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First-principles study on photovoltaic properties of 2D Cs <sub/>2</sub> PbI <sub/>4</sub> -black phosphorus heterojunctions
摘要： Both 2D perovskite Cs2PbI4 and phosphorus are significant optoelectronic semiconductor materials, the optical-electrical characters between both contact interfaces are interesting topics. In present work, we demonstrate comparative investigation of optoelectronic properties for two kinds of electrical contact interfaces. i.e. Pb–I and Cs–I interfaces with black phosphorus contacts. The carrier transport, charge transferring and optical properties for both cases are investigated by using first principle calculation. Both contact interfaces exhibit type II band alignment with direct band gap. Charge carrier migration from Cs–I interface to black phosphorus is more strong than that of Pb–I interface by considering differential charge density and bader charge between distinct electrical contact interfaces. Besides, electron–hole effective masses of heterojunctions for both cases along different direction are investigated. Optical absorption coefficients of both cases are compared with those of free-standing Cs2PbI4 and black phosphorus in the visible spectrum. We systematically compared advantages and disadvantages of two kinds of contact interfaces for photovoltaic application, and the results reveal interfacial engineering of 2D heterojunction plays a important role in tuning optoelectronic properties.
关键词： optical property,first-principles,electronic structures,2D heterojunction,carrier effective masses,charge transfer
更新于2025-09-23 15:19:57
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Structural, electronic and optical properties of RbSnCl3: A first-principles calculation
摘要： The structural, electronic and optical properties of RbSnCl3 are investigated by the first-principles calculations. Two new phases of Cm and Imm2 are predicted and the phonon spectrum are analyzed, which shows that the two phases are all dynamically stable. The band edge positions show that the two phases conform to the criteria of photocatalysts for water splitting, and strains are added to the two phases. The results show that strains can effectively tune the bandgaps and RbSnCl3 is potential candidate for solar energy conversion and photocatalytic water splitting.
关键词： Electronic properties,RbSnCl3,Photocatalytic properties,First-principles
更新于2025-09-23 15:19:57
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Prediction of MCO [M = S, (Cl <sub/>2</sub> B) <sub/>3</sub> B] Systems with Giant Optical Birefringence and Nonlinearity in the Deep-Ultraviolet Region
摘要： Deep-ultraviolet (DUV) materials with giant optical birefringence and nonlinearity are scarce, and their discovery is very challenging. In this Communication, we predict that the MCO [M = S, (Cl2B)3B] compounds containing the polar C?O motif, which have been synthesized in the experiments, could be the ?rst material systems to achieve this rare capability. First-principles calculations demonstrate that (Cl2B)3BCO and SCO exhibit the largest second-harmonic-generation e?ect (～4.4 pm/V) and the largest birefringence (～0.6) in all known DUV nonlinear-optical (NLO) crystals. In addition, SCO might be a DUV NLO material for the practical 193.7 nm laser output. Our discovery could enrich the structural chemistry of NLO crystals and advance the development of functional DUV optical materials.
关键词： Deep-ultraviolet,nonlinearity,polar C?O motif,DUV nonlinear-optical crystals,first-principles calculations,MCO compounds,second-harmonic-generation,optical birefringence
更新于2025-09-23 15:19:57
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Two-dimensional Janus PtSSe for photocatalytic water splitting under the visible or infrared light
摘要： Recently, two-dimensional Janus materials have attracted increasing research interest due to their particular structure and great potential in electronics, optoelectronics and piezoelectronics. Here, we propose 2D Janus PtSSe with compelling photocatalytic properties which were investigated by means of first-principles calculations. 2D Janus PtSSe exhibits high thermal, dynamic and mechanical stability. Most remarkably, single-layer PtSSe exhibits an indirect band gap of 2.19 eV, high absorption coefficients in the visible light region, appropriate band edge positions and strong ability for carrier separation and transfer, thus rendering it a promising candidate for photocatalytic water splitting. Moreover, double-layer PtSSe compounds with different stacking configurations are extraordinary photocatalysts for water splitting even under infrared light, owing to their small band gaps as well as the built-in electrical field. Our results reveal 2D PtSSe with high experimental feasibility as a new platform for the overall water splitting reaction.
关键词： two-dimensional Janus materials,first-principles calculations,photocatalytic water splitting,visible light,infrared light
更新于2025-09-23 15:19:57
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Strain distribution in (InAs) ∕(InSb) multilayer: A first principles calculations
摘要： Using first principles calculations we unveil the interfacial strain relaxation in (wurtzite-InAs)n/(zinc-blend-InSb)m multilayer specimens. We have shown that the distribution of strain along the growth direction depends on the relative thickness of the segments of the multilayer. The observed result has been explained in view of the propagation of lattice deformation due to lattice mismatch between InAs and InSb. To the end we have demonstrated that the fine tuning of the strain with the thickness of layers can be exploited to vary the band gap along the length of the multilayer. The modulation of the band gap in a multilayer system finds various applications in designing optoelectronic devices.
