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Ultra-Thick Organic Pigment Layer Up to 10 ??m Activated by Crystallization in Organic Photovoltaic Cells
摘要: Organic optoelectronic devices tend to have limited thickness. Organic light emitting diodes (OLED) and organic photovoltaic cells (OPV) made of organic pigments are typically with thickness of a few or a few tens of nanometers. Thickness of organic photovoltaic cells made with polymers exceeds them typically up to the order of a few 100 nm but still necessarily co-optimized with respect to light absorption and charge transport. Here, we demonstrate that crystallization made a 10-μm-thick pigment layer active in a photovoltaic cell, using a prototypical pair of pigments, phthalocyanine, and fullerene. It is proved that crystalline pigment layer with a thickness much greater than what is needed for optical optimization can be utilized for organic optoelectronic devices and that organic optoelectronic devices have potentiality to relief their design from co-optimization of optics and charge transport.
关键词: bulk hetero-junction,organic electronics,crystallization,organic photovoltaics,pigment,solar cell
更新于2025-09-19 17:13:59
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Evidence of Low Temperature Joints in Silver Nanowire Based Transparent Conducting Layers for Solar cells
摘要: The primary stage of joint formation of silver nanowires (AgNWs) at 60 °C is investigated using rotary scanning transmission electron microscopy (STEM with tomographic reconstruction images), and super large-scale molecular dynamic (MD) simulation (2×106 atoms). This study proves to establish that silver nanowires do not require the conventional high temperature post treatment process at 200 °C to form fused contacts at the intersections. In fact, a low temperature annealing at 60 °C facilitates formation of highly conductive networks. The connection between the nanowires is made through a stage called thinning, shown in this report for the first time, which occurs before broadening of the nanowires and is caused due to simultaneous effects of loads from the top nanowires and the heating, as confirmed by STEM and MD result. The outcomes of our investigation significantly promote the application of AgNWs as a transparent conductive layer for solar cells with requirement of low temperature processing such as Kasterite, Perovskite and Organic solar cells.
关键词: Low temperature process,Scanning transmission electron microscopy,Molecular dynamic simulation,Junction resistivity,Transparent conductive layer,Silver nanowire
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - Miramar Beach, FL, USA (2019.8.19-2019.8.21)] 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - Multispectral Plasmonic Perfect Absorbers Integrated with Room-Temperature VO <sub/>x</sub> Air-Bridge Bolometers
摘要: The roadmap evolution and historical milestones of electromagnetic energy conversion techniques and related breakthroughs over the years are reviewed and presented with particular emphasis on low-density energy-harvest technologies. Electromagnetic sources responsible for the presence of ambient radio-frequency (RF) energy are examined and discussed. The effective use and recycling of such an ambient electromagnetic energy are the most relevant and critical issue for the current and future practicability of wireless energy-harvesting devices and systems. In this paper, a set of performance criteria and development considerations, required to meet the need of applications of ambient electromagnetic energy harvesting, are also derived from the radiating source analysis. The criteria can be calculated from a simple measurement of the I–V nonlinear behavior of RF rectification devices such as diodes and transistors, as well as linear frequency behavior (S-parameters). The existing rectifying devices are then reviewed in light of the defined performance criteria. Finally, a technological outlook of the performances that can be expected from different device technologies is assessed and discussed. Since the proposed spindiode technology would present the most promising device platform in the development of the most useful ambient energy harvesters, a special highlight of this disruptive scheme is provided in the presentation of this work.
