectance, and transmissionmore » microscopies. Comprehensive image analysis revealed the presence of surface- and bulk-dominated contributions to the various images, which describe either spatially dependent electronic excited-state properties or morphological variations across the probed region of the thin films. Finally, these results show that PL probes effectively the species near or at the film surface.« less

High Temperature Superconductor/Semiconductor Hybrid Microwave Devices and Circuits

NASA Technical Reports Server (NTRS)

Romanofsky, Robert R.; Miranda, Felix A.

1999-01-01

Contents include following: film deposition technique; laser ablation; magnetron sputtering; sequential evaporation; microwave substrates; film characterization at microwave frequencies; complex conductivity; magnetic penetration depth; surface impedance; planar single-mode filters; small antennas; antenna arrays phase noise; tunable oscillations; hybrid superconductor/semiconductor receiver front ends; and noise modeling.

Exciton Recombination, Energy-, and Charge Transfer in Single- and Multilayer Quantum-Dot Films on Silver Plasmonic Resonators

PubMed Central

Shin, Taeho; Cho, Kyung-Sang; Yun, Dong-Jin; Kim, Jinwoo; Li, Xiang-Shu; Moon, Eui-Seong; Baik, Chan-Wook; Il Kim, Sun; Kim, Miyoung; Choi, Jun Hee; Park, Gyeong-Su; Shin, Jai-Kwang; Hwang, Sungwoo; Jung, Tae-Sung

2016-01-01

We examine exciton recombination, energy-, and charge transfer in multilayer CdS/ZnS quantum dots (QDs) on silver plasmonic resonators using photoluminescence (PL) and excitation spectroscopy along with kinetic modeling and simulations. The exciton dynamics including all the processes are strongly affected by the separation distance between QDs and silver resonators, excitation wavelength, and QD film thickness. For a direct contact or very small distance, interfacial charge transfer and tunneling dominate over intrinsic radiative recombination and exciton energy transfer to surface plasmons (SPs), resulting in PL suppression. With increasing distance, however, tunneling diminishes dramatically, while long-range exciton-SP coupling takes place much faster (>6.5 ns) than intrinsic recombination (~200 ns) causing considerable PL enhancement. The exciton-SP coupling strength shows a strong dependence on excitation wavelengths, suggesting the state-specific dynamics of excitons and the down-conversion of surface plasmons involved. The overlayers as well as the bottom monolayer of QD multilayers exhibit significant PL enhancement mainly through long-range exciton-SP coupling. The overall emission behaviors from single- and multilayer QD films on silver resonators are described quantitatively by a photophysical kinetic model and simulations. The present experimental and simulation results provide important and useful design rules for QD-based light harvesting applications using the exciton-surface plasmon coupling. PMID:27184469

Flexible, cathodoluminescent and free standing mesoporous silica films with entrapped quasi-2D perovskites

NASA Astrophysics Data System (ADS)

Vassilakopoulou, Anastasia; Papadatos, Dionysios; Koutselas, Ioannis

2017-04-01

The effective entrapment of hybrid organic-inorganic semiconductors (HOIS) into mesoporous polymer-silica hybrid matrices, formed as free standing flexible films, is presented for the first time. A blend of quasi-2D HOIS, simply synthesized by mixing two-dimensional (2D) and three dimensional (3D) HOIS, exhibiting strong photoluminescence, is embedded into porous silica matrices during the sol-gel synthesis, using tetraethylorthosilicate as precursor and Pluronic F-127 triblock copolymer as structure directing agent, under acidic conditions. The final nanostructure hybrid forms flexible, free standing films, presenting high cathodoluminescence and long stable excitonic luminescence, indicating the protective character of the hybrid matrix towards the entrapped perovskite. A significant result is that the photoluminescence of the entrapped HOIS is not affected even after films' prolonged exposure to water.

Enzyme-assisted extraction of κ/ι-hybrid carrageenan from Mastocarpus stellatus for obtaining bioactive ingredients and their application for edible active film development.

PubMed

Blanco-Pascual, N; Alemán, A; Gómez-Guillén, M C; Montero, M P

2014-02-01

Two hydrolysates were obtained from dried Mastocarpus stellatus using alcalase. The phenolic content was partially removed from one of them. The phenolic-partially-removed hydrolysate (H) was found to be a potent angiotensin-I converting enzyme (ACE) inhibitor. However, the phenolic-containing hydrolysate (Hp) showed a higher Folin-reactive substance content and antioxidant capacity (reducing power and radical scavenging capacity). Hp was therefore selected for the development of antioxidant Mastocarpus carrageenan-based films. F-Hp0 (without the hydrolysate), F-Hp15 (with 15% hydrolysate) and F-Hp30 (with 30% hydrolysate) films were developed. κ/ι-hybrid carrageenan was the main film constituent and hydrolysate addition resulted in an increased sulfated proportion, higher protein content and higher number of hydrogen bonds. Therefore interactions between carrageenan helices, plasticizers and peptides in the film-forming solution were enhanced, especially in F-Hp15, and consequently the water vapour permeability (WVP) of the resulting film decreased. Nevertheless, F-Hp30 considerably improved the transparency, UV/Vis light barrier, water resistance and elongation at break (EAB). The presence of Hp increased both puncture force (F) and puncture elongation (E), but not tensile strength (TS) or Young's modulus (Y). The addition of an increased concentration of hydrolysate to the films led to a considerable increase in the Folin-reactive substance content and the antioxidant activity, especially the radical scavenging capacity.

