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Passive Filters for Nonvolatile Storage Based on Capacitive-Coupled Memristive Effects in Nanolayered Organic-Inorganic Heterojunction Devices
摘要： It is well known that the reprogrammable device is one of the important needs for circuit design. In this paper, nanolayered TiO2 and maple leaves (ML) are combined to form a functional layer (TiO2-ML) inside memristive devices, which demonstrate both the capacitive effect and the non-volatile storage capability. When the voltage increases from zero, the device firstly enters a capacitive-coupled memristive state at low voltage before switch to normal memristive state at a higher voltage. The existence of the capacitive behavior results in a non-zero-crossing I-V characteristic different from the zero-crossing curve observed in normal memristive device. Utilizing this capacitive-coupled memristive behavior, we design a low power passive filter with applications towards reprogrammable analog circuit designs, paving a path towards multifunctional nanodevice in future.
关键词： capacitive effect,memristor,organic-inorganic,heterojunction,passive filter
更新于2025-09-23 15:21:01
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Electroluminescence from amorphous GIZO/p-GaN heterojunction light-emitting diodes
摘要： The electroluminescence from the amorphous gallium-indium-zinc oxide (a-GIZO)/p-GaN heterojunction light-emitting diodes (LEDs) were demonstrated. The heterojunction LEDs showed a current flow under both forward and reverse bias voltages. The light emissions were observed at around 410 nm (originating from p-GaN) and ~450–800 nm (originating from interfacial layer and/or from a-GIZO), which were particularly pronounced under reverse bias condition. As a result, the standard white light with the chromaticity coordinate of (0.2899, 0.3034) was obtained.
关键词： Light emitting diode,Gallium-indium-zinc oxide,Heterojunction,Amorphous
更新于2025-09-23 15:21:01
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Highly efficient charge generation and injection in HAT-CN/TAPC heterojunction for high efficiency tandem organic light-emitting diodes
摘要： An organic heterojunction (OHJ) consisted of 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN)/1,1-bis[(di-4-tolyamino)phenyl)]cyclohexane (TAPC) is employed simultaneously as both charge generation layer (CGL) and charge injectors to fabricate high efficiency and long lifetime tandem organic light-emitting diodes (OLEDs). It can be seen that compared with conventional tandem OLEDs, the tandem OLEDs utilizing OHJ as both CGL and charge injectors significantly improved not only the current and quantum efficiencies, more importantly, but also the power efficiency and stability. The maximum efficiencies were as high as 42.0 %, 159.5 cd A-1 and 92.7 lm W-1, and the lifetime reached 1350 hours, which are more higher than the efficiencies of 34.3% 130.2 cd A-1 and 75.0 lm W-1 and the lifetime of 859 hours of conventional tandem OLEDs. The more balanced charge generation and injection due to the simultaneous utilization of OHJ as CGL and charge injectors contributed to the significant improvement in the performance of resulting tandem OLEDs. These results fully indicate the validity of OHJ as CGL and charge injectors, and also provide a new route for the development of high performance OLEDs.
关键词： Charge generation,Organic heterojunction,Charge injector,long lifetime,high efficiency
更新于2025-09-23 15:21:01
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P-type laser-doped WSe <sub/>2</sub> /MoTe <sub/>2</sub> van der Waals heterostructure photodetector
摘要： Van der Waals heterostructures (vdWHs) based on two-dimensional (2D) materials are being studied extensively for their prospective applications in photodetectors. As the pristine WSe2/MoTe2 heterostructure is a type I (straddling gap) structure, it cannot be used as a photovoltaic device theoretically, although both WSe2 and MoTe2 have excellent photoelectric properties. The Fermi level of p-doped WSe2 is close to its valence band. The p-doped WSe2/MoTe2 heterostructure can perform as a photovoltaic device because a built-in electric field appears at the interface between MoTe2 and p-doped WSe2. Here, a 633 nm laser was used for scanning the surface of WSe2 in order to obtain the p-doped WSe2. X-ray photoelectron spectroscopy (XPS) and electrical measurements verified that p-type doping in WSe2 is produced through laser treatment. The p-type doping in WSe2 includes substoichiometric WOx and nonstoichiometric WSex. A photovoltaic device using p-doped WSe2 and MoTe2 was successfully fabricated. The band structure, light-matter reactions, and carrier-transport in the p-doped WSe2/MoTe2 heterojunction were analyzed. The results showed that this photodetector has an on/off ratio of ≈104, dark current of ≈1 pA, and response time of 72 μs under the illumination of 633 nm laser at zero bias (Vds = 0 V). The proposed p-doping method may provide a new approach to improve the performance of nanoscale optoelectronic devices.
