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Surface rumpling of cubic CaTiO3 from density functional theory
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作者 杨鲲 王春雷 +5 位作者 李吉超 张超 吴清早 张艳飞 尹娜 刘雪燕 《Chinese Physics B》 SCIE EI CAS CSCD 2006年第7期1580-1584,共5页
In this paper, the structure of cubic CaTiO3 (001) surfaces with CaO and TiO2 terminations has been studied from density functional calculations. It has been found that the Ca atom has the largest relaxation for bot... In this paper, the structure of cubic CaTiO3 (001) surfaces with CaO and TiO2 terminations has been studied from density functional calculations. It has been found that the Ca atom has the largest relaxation for both kinds of terminations, and the rumpling of the CaO-terminated surface is much larger than that of TiO2-terminated surface. Also we have found that the metal atom relaxes much more prominently than the O atom does in each layer. The CaO-terminated surface is slightly more energetically favourahle than the TiO2-terminated surface from the analysis of the calculated surface energy. 展开更多
关键词 surface rumpling perovskite density functional theory
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Sensitivity impacts owing to the variations in the type of zero-range pairing forces on the fission properties using the density functional theory
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作者 Yang Su Ze-Yu Li +3 位作者 Li-Le Liu Guo-Xiang Dong Xiao-Bao Wang Yong-Jing Chen 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第3期198-207,共10页
Using the Skyrme density functional theory,potential energy surfaces of^(240)Pu with constraints on the axial quadrupole and octupole deformations(q_(20)and q_(30))were calculated.The volume-like and surface-like pair... Using the Skyrme density functional theory,potential energy surfaces of^(240)Pu with constraints on the axial quadrupole and octupole deformations(q_(20)and q_(30))were calculated.The volume-like and surface-like pairing forces,as well as a combination of these two forces,were used for the Hartree–Fock–Bogoliubov approximation.Variations in the least-energy fission path,fission barrier,pairing energy,total kinetic energy,scission line,and mass distribution of the fission fragments based on the different forms of the pairing forces were analyzed and discussed.The fission dynamics were studied based on the timedependent generator coordinate method plus the Gaussian overlap approximation.The results demonstrated a sensitivity of the mass and charge distributions of the fission fragments on the form of the pairing force.Based on the investigation of the neutron-induced fission of^(239)Pu,among the volume,mixed,and surface pairing forces,the mixed pairing force presented a good reproduction of the experimental data. 展开更多
关键词 Nuclear fission density functional theory Pairing force Potential energy surfaces Fission fragment distribution
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Adsorption of HCN on Ni/Pt(111)Bimetallic Surfaces Investigated with Density Functional Theory Method
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作者 黄攀 史晓琪 +3 位作者 冯晓宁 刘建治 李奕 章永凡 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2016年第10期1491-1500,共10页
We applied periodic density-functional theory to investigate the adsorption of HCN on x Ni@Pt(111) bimetallic surfaces(x = 1~4). The results have been compared with those obtained on pure Ni(111) and Pt(111) s... We applied periodic density-functional theory to investigate the adsorption of HCN on x Ni@Pt(111) bimetallic surfaces(x = 1~4). The results have been compared with those obtained on pure Ni(111) and Pt(111) surfaces. For all bimetallic surfaces,HCN is preferentially tilted with the CN bond parallel to the surface,and adsorption energies increase with an increasing number of layer Ni atoms on the surface. The adsorption energies of HCN on all bimetallic surfaces are larger than that on the Pt(111) surface,whereas the adsorption energies of HCN on 3Ni@Pt(111) and 4Ni@Pt(111) are larger than that on the Ni(111) surface,indicating that the introduction of Ni to the Pt catalyst could increase the activity of bimetallic catalyst in the hydrogenation reaction for nitriles. Larger adsorption energy of HCN leads to a longer C–N bond length and a smaller CN vibrational frequency. The analysis of Bader charge and vibrational frequencies showed obvious weakening of the adsorbed C–N bond and an indication of sp2 hybridization of both carbon and nitrogen atoms. 展开更多
关键词 hydrogen cyanide Ni/Pt(111) bimetallic surfaces density functional theory
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Oxygen adsorption on pyrite (100) surface by density functional theory 被引量:6
