scholarly journals OPTOELECTRONIC STUDY OF DOUBLE PEROVSKITE Rb2SnBr6: A FIRST PRINCIPLES CALCULATIONS

2020 ◽  
pp. 1-5
Author(s):  
MD. ABDUR RAZZAQ ◽  
TARIKUL ISLAM
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Density Functional ◽  
Research Work ◽  
Double Perovskite ◽  
Incident Radiation ◽  
Lattice Parameter ◽  
Dielectric Constants ◽  
Ultraviolet Region ◽  
Ambient Conditions

The aim of this research work is to investigate the structural, mechanical, electronic and optical properties of double perovskite Rb2SnBr6 by density functional theory (DFT) calculations. The calculated lattice parameter is in sensible agreement with the on the market experimental information. From Paugh’s ductility index (B/G), it shows that Rb2SnBr6 is brittle at ambient conditions. The Zener anisotropy factor confirms the anisotropic nature of this compound. The calculated energy band structures indicate that Rb2SnBr6 is a direct band gap semiconductor, with the band gap of 1.228 eV using PBE potentials. In this work, the optical properties such as dielectric constants, refractive index, conductivity, extinction coefficient, loss function, and reflectivity have been studied and reported for radiation up to 20 eV. It is found that the reflectivity is about 50% in the ultraviolet (UV) region regions up to ~11 eV of incident radiation in the ultraviolet region.

scholarly journals STRUCTURAL, MECHANICAL AND OPTOELECTRONIC STUDY OF DOUBLE PEROVSKITE Cs2SnBr6 USING FIRST PRINCIPLES CALCULATION

2020 ◽  
pp. 6-9
Author(s):  
MD. ABDUR RAZZAQ ◽  
TARIKUL ISLAM
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Perovskite Solar Cells ◽  
Double Perovskite ◽  
Lattice Parameter ◽  
Dielectric Constants ◽  
First Principles Calculation ◽  
Functional Theory ◽  
Direct Band ◽  
Ductile Behavior

The structural, mechanical, electronic and optical properties of double perovskite Cs2SnBr6 have been measured by density functional theory (DFT) calculations. The calculated value of lattice parameter is perfectly tailored with the experimental data. The material shows ductile behavior by Paugh’s ductility index (B/G) at ambient condition. The anisotropic nature of this compound is endorsed by the calculation of Zener anisotropy factor. The direct band gap semiconducting nature with the value of gap is 1.33 eV using PBE potential is also corroborated by electronics properties. Eventually, different optical properties of Cs2SnBr6 such as dielectric constants, refractive index, conductivity, absorption, reflectivity and loss function have been observed and disclose for radiation up to 20 eV. Finally the optical properties corroborate the optoelectronic applications of this compound as all as elite candidate for photovoltaic perovskite solar cells.

scholarly journals Electronic and optical properties of vacancy ordered double perovskites A2BX6 (A = Rb, Cs; B = Sn, Pd, Pt; and X = Cl, Br, I): a first principles study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Muhammad Faizan ◽  
K. C. Bhamu ◽  
Ghulam Murtaza ◽  
Xin He ◽  
Neeraj Kulhari ◽  
...  
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Perovskite Solar Cells ◽  
Dielectric Constants ◽  
Maximum Efficiency ◽  
Exchange Potential ◽  
Double Perovskites ◽  
Electronic And Optical Properties

AbstractThe highly successful PBE functional and the modified Becke–Johnson exchange potential were used to calculate the structural, electronic, and optical properties of the vacancy-ordered double perovskites A2BX6 (A = Rb, Cs; B = Sn, Pd, Pt; X = Cl, Br, and I) using the density functional theory, a first principles approach. The convex hull approach was used to check the thermodynamic stability of the compounds. The calculated parameters (lattice constants, band gap, and bond lengths) are in tune with the available experimental and theoretical results. The compounds, Rb2PdBr6 and Cs2PtI6, exhibit band gaps within the optimal range of 0.9–1.6 eV, required for the single-junction photovoltaic applications. The photovoltaic efficiency of the studied materials was assessed using the spectroscopic-limited-maximum-efficiency (SLME) metric as well as the optical properties. The ideal band gap, high dielectric constants, and optimum light absorption of these perovskites make them suitable for high performance single and multi-junction perovskite solar cells.

