Electronic and Optical Properties of Cubic Perovskites CsPbCl3−yIy (y = 0, 1, 2, 3)

2019 ◽  
Vol 74 (10) ◽  
pp. 905-913 ◽  
Author(s):  
R. Padmavathy ◽  
A. Amudhavalli ◽  
R. Rajeswarapalanichamy ◽  
K. Iyakutti
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Density Functional ◽  
Energy Gap ◽  
Phonon Dispersion ◽  
Low Cost ◽  
Normal Pressure ◽  
Metallic Phase ◽  
Halide Perovskites ◽  
Gap Values

AbstractLead-based halide perovskites are attractive substrates for solar cells because of their excellent power conversion efficiency and low cost. The ground-state properties, electronic structure, as well as optical and phonon properties of lead-based halide perovskites (CsPbCl3−yIy (y = 0, 1, 2, 3) are investigated by first-principles calculations based on density functional theory. Their electronic structure indicates that CsPbCl3−y Iy (y = 0, 1, 2, 3) compounds exhibit semiconducting behaviour at normal pressure. The energy gap of CsPbCl3 can be tuned by substituting iodine atoms for chlorine atoms. The energy gap values are found to be 3.06, 2.681, 2.330, and 2.030 eV using HSE06 calculations for CsPbCl3, CsPbCl2I, CsPbClI2, and CsPbI3, respectively. Also, it is found that the energy gap values of these materials decrease with increase in pressure and that a semiconductor-to-metallic phase transition is observed at high pressure. The optical properties of these Pb-based compounds are analysed. The dynamical stability of these perovskites is analysed by their phonon dispersion curves.

Electronic structure and optical properties of CsSnI3−yBry (y = 0, 1, 2, 3) perovskites

2019 ◽  
Vol 33 (04) ◽  
pp. 1950003 ◽  
Author(s):  
R. Padmavathy ◽  
A. Amudhavalli ◽  
R. Rajeswarapalanichamy ◽  
K. Iyakutti
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Density Functional ◽  
Energy Gap ◽  
Phonon Dispersion ◽  
Bromine Atom ◽  
Low Cost ◽  
Normal Pressure ◽  
Metallic Phase ◽  
Halide Perovskites

The halide perovskites-based solar cells have been attractive due to their excellent power conversion efficiency and low cost. The structural, electronic and optical properties of Sn-based cesium halide perovskites CsSnI[Formula: see text]Br[Formula: see text] (y = 0, 1, 2, 3) are investigated based on density functional theory. The computed electronic structure profile of CsSnI[Formula: see text]Br[Formula: see text] (y = 0, 1, 2, 3) reveals that these materials exhibit semiconducting behavior at normal pressure. The energy gap of CsSnI3 is tuned by the substitution of bromine atom for iodine atom. Also, it is found that the energy gap values of these materials decrease with increase in pressure and a semiconductor to metallic phase transition is observed at high pressure. The optical properties of these Sn-based halide perovskite compounds against the incident photon energy radiation indicate that these materials can be effective candidates for solar cell applications. The dynamical stability of these perovskites is analyzed by phonon dispersion curve.

Effects of N Concentration on Electronic Structure and Optical Absorption Properties of N-Doped SrTiO3 from First Principles

2013 ◽  
Vol 749 ◽  
pp. 561-568 ◽  
Author(s):  
Chao Zhang ◽  
Yong Zhong Jia ◽  
Yan Jing ◽  
Ying Yao ◽  
Jun Ma ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Band Gap ◽  
Doping Level ◽  
Density Functional ◽  
Energy Gap ◽  
Nitrogen Concentration ◽  
Band Structure Calculation ◽  
Concentration Effects ◽  
N Doping

The nitrogen concentration effects on electronic structures and optical properties of N-doped SrTiO3 have been investigated on the basis of density functional theory (DFT) calculations. Through band structure calculation, a direct band gap is predicted in SrTiO3-xNx. Electronic structure analysis shows that the doping N could substantially lower the band gap of SrTiO3 by the presence of an impurity state of N 2p on the upper edge of the valence band. When the doping level rises, the energy gap has little further narrowing compared with that at lower doping levels. The calculations of optical properties indicate a possible optimum N-doping level in SrTiO3 with a high photo response for visible light. These conclusions are in agreement with the recent experimental results.