关键词： molybdenum ditelluride,heterojunction,tungsten selenide,photodetector,p-doped
更新于2025-09-23 15:21:01
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Simulation of Silicon Heterojunction Solar Cells for High Efficiency with Lithium Fluoride Electron Carrier Selective Layer
摘要： In this work, to ameliorate the quantum e?ciency (QE), we made a valuable development by using wide band gap material, such as lithium ?uoride (LiFx), as an emitter that also helped us to achieve outstanding e?ciency with silicon heterojunction (SHJ) solar cells. Lithium ?uoride holds a capacity to achieve signi?cant power conversion e?ciency because of its dramatic improvement in electron extraction and injection, which was investigated using the AFORS-HET simulation. We used AFORS-HET to assess the restriction of numerous parameters which also provided an appropriate way to determine the role of diverse parameters in silicon solar cells. We manifested and preferred lithium ?uoride as an interfacial layer to diminish the series resistance as well as shunt leakage and it was also bene?cial for the optical properties of a cell. Due to the wide band gap and better surface passivation, the LiFx encouraged us to utilize it as the interfacial as well as the emitter layer. In addition, we used the built-in electric and band o?set to explore the consequence of work function in the LiFx as a carrier selective contact layer. We were able to achieve a maximum power conversion e?ciency (PEC) of 23.74%, ?ll factor (FF) of 82.12%, Jsc of 38.73 mA cm?2, and Voc of 741 mV by optimizing the work function and thickness of LiFx layer.
关键词： electric ?eld,silicon heterojunction solar cell,lithium ?uoride,electron selectivity contact layer,work function
更新于2025-09-23 15:21:01
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25.1% Higha??Efficient Monolithic Perovskite Silicon Tandem Solar Cell with a High Band Gap Perovskite Absorber
摘要： Monolithic perovskite silicon tandem solar cells can overcome the theoretical efficiency limit of silicon solar cells. This requires an optimum band gap, high quantum efficiency, and high stability of the perovskite. Here, we combine a silicon heterojunction bottom cell with a perovskite top cell with an optimum band gap of 1.68 eV in planar p-i-n tandem configuration. Methylammonium-free FA0.75Cs0.25Pb(I0.8Br0.2)3 perovskite with high Cs-content is investigated for improved stability. A 10% molarity increase to 1.1 M of the perovskite precursor solution resulted in ~75 nm thicker absorber layers and 0.7 mA/cm2 higher short-circuit current density. With the optimized absorber, tandem devices reach a high fill factor of ~80% and up to 25.1% certified efficiency. The unencapsulated tandem device shows an efficiency improvement of 2.3% (absolute) over five months showing the robustness of the absorber against degradation. Moreover, a photoluminescence quantum yield analysis reveals that with adapted charge transport materials and surface passivation, along with improved anti-reflection measures, the high band gap perovskite absorber has the potential for 30% tandem efficiency in the near future.
关键词： interfaces,heterojunction silicon solar cells,perovskite solar cells,thin films,tandem solar cells
更新于2025-09-23 15:21:01
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Effects of Size and Localized States in Charge Carrier Dynamics and Performance of Solution Processed Graphene Quantum Dots/Silicon Heterojunction near-UV Photodetectors
摘要： Influence of size and localized defect states on photogenerated carrier recombination dynamics, which affects the performance of graphene quantum dots (GQDs) based Si-compatible near-UV heterojunction photodetectors, is reported. GQDs of varying size from ~3.0 to ~8.0 nm have been prepared by a top down method of oxidative cutting of graphene oxide followed by hydrothermal reduction and gradient centrifugation at different speeds. Structural, compositional, photophysical characteristics and photocarrier dynamics of different sized samples have been studied. Spectroscopic features and carrier dynamics of GQDs are effectively controlled by their size and localized surface states, which also determine the average recombination lifetime of photo-generated carriers. Two-terminal vertical heterojunction photodetector devices fabricated using solution processed quantum dots exhibit superior performance over a broad spectrum with a peak response in the near UV (380 nm) region. The device fabricated using ~6.0 nm diameter GQDs displayed highest peak responsivity of 3.5 A/W showing an interesting correlation with carrier dynamics. To our best knowledge, this is the only report in graphene quantum dots or carbon nanostructure genre, showing the direct correlation between size of the quantum dots and localized surface states on photocarrier dynamics and consequential performance of photodetector devices.