FP-LMTO study of structural, electronic, thermodynamic and optical properties of MgxCd1−x Se alloys

2014 ◽  
Vol 32 (4) ◽  
pp. 719-728 ◽  
Author(s):  
D. Bensaid ◽  
M. Ameri ◽  
M. El Hanani ◽  
Y. Azaz ◽  
D. Bendouma ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Density Functional ◽  
Molar Fraction ◽  
Dielectric Constants ◽  
Ternary Alloys ◽  
Wide Range ◽  
Direct Band ◽  
Extraordinary Refractive Index

AbstractStructural, electronic and optical properties of MgxCd1−x Se (0 ≤ x ≤ 1) are calculated for the first time using density functional theory. Our results show that these properties are strongly dependent on molar fraction of particular components — x. The bond between Cd and Se is partially covalent and the covalent nature of the bond decreases as the concentration of Mg increases from 0 % to 100 %. It is found that MgxCd1−x Se has a direct band gap in the entire range of x and the band gap of the alloy increases from 0.43 to 2.46 eV with the increase in Mg concentration. Frequency dependent dielectric constants ɛ1(ω), ɛ2(ω) refractive index n(ω) are also calculated and discussed in detail. The peak value of refractive indices shifts to higher energy regions with the increase in Mg. The larger value of the extraordinary refractive index confirms that the material is a positive birefringence crystal. The present comprehensive theoretical study of the optoelectronic properties of the material predicts that it can be effectively used in optoelectronic applications in the wide range of spectra: IR, visible and UV. In addition, we have also predicted the heat capacities (CV), the entropy (S), the internal energy (U) and the Helmholtz free energy (F) of MgxCd1−x Se ternary alloys.

scholarly journals Effect of Dopant Concentration on the Structural, Optical and Sensing Properties of (SnO2)1-x(TiO2:CuO)x Sprayed Films

2019 ◽  
Vol 16 (2) ◽  
pp. 0361
Author(s):  
Mahmood Et al.
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Energy Band ◽  
Spray Pyrolysis Technique ◽  
Single Crystal Silicon ◽  
Dielectric Constants ◽  
Energy Band Gap ◽  
Crystal Silicon ◽  
X Ray ◽  
Regular Manner

      Spray pyrolysis technique was subjected to synthesized (SnO2)1-x (TiO2: CuO) x Thin films on different substrates like glass and single crystal silicon using. The structure of the deposited films was studied using x-ray diffraction. A more pronounced diffraction peaks of SnO2 while no peaks of (CuO , TiO2 ) phase appear in the X-ray profiles by increasing of the content of (TiO2 , CuO) in the sprayed films. Mixing concentration (TiO2 , CuO) influences on the size of the crystallites of the SnO2 films ,the size of crystallites of the spray paralyzed oxide films change in regular manner by increasing of (TiO2 , CuO) amount. The effect of mixing concentration on the optical properties of the films was also investigated. The reflectance and transmittance spectra  in the wavelength range (300-1100) nm were employed to determine the optical properties such as energy band gap (Eg) and refractive index (n),  extinction coefficient  (k) , real and imaginary parts of dielectric constants (ε1, ε2) for (SnO2)1-x(TiO2:CuO)x films. The energy band gap omit of which showed reduction from (3.65 to 2.2) eV by reducing of SnO2 amount from (100 to 70) % .The reduction of energy band gap was ascribed to the new tail states introduced in the band gap of tin oxide. The sensitivity of the prepared sensor film was determined resistance difference of the films when exposed to oxidizing gas. The data declared that the mixed SnO2 films have better sensitivity in comparison with unmixed films.

Electronic and optical properties of zinc-blende GeC by first principles study

2015 ◽  
Vol 29 (20) ◽  
pp. 1550103
Author(s):  
Jinhui Zhai ◽  
Jinguang Zhai ◽  
Ajun Wan
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Dielectric Constants ◽  
Electronic And Optical Properties ◽  
Optical Functions ◽  
Zinc Blende ◽  
The Density Functional Theory ◽  
Valence Bands ◽  
Energy Dependent