Molecular Design of Low-Density Multifunctional Hybrid Materials

DTIC Science & Technology

2016-01-01

properties, but also the synergistic interactions of reactive chemical and simulated solar UV environments with the hybrid film which leads to...applications possible including microelectronic interlayer dielectrics, antireflective coatings for solar cells , optical waveguides, size-selective...membranes, biosensors, micro-fluidic structures, and membranes in fuel cells . A critical aspect for all of these applications is that the hybrids

Metal (Ag/Ti)-Containing Hydrogenated Amorphous Carbon Nanocomposite Films with Enhanced Nanoscratch Resistance: Hybrid PECVD/PVD System and Microstructural Characteristics.

PubMed

Constantinou, Marios; Nikolaou, Petros; Koutsokeras, Loukas; Avgeropoulos, Apostolos; Moschovas, Dimitrios; Varotsis, Constantinos; Patsalas, Panos; Kelires, Pantelis; Constantinides, Georgios

2018-03-30

This study aimed to develop hydrogenated amorphous carbon thin films with embedded metallic nanoparticles (a-C:H:Me) of controlled size and concentration. Towards this end, a novel hybrid deposition system is presented that uses a combination of Plasma Enhanced Chemical Vapor Deposition (PECVD) and Physical Vapor Deposition (PVD) technologies. The a-C:H matrix was deposited through the acceleration of carbon ions generated through a radio-frequency (RF) plasma source by cracking methane, whereas metallic nanoparticles were generated and deposited using terminated gas condensation (TGC) technology. The resulting material was a hydrogenated amorphous carbon film with controlled physical properties and evenly dispersed metallic nanoparticles (here Ag or Ti). The physical, chemical, morphological and mechanical characteristics of the films were investigated through X-ray reflectivity (XRR), Raman spectroscopy, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM) and nanoscratch testing. The resulting amorphous carbon metal nanocomposite films (a-C:H:Ag and a-C:H:Ti) exhibited enhanced nanoscratch resistance (up to +50%) and low values of friction coefficient (<0.05), properties desirable for protective coatings and/or solid lubricant applications. The ability to form nanocomposite structures with tunable coating performance by potentially controlling the carbon bonding, hydrogen content, and the type/size/percent of metallic nanoparticles opens new avenues for a broad range of applications in which mechanical, physical, biological and/or combinatorial properties are required.

Characterization of the Structural and Optical Properties of III-V Semiconductor Materials for Solar Cell Applications

NASA Astrophysics Data System (ADS)

Xie, Hongen

The work contained in this dissertation is focused on the structural and optical properties of III-V semiconductor structures for solar cell applications. By using transmission electron microscopy, many of their structural properties have been investigated, including morphology, defects, and strain relaxation. The optical properties of the semiconductor structures have been studied by photoluminescence and cathodoluminescence. Part of this work is focused on InAs quantum dots (QDs) embedded in AlGaAs matrices. This QD system is important for the realization of intermediate-band solar cells, which has three light absorption paths for high efficiency photovoltaics. The suppression of plastic strain relaxation in the QDs shows a significant improvement of the optoelectronic properties. A partial capping followed by a thermal annealing step is used to achieve spool-shaped QDs with a uniform height following the thickness of the capping layer. This step keeps the height of the QDs below a critical value that is required for plastic relaxation. The spool-shaped QDs exhibit two photoluminescence peaks that are attributed to ground and excited state transitions. The luminescence peak width is associated with the QD diameter distribution. An InAs cover layer formed during annealing is found responsible for the loss of the confinement of the excited states in smaller QDs. The second part of this work is focused on the investigation of the In xGa1-xN thin films having different bandgaps for double-junction solar cells. InxGa1-xN films with x ≤ 0.15 were grown by metal organic chemical vapor deposition. The defects in films with different indium contents have been studied. Their effect on the optical properties of the film have been investigated by cathodoluminescence. InxGa 1-xN films with indium contents higher than 20% were grown by molecular beam epitaxy. The strain relaxation in the films has been measured from electron diffraction patterns taken in cross-sectional TEM

An intelligent displacement pumping film system: a new concept for enhancing heavy metal ion removal efficiency from liquid waste.