关键词： Graphene quantum dots,carrier dynamics,heterojunction,Si-compatible,near-UV photodetectors
更新于2025-09-23 15:21:01
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DFT and TD-DFT studies of new pentacene-based organic molecules as a donor material for bulk-heterojunction solar cells
摘要： The performance of organic cells based on bulk heterojunctions (BHJs) has improved recently, but further improvements are necessary. In this work, we have carried out a thorough examination using density functional theory (DFT) and time-dependent (TD)-DFT to investigate the structural and optoelectronic properties of pentacene-based organic molecules (PbOMs) as potential donor material for organic photovoltaic BHJ devices. Our results show that oxadiazole prefers to attach via its nitrogen atoms to the carbon atoms of the pentacene monomer with an adsorption energy about ? 32.86 kcal/mol, which means that oxadiazole is efficiently adsorbed on the edge of the pentacene. The HOMO energy level of the PbOM with the lowest bandgap is ? 4.00 eV wide, i.e., about 0.86 eV lower and more positive than pentacene, thus providing an ideal open-circuit voltage for photovoltaic devices. The bandgap of the PbOM compounds are about 1.61 and 1.80 eV affording an efficient charge transfer from donor to acceptor. Furthermore, the donor PbOMs are also more stable than the pentacene. We have examined, additionally, the reactivity and absorption properties of individual molecules and PbOM systems. Our results suggest that the PbOM, as a donor material, may significantly improve the efficiency of BHJ solar cells.
关键词： TD-DFT,Pentacene,Bulk-heterojunction,Donor material
更新于2025-09-23 15:21:01
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Heterojunction Incorporating Perovskite and Microporous Metala??Organic Framework Nanocrystals for Efficient and Stable Solar Cells
摘要： In this paper, we present a facile approach to enhance the efficiency and stability of perovskite solar cells (PSCs) by incorporating perovskite with microporous indium-based metal–organic framework [In12O(OH)16(H2O)5(btc)6]n (In-BTC) nanocrystals and forming heterojunction light-harvesting layer. The interconnected micropores and terminal oxygen sites of In-BTC allow the preferential crystallization of perovskite inside the regular cavities, endowing the derived films with improved morphology/crystallinity and reduced grain boundaries/defects. Consequently, the In-BTC-modified PSC yields enhanced fill factor of 0.79 and power conversion efficiency (PCE) of 20.87%, surpassing the pristine device (0.76 and 19.52%, respectively). More importantly, over 80% of the original PCE is retained after 12 days of exposure to ambient environment (25 °C and relative humidity of ~ 65%) without encapsulation, while only about 35% is left to the pristine device.
关键词： Light-harvesting layer,Metal–organic framework,Heterojunction,Perovskite solar cell,Nanocrystal
更新于2025-09-23 15:21:01
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Surface Plasmon Resonance-Enhanced Visible-NIR-Driven Photocatalytic and Photothermal Catalytic Performance by Ag/Mesoporous Black TiO2 Nanotubes Heterojunctions
摘要： Ag/mesoporous black TiO2 nanotubes heterojunctions (Ag-MBTHs) are fabricated through surface hydrogenation, wet-impregnation and photoreduction strategy. The as-prepared Ag-MBTHs possess a relatively high specific surface area of ~85 m2 g-1 and an average pore size of ~13.2 nm. The Ag-MBTHs with narrow bandgap of ~2.63 eV extend the photoresponse from UV to visible light and near-infrared (NIR) region, which exhibit excellent visible-NIR-driven photothermal catalytic and photocatalytic performance for complete conversion nitro aromatic compounds (100%) and mineralization of high-toxic phenol (100%). The enhancement can be attributed to the mesoporous hollow structures increasing the light multi-refraction, the Ti3+ in frameworks and the surface plasmon resonance (SPR) effect of plasmonic Ag nanoparticles favoring light-harvesting and spatial separation of photogenerated electron-hole pairs, which is confirmed by transient fluorescence. The fabrication of this novel SPR-enhanced visible-NIR-driven Ag-MBTHs catalyst may provide new insights for designing other high-performance heterojunctions photocatalytic and photothermal catalytic nanomaterials.
关键词： mesoporous black TiO2 nanotube,photothermal catalysis,surface plasmon resonance,Photocatalysis,heterojunction
更新于2025-09-23 15:21:01