The electronic and optical properties of zinc-blende (zb)[Formula: see text]GeC have been investigated using first principles calculations based on the density functional theory (DFT). The obtained band gap of zb–GeC is 2.30[Formula: see text]eV by means of Heyd–Scuseria–Ernzerhof (HSE) functional. We have discussed the energy-dependent optical functions including dielectric constants, refractive index, absorption, reflectivity, and energy-loss spectrum in detail. The results reveal that zb–GeC has a higher static dielectric constant compared with that of zb–SiC. The optical functions are mainly associated with the interband transitions from the occupied valence bands (VBs) Ge[Formula: see text][Formula: see text] and C[Formula: see text][Formula: see text] states to Ge[Formula: see text][Formula: see text], [Formula: see text] and C[Formula: see text][Formula: see text] states of the unoccupied conduction bands (CBs).

scholarly journals First principles calculations on theoretical band gap improvement of IIIA-VA zinc-blende semiconductor InAs

2020 ◽  
Vol 31 (12) ◽  
pp. 2050178
Author(s):  
Waqas Mahmood ◽  
Arfan Bukhtiar ◽  
Muhammad Haroon ◽  
Bing Dong
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Local Density ◽  
Lattice Parameter ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Zinc Blende ◽  
Valence States ◽  
Direct Band ◽  
Experimental Findings

The structural, electronic, dielectric and vibrational properties of zinc-blende (ZB) InAs were studied within the framework of density functional theory (DFT) by employing local density approximation and norm-conserving pseudopotentials. The optimal lattice parameter, direct band gap, static dielectric constant, phonon frequencies and Born effective charges calculated by treating In-4d electrons as valence states are in satisfactory agreement with other reported theoretical and experimental findings. The calculated band gap is reasonably accurate and improved in comparison to other findings. This work will be useful for more computational studies related to semiconductor devices.

Structural Electronic and Optical Properties of MgO, CaO and SrO Binary Compounds: Comparison Study

2016 ◽  
Vol 257 ◽  
pp. 123-126 ◽  
Author(s):  
Salima Labidi ◽  
Jazia Zeroual ◽  
Malika Labidi ◽  
Kalthoum Klaa ◽  
Rachid Bensalem
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Density Functional ◽  
Local Density ◽  
Alternative Form ◽  
Full Potential ◽  
Generalized Gradient ◽  
Electronic And Optical Properties ◽  
Optical Dielectric Constant ◽  
Reported Data

First-principles calculations for electronic and optical properties under pressure effect of MgO, SrO and CaO compounds in the cubic structure, using a full relativistic version of the full-potential augmented plane-wave (FP-LAPW) method based on density functional theory, within the local density approximation (LDA) and the generalized gradient approximation (GGA), have been reported. Furthermore, band structure calculations have been investigated by the alternative form of GGA proposed by Engel and Vosko (GGA-EV) and modified by Becke-Johnson exchange correlation potential (MBJ-GGA). All calculated equilibrium lattices, bulk modulus and band gap at zero pressure are find in good agreement with the available reported data. The pressure dependence of band gap and the static optical dielectric constant are also investigated in this work.

First-principles investigation of the structural, elastic, electronic, and optical properties of semiconducting AgBr1–xIx (0 ≤ x ≤ 1) ternary alloys in rock-salt and zinc blende structures

2020 ◽  
Vol 98 (9) ◽  
pp. 834-848
Author(s):  
H. Rekab-Djabri ◽  
Mohamed Drief ◽  
Manal M. Abdus Salam ◽  
Salah Daoud ◽  
F. El Haj Hassan ◽  
...  
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Rock Salt ◽  
Density Functional ◽  
Local Density ◽  
Ternary Alloys ◽  
Full Potential ◽  
Zinc Blende ◽  
Lmto Method ◽  
Direct Band

In this work, first principle calculations of the structural, electronic, elastic, and optical properties of novel AgBr1–xIx ternary alloys in rock-salt (B1) and zinc-blende (B3) structures are presented. The calculations were performed using the full-potential linear muffin-tin orbital (FP-LMTO) method within the framework of the density functional theory (DFT). The exchange and correlation potentials were treated according to the local density approximation (LDA). The lattice constants for the B1 and B3 phases versus iodide concentration (x) were found to deviate slightly from the linear relationship of Vegard’s law. The calculated electronic properties showed that AgBr1–xIx alloys in the B3 structure have a direct band gap (Γ – Γ) for all concentrations of x, which means that they can be used in long-wavelength optoelectronic applications, while in the B1 structure they have an indirect (Γ – R) band gap. The elastic constants Cij, shear modulus G, Young’s modulus E, Poisson’s ratio ν, index of ductility B/G, sound velocities vt, vl, and vm, and Debye temperature θD were also reported and analyzed. By incorporating the basic optical properties, we discussed the dielectric function, refractive index, optical reflectivity, absorption coefficient, and optical conductivity in terms of incident photon energy up to 13.5 eV. The present results were found to be in good agreement with the available experimental and other theoretical results.