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作者 孙伟 胡岳华 +1 位作者 邱冠周 覃文庆 《Journal of Central South University of Technology》 2004年第4期385-390,共6页
Pyrite (FeS2) bulk and (100) surface properties and the oxygen adsorption on the surface were studied by using density functional theory methods. The results show that in the formation of FeS2 (100) surface, the... Pyrite (FeS2) bulk and (100) surface properties and the oxygen adsorption on the surface were studied by using density functional theory methods. The results show that in the formation of FeS2 (100) surface, there exists a process of electron transfer from Fe dangling bond to S dangling bond. In this situation, surface Fe and S atoms have more ionic properties. Both Fe2+ and S2- have high electrochemistry reduction activity, which is the base for oxygen adsorption. From the viewpoint of adsorption energy, the parallel form oxygen adsorption is in preference. The result also shows that the state of oxygen absorbed on FeS2 surface acts as peroxides rather than O2. 展开更多
关键词 density functional theory FeS_2 (100) surface surface relaxation oxygen adsorption sulfide flotation
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Interaction of Photoactive[Fe(CN)_6]^(4-) with TiO_2 Anatase(101) Surface:A Periodic Density Functional Theory Study 被引量:2
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作者 XU Ying CHEN Wen-Kai CAO Mei-Juan LIU Shu-Hong LI Jun-Qian 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2007年第3期361-366,共6页
The plane-wave pseudopotential function method, based on density-functional theory, has been used to calculate the adsorption, electronic band structures, orbitals and optical absorption spectrum of [Fe(CN)6]^4- on ... The plane-wave pseudopotential function method, based on density-functional theory, has been used to calculate the adsorption, electronic band structures, orbitals and optical absorption spectrum of [Fe(CN)6]^4- on TiOz anatase(101) surface. Our calculations reveal that the surface-modified anatase system has large adsorption energy and a much narrower band gap. [Fe(CN)6]^4- adsorption on the (101) surface could lead to a large red shift of the anatase optical absorption threshold, which extends into a visible region significantly. The calculated results are in agreement with the experiment and other theoretical studies reasonably. It is very important for the understanding and further development ofphotovoltaic materials that are active under visible light. 展开更多
关键词 density functional theory (DFT) [Fe(CN)6]^4- anatase(101) surface adsorption absorption
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Band-gap engineering of La1-xNdxAlO3(x = 0,0.25,0.50,0.75,1)perovskite using density functional theory:A modified Becke Johnson potential study
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作者 Sandeep D P Rai +6 位作者 A Shankar M P Ghimire Anup Pradhan Sakhya T P Sinha R Khenata S Bin Omran R K Thapa 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第6期376-382,共7页
The structural,electronic,and magnetic properties of the Nd-doped Rare earth aluminate,La1-xNdxAlO3(x = 0%to 100%) alloys are studied using the full potential linearized augmented plane wave(FP-LAPW) method within... The structural,electronic,and magnetic properties of the Nd-doped Rare earth aluminate,La1-xNdxAlO3(x = 0%to 100%) alloys are studied using the full potential linearized augmented plane wave(FP-LAPW) method within the density functional theory.The effects of the Nd substitution in La AlO3 are studied using the supercell calculations.The computed electronic structure with the modified Becke–Johnson(m BJ) potential based approximation indicates that the La1-xNdxAlO3 alloys may possess half-metallic(HM) behaviors when doped with Nd of a finite density of states at the Fermi level(EF).The direct and indirect band gaps are studied each as a function of x which is the concentration of Nddoped La AlO3.The calculated magnetic moments in the La1-xNdxAlO3 alloys are found to arise mainly from the Nd-4f state.A probable half-metallic nature is suggested for each of these systems with supportive integral magnetic moments and highly spin-polarized electronic structures in these doped systems at EF.The observed decrease of the band gap with the increase in the concentration of Nd doping in La AlO3 is a suitable technique for harnessing useful spintronic and magnetic devices. 展开更多
关键词 density functional theory rare earth aluminates perovskites electronic structures
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A Density Functional Theory Study on the Adsorption of CN on Ni(111) Surface
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作者 LIYi HUJian-Ming LIJun-Qian 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2005年第4期387-394,共8页
