- 标题
- 摘要
- 关键词
- 实验方案
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ThCr2Si2-type quaternary chalcogenides as efficient Pt-free counter electrodes for dye-sensitized solar cells
摘要： Two quaternary chalcogenides of ThCr2Si2-type K2FeCu3Q4 (Q for S and Se) were utilized as new type of Pt-free counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The X-ray photoelectron spectroscopy (XPS), Mott-Schottky analysis, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed to clarify the differences in energy band alignments, electrocatalytic and photovoltaic performances. A photoelectric conversion efficiency (PCE) of 5.07% was achieved in DSSCs assembled with K2FeCu3Se4 CE, which was obviously superior to that of K2FeCu3S4 CE (3.42%) and comparable with that of Pt CE (6.25%) under one sun AM 1.5 G illumination (100 mW cm-2). Compared to K2FeCu3S4 CE, the higher PCE of K2FeCu3Se4 CE can be attributed to the better catalytic activity for I3- reduction, stronger driving force for electron injection from CE to electrolyte, faster electron transfer and electrolyte diffusion channels.
关键词： ThCr2Si2-type structure,Counter electrode,Quaternary chalcogenides,Dye-sensitized solar cell,Pt-free
更新于2025-09-12 10:27:22
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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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Comparison of Clusters Produced from Sb2Se3 Homemade Polycrystalline Material, Thin Films, and Commercial Polycrystalline Bulk Using Laser Desorption Ionization with Time of Flight Quadrupole Ion Trap Mass Spectrometry
摘要： This study compared Sb2Se3 material in the form of commercial polycrystalline bulk, sputtered thin film, and homemade polycrystalline material using laser desorption ionization (LDI) time of flight mass spectrometry with quadrupole ion trap mass spectrometry. It also analyzed the stoichiometry of the SbmSen clusters formed. The results showed that homemade Sb2Se3 bulk was more stable compared to thin film; its mass spectra showed the expected cluster formation. The use of materials for surface-assisted LDI (SALDI), i.e., graphene, graphene oxide, and C60, significantly increased the mass spectra intensity. In total, 19 SbmSen clusters were observed. Six novel, high-mass clusters—Sb4Se4+, Sb5Se3-6+, and Sb7Se4+—were observed for the first time when using paraffin as a protective agent.
关键词： Antimony selenide,Clusters,Laser desorption ionization,Paraffin,Chalcogenides
更新于2025-09-11 14:15:04
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Highly-efficient overall water splitting in 2D Janus group-III chalcogenide multilayers: the roles of intrinsic electric filed and vacancy defects
摘要： Two-dimensional (2D) van der Waals materials have been widely adopted as photocatalysts for water splitting, but the energy conversion efficiency remains low. On the basis of first-principles calculations, we demonstrate that the 2D Janus group-III chalcogenide multilayers: InGaXY, M2XY and InGaX2 (M = In/Ga; X, Y = S/Se/Te), are promising photocatalysts for highly-efficient overall water splitting. The intrinsic electric field enhances the spatial separations of photogenerated carriers and alters the band alignment, which is more pronounced compared with the Janus monolayers. High solar-to-hydrogen (STH) efficiency with the upper limit of 38.5% was predicted in the Janus multilayers. More excitingly, the Ga vacancy of InGaSSe bilayer effectively lowers the overpotentials of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) to the levels provided solely by the photogenerated carriers. Our theoretical results suggest that the 2D Janus group-III chalcogenide multilayers could be utilized as highly efficient photocatalysts for overall water splitting without the needs of sacrificial reagents.
关键词： Photocatalytic water splitting,Janus group-III chalcogenides,Intrinsic electric fields,First-principle calculation,Solar-to-hydrogen efficiency
更新于2025-09-11 14:15:04
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[IEEE 2019 Photonics North (PN) - Quebec City, QC, Canada (2019.5.21-2019.5.23)] 2019 Photonics North (PN) - Design of a mid-infrared multispecies gas sensor based on Pr <sup>3+</sup> -doped chalcogenides waveguides
摘要： Praseodymium-doped selenide thin films are deposited by radio frequency (RF) magnetron sputtering on thermally oxidized silicon wafers. Ridge waveguides are then processed using photolithography and dry etching techniques. Under optical pumping at 1.55 μm, broadband guided mid-infrared photoluminescence is recorded between 3.5 and 5.5 μm. Optical design confirmed that these active waveguides allow single-mode optical propagation at different absorption wavelengths of important environmental gases (CO2, CO, NO). Mid-Wave Infrared (MWIR) multimode interferometer (MMI)-based demultiplexer are designed for multispecies gas sensing.
