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[IEEE 2017 International Conference on Electron Devices and Solid-State Circuits (EDSSC) - Hsinchu (2017.10.18-2017.10.20)] 2017 International Conference on Electron Devices and Solid-State Circuits (EDSSC) - Influence of sensitization on the surface properties of PbSe thin films
摘要： This report focuses on the surface properties of sensitized polycrystalline lead selenide (PbSe) thin films that could significantly affect the final performance of photoconductive devices. By characterization the element chemical state and the current distribution along with the relevant morphologies at surface of sensitized and original PbSe films, it is confirmed that after sensitization surface properties, as well as the performance of photoconductive devices have been significantly modified. The mechanism was also discussed.
关键词： surface properties,lead selenide,photoconductive,sensitization
更新于2025-09-23 15:23:52
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Reaction Packaging CoSe <sub/>2</sub> Nanoparticles in N-Doped Carbon Polyhedra with Bifunctionality for Overall Water Splitting
摘要： Water electrolysis is a promising approach for green and large-scale hydrogen production; however, there are still challenges for developing efficient and stable bi-functional electrocatalysts towards the hydrogen and oxygen evolution reactions. Herein, zeolitic imidazolate framework-67 (ZIF67) was used as the precursor for the construction of CoSe2 nanoparticles trapped in N-doped carbon polyhedra (NC). Among as-obtained CoSe2-NC hybrid, highly active CoSe2 nanoparticles in sizes of 10-20 nm are encapsulated in N-doped few-layer carbon shell, avoiding their easy aggregations of CoSe2 nanoparticles as well as enhancing the long-term stability. The unique nanostructured CoSe2-NC hybrid with a hierarchical porosity and 3D conductive framework thus fully exerts outstanding bi-functional catalytic activity of CoSe2 centers. As a result, the CoSe2-NC hybrid as bi-functional catalysts for overall water splitting delivers a high current density of 50 mA cm-2 with applied voltage of ~1.73 V in alkaline electrolyte, with a promising stability over 50000 s.
关键词： selenide reaction,ZIF67,bifunctional electrocatalyst,overall water splitting,carbon polyhedra
更新于2025-09-23 15:22:29
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Effects of selenisation temperature on photoluminescence and photoluminescence excitation spectra of ZnO/CdS/Cu2ZnSnSe4/Mo/glass
摘要： The effect of solar cell processing (including etching in KCN along with deposition of CdS and ZnO) on photoluminescence (PL) spectra and bandgap Eg (measured at 4.2 K by photoluminescence excitation) of Cu2ZnSnSe4 films, produced by selenising metallic precursors at 450°C, 500°C and 550°C, was studied. Temperature and excitation intensity analysis of the P1 dominant band in the PL spectra of solar cells suggests that after processing this band still can be assigned to the free-to-bound recombination of free electrons with holes bound at deep acceptor levels influenced by valence band-tails. However processing increased the intensity of P1 and blue shifted it. The strongest effect was observed for the film selenised at 500°C. For the film selenised at 450°C the blue shift and increase in the intensity were smaller and only a slight intensity rise was found for the film selenised at 550°C. The intensity increase we assign to a reduction in the concentration of non-radiative recombination centers on the surface because of the etching and changes in doping due to inter-diffusion of Cd, S, Se and Zn after the deposition of CdS. Such an inter-diffusion depends on the elemental composition of the films defining the chemistry of defects and influencing Eg which increased in the film selenised at 500°C but decreased in the other films. Processing increased the P1 shift rate (j-shift) with excitation power change in all the films demonstrating a higher compensation degree in the solar cells which is consistent with the formation of an interface layer containing new donors CdCu.