The interaction of cyanide (CN) with different sites on Ni(111) surface is studied by using density functional theory (DFT). Ni19 cluster is used to simulate the surface. The present calculations show that the end-o... The interaction of cyanide (CN) with different sites on Ni(111) surface is studied by using density functional theory (DFT). Ni19 cluster is used to simulate the surface. The present calculations show that the end-on bonded (through C atom) configuration is much more preferable than the side-on bonded CN or other configurations on the same adsorption site. For all adsorption modes, adsorption energies at the top, bridge, and three-fold sites on Ni(111) are comparable, with the bridge site of the end-on bonded CN (through C atom) more favorable than other adsorption sites. CN vibrational frequencies are red-shifted at all cases, except that the end-on CN bonded (through C atom) on the top site is blue-shifted. The bonding of CN on the Ni(111) surface is large- ly ionic. 展开更多
关键词 density functional theory ADSORPTION CYANIDE Ni(111) surface
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Study of H_2O and HOCH_2CH_2OH Adsorption on the Relaxation Surface of β-Si_3N_4(0001) by Density Functional Theory
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作者 彭新宇 王学业 +1 位作者 王玲 谭援强 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2008年第12期1439-1444,共6页
Density functional theory (DFT) B3LYP method is used to theoretically investigate the adsorption conformations of H2O and glycol on the relaxation surface of β-Si3N4(0001) with cluster models. For H2O, the most s... Density functional theory (DFT) B3LYP method is used to theoretically investigate the adsorption conformations of H2O and glycol on the relaxation surface of β-Si3N4(0001) with cluster models. For H2O, the most stable structure is that adsorbed through the H atom lying above a N(3) site of the relaxation surface of β-Si3N4(0001); while for glycol, it is the one adsorbed via the H atom lying above the center of Si(2) and N(3) of the same relaxation surface. The adsorption energy, adsorption bond and transfer electrons of the two adsorbed substances prove that glycol is easy to be adsorbed on the relaxation surface of β-Si3N4(0001). 展开更多
关键词 ADSORPTION density functional theory β-silicon nitride surface
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Study on Surface Properties for Non-polar Fluids with Density Functional Theory
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作者 吴畏 陆九芳 +2 位作者 付东 刘金晨 李以圭 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2004年第2期256-262,共7页
The density functional theory, simplified by the local density approximation and mean-field approxi-mation, is applied to study the surface properties of pure non-polar fluids. A reasonable long rang correction is ado... The density functional theory, simplified by the local density approximation and mean-field approxi-mation, is applied to study the surface properties of pure non-polar fluids. A reasonable long rang correction is adopted to avoid the truncation of the potential. The perturbation theory is applied to establish the equation for the phase equilibrium, in which the hard-core chain fluid is as the reference fluid and the Yukawa potential is used as the perturbation term. Three parameters, ε/κ, d and ms, are regressed frorn the vapor-liquid equilibria, and the surface properties, including density profile, surface tension and local surface tension profile are predicted with these parameters. 展开更多
关键词 density functional theory surface tension density profile pure non-polar fluids
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Adsorption and Reaction of CN +O→OCN on Cu(100) Surface: A Density Functional Theory Study
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作者 LI Yi HU Jian-Ming +1 位作者 ZHANG Yong-Fan LI Jun-Qiana 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2005年第8期865-874,共10页
The adsorption and reaction of O + CN → OCN on Cu(100) are studied by using density functional theory and cluster model. Cu14 cluster model is used to simulate the surface. The calculated results show that the OCN... The adsorption and reaction of O + CN → OCN on Cu(100) are studied by using density functional theory and cluster model. Cu14 cluster model is used to simulate the surface. The calculated results show that the OCN species with the molecule perpendicular to the surface via N atom (N-down) is more favorable than other adsorption models, and the N-down at the bridge site is the most favorable. For N-down, calculated OCN symmetric and asymmetric stretching frequencies are all blue-shifted compared