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Dynamic Interplay between Transport and Reaction Kinetics of Luminophores on the Operation of AC-driven Electrochemiluminescence Devices
摘要： Electrochemiluminescence (ECL) involves light emission accompanied by a series of electrochemical processes on luminophores, which has been recently exploited in a new light-emitting device platform, referred to as the ECL device (ECLD). Here, we investigate the influence of the transport of the ECL luminophores and their reaction kinetics on the emission properties of AC-voltage-driven ECLDs. A model based on the diffusion and reaction rate equations is developed to predict the operational frequency (f)-dependent luminance properties of the ECLD. It is found that more frequent generation of the redox precursors with a shorter time interval enhances their probability of encountering each other, and therefore, the luminance of the device increases with increasing f initially. The luminance at a higher f, however, is suppressed eventually due to the decreased rate of the electrode reactions. Using the model, the influence of diffusion and reaction rates on the performance of an ECLD is analyzed separately and systematically. The results provide insight on the operation of this emerging class of light-emitting device platform.
关键词： electrochemiluminescence,ionic transition metal complex,reaction kinetics,mass transport,ionic liquid,light-emitting device
更新于2025-09-23 15:21:01
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One-step hydrothermal synthesis of NiCo2S4 loaded on electrospun carbon nanofibers as an efficient counter electrode for dye-sensitized solar cells
摘要： Possing excellent catalytic performance about counter electrode (CE) is the prerequisite for obtaining high performance dye sensitized solar cells (DSSCs). Herein, The NiCo2S4/carbon nanofibers (NiCo2S4/CNFs) are successfully synthetised via hydrothermal and electrospinning method, and then directly used in DSSCs. Owing to the synergistic effect between the catalytic of NiCo2S4 materials and the electrical conductivity of CNFs, All chemical measurements reveal that NiCo2S4/CNFs applied in DSSCs exhibit good power conversion efficiency (9.0%) and stability, which surpass that of DSSCs with Pt CE (7.48%), indicating that NiCo2S4/CNFs composite would be helpful for the low-cost and efficient application of DSSCs.
关键词： Dye-sensitized solar cells,Electrospinning technology,Counter electrode,Transition metal sulfides
更新于2025-09-23 15:21:01
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van der Waals epitaxial growth of single crystal α-MoO3 layers on layered materials growth templates
摘要： Monolayer and multilayer α-MoO3 nanosheets are successfully grown on a 2D substrate by simply evaporating amorphous molybdenum oxide thin film in ambient conditions. A single-crystal α-MoO3 nanosheet without grain boundary is epitaxially grown on various 2D substrates despite a large lattice mismatch. During growth, the quasi-stable monolayer α-MoO3 first covers the 2D substrate, then additional layers are continuously grown on the first monolayer α-MoO3. The band gap of the α-MoO3 increases from 2.9 to 3.2 eV as the thickness decreases. Furthermore, due to oxygen vacancies and surface adsorbates, the synthesized α-MoO3 is highly n-doped with a small work function. Therefore, α-MoO3 field-effect transistors (FETs) exhibit a typical n-type conductance. This work shows the great potential of ultra-thin α-MoO3 in 2D-material-based electronics.
关键词： work function,van der Waals epitaxy,band structure,vacancy,transition metal oxide,stability,2D materials,lattice mismatch,transistor,heterostructure
更新于2025-09-23 15:21:01
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Hybrid Single-Layer/Bulk Tungsten Diselenide Transistors by Lithographic Encoding of Material Thickness in Chemical Vapor Deposition
摘要： whose bulk-like (3D) portion can be used for metal contacts and efficient charge injection into the metal dichalcogenide (TMD) transistors; because of the small number of charge carriers in a 2D demonstrate that lithographic pre-patterning of a growth substrate prior to chemical vapor deposition of a TMD film can shape the TMD material into nanoscale hybrid 2D/3D structures enhanced reduction of performance compared to conventional bulk Schottky Barriers. Here we single-layer (2D) areas which serve as transistor channels with excellent mobilities and on-off Schottky-like barriers are an important limitation of the performance of single-layer transition semiconductor, the screening of metal contacts is inefficient leading to large depletion zones and devices (through 300nm of oxide) at realistic operation temperatures near 100°C using ratios. We observe mobilities of nearly 100 cm2V-1s-1 with an on/off ratio >105 for bottom-gated TMD growth. Bulk-like 3D WSe2 is observed to grow at the location of the hafnia, while 2D comparatively long channels (>5 microns) and absent other contact optimization. Our process involves lithographic patterning of a hafnium (IV) dioxide film onto the SiO2/Si substrate prior to allows us to extract Schottky barrier heights and other fundamental properties of our hybrid single-layer material is grown in regions of bare SiO2. Systematic evaluation of transport data devices.
关键词： Tungsten Diselenide,Schottky-Barrier,Transition Metal Dichalcogenides,2D Materials
更新于2025-09-23 15:21:01
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Two-dimensional transition metal dichalcogenides mediated long range surface plasmon resonance biosensors
摘要： Two-dimensional transition metal dichalcogenides (TMDCs), as promising alternative plasmon supporting materials to graphene, exhibit potential applications in sensing. Here, we propose a TMDCs-mediated long range surface plasmon resonance (LRSPR) imaging biosensor, which shows tremendous improvements in both imaging sensitivity (> ×2) and detection accuracy (> ×10) as compared to conventional surface plasmon resonance (cSPR) biosensor. It is found that the imaging sensitivity of the LRSPR biosensor can be enhanced by the integration of TMDC layers, which is di?erent from the previously reported graphene-mediated cSPR imaging sensor whose imaging sensitivity decreases with the number of graphene layers. This imaging sensitivity enhancement e?ect for the TMDCs-mediated LRSPR sensor originates from the propagating nature of the LRSPR at both interfaces of sensing medium/gold and gold/cytop layer (with matching refractive index as sensing medium). By tuning the thickness of gold ?lm and cytop layer, it is possible to achieve optimized imaging sensitivity for LRSPR sensor with any known integrated number of TMDC layers and the analyte refractive index. The proposed TMDCs-mediated LRSPR imaging sensor could provide potential applications in chemical sensing and biosensing applications.
