- 标题
- 摘要
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- 实验方案
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Demonstration of Photovoltaic Action and Enhanced Stability from a Quasi-Two-Dimensional Hybrid Organic–Inorganic Copper–Halide Material Incorporating Divalent Organic Groups
摘要： Commercialization of solar cells based on photoactive lead–halide perovskites is in-part limited by their toxicity and instability. In this study, new and related copper–halide hybrid organic–inorganic materials containing dicationic 1,6-hexanediammonium (+H3N-C6H12-NH3+) demonstrated superior stability to heat and moisture in comparison to the analogous material containing monocationic 1-propylammonium (C3H7-NH3+) in twice the stoichiometry. Electronic absorption spectra taken of the materials were consistent with an indirect optical bandgap of ~1.8 eV, making them well-suited for application as the photoactive layer in the top cell of a tandem solar cell with silicon. The best-performing single-junction solar cells containing the dicationic material as the photoactive layer exhibited an open-circuit photovoltage in excess of 400 mV and a short-circuit photocurrent density of ~30 μA/cm2. These values are similar to those reported for state-of-the-art copper–halide hybrid organic–inorganic materials containing organic monocations and motivate further research on this class of materials.
关键词： photovoltaic,two-dimensional material,dications,solar cell,copper halide,hybrid material,stability,perovskite
更新于2025-11-19 16:56:42
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Alcohol-Guided Growth of Two-Dimensional Narrow-Band Red-Emitting K2TiF6:Mn4+ for White Light-Emitting Diodes
摘要： The use of red phosphors with low light-scattering loss could improve the luminous efficacy and color rendering of white light-emitting diodes (LEDs). Thus, the discovery of such phosphors is highly desired. In this work, high-efficiency two-dimensional red-emitting K2TiF6:Mn4+ (KTFM) were synthesized via an alcohol-assisted coprecipitation route. The synergistic effects of 1-propanol and hydrofluoric acid (HF) on the growth of KTFM microsheets (MSs) were studied through the first-principles calculations, which revealed that 1-propanol promoted the growth of KTFM MSs by preferentially adsorbing on the H-terminated K2TiF6 (001) surface. The photoluminescence quantum efficiency (QE) of Mn4+-activated K2TiF6 MSs was highly related to their size and thickness. The morphology-optimal KTFM MSs presented high internal QE (> 90 %), external QE (> 71%), and thermal quenching temperature (102% at 150 °C relative to that at 25 °C). A prototype phosphor-converted LED with KTFM as the red-emitting component showed an excellent color rendition (Ra = 91, R9 = 79) and high luminous efficacy (LE =156 lm/w).
关键词： light emitting diode,two-dimensional material,Narrow band,K2TiF6:Mn4+,backlight,red emission
更新于2025-11-14 17:04:02
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Facile synthesis of two-dimensional tailored graphitic carbon nitride with enhanced photoelectrochemical properties through a three-step polycondensation method for photocatalysis and photoelectrochemical immunosensor
摘要： Graphitic carbon nitride (g-C3N4) is an ideal alternative two-dimensional (2D) nanostructure for photocatalysis and photoelectrochemical (PEC) application, while controllably fabricating 2D shaped g-C3N4 nanolayers/nanosheets is still facing challenges. On the basis of temperature-dependent polymorphic characters, herein, a 2D extending g-C3N4 (g-CNS3) is synthesized from dicyandiamide as the precursor by operating the condensation temperature in a continuously three-step thermal polycondensation procedure. The g-CNS3 with film-like morphology showed improved visible-light absorption ability and enhanced PEC performance compared to g-CNS1 synthesized via the traditional one-step thermal polymerization method. Benefiting from its excellent PEC properties, the g-CNS3 exhibited high photocatalytic activity to removal MB with fast kinetics and served as the photoactive layer to construct a PEC immunosensor with high sensitivity and specificity for subgroup J avian leukosis virus detection. A linear range from 102.14 to 103.35 TCID50/mL and a detection limit of 102.08 TCID50/mL were obtained for the PEC immunoassay of the target virus. This work might provide a novel protocol for tailoring shaped 2D g-C3N4 nanosemiconductor with superior properties and shed light on its promising PEC applications.
