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Raman study of laser-induced formation of IIa??VI nanocrystals in zinc-doped Asa??S(Se) films
摘要： Zn-doped As2Se3 and As2S3 films were prepared by thermal evaporation. Their amorphous structure was confirmed by Raman spectroscopy. Zinc chalcogenide nanocrystals can be formed in the films under laser irradiation due to the photoenhanced diffusion of atoms in the arsenic chalcogenide films, which enables aggregation of Zn and S(Se) atoms in nanocrystals. For As2S3:Zn films, not only ZnS, but also ZnO crystallites can be formed under irradiation with UV laser light due to oxidation of the film surface with abundant zinc atoms.
关键词： Raman scattering,Amorphous films,II–VI nanocrystals,Arsenic chalcogenides
更新于2025-09-19 17:13:59
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Chalcogenide Materials and Derivatives for Photovoltaic Applications
摘要： Chalcogenide AB(S,Se)3 materials have recently attracted increased attention as they could simultaneously solve both the stability and toxicity issues faced by conventional perovskite solar cells. Computer-aided design of metal chalcogenide semiconductors has experienced important progress over the past few years, leading to the discovery of very promising AB(S,Se)3 compounds and derivatives for application as absorbers in thin-film photovoltaic devices. Experimental evidence demonstrates that the synthesis of such compounds is possible, confirming the theoretical predictions, although more research work needs to be done to further investigate the optoelectrical properties of the corresponding thin films. With the aim to provide an exhaustive starting point to further develop chalcogenide absorbers and related devices, this Review presents both an overview of the predicted chalcogenide materials and interesting derivatives for thin-film solar cells applications, as well as a summary of the synthesis techniques developed so far to prepare such materials. The possible challenges that can be encountered during the development of chalcogenide-based solar cells are also discussed.
关键词： lead-free perovskites,chalcogenides,solar cells,computational materials designs,thermodynamic stabilities
更新于2025-09-19 17:13:59
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Numerical modeling of lead-free perovskite solar cell using inorganic charge transport materials
摘要： Ten years after their first mention in report on solar cell implementation, organic-inorganic hybrid perovskites are still the focal point of photovoltaic research. Proper selection of material for different layers has enabled high power conversion efficiency (PCE) values that presently surpass 24%. Unfortunately, the metal halide perovskite solar cells (PSC) contain toxic lead, which is a serious concern for their commercialization process. To tackle lead toxicity issues in perovskite-based solar cells, intensive research by PSC research fraternity is ongoing to develop lead-free metal halide perovskite. In this paper, a novel solar cell configuration which consists of FTO/Transition Metal Di-Chalcogenides/Perovskite/Copper thiocyanate/Au is proposed. In this Transition Metal Di-Chalcogenides (Tungsten Disulfide) is used as an electron transport metal (ETM) due to its high electron mobility and Copper thiocyanate (CuSCN) is used as a hole transport metal (HTM) due to its high transparency and ideal band alignment with perovskite. Impact of variation in thickness of perovskite layer, electron transport layer and hole transport layer on performance parameters were examined. A PCE of 19.84% is achieved at the optimal perovskite layer thickness of 700 nm. When the thickness surpasses 700 nm, PCE drops due to an increase in the recombination of electron-hole pairs. Impact of interfacial defects on the performance parameter was also scrutinized. Simulation results reveal that the interfacial defect of ETM/Perovskite has a larger impact on performance parameters than that of Perovskite/HTM defect when light is irradiated from the ETM side. We also investigated the effect of temperature variation on device performance. The PSC showed optimum performance in the range of 20 °C to 50 °C and the ideal working temperature was viewed as 30 °C.
关键词： Transition metal di-chalcogenides,Power conversion efficiency,Stability,Lead-free perovskite,Copper thiocyanate
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) - Machine learning defect properties in Cd-based chalcogenides
摘要： Impurity energy levels in the band gap can have serious consequences for a semiconductor’s performance as a photovoltaic absorber. Data-driven approaches can help accelerate the prediction of point defect properties in common semiconductors, and thus lead to the identification of potential deep lying impurity states. In this work, we use density functional theory (DFT) to compute defect formation energies and charge transition levels of hundreds of impurities in CdX chalcogenide compounds, where X = Te, Se or S. We apply machine learning techniques on the DFT data and develop on-demand predictive models for the formation energy and relevant transition levels of any impurity atom in any site. The trained ML models are general and accurate enough to predict the properties of any possible point defects in any Cd-based chalcogenide, as we prove by testing on a few selected defects in mixed chalcogen compounds CdTe0.5Se0.5 and CdSe0.5S0.5. The ML framework used in this work can be extended to any class of semiconductors.