关键词: Schottky diode,magnetic tunnel junction (MTJ),energy harvesting,diodes,spindiode,backward diode,metal–insulator–metal (MIM),crystal rectifier,Ambient radio-frequency (RF) energy
更新于2025-09-19 17:13:59
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[IEEE 2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS) - Shenzhen, China (2019.11.25-2019.11.27)] 2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS) - Junction Temperature Prediction of the Multi-LED Module with the Modified Thermal Resistance Matrix
摘要: The junction temperature of LEDs is important for its life, reliability and efficacy. The existing transient measurement method of the junction temperature of using transient thermal tester (T3ster) based on the time-resolved measuring with a constant bias current according to the JESD51-14 is able to obtain the LED junction temperature rise based on the known temperature of thermostat module as the heatsink. In practice, without T3ster and the thermostat module, for multi-LED module with multiple heat sources in the luminaries, the thermal resistance matrix needs to be built to realize the thermal transfer between one another such that their junctions temperature raises can be calculated from their thermal power consumption. It is demonstrated that without measurement of the temperature heatsink temperature, the individual junction temperature of LEDs (groups) in multi-LED module with a thermistor (NTC or PTC) on its PCB measuring the local reference temperature can be obtained from the modified N x (N+1) thermal resistance matrix having N LED heat sources and N+1 junction temperature rise. A multi-LED module sample with 3 groups of LEDs has been studied at 5 different ambient temperatures and 2 additional different power combinations using 3 thermal resistance matrices built at 3 different ambient temperatures for comparison. The result showed that the modified method is effective and convenient for measurement of the junction temperature of the multi- LED modules with a similar accuracy comparing to the conventional one in the local reference temperature range of 20~100?C.
关键词: junction temperature,multi-LED module,T3ster,thermal resistance,thermal resistance matrix
更新于2025-09-19 17:13:59
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ZnTe-coated ZnO nanorods: Hydrogen sulfide nano-sensor purely controlled by pn junction
摘要: In this study, the double hydrothermal method is proposed as a facile approach to the synthesis of ZnTe/ZnO core–shell nanorods. The coating thickness of the p-type ZnTe is varied to adjust the junction depth in the n-type ZnO nanorods, and the conductance measurements reveal the change in the conduction path in the heterojunction structures. Structural and chemical investigations conducted using X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy confirm the hetero-nanostructure formation of ZnTe/ZnO. The role of ZnTe in H2S-gas sensing by the ZnO nanorods is discussed. The enhanced sensing performance observed with a thin ZnTe coating confirms the importance of the base resistance of the nano-transducer in achieving high response characteristics. The composite structure also demonstrates a superior sensing performance of good repeatability, stability, linearity, and gas selectivity at temperatures greater than 200 °C.
关键词: p-n junction,ZnO gas sensor,H2S gas sensor,nanosensor
更新于2025-09-19 17:13:59
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A novel AH-D-A-type phase junction material to improve photovoltaic performance and device stability in fullerene OSCs
摘要: In order to boost power conversion efficiency (PCE) and operation stability of organic solar cells (OSCs), we propose a new idea of phase junction materials (PJMs) used as a photoactive layer component to improve device performance and stability. For this purpose, a novel PJM of H-TRC8 based on rhodanine unit was designed with a conjugated AH-D-A framework. Here, AH is a hydrogen-donating electron acceptor unit, D-A is an electron donor-acceptor unit. It is found that H-TRC8 has a good carrier-transporting ability, as well as definite hydrogen-bond and D-A interaction with donor/acceptor materials. While H-TRC8 is added into the PBDB-T/PC60BM blend film with 1.0 vol% DIO (1,8-diiodooctane), the resulting blend film exhibited an enhanced absorption and improved morphology. The intermolecular hydrogen bond between H-TRC8 and PBDB-T plays an important role for them, which is confirmed via FT-IR spectra and 2D 1H NMR. As a result, the PBDB-T/PC60BM-based devices with 1.25 wt% H-TRC8 and 1.0 vol% DIO exhibit a significantly improved PCE of 8.06%, which is increased by 20.6% in comparison to that in the binary devices with 1.0 vol% DIO only (PCE = 6.68%). Furthermore, the device stability is significantly enhanced with only 43% PCE roll-off at 150 °C for 120 h. This work indicates that AH-D-A-type PJMs are promising photovoltaic materials used as photoactive-layer components to achieve high-performance fullerene OSCs with high device stability.
关键词: AH-D-A,H-bond,Performance and stability,H-TRC8,Phase junction material
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Analysis and Enhancement of Quantum Efficiency for Multi-Junction Solar Cell
摘要: Photovoltaics(PVs) has always been considered to be the most prominent resource for the generation of electricity without the use of fossil fuels. The dependency of humans on PVs has been remarkably less when compared to the potential possessed by the availability and abundance of the energy being received, the major obstacle being the ef?ciency of the cell. Multi-junction Solar cells have been an outstanding concept for tackling the problem of ef?ciency. In this paper, we have presented a model of ?ve layered, four-junction solar cells which concentrates on the conversion of the maximum spectrum of the light energy received by the sun. The concluding energy band diagram, current-voltage characteristics and quantum ef?ciency have been presented in this paper. The Fill Factor of the cell so developed is 43.61%, and the highest quantum ef?ciency of the cell is 76.198%. We have compared our results with the previous papers and found a signi?cant increase in the Fill Factor and Quantum Ef?ciency of the developed cell.