关键词： Two-dimensional material,Photocurrent response,Graphitic carbon nitride,Photocatalysis,Photoelectrochemical immunosensor
更新于2025-09-23 15:23:52
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Understanding Spatiotemporal Photocarrier Dynamics in Monolayer and Bulk MoTe <sub/>2</sub> for Optimized Optoelectronic Devices
摘要： Semiconducting molybdenum ditelluride has emerged as a promising transition-metal dichalcogenide with a number of novel properties. In particular, its bandgap in infrared range makes it an attractive candidate for ultrathin and high-performance infrared optoelectronic applications. Dynamical properties of photocarriers play a key role in determining performance of such devices. We report an experimental study on spatiotemporal dynamics of photocarriers in both monolayer and bulk MoTe2. Transient absorption measurement in reflection geometry revealed ultrafast thermalization and relaxation processes of photocarriers and lifetimes of about 60 and 80 ps in monolayer and bulk MoTe2, respectively. By spatially resolved transient absorption measurements on monolayer, we obtained an exciton diffusion coefficient of 20 ± 10 cm2 s?1, a mean free time of 200 fs, a mean free path of 20 nm, and a diffusion length of 350 nm. The corresponding values for the bulk sample are 40 ± 10 cm2 s?1, 400 fs, 40 nm, and 570 nm, respectively. These results provide fundamental information for understanding and optimizing performance of MoTe2-based optoelectronic devices.
关键词： two-dimensional material,exciton,transient absorption,molybdenum ditelluride,transition-metal dichalcogenide,diffusion,photocarrier dynamics
更新于2025-09-23 15:23:52
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Revealing the Role of Gold in the Growth of Two-dimensional Molybdenum Disulfide by Surface Alloy Formation
摘要： Formation of Mo-Au surface alloy during Au-assisted chemical vapor deposition (CVD) of MoS2 was confirmed by a series of control experiments. We adapted a metalorganic chemical vapor deposition (MOCVD) system to conduct two-dimensional MoS2 growth in a controlled environment. Sequential injection of Mo and S precursors, which does not yield any MoS2 on a SiO2/Si, grows atomically thin MoS2 on Au, indicating formation of an alloy phase. Transmission electron microscopy of a cross-section of the specimen confirmed the confinement of the alloy phase near the surface only. These results show that the reaction intermediate is the surface alloy and that the role of Au in the Au-assisted CVD is formation of an atomically thin reservoir of Mo near the surface. This mechanism is clearly distinguished from that of MOCVD, which does not involve formation of any alloy phases.
关键词： Molybdenum Disulfide,Surface Alloy,Two-dimensional Material,Chemical vapor deposition,Metalorganic Chemical Vapor Deposition
更新于2025-09-23 15:21:01
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First-principle study of g-AlxGa1-xN alloys: planar and buckled structures
摘要： The fundamental properties of g-AlxGa1-xN alloys with planar and buckled structures are investigated based on the first-principles. The results show that the band gaps of g-AlxGa1-xN alloys can be tuned, making them promising candidate materials for future light-emitting applications. For two-dimensional planar single layer structures, the band gap of g-AlxGa1-xN alloy increase monotonically with the increase of Al concentration. In contrast, for the buckled structures, as Al concentration increases, the band gap of the alloy structure first increase and then decrease, for the Al0.5Ga0.5N alloy, maximum band gap values can be achieved. The ε peaks and absorption coefficients of planar structures blue-shift, but those of the buckled structures red-shift. The absorption coefficients of the two type structures show two distinct absorption peaks in the deep ultraviolet, therefore deep ultraviolet emission is considered to be a remarkable feature of g-AlxGa1-xN alloys, indicating the potential use of g-AlxGa1-xN alloys for future UV luminescence applications.
关键词： g-AlxGa1-xN alloys,Electronic structure,Optical properties,Two-dimensional material,The first principles
更新于2025-09-23 15:19:57
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Theoretical characterization of hexagonal 2D Be <sub/>3</sub> N <sub/>2</sub> monolayers
摘要： First-principles density functional theory (DFT) calculations are performed to assess the stability, geometric, mechanical, optical and electronic properties of monolayer graphene-like Be3N2. We find that Be3N2 is a large band gap semiconductor with small electron and hole effective masses, which may promote its use in nanoelectronic devices. Furthermore, the excellent thermal, dynamical, and mechanical stability makes it a material of the comparable caliber to that of graphene. In addition, the excellent electrochemical properties of Be3N2 makes it a unique material with the possible theoretical capacities of 974 mAh/g for Li, Na, and K. Moreover, Be3N2 can form bulk graphite-like layered structures with two different configurations, i.e. N2-N1 and N2-Be1. Finally, the derivatives of Be3N2 (Be3N2 nanoribbons) also possess direct band gaps which can finely be tuned to the desired level by geometry and morphology constraints. Based on these fascinating properties, Be3N2 and its derivatives can find a broad range of applications in nanoelectronics and battery technologies.
