A DFT study of the electronic, optical and topological properties of free and biaxially strained CuIn1−xAlxSe2

2019 ◽  
Vol 7 (19) ◽  
pp. 5803-5815 ◽  
Author(s):  
Pingping Jiang ◽  
Pascal Boulet ◽  
Marie-Christine Record
Keyword(s):  
Thin Films ◽  
Absorption Coefficient ◽  
Band Gap ◽  
Conversion Efficiency ◽  
Dft Study ◽  
Topological Properties

Among the CuIn1−xAlxSe2 alloys, that with x = 0.25 is the optimal one in terms of band gap and conversion efficiency. Its absorption coefficient is highly modified under biaxial strains that occur in thin films.

scholarly journals Effect of gamma irradiation on structural, morphological and optical properties of p-quaterphenyl thin films

2018 ◽  
Vol 14 (2) ◽  
pp. 5624-5637
Author(s):  
A.A. Attia ◽  
M.M. Saadeldin ◽  
K. Sawaby
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Surface Morphology ◽  
Absorption Coefficient ◽  
Gamma Irradiation ◽  
Band Gap ◽  
Optical Band Gap ◽  
Thermal Evaporation Method ◽  
Single Oscillator Model

Para-quaterphenyl thin films were deposited onto glass and quartz substrates by thermal evaporation method. p-quaterphenyl thin films wereexposed to gamma radiation of Cobat-60 radioactive source at room temperature with a dose of 50 kGy to study the effect of ?-irradiation onthe structure and the surface morphology as well as the optical properties of the prepared films. The crystalline structure and the surface morphology of the as-deposited and ?-irradiated films were examined using the X-ray diffraction and the field emission scanning electron microscope. The optical constants (n & k) of the as-deposited and ?-irradiated films were obtained using the transmittance and reflectance measurements, in the wavelength range starting from 250 up to 2500 nm. The analysis of the absorption coefficient data revealed an allowed direct transition with optical band gap of 2.2 eV for the as-deposited films, which decreased to 2.06 eV after exposing film to gamma irradiation. It was observed that the Urbach energy values change inversely with the values of the optical band gap. The dispersion of the refractive index was interpreted using the single oscillator model. The nonlinear absorption coefficient spectra for the as-deposited and ?-irradiated p-quaterphenyl thin films were obtained using the linear refractive index.

scholarly journals Conductivity and Density of States of New Polyphenylquinoline

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 934 ◽  
Author(s):  
Shamil R. Saitov ◽  
Dmitriy V. Amasev ◽  
Alexey R. Tameev ◽  
Vladimir V. Malov ◽  
Marine G. Tedoradze ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Absorption Coefficient ◽  
Band Gap ◽  
Density Of States ◽  
Optical Band Gap ◽  
Dark Conductivity ◽  
Localized States ◽  
Energy Distance ◽  
Temperature Dependences

Electrical, photoelectrical, and optical properties of thin films of a new heat-resistant polyphenylquinoline synthesized using facile methods were investigated. An analysis of the obtained temperature dependences of the dark conductivity and photoconductivity indicates the hopping mechanism of conductivity over localized states arranging at the energy distance of 0.8 eV from the Fermi level located inside the band gap of the investigated material. The optical band gap of the studied material was estimated from an analysis of the spectral dependences of the photoconductivity and absorption coefficient before (1.8–1.9 eV) and after (2.0–2.2 eV) annealing at temperatures exceeding 100 °C. The Gaussian character of the distribution of the localized states of density inside the band gap near the edges of the bands was established. A mechanism of changes in the optical band gap of the investigating polymer under its annealing is proposed.

scholarly journals SCAPS SIMULATION OF ZnO/In2S3/Cu2Sn3S7/Mo SOLAR CELL

2018 ◽  
Vol 54 (1A) ◽  
pp. 183
Author(s):  
Phung Dinh Hoat
Keyword(s):  
Solar Cell ◽  
Absorption Coefficient ◽  
Band Gap ◽  
Carrier Concentration ◽  
Conversion Efficiency ◽  
Energy Band ◽  
Input Data ◽  
Energy Band Gap ◽  
Main Input