关键词： Strain,First principles calculations,InAs/InSb,Multilayers,Density of states
更新于2025-09-19 17:15:36
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First-principles calculations on effects of Al and Ga dopants on atomic and electronic structures of amorphous Ge <sub/>2</sub> Sb <sub/>2</sub> Te <sub/>5</sub>
摘要： Effects of post-transition metal dopants M (M = Al, Zn, and Ga) on structural and electronic properties of amorphous Ge2Sb2Te5 (a-GST) are investigated through first-principles calculations based on the density functional theory. The doped a-GST is generated through the melt-quench procedure using molecular dynamics simulations. It is found that the three dopants behave similarly in a-GST, and they are mostly coordinated by Te atoms in tetrahedral geometry, which is similar to those in crystalline MxTey. This is in contrast with crystalline GST wherein the most stable position of dopant M is the octahedral vacancy site. The number of wrong bonds such as Ge–Ge, Ge–Sb, or Sb–Sb increases as dopant atoms predominantly bond with Te atoms. The number of 4-fold ring structures, especially ABAB-type, decreases significantly, explaining the enhanced thermal stability of doped a-GST in the experiment. The bandgap estimated from density of states and the optical gap obtained from Tauc plot increase upon doping, which is also in good agreement with the experiment. By successfully relating the experimental doping effects and changes in the atomic structure, we believe that the present work can serve as a key to offer better retention and lower power consumption in phase-change memory.
关键词： amorphous Ge2Sb2Te5,electronic structures,first-principles calculations,atomic structures,Al and Ga dopants
更新于2025-09-19 17:15:36
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Efficient Visible-Light-Induced Photocatalytic Activity of SrTiO <sub/>3</sub> Co-Doped With Os and N: A GGA?+? <i>U</i> Investigation
摘要： A systematic investigation based on spin-polarized DFT + U has been carried out to study the electronic structure of charge compensated (Os, 2N)-codoped SrTiO3 as compared with that of pure SrTiO3, Os-doped SrTiO3, N-doped SrTiO3, and charge non-compensated (Os, N)-codoped SrTiO3. The calculated band gap of pure SrTiO3 is improved to 3.22 eV using GGA + U method by choosing appropriate U values, which is in good agreement with the experimental value (3.25 eV). Although charge non-compensated co-doping with (Os, N) significantly reduces the photoabsorption energy by introducing localized in-gap impurity states of Os-5d, N-2p, and O-2p, unfortunately, the presence of these states may hinder charge carrier mobility. The calculated results show that the charge compensated co-doping with one Os and two N leads to the complete passivation of the mid gap Os-5d and O-2p impurity states, thus the positions of the band edges are extended to satisfy the criteria for overall water splitting under visible-light. The present predictions demonstrate that the charge compensated (Os, 2N)-codoped SrTiO3 can be a desirable effective photocatalyst for highly active visible-light-induced hydrogen production from water splitting due to the enhanced visible-light activity as well as decreased electron–hole recombination rate.
关键词： photocatalytic activity,doping,first-principles calculations,SrTiO3
更新于2025-09-19 17:15:36
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Effect of position and concentration of Li on ZnO physical properties : Density functional investigation
摘要： In this paper, we study the effect of Li position on the physical properties of Li doped ZnO with different concentrations (6.25%,12.5% and 18.75%), by using density functional theory and Boltzmann transport theory. In this work, two possible configurations of Li-doped ZnO are considered : substitution of Zn by Li atom (LiZn), and Li takes the interstitial position (Lii). It is found found that the position and the concentration of Li play an important role in determining the suitable applications for Li doped ZnO. It is also shown that the obtained results are in good agreement with experimental studies.
关键词： Li doped ZnO,Electronic Structure,First principles study,interstitial.,substitution
更新于2025-09-19 17:15:36
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Intercalated complexes of 1T′-MoS <sub/>2</sub> nanosheets with alkylated phenylenediamines as excellent catalysts for electrochemical hydrogen evolution
摘要： Two-dimensional layered MoS2 has recently been considered as an excellent catalyst for the water-splitting hydrogen evolution reaction (HER). Herein, we synthesize 1T0 phase MoS2 that was intercalated with a series of alkylated p-phenylenediamines (PDs). The substituted N atoms produced S vacancies, leading to a composition of MoS2-2xNx (x = 0.1). The more abundant methyl groups induce a larger charge transfer, resulting in excellent HER performance: for tetramethyl PD, the overpotential is 0.15 V at 10 mA cm-2 with a Tafel slope of 35 mV dec-1. The catalytic activity of the complexes depends on the concentration of the intercalated molecules, showing an optimum at a concentration of 8 mol%. First-principles calculations showed that the intercalated complexes (1T0 phase) having N atom–S vacancy (N–VS) pairs are stabilized by a large charge transfer from the PD molecules that is enhanced by the methyl groups (i.e., 0.40e–0.84e per molecule at 6.25 mol% intercalation). The charge transfer increases the density of states at and just above the Fermi level, thereby increasing the electron concentration at low cathodic bias. The active sites for the Volmer reaction are found to be N atoms in the proximal N–VS pairs. The activation barrier for the Heyrovsky reaction becomes higher at higher concentrations of the intercalants, suggesting that the experimental HER performance is also kinetically controlled.
关键词： catalysis,first-principles calculations,MoS2,hydrogen evolution reaction,intercalation
更新于2025-09-19 17:15:36
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First Principles Study on Magnetic and Optical Properties of Single Layer CrSi<sub>2</sub>
摘要： According to first-principle based on the density functional theory, the magnetic and optical properties of single layer CrSi2 are calculated and analyzed by plane wave pseudo potential method. The band structure, density of state, optical absorption spectra, reflectivity and energy loss function of single layer CrSi2 are obtained. The results show that single layer CrSi2 has the properties of metal and magnetism. The calculations of optical properties of single layer CrSi2 material deduce that it can absorb photons which belong to visible to ultraviolet region, even in far-infrared and far-ultraviolet regions. Single layer CrSi2 has a good optical permeability to photon (with energy from 13 to 40eV), which shows that single layer CrSi2 is suitable for optoelectronic devices, especially in infrared and vacuum ultraviolet detection applications.
关键词： single layer CrSi2,first-principles,electronic structure,optical properties
更新于2025-09-19 17:15:36