Structural and optical properties of Ba3(Nb6−xTax)Si4O26 (x = 0.6, 1.8, 3.0, 4.2, 5.4)

2019 ◽  
Vol 34 (4) ◽  
pp. 331-338
Author(s):  
W. Wong-Ng ◽  
G. Y. Liu ◽  
W. F. Liu ◽  
Y. Q. Yang ◽  
S. Y. Wang ◽  
...  
Keyword(s):  
Solid Solution ◽  
Optical Properties ◽  
Density Functional ◽  
Salient Feature ◽  
Lattice Parameter ◽  
Structural And Optical Properties ◽  
Functional Theory ◽  
Coordination Environment ◽  
Distorted Octahedra ◽  
Bond Valence Sum

Structure and optical properties have been successfully determined for a series of niobium- and tantalum-containing layered alkaline-earth silicate compounds, Ba3(Nb6−xTax)Si4O26 (x = 0.6, 1.8, 3.0, 4.2, 5.4). The structure of this solid solution was found to be hexagonal P-62m (No. 189), with Z = 1. With x increases from 0.6 to 5.4, the lattice parameter a increases from 8.98804(8) to 9.00565(9) Å and c decreases from 7.83721(10) to 7.75212(12) Å. As a result, the volume decreases from 548.304(11) to 544.479(14) Å3. The (Nb/Ta)O6 distorted octahedra form continuous chains along the c-axis. These (Nb/Ta)O6 chains are in turn linked with the Si2O7 groups to form distorted pentagonal channels in which Ba ions were found. These Ba2+ ions have full occupancy and a 13-fold coordination environment with neighboring oxygen sites. Another salient feature of the structure is the linear Si–O–Si chains. When x in Ba3(Nb6−xTax)Si4O26 increases, the bond valence sum (BVS) values of the Ba sites increase slightly (2.09–2.20), indicating the size of the cage becoming progressively smaller (over-bonding). While SiO cages are also slightly smaller than ideal (BVS range from 4.16 to 4.19), the (Nb/Ta)O6 octahedral cages are slightly larger than ideal (BVS range from 4.87 to 4.90), giving rise to an under-bonding situation. The bandgaps of the solid solution members were measured between 3.39 and 3.59 eV, and the x = 3.0 member was modeled by density functional theory techniques to be 3.07 eV. The bandgaps of these materials indicate that they are potential candidates for ultraviolet photocatalyst.

Electronic and Optical Properties of Indium Selenide Nanosheet Using First-Principle Calculations

2019 ◽  
Vol 11 (11) ◽  
pp. 1148-1154
Author(s):  
Hamza A. Mezerh ◽  
Kadhim J. Kadhim ◽  
Hamad Rahman Jappor
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Density Functional ◽  
Visible Region ◽  
High Refractive Index ◽  
Indium Selenide ◽  
Experimental Investigations ◽  
Ultraviolet Region ◽  
Electronic And Optical Properties ◽  
Index Value

Density functional theory (DFT) have been used to examine the electronic and optical, properties of two-dimensional (2D) indium selenide (InSe) nanosheet. Our calculations indicate that the energy band gap of InSe is indirect and equal to 1.53 eV. It can be seen that for the pristine case, the majority and minority density of state (DOS) are fully symmetric. The optical properties are considered up to 36 eV. Our results established that the absorption starts in the visible region, while the peaks in the ultraviolet region. The refractive index value is 1.84 at zero photon energy limit and increase to 2.31. The high refractive index allows this nanosheet to be utilized as an internal layer coating between the substrate and the ultraviolet absorbing layer. Additionally, we observed that the gained optical properties of InSe nanosheet are in the ultraviolet range and the results are significant. It is expected that from these calculations to provide useful information for further experimental investigations of InSe nanosheet.

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