Operation of ZnO/In2S3/Cu2Sn3S7/Mo solar cell was calculated using the SCAPS software. Main input data were energy band gap Eg, absorption coefficient α, thickness d, mobility μ and carrier concentration n of the ZnO, In2S3 and Cu2Sn3S7 films obtained from experiments. In all calculation processes, parameters of the ZnO (Eg = 3.3 eV, d = 0.2 μm, μn = 100 cm2/(Vs)) and In2S3 (Eg = 2.96 eV, d = 0.1 μm, μn = 50 cm2/(Vs)) films were kept constant. Effects of thickness d and carrier concentration np of the Cu2Sn3S7 (αmax = 4.2×104 cm-1, Eg = 1.46 eV) film on Voc, Jsc, Vm, Jm, FF and η of the cell were investigated in the ranges of d = 0.3 – 3.5 μm and np = 1017 – 1020 cm-3. Under the standard AM 1.5G illumination at 300 K, the ZnO/In2S3/Cu2Sn3S7/Mo solar cell having Rs = 10 Ω.cm2 and Rsh = 1×106 Ω.cm2 using Cu2Sn3S7 film having d = 2 μm, αmax = 4.2×104 cm-1, Eg = 1.46 eV, μp = 15 cm2/(Vs) and np = 1020 cm-3 has the highest conversion efficiency ηmax = 18.0 % with Voc = 0.98 V, Jsc = 31.2 mA/cm2, Vm = 0.62 V, Jm = 28.8 mA/cm2 and FF = 58.8 %.

scholarly journals Influence of temperature on optical proper¬ties of thin films Cu2ZnSnSe4

2018 ◽  
pp. 50-54
Author(s):  
E. V. Maistruk ◽  
I. P. Koziarskyi ◽  
D. P. Koziarskyi ◽  
P. D. Maryanchuk
Keyword(s):  
Thin Films ◽  
Solar Cells ◽  
Absorption Coefficient ◽  
Band Gap ◽  
Room Temperature ◽  
Optical Band Gap ◽  
Materials Science ◽  
Scientific Activity ◽  
Optical Absorption Coefficient ◽  
Effect Of Temperature

The use of solar cells in various fields of science and technology contributes to the development of materials science and scientific activity in this area. Recently, scientists have been researching the optical and electrical properties of materials such as casterite. Casterite is a natural mineral which consists mainly of copper, zinc, tin, sulfur and selenium, that is, elements that are fairly widespread in nature. Therefore, solar cells, developed on the basis of casterite, will have, according to the researchers, a low cost. In addition, casterites belong to direct-gap semiconductors with a band gap of 0.9—1.5 eV and with a large optical absorption coefficient (≈ 104 cm–1). In this work, the authors investigate the effect of temperature on the optical properties of Cu2ZnSnSe4 thin films of casterite obtained by the method of RF magnetron sputtering of previously synthesized material on glass substrates. Optical coefficients were determined by a method based on independent measurement of reflection and transmission coefficients. The reflection coefficient was studied at room temperature, and the transmittance — in the temperature range of 111—290 K. The measurements were made in the wavelength range from 0.9 to 26 µm. The obtained data were used to calculate the absorption coefficient and the band gap of the samples at different temperatures from the range under study. Studies have shown that direct interband optical transitions are observed in Cu2ZnSnSe4 films. The optical band gap at room temperature was 0.92 eV at a temperature coefficient of –1,29∙10–4 eV/K, that is, the optical band gap decreases with temperature, which is typical of classical semiconductors.

scholarly journals Compositional dependence of absorption coefficient and band-gap for Nb2O5–SiO2 mixture thin films

2008 ◽  
Vol 516 (16) ◽  
pp. 5478-5482 ◽  
Author(s):  
Jordi Sancho-Parramon ◽  
Vesna Janicki ◽  
Hrvoje Zorc
Keyword(s):  
Thin Films ◽  
Absorption Coefficient ◽  
Band Gap ◽  
Compositional Dependence

A thiourea additive-based quadruple cation lead halide perovskite with an ultra-large grain size for efficient perovskite solar cells

Nanoscale ◽  
2019 ◽  
Vol 11 (45) ◽  
pp. 21824-21833 ◽  
Author(s):  
Jyoti V. Patil ◽  
Sawanta S. Mali ◽  
Chang Kook Hong
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Solar Cells ◽  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Power Conversion ◽  
Perovskite Solar Cells ◽  
Inorganic Perovskite ◽  
Halide Perovskite ