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Photo-Induced Phase Transition of CdZnS Based Nanocomposite at Room Temperature Under Solar Irradiation
摘要： Photo-induced phase transition (PIPT) of CdZnS based nanocomposites that was performed at the room temperature under the solar light illumination is reported here for the first time. CdZnS particles were decorated on reduced graphene oxide (RGO) with a solvothermal process and consequently RGO-CdZnS-5%Pt nanocomposites (PC) have been synthesized as zinc blende (cubic) phase of CdZnS. Zinc blende structure (cubic) of CdZnS components of PC was turned to wurtzite (hexagonal) crystal structure with PIPT during the photocatalytic hydrogen evolution reaction. The band gap of the photocatalyst decreased from 2.42 to 2.19 eV and the hydrogen evolution rate increased from 37.3 to 184.0 μ mol h?1 due to the PIPT process.
关键词： Photo-induced phase transition,Hydrogen production,Metal chalcogenides,Photocatalyst
更新于2025-09-23 15:22:29
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A hydrothermally synthesized MoS <sub/>2(1a??x)</sub> Se <sub/>2x</sub> alloy with deep-shallow level conversion for enhanced performance of photodetectors
摘要： Photoelectric detectors based on binary transition metal chalcogenides have attracted widespread attention in recent years. However, due to the high-temperature synthesis of binary TMD, high-density deep-level defect states may be generated, leading to poor responsiveness or a long response time. Besides, the addition of an alloy will change the DLDSs from deep to shallow energy levels caused by S vacancies. In this paper, MoS2(1?x)Se2x nanostructures were synthesized by a hydrothermal method, and a novel type of photodetector was fabricated by using the synthesized material as a light sensitive material. The MoSSe-based photodetector not only has a high photocurrent, but also exhibits a wide spectral response in the range of 405 nm to 808 nm. At the same time, it can achieve a responsivity of 1.753 mA W?1 under 660 nm laser irradiation of 1.75 mW mm?2. Therefore, this work can be considered as a method of constructing a new type of photodetector with a simple process and low cost.
关键词： MoS2(1?x)Se2x,photoelectric detectors,photodetector,transition metal chalcogenides,hydrothermal synthesis
更新于2025-09-23 15:21:01
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Strained bubbles in van der Waals heterostructures as local emitters of photoluminescence with adjustable wavelength
摘要： The possibility to tailor photoluminescence (PL) of monolayer transition metal dichalcogenides (TMDCs) using external factors such as strain, doping and external environment is of significant interest for optoelectronic applications. Strain in particular can be exploited as a means to continuously vary the bandgap. Micrometer-scale strain gradients were proposed for creating ‘artificial atoms’ that can utilize the so-called exciton funneling effect and work, for example, as exciton condensers. Here we describe room-temperature PL emitters that naturally occur whenever monolayer TMDC is deposited on an atomically flat substrate. These are hydrocarbon-filled bubbles which provide predictable, localized PL from well-separated submicron areas. Their emission energy is determined by the built-in strain controlled only by the substrate material, such that both the maximum strain and the strain profile are universal for all bubbles on a given substrate, i.e., independent of the bubble size. We show that for bubbles formed by monolayer MoS2, PL can be tuned between 1.72 to 1.81 eV by choosing bulk PtSe2, WS2, MoS2 or graphite as a substrate and its intensity is strongly enhanced by the funneling effect. Strong substrate-dependent quenching of the PL in areas of good contact between MoS2 and the substrate ensures localization of the luminescence to bubbles only; by employing optical reflectivity measurements we identify the mechanisms responsible for the quenching. Given the variety of available monolayer TMDCs and atomically flat substrates and the ease of creating such bubbles, our findings open a venue for making and studying the discussed light-emitting ‘artificial atoms’ that could be used in applications.
关键词： photoluminescence,exciton funneling,monolayer transition metal chalcogenides,excitons,strain engineering
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE 13th Nanotechnology Materials and Devices Conference (NMDC) - Portland, OR, USA (2018.10.14-2018.10.17)] 2018 IEEE 13th Nanotechnology Materials and Devices Conference (NMDC) - Magnetic Characterization of Cobalt Selenide and Nickel Selenide Thin Films
摘要： Transition metal dichalcogenides (TMDCs) are a family of materials whose crystalline structure consists of a layer of transition metal atoms sandwiched between 2 layers of chalcogenide atoms. Some of these materials can be grown in 2D hexagonal phase and show tunability of their electrical and magnetic properties based on layer thickness. One aspect of these materials that has received little attention is their magnetic properties. Hence, we have investigated magnetic properties of CoSe and NiSe their heterostructure. The reason for choosing these intrinsically ferromagnetic transition metal atoms based TMCs was to examine how reduction from the bulk to 2D films would influence the magnetic activity of these samples. In order to produce large area films, we have employed atomic layer deposition (ALD) for growth of uniform, few layer-thick films. First the composition and crystal structure of these films are characterized, and then their magnetic properties analyzed. We have found that thin films of both these materials show mostly paramagnetic behavior.