Electronic Structure and Optical Properties of Non-Metals (N, F, P, Cl, S)-Doped Cubic NaTaO3 by Density Functional Theory

2009 ◽  
Vol 79-82 ◽  
pp. 1245-1248 ◽  
Author(s):  
Pei Lin Han ◽  
Xiao Jing Wang ◽  
Yan Hong Zhao ◽  
Chang He Tang
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Electronic Structure ◽  
Visible Light ◽  
Absorption Edge ◽  
Density Functional ◽  
Red Shift ◽  
Functional Theory ◽  
Photoactive Materials ◽  
Metal Doped

Electronic structure and optical properties of non-metals (N, S, F, P, Cl) -doped cubic NaTaO3 were investigated systematically by density functional theory (DFT). The results showed that the substitution of (N, S, P, Cl) for O in NaTaO3 was effective in narrowing the band-gap relative to the F-doped NaTaO3. The larger red shift of the absorption edge and the higher visible light absorption at about 520 nm were found for the (N and P)-doped NaTaO3. The excitation from the impurity states to the conduction band may account for the red shift of the absorption edge in an electron-deficiency non-metal doped NaTaO3. The obvious absorption in the visible light region for (N and P)-doped NaTaO3 provides an important guidance for the design and preparation of the visible light photoactive materials.

Theoretical investigation on tautomerism and NLO properties of Salicylideneaniline derivatives

2021 ◽  
Author(s):  
N. Daho ◽  
N. Benhalima ◽  
F. KHELFAOUI ◽  
O. SADOUKI ◽  
M. Elkeurti ◽  
...  
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Energy Gap ◽  
Intramolecular Proton Transfer ◽  
Basis Set ◽  
Frontier Molecular Orbital ◽  
Molecular Orbital Calculations ◽  
Visible Absorption ◽  
Charge Delocalization ◽  
Intramolecular Hydrogen

In this work, a comprehensive investigation of the salicylideneaniline derivatives is carried out using density functional theory to determine their linear and non-linear optical properties. Geometry optimizations, for gas and solvent phases, of the tautomers (enol and keto forms) are calculated using B3LYP levels with 6–31G (d,p) basis set . An intramolecular proton transfer, for 1SA-E and 2SA-E, is performed by a PES scan process at the B3LYP/6-31G (d,p) level. The optical properties are determined and show that they have extremely high nonlinear optical properties. In addition, the RDG analysis, MEP, and gap energy are calculated. The low energy gap value indicates the possibility of intramolecular charge transfer. The frontier molecular orbital calculations clearly show the inverse relationship of HOMO–LUMO gap with the first-order hyperpolarizability (β = 59.6471 × 10-30 esu), confirming that the salicylideneaniline derivatives can be used as attractive future NLO materials. Therefore, the reactive sites are predicted using MEP and the visible absorption maxima are analyzed using a theoretical UV–Vis spectrum. Natural bond orbitals are used to investigate the stability, charge delocalization, and intramolecular hydrogen bond.

scholarly journals Oxygen vacancy and doping atom effect on electronic structure and optical properties of Cd2SnO4

RSC Advances ◽  
2018 ◽  
Vol 8 (2) ◽  
pp. 640-646 ◽  
Author(s):  
Mei Tang ◽  
JiaXiang Shang ◽  
Yue Zhang
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Oxygen Vacancy ◽  
Density Functional ◽  
Generalized Gradient ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
La Doped ◽  
Doping Atom ◽  
Atom Effect

The electronic structure and optical properties of oxygen vacancy and La-doped Cd2SnO4 were calculated using the plane-wave-based pseudopotential method based on the density functional theory (DFT) within the generalized gradient approximation (GGA).

scholarly journals The Effect of Carbon Defects in the Coal–Pyrite Vacancy on the Electronic Structure and Optical Properties: A DFT + U Study