with the calculated values of free and in good agreement with the experiments. The charge transfer from the surface to the OCN species leads to that the bonding of OCN to the metal surface is largely ionic. The present studies also show that CN with the molecule perpendicular to the surface via C atom (NC-down) at the top site is the most stable. Except NC-down at the top site, the calculated CN stretching frequencies are all red-shifted. With O coadsorbed at the hollow site, the adsorption of NC-down at the next nearest bridge or top site is energetically more favorable than that at the adjacent hollow site. The reaction of O + CN → OCN on Cu(100) has no energy barrier via both Eley-Rideal and Langmuir-Hinshelwood processes. 展开更多
关键词 density functional theory adsorption and reaction cyanate cyanide Cu(100) surface
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First-Principles Calculations on Novel Rb-Based Halide Double Perovskites Alloys for Spintronics and Optoelectronic Applications
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作者 Saadi Berri Nadir Bouarissa 《Optics and Photonics Journal》 2024年第1期1-22,共22页
The outcomes of computational study of electronic, magnetic and optical spectra for A2BX6 (A = Rb;B = Tc, Pb, Pt, Sn, W, Ir, Ta, Sb, Te, Se, Mo, Mn, Ti, Zr and X = Cl, Br) materials have been proceeded utilizing Vande... The outcomes of computational study of electronic, magnetic and optical spectra for A2BX6 (A = Rb;B = Tc, Pb, Pt, Sn, W, Ir, Ta, Sb, Te, Se, Mo, Mn, Ti, Zr and X = Cl, Br) materials have been proceeded utilizing Vanderbilt Ultra Soft Pseudo Potential (US-PP) process. The Rb2PbBr6 and Rb2PbCl6 are found to be a (Г-Г) semiconductors with energy gaps of 0.275 and 1.142 eV, respectively making them promising photovoltaic materials. The metallic behavior of the materials for Rb2BX6 (B = Tc, W, Ir, Ta, Mn, Sb, Mo) has been confirmed showing the attendance of conducting lineaments. The dielectric function is found to be large close to the ultraviolet districts (3.10 - 4.13 eV). The extinction coefficient of the Rb2BX6 has the ability to be used for implements. The band structures and density of states ensure the magnetic semiconductors’ nature of the Rb2Mn (Cl, Br)6 perovskites. The total calculated magnetic moment of Rb2MnCl6 and Rb2MnB6 is 3.00μβ. Advanced spintronic technology requires room-temperature ferromagnetism. The present work confirms that, bromine and chlorine-founded double perovskites are extremely attractive for photovoltaic and optoelectronic devices. 展开更多
关键词 Halide Double perovskites density functional theory SPINTRONIC Photovoltaic Solar Cells
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Electronic Structure and Stability of Lead-free Hybrid Halide Perovskites:A Density Functional Theory Study
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作者 邬嘉义 戚文 +2 位作者 罗哲 刘科 朱虹 《Journal of Shanghai Jiaotong university(Science)》 EI 2018年第1期202-208,共7页
The most commonly used and studied hybrid halide perovskite is ABX_3, where A usually stands for CH_3NH_3, B for Pb, and X for I. A lead-free perovskite with high stability and ideal electronic band structure would be... The most commonly used and studied hybrid halide perovskite is ABX_3, where A usually stands for CH_3NH_3, B for Pb, and X for I. A lead-free perovskite with high stability and ideal electronic band structure would be of essence, especially considering the toxicity of lead. In this work, we have considered 11 metal elements for the B site and three halide elements(Cl, Br, and I) including various combinations among the three halides for the X site. A total number of 99 hybrid perovskites are studied to understand how the crystal structure, band gap and stability can be tuned by the chemistry modification, i.e., the replacement of toxic element, Pb in the original MAPbX_3, with non-toxic metal elements. We find that the favorable substitutes for Pb in MAPbI_3 are Ge and Sn. 展开更多
关键词 hybrid halide perovskites band gap phase stability density functional theory(DFT)
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Three-dimensional potential energy surface for fission of^(236)U within covariant density functional theory 被引量:1
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作者 周明晖 李泽宇 +2 位作者 陈盛远 陈永静 李志攀 《Chinese Physics C》 SCIE CAS CSCD 2023年第6期143-149,共7页