PubMed

Wang, Zhongde; Feng, Yanting; Hao, Xiaogang; Huang, Wei; Guan, Guoqing; Abudula, Abuliti

2014-06-15

A concept of electrochemically switched ion exchange (ESIX) hybrid film system with piston-like proton pumping effect for the removal of heavy metal ions was proposed. Based on this concept, a novel ESIX hybrid film composed of layered alpha zirconium phosphate (α-Zr(HPO4)2; α-ZrP) nanosheets intercalated with a potential-responsive conducting polyaniline (PANI) was developed for the removal of Ni(2+) ions from wastewater. It is expected that the space between α-ZrP nanosheets acts as the reservoir for the functional ions while the intercalated PANI works as the potential-sensitive function element for piston-like proton pumping in such ESIX hybrid films. The prepared ESIX hybrid film showed an excellent property of rapid removal of Ni(2+) ions from wastewater with a high selectivity. The used film was simply regenerated by only altering the applied potential. The ion pumping effect for the ESIX of Ni(2+) ions using this kind of film was proved via XPS analysis. The proposed ESIX hybrid film should have high potential for the removal of Ni(2+) ions and/or other heavy metal ions from wastewater in various industrial processes. Copyright © 2014 Elsevier B.V. All rights reserved.

Photoinitiator Nucleotide for Quantifying Nucleic Acid Hybridization

PubMed Central

Johnson, Leah M.; Hansen, Ryan R.; Urban, Milan; Kuchta, Robert D.; Bowman, Christopher N.

2010-01-01

This first report of a photoinitiator-nucleotide conjugate demonstrates a novel approach for sensitive, rapid and visual detection of DNA hybridization events. This approach holds potential for various DNA labeling schemes and for applications benefiting from selective DNA-based polymerization initiators. Here, we demonstrate covalent, enzymatic incorporation of an eosin-photoinitiator 2′-deoxyuridine-5′-triphosphate (EITC-dUTP) conjugate into surface-immobilized DNA hybrids. Subsequent radical chain photoinitiation from these sites using an acrylamide/bis-acrylamide formulation yields a dynamic detection range between 500pM and 50nM of DNA target. Increasing EITC-nucleotide surface densities leads to an increase in surface-based polymer film heights until achieving a film height plateau of 280nm ±20nm at 610 ±70 EITC-nucleotides/μm2. Film heights of 10–20 nm were obtained from eosin surface densities of approximately 20 EITC-nucleotides/μm2 while below the detection limit of ~10 EITC-nucleotides/μm2, no detectable films were formed. This unique threshold behavior is utilized for instrument-free, visual quantification of target DNA concentration ranges. PMID:20337438

Scanning tunneling spectroscopy of molecular thin films and semiconductor nanostructures

NASA Astrophysics Data System (ADS)

Gaan, Sandeep

Work presented in this thesis mostly deals with nano-scale study of electronic properties of organic semiconducting molecules using pentacene (Pn) as a model system and compared with various SiC surfaces to gain more insight into physical processes at nano-scale. In addition, InAs quantum dots (QDs) in a GaAs matrix are studied to probe electronic states of individual QDs. Scanning tunneling microscopy (STM) and spectroscopy (STS) are the primary experimental techniques used to probe local electronic properties on the nano-scale. Vacuum sublimated Pn thin films were deposited onto SiC substrates for STM/STS experiments. STM studies show high quality ordered Pn films. Atomic force microscopy (AFM) images reveal dendritic growth pattern of these films. Local density of states (LDOS) measurements using STS reveals a HOMO-LUMO bandgap. In order to study charge transport properties of Pn films, different amount of charge were injected into the sample by systematically changing the tip-sample separation. Saturation of the tunnel current was observed at positive sample voltages (LUMO states). This effect was attributed to a transport/space charge limitation in tunnel current by treating it as a situation analogous to charge injection into insulators which gives rise to space charge limited current (also previously observed in the case of organic semiconductors). Using a simple model we were able to derive a hopping rate that characterizes nano-scale transport in Pn films at least in the vicinity of the STM probe-tip. We have studied effect of transport limitation in the tunnel current for various semiconductor surfaces. In order to probe surfaces of varying conductivities, we have used Si-rich SiC surfaces such as 3x3 and 3x3 -R30° (both Mott-Hubbard insulators) as well as a highly conducting C-rich graphene surface, and compared those results with the data obtained from Pn. We observe variation of the decay constant kappa (which characterizes the tunneling process) on

Development of an ultra-thin film comprised of a graphene membrane and carbon nanotube vein support.