关键词： Optical spectroscopy,Copper zinc tin selenide,Photoluminescence,Solar cells,Selenisation
更新于2025-09-23 15:22:29
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Two Dimensional β-InSe with Layer-Dependent Properties: Band Alignment, Work Function and Optical Properties
摘要： Density functional theory calculations of the layer (L)-dependent electronic band structure, work function and optical properties of β-InSe have been reported. Owing to the quantum size effects (QSEs) in β-InSe, the band structures exhibit direct-to-indirect transitions from bulk β-InSe to few-layer β-InSe. The work functions decrease monotonically from 5.22 eV (1 L) to 5.0 eV (6 L) and then remain constant at 4.99 eV for 7 L and 8 L and drop down to 4.77 eV (bulk β-InSe). For optical properties, the imaginary part of the dielectric function has a strong dependence on the thickness variation. Layer control in two-dimensional layered materials provides an effective strategy to modulate the layer-dependent properties which have potential applications in the next-generation high performance electronic and optoelectronic devices.
关键词： optical properties,Layer-dependent,density functional theory,Indium Selenide,work function
更新于2025-09-23 15:22:29
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Fabrication of IR windows grade zinc selenide by the reactive diffusive process
摘要： The preparation of infra-red windows grade zinc selenide (ZnSe) by the reactive diffusion process between liquid zinc and selenium was the goal of present work. In this regards, high purity zinc and Se elements with a nominal composition of Zn50Se50 were capsulated in quartz ampoule and annealed in the temperature range of 550-950 °C. The wurtzite structure of zinc selenide phase was successfully obtained during annealing process beyond 750 oC. The hexagonal structure of zinc selenide was an unstable phase and totally transformed to the cubic construction by increasing the annealing temperature (950 °C) that is appropriate for infra-red windows application. The formation of zinc selenide phase during the annealing process has been performed by the development of an unceasing layer of porous zinc selenide compound in zinc/ selenium interface. The formation of porous zinc selenide can be associated to the different diffusion constants of selenium and zinc atoms in zinc selenide lattice based on the Kirkendall theory.
关键词： Interfaces,zinc selenide.,Kinetics,Chalcogenides
更新于2025-09-23 15:22:29
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Hot Carrier and Surface Recombination Dynamics in Layered InSe Crystals
摘要： Layered indium selenide (InSe) is a van der Waals solid that has emerged as a promising material for high-performance ultrathin solar cells. The optoelectronic parameters that are critical to photoconversion efficiencies, such as hot carrier lifetime and surface recombination velocity, are however largely unexplored in InSe. Here, these key photophysical properties of layered InSe are measured with femtosecond transient reflection spectroscopy. The hot carrier cooling process is found to occur through phonon scattering. The surface recombination velocity and ambipolar diffusion coefficient are extracted from fits to the pump energy-dependent transient reflection kinetics using a free carrier diffusion model. The extracted surface recombination velocity is approximately an order of magnitude larger than that for methylammonium lead-iodide perovskites, suggesting that surface recombination is a principal source of photocarrier loss in InSe. The extracted ambipolar diffusion coefficient is consistent with previously reported values of InSe carrier mobility.
关键词： transient reflection spectroscopy,hot carrier dynamics,Layered indium selenide,solar cell,van der Waals solid,surface recombination velocity,ambipolar diffusion coefficient
更新于2025-09-23 15:22:29
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[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa, Ukraine (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Colloidal CdSe Nanocrystals as a Material for Optoelectronics and Biomedical Imaging
摘要： Cadmium selenide nanocrystals were prepared in water phase chemistry technique with gelatin, polivinil alcohol, lactose, triton-100 acting as capping agent. Structures were characterized using scanning electron microscopy (SEM), visible absorption and photoluminescence spectroscopies. Influence of component concentrations and technological parameters on nanocrystals average size and properties was studied
关键词： photoluminescence,optical,selenide,optoelectronics,biomedical imaging,cadmium,nanocrystals,absorption
更新于2025-09-23 15:21:21
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Surfactant-free stable SnS2 nanoparticles dispersion for deposition of device-quality films
摘要： Tin sulfide (SnS2) has recently attracted considerable attention due to its layered structure that may form two dimensional morphologies. It is an n-type semiconductor with band gap and electron affinity similar to CdS and In2S3; therefore can be regarded as an alternative for these materials in thin film solar cells. Here, we synthesis of SnS2 nanoparticles with different morphology in different ratio of water-ethanol mixed solution by solvothermal method, and observe that more ethanol leads to large sheet like morphologies, while water based synthesis results in very small nanosheets. A challenge in wet deposition of device-quality thin films of SnS2 is the requirement for highly dispersed particles/sheets. We found highly polar dimethylformamide (DMF) as the right dispersing medium, yielding highly stable dispersions. Very uniform nanocrystalline thin films with [001] preferred orientation and good adhesion to substrate are simply deposited by drop casting and spin coating a 0.5 wt% DMF sol of SnS2 at 2000 rpm for 1 min. Electron affinity and band gap of the films are 4.33 eV and 2.27 eV, which is well aligned for copper indium gallium sulfo-selenide (CIGS) solar cells.