关键词： detection accuracy,biosensor,long range surface plasmon resonance,Two-dimensional transition metal dichalcogenides,imaging sensitivity
更新于2025-09-23 15:21:01
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Surface characterization of clean SrTiO <sub/>3</sub> (100) substrates by x-ray photoelectron spectroscopy
摘要： The authors analyze the x-ray photoelectron spectra of SrTiO3(100) (STO) substrates to clarify the electronic structure characteristics induced by a sputter–anneal procedure. The survey spectra, the valence band spectra, and the relevant core level spectra, i.e., Sr 3s, Sr 3p, Sr 3d, Sr 4s, Sr 4p, Ti 2p, Ti 3s, Ti 3p, O 1s, and O 2s along with their satellite structures, of both pristine and sputtered and annealed STO have been measured. A comparison of spectra reveals the appearance of new features in the Ti 2p spectra of sputtered and annealed STO, corresponding to Ti3+ states and gap states near the Fermi energy. The presence of Ti3+ states points to the formation of a two-dimensional electron system at the STO surface generated by Ar+ sputtering and annealing in vacuum. Furthermore, the sputter-annealed surface shows only minor carbon contamination as compared to that of the pristine substrate.
关键词： XPS,transition metal oxide,sputtering,2DES,strontium titanium oxide,core level,single crystal
更新于2025-09-23 15:21:01
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Self-hybridized exciton-polaritons in multilayers of transition metal dichalcogenides for efficient light absorption
摘要： Transition metal dichalcogenides (TMDCs) have attracted significant attention recently in the context of strong light-matter interaction. To observe strong coupling using these materials, excitons are typically hybridized with resonant photonic modes of stand-alone optical cavities, such as Fabry-Pérot microcavities or plasmonic nanoantennas. Here, we show that thick flakes of layered van der Waals TMDCs can themselves serve as low quality resonators due to their high background permittivity. Optical modes of such “cavities” can in turn hybridize with excitons in the same material. We perform an experimental and theoretical study of such self-hybridization in thick flakes of four common TMDC materials: WS2, WSe2, MoS2, and MoSe2. We observe splitting in reflection and transmission spectra in all four cases and provide angle-resolved dispersion measurements of exciton-polaritons as well as thickness-dependent data. Moreover, we observe significant enhancement and broadening of absorption in thick TMDC multilayers, which can be interpreted in terms of strong light-matter coupling. Remarkably, absorption reaches >50% efficiency across the entire visible spectrum, while simultaneously being weakly dependent on polarization and angle-of-incidence. Our results thus suggest formation of self-hybridized exciton-polaritons in thick TMDC flakes, which in turn may pave the way towards polaritonic and optoelectronic devices in these simple systems.
关键词： transition metal dichalcogenides,exciton-polaritons,strong coupling,nanocavities
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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Enhanced Photocatalytic Activity of 2 <i>H</i> -MoSe <sub/>2</sub> by 3 <i>d</i> Transition Metal Doping
摘要： To develop MoSe2-based photocatalysts, increasing the catalytic activity of 2H-MoSe2 is essential. In this work, the electronic and photocatalytic properties of 3d transition metal (TM) doped (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) 2H-MoSe2 were investigated by first-principles calculations. The results indicate that Sc, Ti, V, Cr, Mn, Fe and Co atoms tend to substitute the Mo atoms under Se-rich condition, while Ni, Cu and Zn atoms prefer to occupy the interstitial positions. More importantly, Sc- and Ti-doped 2H-MoSe2 can enhance the photocatalytic activity by increasing the oxidizability of photogenerated holes, suppressing the recombination of photogenerated carriers and increasing the number of catalytic active sites.
关键词： photocatalytic activity,2H-MoSe2,3d transition metal doping,electronic properties,first-principles calculations
更新于2025-09-23 15:21:01
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A facile hydrothemal synthesis of MoS2@Co3S4 composites based on metal organic framework compounds as a high-efficiency liquid-state solar cell counter electrode
摘要： A hollow Co3S4 polyhedral loads MoS2 nanosheet composite MoS2@Co3S4-0.5 is prepared by hydrothermal method using Co-based metal organic framework material ZIF-67 as precursor. Hollow Co3S4 polyhedron and uniformly distributed MoS2 nanosheet structure can not only prevent MoS2 aggregation, but also increase the specific surface area of the material and expose more catalytically active sites. The composites afford a promising synergistic effect on the catalyzing of triiodide reduction. As a counter electrode material applied to dye-sensitized solar cells, MoS2@Co3S4-0.5 exhibits excellent catalytic activity, achieving a photoelectric conversion efficiency of 7.86%, which is superior to 6.99% of Pt counter electrode performance in dye-sensitized solar cells. This indicates that MoS2@Co3S4-0.5 composite material can be used to replace precious metal Pt as an efficient and low-cost counter electrode material in dye-sensitized solar cells.
关键词： metal-organic framework,facile hydrothemal synthesis,transition metal sulfide,dye-sensitized solar cells,counter electrode
更新于2025-09-23 15:19:57