关键词： DFT calculations,Two-dimensional material,Nano-ribbons,Electrochemical properties,Electronic properties
更新于2025-09-19 17:15:36
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Solution-processed ultrathin SnS <sub/>2</sub> -Pt nanoplates for photoelectrochemical water oxidation
摘要： Tin disulfide (SnS2) is attracting significant interest due to the abundance of its elements and its excellent optoelectronic properties in part related to its layered structure. In this work, we detail the preparation of ultrathin SnS2 nanoplates (NPLs) through a hot-injection solution-based process. Subsequently, Pt was grown on their surface via in-situ reduction of a Pt salt. The photoelectrochemical (PEC) performance of such nanoheterostructures as photoanode toward water oxidation was afterward tested. Optimized SnS2-Pt photoanodes provided significantly higher photocurrent densities than bare SnS2 and SnS2-based photoanodes previously reported. Mott-Schottky analysis and PEC impedance spectroscopy (PEIS) were used to analyze in more detail the effect of Pt on the PEC performance. From these analyses, we attribute the enhanced activity of the SnS2-Pt photoanodes here reported to a combination of the very thin SnS2 NPLs and the proper electronic contact between Pt nanoparticles (NPs) and SnS2.
关键词： photoanode,Tin disulfide,SnS2-Pt heterostructure,two-dimensional material,photoelectrochemical water oxidation
更新于2025-09-19 17:15:36
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Two-Dimensional Hydroxyl-Functionalized and Carbon-Deficient Scandium Carbide, ScC <sub/><i>x</i> </sub> OH, a Direct Bandgap Semiconductor
摘要： Two-dimensional (2D) materials have attracted intensive attention in nanoscience and nanotechnology due to their outstanding properties. Among these materials, the emerging family of 2D transition metal carbides, carbonitrides, and nitrides (referred to as MXenes) stands out because of the vast available chemical space for tuning materials chemistry and surface termination, offering opportunities for property tailoring. Specifically, semiconducting properties are needed to enable utilization in optoelectronics, but direct bandgaps are experimentally challenging to achieve in these 2D carbides. Here, we demonstrate the fabrication of 2D hydroxyl-functionalized and carbon-deficient scandium carbide, namely ScCxOH, by selective etching of a layered parent ScAl3C3 compound. The 2D configuration is determined as a direct bandgap semiconductor, with an experimentally measured bandgap approximated to 2.5 eV. Furthermore, this ScCxOH based device exhibits excellent photoresponse in the ultraviolet-visible light region (responsivity of 0.125 A/W@360 nm/10 V, and quantum efficiency of 43%). Thus, this 2D ScCxOH direct-bandgap semiconductor may find applications in visible-light detectors, photocatalytic chemistry, and optoelectronic devices.
关键词： DFT calculation,photodetector,electronic properties,two-dimensional material,selective etching,MXene
更新于2025-09-19 17:15:36
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Remote Phonon Scattering in Two-Dimensional InSe FETs with High-κ Gate Stack
摘要： This work focuses on the effect of remote phonon arising from the substrate and high-κ gate dielectric on electron mobility in two-dimensional (2D) InSe field-effect transistors (FETs). The electrostatic characteristic under quantum confinement is derived by self-consistently solving the Poisson and Schr?dinger equations using the effective mass approximation. Then mobility is calculated by the Kubo–Greenwood formula accounting for the remote phonon scattering (RPS) as well as the intrinsic phonon scatterings, including the acoustic phonon, homopolar phonon, optical phonon scatterings, and Fr?hlich interaction. Using the above method, the mobility degradation due to remote phonon is comprehensively explored in single- and dual-gate InSe FETs utilizing SiO2, Al2O3, and HfO2 as gate dielectric respectively. We unveil the origin of temperature, inversion density, and thickness dependence of carrier mobility. Simulations indicate that remote phonon and Fr?hlich interaction plays a comparatively major role in determining the electron transport in InSe. Mobility is more severely degraded by remote phonon of HfO2 dielectric than Al2O3 and SiO2 dielectric, which can be effectively insulated by introducing a SiO2 interfacial layer between the high-κ dielectric and InSe. Due to its smaller in-plane and quantization effective masses, mobility begins to increase at higher density as carriers become degenerate, and mobility degradation with a reduced layer number is much stronger in InSe compared with MoS2.
关键词： two-dimensional material,indium selenide,mobility,phonon scattering,high-κ dielectric,field effect transistor
更新于2025-09-19 17:15:36