关键词： Two dimensional structures,Surfactant-free dispersion,copper indium gallium sulfo-selenide solar cells,SnS2 thin film,Dimethylformamide,Buffer layer
更新于2025-09-23 15:21:21
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Investigation on annealing temperature-dependent optical properties of electron beam evaporated ZnSe thin films
摘要： This research work is devoted to studying optical properties of zinc selenide (ZnSe) thin films deposited by electron beam evaporation technique and annealed at different temperatures in a nitrogen environment. The structural analysis by X-ray diffraction confirmed that the obtained ZnSe films had cubic zinc-blende structure with preferred orientation along plane (111). Based on Swanepoel's envelope method, some important optical parameters such as absorption coefficient, extinction coefficient, refractive index and optical band gap, were evaluated through the transmission spectrum ranging from 300 to 1500 nm at room temperature. The optical band gap increased from 2.52 to 2.65 eV with the increasing annealing temperature. However, both the thickness and refractive index of the films decreased. In addition, the dispersion parameters of the refractive index and energy were also studied by using Wemple-DiDomenico single oscillator model.
关键词： Optical properties,Thin films,Electron beam evaporation,Zinc selenide,Thermal annealing
更新于2025-09-23 15:21:21
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Mercaptoalkanoic Acida??Induced Band Gap Attenuation of Copper Selenide Quantum Dot
摘要： Copper selenide quantum dot (CuSeQD) materials functionalised with mercaptoalkanoic acids {3-mercaptopropionic acid (3-MPA), 6-mercaptohexanoic acid (6-MHA) and mercaptosuccinic acid (MSA)} were synthesized by a reproducible aqueous colloidal technique at room temperature. The impact of the capping agents on the size and the crystallinity of the CuSeQD materials, were investigated by small angle X-ray scattering (SAXS) and X-ray diffraction (XRD) spectroscopic techniques, respectively. SAXS results confirmed that 6-MHA-CuSeQD had the smallest average particle core size when dried, whereas MSA-CuSeQD had the smallest size in aqueous solution, though with a tendency to aggregate. Dynamic light scattering (DLS) measurements indicated strong bonding of the capping agents to CuSe particles, with MSA being the weakest binding agent, confirmed by low Zeta potential(ζ = (cid:0) 31.1 mV) and high polydispersity index (0.469) values. UV-Vis absorption studies confirmed a large blue shift of the band gap for the QD compared to the bulk material, with characteristic absorption band (λ) and direct band gap (Egd) values being (λ = 435 nm, Egd = 5.6 eV) and (λ = 400 nm, Egd = 8.0 eV), (λ = 340 nm, Egd = 4.0 eV), for 6-MHA-CuSeQD, 3-MPA-CuSeQD and MSA-CuSeQD, respectively. As supported by the formal potential values for 6-MHA-CuSeQD (E0’ ? 120 mV), 3-MPA-CuSeQD (E0’ ? 159 mV) and MSA-CuSeQD (E0’ ? 183 mV), the smaller the particle size, the lower the potential required for the application of the quantum dots in an electron transfer process.
关键词： Cyclic Voltammetry,biocompatible,copper selenide,Aqueous synthesis,quantum dots
更新于2025-09-23 15:21:01