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 815
Author(s):  
Wei Cheng ◽  
Chen Cheng ◽  
Baolin Ke
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Absorption Coefficient ◽  
Light Absorption ◽  
Density Functional ◽  
Doping Concentration ◽  
Carbon Doping ◽  
Photovoltaic Materials ◽  
Light Absorption Coefficient ◽  
Carbon Impurities

Pyrite is a mineral often associated with coal in coal seams and is a major source of sulfur in coal. Coal–pyrite is widely distributed, easily available, low-cost, and non-toxic, and has high light absorption coefficient. So, it shows potential for various applications. In this paper, the density-functional theory (DFT + U) is used to construct coal–pyrite with carbon doped in the sulfur and iron vacancies of pyrite. The effects of different carbon defects, different carbon doping concentrations, and different doping distributions in the same concentration on the electronic structure and optical properties of coal–pyrite were studied. The results show that the absorption coefficient and reflectivity of coal–pyrite, when its carbon atom substitutes the iron and sulfur atoms in the sulfur and iron vacancies, are significantly higher than those of the perfect pyrite, indicating that coal–pyrite has potential for application in the field of photovoltaic materials. When carbon is doped in the sulfur vacancy, this impurity state reduces the width of the forbidden band; with the increase in the doping concentration, the width of the forbidden band decreases and the visible-light absorption coefficient increases. The distribution of carbon impurities impacts the band gap but has almost no effect on the light absorption coefficient, complex dielectric function, and reflectivity, indicating that the application of coal–pyrite to photovoltaic materials should mainly consider the carbon doping concentration instead of the distribution of carbon impurities. The research results provide a theoretical reference for the application of coal–pyrite in the field of photoelectric materials.

scholarly journals Effect of Vacancy Defects on the Electronic Structure and Optical Properties of GaN

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Lili Cai ◽  
Cuiju Feng
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Lower Energy ◽  
Density Functional ◽  
Nitrogen Vacancy ◽  
Main Peak ◽  
Generalized Gradient ◽  
Vacancy Defects ◽  
Gallium Vacancy ◽  
Defect Levels

The effect of gallium vacancy (VGa) and nitrogen vacancy (VN) defects on the electronic structure and optical properties of GaN using the generalized gradient approximation method within the density functional theory were investigated. The results show that the band gap increases in GaN with vacancy defects. Crystal parameters decrease in GaN with nitrogen vacancy (GaN:VN) and increase in GaN with gallium vacancy (GaN:VGa). The Ga vacancy introduces defect levels at the top of the valence band, and the defect levels are contributed by N2p electron states. In addition, the energy band shifts to lower energy in GaN:VNand moves to higher energy in GaN:VGa. The level splitting is observed in the N2p states of GaN:VNand Ga3d states of GaN:VGa. New peaks appear in lower energy region of imaginary dielectric function in GaN:VNand GaN:VGa. The main peak moves to higher energy slightly and the intensity decreases.

First Principles Calculations of Electronic Structure and Optical Properties of Cu-Doped SnS2

2013 ◽  
Vol 373-375 ◽  
pp. 1965-1969
Author(s):  
Kun Nan Qin ◽  
Ling Zhi Zhao ◽  
Yong Mei Liu ◽  
Fang Fang Li ◽  
Chao Yang Cui
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Optical Absorption Coefficient ◽  
Impurity Level ◽  
First Principles Calculations ◽  
Absorption Region ◽  
Functional Theory ◽  
The Density Functional Theory

The electronic structure and optical properties of Cu-doped SnS2with Sn-substituted content of 0, 12.5 and 37.5 at.% were successfully calculated by the first principles plane-wave pseudopotentials based on the density functional theory. It is found that the intermediate belts appear near the Fermi level and the energy band gap becomes narrower after the doping of the Cu atoms. The absorption peaks show a remarkable redshift and the absorption region broadens relatively after introducing acceptor impurity level. When Sn atoms of 37.5 at% were substituted by Cu, the optical absorption coefficient is significantly improved in the frequency range below 5.58 eV and over 8.13 eV.

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