We calculate the three-dimensional potential energy surface(PES)for the fission of the compound nucleus^(236)U using covariant density functional theory with constraints on the axial quadrupole and octupole deformatio... We calculate the three-dimensional potential energy surface(PES)for the fission of the compound nucleus^(236)U using covariant density functional theory with constraints on the axial quadrupole and octupole deformations(β_(2),β_(3))coexistence of the elongated and compact fission modes is predicted for comes shallow across a large range of quadrupole and octupole deformations for small scission line in the(β_(2),β_(3))plane extends to a shallow band,leading to fluctuations of several to ten MeV in the estimated total kinetic energies and of several to approximately ten nucleons in the fragment masses. 展开更多
关键词 multi-dimensional potential energy surface covariant density functional theory SCISSION total kinetic energy
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Influence of Organic Cations on the Crystal and Electronic Structures of Two-dimensional Lead Iodide Perovskites
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作者 杜定谨 甘小燕 +3 位作者 LU Shun ZHENG Wei GUO Liling LIU Hanxing 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第3期496-504,共9页
The crystal structures and electronic structures(including band gap,project density of states,partial charge density,effective mass and electron localization function)of the 2D lead iodide perovskites hybrids with dif... The crystal structures and electronic structures(including band gap,project density of states,partial charge density,effective mass and electron localization function)of the 2D lead iodide perovskites hybrids with different organic spacer cations of 4-fluorophenylethanaminium(4F-PEA^(+)),ethanolamine(EA^(+)),thienylethylamine(TEA^(+))were investigated using first-principles calculations.It was found the higher dipole moment,the stronger the hydrogen bonding between the organic amino and iodide in the inorganic layer,and the larger the[PbI_(6)]^(4-)octahedral distortions in these crystal structure.Further quantifying the degree of the distortions using OctaDist software showed that the distortion of adjacent[PbI_(6)]^(4-)octahedra had a decisive effect on the band gap.Specifically,the greater deviation of Pb-I-Pb bond angles from 180°,together with the larger distortion of multiple[PbI_(6)]^(4-)octahedron resulted in a wider band gap,which was verified by calculated band gap using different DFT methods.The results outlined the relationships of hydrogen bonding,ocathedra distortion and band structure in 2D perovskites,highlighting the importance of the cations on the structural tuning and optoelectronic properties. 展开更多
关键词 2D perovskites density functional theory(DFT) octahedral distortion 4F-PEA EA TEA
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First Principle Study of Cesium-based Lead-free Halide Double Perovskites
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作者 郑伟 甘小燕 +4 位作者 DU Dingjin WANG Yajie DAI Siqi GUO Liling LIU Hanxing 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第3期520-529,共10页
Inorganic halide double perovskites A_(2)B'B"X_(6) have gained significant interests for their diverse composition,stable physicochemical properties,and potential for photoelectric applications.The influences... Inorganic halide double perovskites A_(2)B'B"X_(6) have gained significant interests for their diverse composition,stable physicochemical properties,and potential for photoelectric applications.The influences of trivalent and monovalent cations on the formation energy,decomposition energy,electronic structure and optical properties of cesium-based lead-free Cs^(+)_(2)B'B"Br_(6) (B'=Na^(+),In^(+)Cu^(+),or Ag^(+);B"=Bi^(3),Sb^(3+),In^(3+)) are systematically studied.In view of the analysis and results of the selected double perovskites,for the double perovskites with different B-site trivalent cation,the band gap increases in the order of Cs_(2)AgInBr_(6),Cs_(2)AgSbBr_(6) and Cs_(2)AgBiBr_(6),with Cs_(2)AgBiBr_(6) possessing the highest thermodynamic stability.Therefore,the Bi-based perovskites are further studied to elucidate the effect of monovalent cation on their stability and electronics.Results show that the thermodynamic stability rises in the sequence of Cs_(2)NaBiBr_(6),Cs_(2)InBiBr_(6),Cs_(2)AgBiBr_(6) and Cs_(2)CuBiBr_(6).Notably,Cs_(2)CuBiBr_(6) exhibits a relatively narrow and appropriate band gap of 1.4634 eV,together with the highest absorption coefficient than other compounds,suggesting that Cs_(2)CuBiBr_(6) is a promising light absorbing material that can be further explored experimentally and be applied to optoelectronic devices.Our research offers theoretical backing for the potential optoelectronic application of cesium-based lead-free halide double perovskites in solar energy conversion. 展开更多
关键词 lead-free double perovskites density functional theory Cs_(2)B'B"Br_(6) STABILITY electronic properties optical property STABILITY