关键词: Photovoltaics,Solar Cell,SCAPS-1D,Quantum Ef?ciency,Multi-junction
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Electron-Conductive, Hole-Blocking Contact for Silicon Solar Cells
摘要: This paper presents a simple mathematical expression to model the effect of statistical dopant fluctuations on threshold voltage (Vth) of junction field-effect transistors (JFETs). The random discrete doping (RDD) in the active device area is used to derive an analytical model to compute the standard deviation, σ Vth,RDD of the Vth-distribution for any arbitrary channel doping profiles. The model shows that the Vth-variability in JFETs depends on the active device area, channel doping concentration, and the depth of the channel depletion region of the gate/channel pn-junction. The model is applied to compute σ Vth,RDD for symmetric and asymmetric source/drain double-gate n-channel JFETs. The simulation results show that the model can be used for predicting Vth-variability in JFETs.
关键词: modeling threshold voltage variability,random discrete doping,process variability in JFETs,statistical dopant fluctuations,JFET threshold voltage variability,Junction field-effect transistor (JFET)
更新于2025-09-19 17:13:59
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Laser microdissection-based microproteomics of the hippocampus of a rat epilepsy model reveals regional differences in protein abundances
摘要: Mesial temporal lobe epilepsy (MTLE) is a chronic neurological disorder affecting almost 40% of adult patients with epilepsy. Hippocampal sclerosis (HS) is a common histopathological abnormality found in patients with MTLE. HS is characterised by extensive neuronal loss in different hippocampus sub-regions. In this study, we used laser microdissection-based microproteomics to determine the protein abundances in different regions and layers of the hippocampus dentate gyrus (DG) in an electric stimulation rodent model which displays classical HS damage similar to that found in patients with MTLE. Our results indicate that there are differences in the proteomic profiles of different layers (granule cell and molecular), as well as different regions, of the DG (ventral and dorsal). We have identified new signalling pathways and proteins present in specific layers and regions of the DG, such as PARK7, RACK1, and connexin 31/gap junction. We also found two major signalling pathways that are common to all layers and regions: inflammation and energy metabolism. Finally, our results highlight the utility of high-throughput microproteomics and spatial-limited isolation of tissues in the study of complex disorders to fully appreciate the large biological heterogeneity present in different cell populations within the central nervous system.
关键词: microproteomics,rat epilepsy model,hippocampus,protein abundances,Laser microdissection,PARK7,energy metabolism,connexin 31/gap junction,RACK1,inflammation
更新于2025-09-19 17:13:59
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Annealed Polycrystalline TiO <sub/>2</sub> Interlayer of the n-Si/TiO <sub/>2</sub> /Ni Photoanode for Efficient Photoelectrochemical Water Splitting
摘要: High photovoltage generation from a photoelectrode is important for efficient solar-driven water splitting. Here, we report a thermal treatment process that greatly enhances photovoltage generation from an n-Si/TiO2/Ni photoanode. By selectively annealing the TiO2 interlayer, the photoanode generates a high photovoltage of 570 mV, which is very competitive as compared with photovoltages produced using other similar metal?insulator?semiconductor structures with earth-abundant metal catalysts. Different annealing conditions and junction layer thicknesses were systematically investigated. It is found that the optimal annealing temperature occurs between 500 and 600 °C. Within this temperature range, the deposited amorphous Ti is converted into polycrystalline anatase phase TiO2. The optimal annealing time scales linearly with TiO2 thickness and inversely with annealing temperature. The large photovoltage generation is attributed to the reduced defect states and improved junction barrier height by the annealed TiO2 interlayer. This study demonstrates that thermal annealing offers an attractive approach to modify the TiO2 interlayer material’s properties for photovoltage optimization.
关键词: photovoltage,photoanode,water splitting,thermal annealing,photoelectrochemistry,junction interlayer
更新于2025-09-19 17:13:59