关键词： machine learning,point defects,CdTe,density functional theory,chalcogenides
更新于2025-09-19 17:13:59
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Recent progress in quantum dot-sensitized solar cells employing metal chalcogenides
摘要： As one of the most promising third-generation photovoltaics devices, quantum dot-sensitized solar cells (QDSCs) have attracted increasing attention due to their easy fabrication, low cost, potential high efficiency, etc. Thus, substantial efforts have been taken to boost their photoelectrical conversion efficiencies (PCEs) and device stability consistently by precisely optimizing the structure of materials and device architecture. Throughout the development of QDSCs, it is noteworthy to mention that metal chalcogenide-based semiconductors have been key materials in capturing sunlight as sensitizers, catalytic electrolyte reduction as counter electrodes (CEs), and interface charge transport as interface modification layers. Herein, we systematically review the recent progress on metal chalcogenide-based QDSCs in practical applications from three main functional points, specifically, QD sensitizers, counter electrodes (CEs), and interface modification layers. Besides, we have outlined the fundamental structure, operation principle, and brief history of these sensitized solar cells. Finally, the state of existing challenges and future prospects for QDSCs employing various metal chalcogenides are also discussed.
关键词： interface modification layers,photoelectrical conversion efficiencies,sensitizers,counter electrodes,quantum dot-sensitized solar cells,metal chalcogenides
更新于2025-09-16 10:30:52
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Screen printed tin selenide films used as the counter electrodes in dye sensitized solar cells
摘要： In this work, the scalable screen printing process has been adopted to prepare low-cost and earth-abundant tin selenide (SnSe) films to study as the counter electrode in dye-sensitized solar cells (DSSCs). The SnSe powder was synthesized by solid state reaction method and corresponding films were fabricated by screen printing technique. The electrocatalytic activity of SnSe for redox iodide/triiodide (I?/I3?) couple and charge transfer resistance at the CE/electrolyte interface were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The DSSC with SnSe counter electrode exhibited with power conversion efficiency (PCE) of ~5.76% with open-circuit voltage of 0.63 V and short circuit current density of 12.39 mA/cm2 whereas the DSSC with platinum counter electrode showed PCE of 8.09% with open-circuit voltage of 0.68 V and short circuit current density of 14.77 mA/cm2. Thus, earth abundant and low cost SnSe films fabricated by screen printing technique could be an alternative to costly platinum counter electrode in DSSC.
关键词： Counter electrode,SnSe films,DSSC,Chalcogenides,Screen printing
更新于2025-09-16 10:30:52
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On efficiency of earth-abundant chalcogenide photovoltaic materials buffered with CdS: the limiting effect of band alignment
摘要： Earth-abundant and environmentally-friendly Cu2–II–IV–VI4 (II = Sr, Ba; IV = Ge, Sn; VI = S,Se) are considered materials for the absorber layers in thin film solar cells. Attempts to understand and improve optoelectronic properties of these newly emerged absorbers resulted in an efficiency of 5.2% in less than two years. However, the energy band alignment at the buffer/absorber interface has not been studied yet; an information which is of crucial importance for designing high performance devices. Therefore, current study focuses on the band offsets between these materials and the CdS buffer. Using first-principles calculations, band discontinuities are calculated at the buffer/absorber interface. The results yield a type-II band alignment between all Cu2–II–IV–VI4 absorbers and CdS, hence a negative DEc. Adoption of a negative DEc (cliff-like conduction band offset) at the buffer/absorber interface, however, gives rise to low open circuit voltage and high interface-related recombinations. Therefore, it is necessary to search for an alternative buffer material that forms a type-I band alignment with these absorbers, where the conduction band minimum and the valence band maximum are both localized on the absorber side.
