Electronic and Optical Properties of TiO2 Solid-Solution Nanosheets for Bandgap Engineering: A Hybrid Functional Study

2017 ◽  
Vol 121 (34) ◽  
pp. 18683-18691 ◽  
Author(s):  
Yanyu Liu ◽  
Wei Zhou ◽  
Naoto Umezawa
Keyword(s):  
Solid Solution ◽  
Optical Properties ◽  
Functional Study ◽  
Bandgap Engineering ◽  
Hybrid Functional ◽  
Electronic And Optical Properties

The effect of substitutional doping of Yb2+ on structural, electronic, and optical properties of CsCaX3 (X: Cl, Br, I) phosphors: A first-principles study

2021 ◽  
Author(s):  
Rashid Khan ◽  
Kaleem Ur Rahman ◽  
Qingmin Zhang ◽  
Altaf Ur Rahman ◽  
Sikander Azam ◽  
...  
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Dielectric Susceptibility ◽  
Hybrid Functional ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Electronic And Optical Properties ◽  
Substitutional Doping ◽  
Bandgap Semiconductors ◽  
Magnetic Insulator

Abstract Using first-principles calculations, the effects of Yb$^{2+}$ substitutional doping on structural, electronic, and optical properties of a series of perovskite compounds CsCaX$_3$ (X: Cl, Br, I), have been investigated. We employed generalized gradient approximation (GGA) and HSE hybrid functional to study the electronic and optical properties. A series of pristine CsCaX$_3$(X: Cl, Br, I) is characterized as a non-magnetic insulator with indirect bandgap perovskite materials. These phosphor materials are suitable candidates for doping with lanthanide series elements to tune their electronic bandgaps according to our requirements because of their wide bandgaps. The calculated electronic bandgaps of CsCaX$_3$ (X: Cl, Br, I) are 3.7 eV(GGA) and 4.5 eV (HSE) for CsCaI$_3$, 4.5 eV (GGA) and 5.3 eV (HSE) for CsCaBr$_3$, and 5.4 eV (GGA) and 6.4 eV (HSE) for CsCaCl$_3$. According to formation energies, the Yb$^{2+}$ doped at the Ca-site is thermodynamically more stable as compared to all possible atomic sites. The electronic band structures show that the Yb$^{2+}$ doping induces defective states within the bandgaps of pristine CsCaX$_3$. As a result, the Yb$^{2+}$ doped CsCaX$_3$ (X: Cl, Br, I) become the direct bandgap semiconductors. The defective states above the VBM are produced due to the $f$-orbital of the Yb atom. The impurity states near the CBM are induced due to the major contribution of $d$-orbital of the Yb atom and the minor contribution of $s$-orbital of the Cs atom. The real and imaginary parts of the dielectric function, optical reflectivity, electron energy loss spectrum, extinction coefficient, and refractive index of pristine and Yb$^{2+}$ doped CsCaX$_3$ were studied. The optical dispersion results of dielectric susceptibility closely match their relevant electronic structure and align with previously reported theoretical and experimental data. We conclude that the Yb$^{2+}$ doped CsCaX$_3$ (X: Cl, Br, I) are appealing candidates for optoelectronic devices.

scholarly journals Density Functional Study of Electronic and Optical Properties of Ternary Mixed Chalcogenides Topological Insulators

2016 ◽  
Vol 846 ◽  
pp. 599-606
Author(s):  
Alhassan Shuaibu ◽  
Md Mahmudur Rahman ◽  
Hishamuddin Zainuddin ◽  
Zainal Abdib Talib
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Topological Insulators ◽  
Local Density ◽  
Refraction Index ◽  
Functional Study ◽  
Electronic Band ◽  
Electronic And Optical Properties ◽  
Conductivity Function ◽  
Energy Dependent

This paper presented a theoretical study of structural, electronic, and optical properties of the ternary mixed chalcogenides Topological Insulators with a formula M2X2Y (M = Bi, X = Te and Y= Se, S) using density functional theory (DFT) within the local density approximation (LDA). From the calculation, we have evaluated the bulk modulus and its corresponding pressure derivatives of these compounds. The linear photon-energy dependent of dielectric functions, some optical properties such as reflectivity, refraction index, conductivity function, and energy-loss spectra, have also been obtained and analyzed within the electronic band structures and density of states of these compounds.

scholarly journals First Principles Study on Electronic and Optical Properties of Quinary Copper-based Sulfides and Selenides Cu2HgGe(S1-xSex)4

2021 ◽  
Vol 37 (1) ◽  
Author(s):  
Pham Dinh Khang ◽  
Vo Duy Dat ◽  
Dang Phuc Toan ◽  
Vu Van Tuan
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Density Functional ◽  
Hybrid Functional ◽  
Electron Hole ◽  
Functional Theory ◽  
Electronic And Optical Properties ◽  
Pair Separation ◽  
Electron Hole Pair ◽  
Band Transition

Electronic and optical properties of Cu2HgGe(S1-xSex)4 compounds (x = 0, 0.25, 0.5, 0.75, and 1) were revealed by density functional theory (DFT), in which the Heyd-Scuseria-Ernzerhof hybrid functional was used. Dependence of band gap on the Se constituent in Cu2HgGe(S1-xSex)4 was reported. The substitution of Se element basically cause a slightly lattice expansion and minor change of the band gap. Meanwhile, the overlap of Cu and S/Se states becomes more dense leading to better electron/hole pair separation and inter-band transition of photo-excited electrons. The Cu2HgGe(S0.75Se0.25)4 compound was predicted to be very promising absorber due to the low band gap, high absorption rate, and low reflectivity in the incoming light energy range from 0 eV to 2 eV.    

Effects of vacancies on electronic and optical properties of GaN nanosheet: A density functional study

2015 ◽  
Vol 47 ◽  
pp. 44-50 ◽  
Author(s):  
Sh. Valedbagi ◽  
S. Mohammad Elahi ◽  
M.R. Abolhassani ◽  
A. Fathalian ◽  
A. Esfandiar
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Functional Study ◽  
Density Functional Study ◽  
Electronic And Optical Properties

Bandgap engineering and manipulating electronic and optical properties of ZnO nanowires by uniaxial strain

Nanoscale ◽  
2014 ◽  
Vol 6 (9) ◽  
pp. 4936-4941 ◽  
Author(s):  
Rui-wen Shao ◽  
Kun Zheng ◽  
Bin Wei ◽  
Yue-fei Zhang ◽  
Yu-jie Li ◽  
...  
Keyword(s):  
Optical Properties ◽  
Physical Properties ◽  
Zno Nanowires ◽  
Uniaxial Strain ◽  
Bandgap Engineering ◽  
Electronic And Optical Properties

Bandgap engineering is a common practice for tuning semiconductors for desired physical properties.

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