关键词： MWIR,MMI,mid-infrared,multispecies sensing,rare-earth,chalcogenides
更新于2025-09-11 14:15:04
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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
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Low temperature phase-controlled synthesis of titanium di- and tri-sulfide by atomic layer deposition
摘要： Phase-controlled synthesis of two-dimensional (2D) transition metal chalcogenides (TMCs) at low temperature with a precise thickness control has to date been rarely reported. Here, we report on a process for the phase-controlled synthesis of TiS2 (metallic) and TiS3 (semiconducting) nano-layers by atomic layer deposition (ALD) with precise thickness control. The phase-control has been obtained by carefully tuning the deposition temperature and co-reactant composition during ALD. In all cases, characteristic self-limiting ALD growth behavior with a growth per cycle (GPC) of ~0.16 nm per cycle was observed. TiS2 was prepared at 100 °C using H2S gas as co-reactant, and was also observed using H2S plasma as co-reactant at growth temperatures between 150 and 200 °C. TiS3 was only synthesized at 100 °C using H2S plasma as co-reactant. The S2 species in the H2S plasma, as observed by optical emission spectroscopy, has been speculated to lead to the formation of the TiS3 phase at low temperature. The control between synthesis of TiS2 and TiS3 was elucidated by Raman spectroscopy, X-ray photoelectron spectroscopy, high-resolution electron microscopy, and Rutherford back scattering studies. Electrical transport measurements showed the low resistive nature of ALD grown 2D-TiS2 (1T-phase). Post-deposition annealing of the TiS3 layers at 400 °C in a sulfur-rich atmosphere improved the crystallinity of the film and yielded photoluminescence at ~0.9 eV, indicating the semiconducting (direct bandgap) nature of TiS3. The current study opens up a new ALD-based synthesis route for controlled, scalable growth of transition metal di- and tri-chalcogenides at low temperatures.
关键词： phase-controlled synthesis,low temperature,titanium sulfide,transition metal chalcogenides,atomic layer deposition
更新于2025-09-11 14:15:04
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Cu2ZnGe(S1-xSe x)4 – The challenge to synthesize single phase material
摘要： The variation of the band gap energy in Cu2ZnGeSe4 and Cu2ZnGeS4 from 1.4 eV to 1.7 eV, which is controlled by different S/(S+Se) ratios renders the Cu2ZnGe(S1-xSex)4 solid solution an interesting material for the application in multi-junction solar cells. Nevertheless, this system has a certain complexity due to the existence of different polymorphs. Cu2ZnGeSe4 crystallizes in the tetragonal kesterite type structure, whereas Cu2ZnGeS4 may crystallize in the tetragonal stannite or the orthorhombic wurtz-stannite type structure, respectively. To gain deeper insights into this complex system a systematic study of the solid solution series Cu2ZnGe(S1-xSex)4 was performed using polycrystalline material prepared by solid state reaction. The chemical analysis performed by wavelength dispersive X-ray spectroscopy showed remarkable inhomogeneities with different quaternary phases co-existing within one sample. Additionally, a wide variety of binary and ternary secondary phases as well as elemental Ge was observed. The variety of secondary phases is higher in S-rich samples than in Se-rich samples of the solid solution. Thus, synthesis of Cu2ZnGe(S1-xSex)4 mixed crystals with off-stoichiometric composition is readily accompanied by the formation of various secondary phases making it a difficult task to obtain single phase material.
关键词： Wavelength dispersive X-ray spectroscopy,Solid state reaction,Polycrystalline powders,Chalcogenides,Secondary phases,Copper zinc germanium selenide,Copper zinc germanium sulfide
更新于2025-09-11 14:15:04
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Parallels and Interrelated Regularities in the Change of the Bulk and Surface Properties of CdBVI–CdTe Systems
摘要： Comprehensive studies of the volume (structural, optical, electrophysical) and surface (acid-base, adsorption) properties of solid solutions and binary components of the CdS–CdTe and CdSe–CdTe systems are carried out. The regularities in the changes of these properties with a variation in the composition and the parallels between the patterns within each system and under their comparison are established. The leading influence of the common binary component, cadmium telluride, on the properties of solid solutions of both systems is revealed. The possibility of predicting the surface activity of these new materials with respect to gases of different electronic natures is shown on the basis of the results of less labor-intensive studies of the bulk physical and chemical properties (in comparison with direct studies of the surface characteristics, i.e., acid-base and adsorption characteristics). Practical recommendations on using the obtained materials in corresponding sensors are made.
关键词： acid-base,adsorption properties,sensors,solid solutions,chalcogenides,new materials,electrophysical,structural,optical
更新于2025-09-11 14:15:04