关键词： buffer/absorber interface,earth-abundant chalcogenides,band alignment,first-principles calculations
更新于2025-09-16 10:30:52
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Pulsed Laser Deposition of Nanostructured MoS3/np-Mo//WO3?y Hybrid Catalyst for Enhanced (Photo) Electrochemical Hydrogen Evolution
摘要： Pulsed laser ablation of MoS2 and WO3 targets at appropriate pressures of background gas (Ar, air) were used for the preparation of new hybrid nanostructured catalytic ?lms for hydrogen production in an acid solution. The ?lms consisted of a nanostructured WO3?y underlayer that was covered with composite MoS3/np-Mo nanocatalyst. The use of dry air with pressures of 40 and 80 Pa allowed the formation of porous WO3?y ?lms with cauli?ower- and web-like morphology, respectively. The ablation of the MoS2 target in Ar gas at a pressure of 16 Pa resulted in the formation of amorphous MoS3 ?lms and spherical Mo nanoparticles. The hybrid MoS3/np-Mo//WO3?y ?lms deposited on transparent conducting substrates possessed the enhanced (photo)electrocatalytic performance in comparison with that of any pristine one (MoS3/np-Mo or WO3?y ?lms) with the same loading. Modeling by the kinetic Monte Carlo method indicated that the change in morphology of the deposited WO3?y ?lms could be caused by the transition of ballistic deposition to di?usion limited aggregation of structural units (atoms/clusters) under background gas pressure growth. The factors and mechanisms contributing to the enhancement of the electrocatalytic activity of hybrid nanostructured ?lms and facilitating the e?ective photo-activation of hydrogen evolution in these ?lms are considered.
关键词： pulsed laser deposition,tungsten oxides,transition metal chalcogenides,nanocatalysts,hydrogen evolution reaction,background gas
更新于2025-09-16 10:30:52
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Self-Powered SnS1-xSex Alloy/Silicon Heterojunction Photodetectors with High Sensitivity in a Wide Spectral Range
摘要： Alloy engineering and heterostructures designing are two efficient methods to improve the photosensitivity of 2D material-based photodetectors. Herein, we report the first-principle calculation about the band structure of SnS1-xSex (0 ≤ x ≤ 1) and synthesize these alloy nanosheets. Systematic measurements indicate that SnS0.25Se0.75 exhibits the highest hole mobility (0.77 cm2·V-1·s-1) and a moderate photoresponsivity (4.44 × 102 A·W-1) with fast response speed (32.1/57.5 ms) under 635 nm irradiation. Furthermore, to reduce the dark current and strengthen the light absorption, a self-driven SnS0.25Se0.75/n-Si device has been fabricated. The device achieved a preeminent photo-responsivity of 377 mA·W-1, a detectivity of ~1011 Jones and Ilight/Idark ratio of ~4.5×102. In addition, the corresponding rising/decay times are as short as 4.7/3.9 ms. Moreover, a broadband sensitivity from 635 nm to 1200 nm is obtained and the related photoswitching curves are stable and reproducibility. Noticeably, the above parameters are comparable or superior to the most of reported group IVA layered materials-based self-driven photodetectors. Last, the synergistic effects between the SnS0.25Se0.75 nanosheets and the n-Si have been discussed by the band alignment. These brilliant results will pave a new pathway for the development of next generation 2D alloy-based photoelectronic devices.
关键词： alloy engineering,photodetectors,Tin chalcogenides,physical vapor deposition,van der Waals heterostructure
更新于2025-09-16 10:30:52
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Laser irradiation-induced structural, microstructural and optical properties change in Bi-doped As <sub/>40</sub> Se <sub/>60</sub> thin films
摘要： The laser irradiation of thermally evaporated As40Se55Bi5 and As40Se45Bi15 thin films was found to be accompanied by structural changes which in turn changed the optical constant. The thin films under investigation were characterized by the X-ray diffraction method to study the structural change and the surface morphology was checked by field emission scanning electron microscope. The composition of the films was verified from the energy dispersive X-ray analysis. The changes in optical properties due to the influence of laser irradiation were calculated from the transmission spectrum recorded by UV–Visible spectrometer in the wavelength region 400–1200 nm. The decrease in optical band gap (photodarkening) is explained on the basis of density of state model proposed by Mott–Davis. The Raman analysis showed the Raman shift and symmetric stretching vibration of As–Se.
关键词： thin films,optical properties,optical band gap,Chalcogenides,laser irradiation
更新于2025-09-12 10:27:22