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Recent theoretical progress in the development of perovskite photovoltaic materials 被引量:1
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作者 Xin Zhou Joanna Jankowska +1 位作者 Hao Dong Oleg V.Prezhdo 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2018年第3期637-649,共13页
Since the seminal work by Kojima et al. in 2009, solar cells based on hybrid organic-inorganic perovskites have attracted considerable attention and experienced an exponential growth, with photovoltaic efficiencies as... Since the seminal work by Kojima et al. in 2009, solar cells based on hybrid organic-inorganic perovskites have attracted considerable attention and experienced an exponential growth, with photovoltaic efficiencies as of today reaching above 22%. Despite such an impressive development, some key scientific issues of these materials, including the presence of toxic lead, the poor long-term device stability under heat and humidity conditions, and the anomalous hysteresis of the current-voltage curves shown by various solar cell devices, still remain unsolved and constitute an important focus of experimental and theoretical researchers throughout the world. Density functional theory calculations have been successfully applied to exploring structural and electronic properties of semiconductors, complementing the experimental results in search and discovery of novel functional materials. In this review, we summarize the current progress in perovskite photovoltaic materials from a theoretical perspective. We discuss design of lead-free perovskite materials, humidity-induced degradation mechanisms and possible origins for the observed solar cell hysteresis, and assess future research directions for advanced perovskite solar cells based on computational materials design and theoretical understanding of intrinsic properties. 展开更多
关键词 Solar cells perovskite materials density functional theory
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Charge Localization Induced by Reorientation of FA Cations Greatly Suppresses Nonradiative Electron-Hole Recombination in FAPbI3 Perovskites:a Time-Domain Ab Initio Study
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作者 Jin-lu He Yong-hao Zhu Run Long 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2020年第5期642-648,I0079,共8页
Recent experiments report the rotation of FA(FA=HC[NH2]2+)cations significantly influence the excited-state lifetime of FAPbI3.However,the underlying mechanism remains unclear.Using ab initio nonadiabatic(NA)molecular... Recent experiments report the rotation of FA(FA=HC[NH2]2+)cations significantly influence the excited-state lifetime of FAPbI3.However,the underlying mechanism remains unclear.Using ab initio nonadiabatic(NA)molecular dynamics combined with time-domain density functional simulations,we have demonstrated that reorientation of partial FA cations significantly inhibits nonradiative electron-hole recombination with respect to the pristine FAPbI3 due to the decreased NA coupling by localizing electron and hole in different positions and the suppressed atomic motions.Slow nuclear motions simultaneously increase the decoherence time,which is overcome by the reduced NA coupling,extending electron-hole recombination time scales to several nanoseconds and being about 3.9 times longer than that in pristine FAPbI3,which occurs within sub-nanosecond and agrees with experiment.Our study established the mechanism for the experimentally reported prolonged excited-state lifetime,providing a rational strategy for design of high performance of perovskite solar cells and optoelectronic devices. 展开更多
关键词 Hybrid organic-inorganic perovskite Localized charge Non-radiative electronhole recombination Nonadiabatic molecular dynamics Time-dependent density functional theory
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First-principles study of the electronic structure and optical properties of cubic Perovskite NaMgF_3 被引量:3
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作者 李贞丽 安辛友 +4 位作者 程新路 王雪敏 张红 彭丽萍 吴卫东 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第3期469-474,共6页
The structural, electronic, and optical properties of cubic perovskite NaMgF3 are calculated by plane-wave pseudopo- tential density functional theory. The calculated lattice constant a0, bulk modulus B0, and the deri... The structural, electronic, and optical properties of cubic perovskite NaMgF3 are calculated by plane-wave pseudopo- tential density functional theory. The calculated lattice constant a0, bulk modulus B0, and the derivative of bulk modulus B~ are 3.872/~, 78.2 GPa, and 3.97, respectively. The results are in good agreement with the available experimental and theo- retical values. The electronic structure shows that cubic NaMgF3 is an indirect insulator with a wide forbidden band gap of Eg = 5.90 eV. The contribution of the different bands is analyzed by total and partial density of states curves. Population analysis of NaMgF3 indicates that there is strong ionic bonding in the MgF2 unit, and a mixture of ionic and weak covalent bonding in the NaF unit. Calculations of dielectric function, absorption coefficient, refractive index, electronic energy loss spectroscopy, optical reflectivity, and conductivity are also performed in the energy range 0 to 70 eV. 展开更多