PubMed

Lin, Xiaoyang; Liu, Peng; Wei, Yang; Li, Qunqing; Wang, Jiaping; Wu, Yang; Feng, Chen; Zhang, Lina; Fan, Shoushan; Jiang, Kaili

2013-01-01

Graphene, exhibiting superior mechanical, thermal, optical and electronic properties, has attracted great interest. Considering it being one-atom-thick, and the reduced mechanical strength at grain boundaries, the fabrication of large-area suspended chemical vapour deposition graphene remains a challenge. Here we report the fabrication of an ultra-thin free-standing carbon nanotube/graphene hybrid film, inspired by the vein-membrane structure found in nature. Such a square-centimetre-sized hybrid film can realize the overlaying of large-area single-layer chemical vapour deposition graphene on to a porous vein-like carbon nanotube network. The vein-membrane-like hybrid film, with graphene suspended on the carbon nanotube meshes, possesses excellent mechanical performance, optical transparency and good electrical conductivity. The ultra-thin hybrid film features an electron transparency close to 90%, which makes it an ideal gate electrode in vacuum electronics and a high-performance sample support in transmission electron microscopy.

Preparation of hybrid nano biocomposite κ-carrageenan/cellulose nanocrystal/nanoclay

NASA Astrophysics Data System (ADS)

Zakuwan, Siti Zarina; Ahmad, Ishak; Ramli, Nazaruddin

2013-11-01

Biodegradable composites film based on κ-carrageenan and nano particles as filler was prepared to study the mechanical strength of carrageenan composites. Solution casting technique was used to prepare_this biocomposite. Preparation of composite film and nano filler involve two stages, preparation of cellulose nanocrystals (CNC) from kenaf with alkali treatment, bleaching, and hydrolysis followed by the preparation of two types of nano composite. Tensile test was carried on the composite film based on κ-carrageenan with the variation percentage of CNC and nano clay to obtain the optimum CNC and nano clay loading. After that hybrid nano-biocomposite film based on κ-carrageenan with the variation percentage of CNC/nano clay (OMMT) according to optimum value of composite carrageenan/CNC and composite carrageenan/nano clay film was prepared. The effect of nano filler on the mechanical properties of carrageenan films was examined. κ-carrageenan biocomposite increased with the optimum at 4% CNC and nano clay composition. Additional improvement of tensile strength with hybridization of CNC and nanoclay indicated better mechanical properties.

TiO2 hierarchical porous film constructed by ultrastable foams as photoanode for quantum dot-sensitized solar cells

NASA Astrophysics Data System (ADS)

Du, Xing; He, Xuan; Zhao, Lei; Chen, Hui; Li, Weixin; Fang, Wei; Zhang, Wanqiu; Wang, Junjie; Chen, Huan

2016-11-01

It reported a novel and simple method for the first time to prepare TiO2 hierarchical porous film (THPF) using ultrastable foams as a soft template to construct porous structures. Moreover, dodecanol as one foam component was creatively used as solvent during the synthesis of CdSe quantum dots (QDs) to decrease reaction temperature and simplify precipitation process. The result showed that hierarchical pores in scale of microns introduced by foams were regarded to benefit for high coverage and unimodal distribution of QDs on the surface of THPF to increase the efficiencies of light-harvesting, charge-collection and charge-transfer. The increased efficiencies caused an enhancement in quantum efficiency of the cell and thus remarkably increased the short circuit current density (Jsc). In addition, the decrease of charge recombination resulted in the increase of the open circuit voltage (Voc) as well. The QDSSC based on THPF exhibited about 2-fold higher power conversion efficiency (η = 2.20%, Jsc = 13.82 mA cm-2, Voc = 0.572 V) than that of TiO2 nanoparticles film (TNF) (η = 1.06%, Jsc = 6.70 mA cm-2, Voc = 0.505 V). It provided a basis to use foams both as soft template and carrier to realize simultaneously construction and in-situ sensitization of photoanode in further work.

An investigation of a thermally steerable electroactive polymer/shape memory polymer hybrid actuator

NASA Astrophysics Data System (ADS)

Ren, Kailiang; Bortolin, Robert S.; Zhang, Q. M.

2016-02-01

This paper investigates the thermal response of a hybrid actuator composed of an electroactive polymer (EAP) and a shape memory polymer (SMP). This study introduces the concept of using the large strain from a phase transition (ferroelectric to paraelectric phase) induced by temperature change in a poly(vinylidene fluoride-trifluoroethylene) film to tune the shape of an SMP film above its glass transition temperature (Tg). Based on the material characterization data, it is revealed that the thickness ratio of the EAP/SMP films plays a critical role in the displacement of the actuator. Further, it is also demonstrated that the displacement of the hybrid actuator can be tailored by varying the temperature, and finite element method simulation results fit well with the measurement data. This specially designed hybrid actuator shows great promise for future morphing aircraft applications.

Bioinspired design and assembly of layered double hydroxide/poly(vinyl alcohol) film with high mechanical performance.

PubMed