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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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Synthesis of Chalcogenides and Metal Complex of 2-Phenylbenzo[ 1,3,2]dioxophosphinin-4-one
摘要： The chalcogenides and the metal complexes of 2-phenyl-benzo[1,3,2]dioxophosphinin-4-one are prepared by single step reaction of 2-phenyl-benzo[1,3,2]dioxophosphinin-4-one (1) with DMSO, elemental S, Se and W(CO)5CH3CN.
关键词： P-heterocycles,Salicylic acid,Phosphorous-chalcogenides,Triethylamine
更新于2025-09-23 15:21:01
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Thermal stability study of transition metal perovskite sulfides
摘要： Transition metal perovskite chalcogenides, a class of materials with rich tunability in functionalities, are gaining increased attention as candidate materials for renewable energy applications. Perovskite oxides are considered excellent n-type thermoelectric materials. Compared to oxide counterparts, we expect the chalcogenides to possess more favorable thermoelectric properties such as lower lattice thermal conductivity and smaller band gap, making them promising material candidates for high temperature thermoelectrics. Thus, it is necessary to study the thermal properties of these materials in detail, especially thermal stability, to evaluate their potential. In this work, we report the synthesis and thermal stability study of five compounds, a-SrZrS3, b-SrZrS3, BaZrS3, Ba2ZrS4, and Ba3Zr2S7. These materials cover several structural types including distorted perovskite, needle-like, and Ruddlesden–Popper phases. Differential scanning calorimeter and thermogravimetric analysis measurements were performed up to 1200 °C in air. Structural and chemical characterizations such as X-ray diffraction, Raman spectroscopy, and energy dispersive analytical X-ray spectroscopy were performed on all the samples before and after the heat treatment to understand the oxidation process. Our studies show that perovskite chalcogenides possess excellent thermal stability in air at least up to 550 °C.
关键词： differential scanning calorimeter,thermoelectric materials,Transition metal perovskite chalcogenides,thermal stability,thermogravimetric analysis,Raman spectroscopy,Ruddlesden–Popper phases,X-ray diffraction,energy dispersive analytical X-ray spectroscopy
更新于2025-09-23 15:21:01
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Prolonged Lifetime in Nanocrystal Light-Emitting Diodes Incorporating MoS <sub/>2</sub> -Based Conjugated Polyelectrolyte Interfacial Layer as an Alternative to PEDOT:PSS
摘要： Colloidal semiconductor nanocrystals (NCs), and recently nanoplatelets (NPLs), owing to their efficient and narrowband luminescence, are considered as frontier materials for the light-emitting diode (LED) technology. NC-LEDs typically incorporate interfacial layers as charge regulators to ensure charge balancing and high performance. In this communication, we show the prolongation of the lifetime of multilayer solution-processed NC-LEDs by combining a self-doped conductive conjugated polyelectrolyte and exfoliated molybdenum disulfide (MoS2) flakes as an alternative to PEDOT:PSS. The ink features a neutral pH and a tunable hydrophobicity that mainly results in a remarkable stability of LEDs, using CdSe/CdZnS NPLs.
关键词： di-chalcogenides,colloidal nanoplatelets,interfacial layers,light-emitting devices,conjugated polyelectrolytes
更新于2025-09-23 15:19:57
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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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Photo and thermal induced Bi2Se3 formation from Bi/GeSe2 hetero junction layer for topological insulator
摘要： In the present paper, we report the evolution of Bi2Se3 topological phase from the Bi diffusion into GeSe2 layer in the Bi/GeSe2 hetero junction film with light and thermal energy. The photo and thermal induced changes in the structural and optical properties of thermally evaporated Bi/GeSe2 bilayer film has been studied by various characterization techniques. The amorphous to crystalline phase transition and the formation of Bi2Se3 topological phase was confirmed from the X-ray diffraction analysis. The deposition as well as diffusion of Bi into GeSe2 layer changed the optical constants like transmitivity, absorption power, optical band gap, Urbach energy, Tauc parameter as studied from UV–Vis–NIR spectroscopy. The transmission power decreased after thermal annealing and laser irradiation where the reverse effect was found in case of absorption coefficient. The optical band gap decreased after diffusion which can be explained on the basis of density of defect states with an increase in disorder. Scanning electron microscopy investigations showed that the surface morphology was influenced by the diffusion phenomena. The Raman analysis also confirms the Bi2Se3 phase evolution with appropriate vibrational peaks. The modifications in optical parameters with thermal and light induced diffusion can be used in various optical applications using such metal/chalcogenides heterojunction layers.
关键词： Amorphous materials,Optical properties,Bi2Se3 phase,Chalcogenides,Thin films,Band gap
更新于2025-09-19 17:15:36
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LiBa <sub/>4</sub> Ga <sub/>5</sub> Q <sub/>12</sub> (Q = S, Se): Noncentrosymmetric Metal Chalcogenides with a Cesium Chloride Topological Structure Displaying a Remarkable Laser Damage Threshold
摘要： The exploration of novel infrared nonlinear optical (IR NLO) materials with large second-harmonic generation (SHG) responses and wide band gaps has become very imperative recently. Herein we reported two noncentrosymmetric compounds, LiBa4Ga5Q12 (Q = S, Se), crystallizing in space group P421c (No. 114), which feature 3D frameworks built by a basic [Ga5Q16]17? windmill cluster and LiQ4 tetrahedra in a cesium chloride topological structure. Both compounds satisfy the desired balance between good SHG responses (～1.5× that of AgGaS2) and wide band gaps (3.43 and 2.44 eV) with remarkable laser damage thresholds (21× and 6× that of AgGaS2). The theoretical calculations uncover that the [Ga5Q16]17? cluster makes major contributions to the SHG e?ect in LiBa4Ga5Q12. In addition, the structure?performance relationship among all compounds in the I?II4?III5?VI12 system has been discussed systematically, which indicates that the introduction of the alkali metal lithium in the I site is bene?cial for the production of large band gaps. This work will be helpful in exploring novel IR NLO materials with special structures and comprehensive properties in the chalcogenide system.
关键词： chalcogenides,infrared nonlinear optical materials,laser damage thresholds,cesium chloride topological structure,second-harmonic generation
更新于2025-09-19 17:13:59
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Deciphering the role of key defects in Sb2Se3, a promising candidate for chalcogenide based solar cells
摘要： Herein we report a thorough investigation on Sb2Se3, a promising absorber material for photovoltaic applications, using state of the art quantum methods to understand the impact of defects on its electrical properties. The results show that despite a rather small stability domain, Sb2Se3 is easy to synthetize because there is no other possible stable competing binary phase in the Sb/Se system. Our calculations prove that formation of intrinsic n-type defects is unlikely, because Sb vacancies restrain the Fermi level from reaching the CBM vicinity. In contrast, intrinsic p-type semiconductor behavior is expected due to SbSe antisite defects. Doping is a commonly used technique to impact on the charge carrier concentration as well as the charge carrier nature. In that context, several extrinsic defects were considered, based on tin and copper to enhance the native p-typeness, and halogenides (Cl, Br, I) to induce n-type doping in Sb2Se3. Our results tend to prove that Sb2Se3:Cu(p)/Sb2Se3:I(n) might be a viable homojunction for photovoltaic devices.
关键词： point defects,chalcogenides,absorber,photovoltaics,Sb2Se3,modelling,DFT
更新于2025-09-19 17:13:59
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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