关键词 density functional theory cubic perovskite NaMgF3 electronic properties optical properties
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Pseudohalide induced tunable electronic and excitonic properties in two-dimensional single-layer perovskite for photovoltaics and photoelectronic applications 被引量:1
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作者 Zhuo Xu Ming Chen Shengzhong(Frank)Liu 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2019年第9期106-113,共8页
Two-dimensional(2D) layered organic-inorganic hybrid perovskites have attracted much more attention for some applications than their three-dimensional(3D) perovskite counterparts due to their promising thermal and moi... Two-dimensional(2D) layered organic-inorganic hybrid perovskites have attracted much more attention for some applications than their three-dimensional(3D) perovskite counterparts due to their promising thermal and moisture stabilities.In particular, the 2D perovskite devices have shown better promise for optoelectronic applications.However, tunability of optoelectronic properties is often demanded to improve the device performance.Herein, we adopt a newly method to tune the electronic properties of 2D perovskite by introducing pseudohalide into the structure.In this work, we designed a pseudohalidesubstituted 2D perovskite by substituting the out-of-plane halide with pseudohalide and studied the electronic and excitonic properties of 2D-BA2MX4 and 2D-BA2MX2Ps2(M=Ge^(2+), Sn^(2+), and Pb^(2+);X=I;Ps=NCO, NCS, OCN, SCN, Se CN).We revealed the dependence of electronic properties including band gaps, composition of band edges, bonding characteristics, work functions, effective masses, and exciton binding energies on different pseudohalides substituted in 2D perovskite.Our results indicate that the substitution of pseudohalide in 2D perovskites is energetically favorable and can significantly affect the bonding characteristics as well as the CBM and VBM that often play major role in determining their performance in optoelectronic devices.It is expected that the pseudohalide substitution will be helpful in developing more advanced optoelectronic device based on 2D perovskite by optimizing band alignment and promoting charge extraction. 展开更多
关键词 Two-dimensional perovskites Pseudohalides density functional theory Electronic and excitonic properties
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Theoretical Study of Using Kinetics Strategy to Enhance the Stability of Tin Perovskite 被引量:1
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作者 Qi Wei Youqi Ke Zhijun Ning 《Energy & Environmental Materials》 SCIE 2020年第4期541-547,共7页
Tin perovskite solar cell received great attention in recent years owing to its optimum bandgap and heavy metal-free property.The main concern for the development of tin perovskite is the oxidation from Sn^(2+)to Sn^(... Tin perovskite solar cell received great attention in recent years owing to its optimum bandgap and heavy metal-free property.The main concern for the development of tin perovskite is the oxidation from Sn^(2+)to Sn^(4+).Herein,we report a surface hetero-protection strategy to avoid the surface reaction of tin perovskite.Three types of materials,including low-dimensional tin perovskite,alkali metal halide,and oxides of group IVA element,are exploited as protecting materials on tin perovskite surface with first-principles calculation.The lattice mismatch,oxidation resistance,and interface stability of these materials are investigated to search for ideal protecting-layer materials.After screening over 30 candidates,we finally obtain 8 suitable materials(SiO_(2),GeO_(2),KCl,Na Br,Cs F,Li F,Li I,CsSn_(2)Br_(5))for hetero-protection of tin perovskite.To further understand their application potential in a solar cell device,we then calculate the property of charge transfer between the interface of these materials and tin perovskite.Our study provides a guide for the experimental realization of efficient and stable tin perovskite solar cell. 展开更多
关键词 density functional theory interface oxidation stability tin perovskite
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