关键词： cobalt selenide,magnetic properties,Transition metal chalcogenides,thin film,nickel selenide
更新于2025-09-19 17:15:36
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Comparative Study of the Structure, Composition, and Electrocatalytic Performance of Hydrogen Evolution in MoSx~2+?′/Mo and MoSx~3+?′ Films Obtained by Pulsed Laser Deposition
摘要： Systematic and in-depth studies of the structure, composition, and efficiency of hydrogen evolution reactions (HERs) on MoSx films, obtained by means of on- and off-axis pulsed laser deposition (PLD) from a MoS2 target, have been performed. The use of on-axis PLD (a standard configuration of PLD) in a buffer of Ar gas, with an optimal pressure, has allowed for the formation of porous hybrid films that consist of Mo particles which support a thin MoSx~2+δ (δ of ~0.7) film. The HER performance of MoSx~2+δ/Mo films increases with increased loading and reaches the highest value at a loading of ~240 μg/cm2. For off-axis PLD, the substrate was located along the axis of expansion of the laser plume and the film was formed via the deposition of the atomic component of the plume, which was scattered on Ar molecules. This made it possible to obtain homogeneous MoSx~3+δ (δ~0.8–1.1) films. The HER performances of these films reached saturation at a loading value of ~163 μg/cm2. The MoSx~3+δ films possessed higher catalytic activities in terms of the turnover frequency of their HERs. However, to achieve the current density of 10 mA/cm2, the lowest over voltages were ?162 mV and ?150 mV for the films obtained by off- and on-axis PLD, respectively. Measurements of electrochemical characteristics indicated that the differences in the achievable HER performances of these films could be caused by their unique morphological properties.
关键词： nanocatalysts,buffer gas,pulsed laser deposition,transition metal chalcogenides,hydrogen evolution reaction
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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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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Salt‐Assisted Growth of P‐type Cu <sub/>9</sub> S <sub/>5</sub> Nanoflakes for P‐N Heterojunction Photodetectors with High Responsivity
摘要： P-n junctions based on two dimensional (2D) van der Waals (vdW) heterostructure are one of the most promising alternatives in next-generation electronics and optoelectronics. By choosing different 2D transition metal dichalcogenides (TMDCs), the p-n junctions have tailored energy band alignments and exhibit superior performance as photodetectors. The p-n diodes working at reverse bias commonly have high detectivity due to suppressed dark current but suffer from low responsivity resulting from small quantum efficiency. Greater build-in electric field in the depletion layer can improve the quantum efficiency by reducing recombination of charge carriers. Herein, Cu9S5, a novel p-type semiconductor with direct bandgap and high optical absorption coefficient, is synthesized by salt-assisted chemical vapor deposition (CVD) method. The high density of holes in Cu9S5 endows the constructed p-n junction, Cu9S5/MoS2, with strong build-in electric field according to Anderson heterojunction model. Consequently, the Cu9S5/MoS2 p-n heterojunction has low dark current at reverse bias and high photoresponse under illumination due to the efficient charge separation. The Cu9S5/MoS2 photodetector exhibits good photodetectivity of 1.6 × 1012 Jones and photoresponsivity of 76 A W?1 under illumination. This study demonstrates Cu9S5 as a promising p-type semiconductor for high-performance p-n heterojunction diodes.
关键词： Cu9S5,2D metal chalcogenides,photodetectors,van der Waals epitaxy,p-n heterojunctions
更新于2025-09-12 10:27:22
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Flexible and stretchable photodetectors and gas sensors for wearable healthcare based on solution-processable metal chalcogenides
摘要： Wearable smart sensors are considered to be the new generation of personal portable devices for health monitoring. By attaching to the skin surface, these sensors are closely related to body signals (such as heart rate, blood oxygen saturation, breath markers, etc.) and ambient signals (such as ultraviolet radiation, inflammable and explosive, toxic and harmful gases), thus providing new opportunities for human activity monitoring and personal telemedicine care. Here we focus on photodetectors and gas sensors built from metal chalcogenide, which have made great progress in recent years. Firstly, we present an overview of healthcare applications based on photodetectors and gas sensors, and discuss the requirement associated with these applications in detail. We then discuss advantages and properties of solution-processable metal chalcogenides, followed by some recent achievements in health monitoring with photodetectors and gas sensors based on metal chalcogenides. Last we present further research directions and challenges to develop an integrated wearable platform for monitoring human activity and personal healthcare.
关键词： gas sensor,photodetector,solution-processable metal chalcogenides,healthcare
更新于2025-09-12 10:27:22
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Nucleation promoted synthesis of large-area ReS<sub>2</sub> film for high-speed photodetectors
摘要： Rhenium disulfide (ReS2) is a transition metal dichalcogenide with a layer-independent direct bandgap. Notably, the weak interlayer coupling owing to its T-phase structure enables multi-layer ReS2 to behave similarly to decoupled monolayers. This inherent characteristic makes continuous multi-layer ReS2 film a unique platform for large-area electronic applications. To date, the bulk of work on ReS2 has been conducted using mechanically exfoliated samples or small size flakes (< 1mm2) with no potential for large-scale electronics. A chemical vapor deposition (CVD) synthesis of a large area, continuous ReS2 film directly on a SiO2 substrate is also known to be more challenging compared with that of other 2D materials, such as MoS2 and WS2. This is partly due to its tendency to grow into discrete dendritic structures. In this study, a large-area (> 1 cm2), continuous multilayer ReS2 film is directly synthesized on a SiO2 substrate without any transfer process. The polycrystalline ReS2 film synthesized by this method exhibits one of the fastest photoresponse speeds (0.03 s rise time and 0.025 s decay time) among the reported CVD films. The responsivity Rλ was also the highest among large-area CVD films. The synthesis method for a continuous multilayer ReS2 film is amenable to large-scale integration and will pave the way for practical optoelectronic applications based on 2D layered materials.
关键词： Photodetector,Large-area synthesis,Metal chalcogenides,Chemical vapor deposition,Two-dimensional material,Nucleation promotor
更新于2025-09-11 14:15:04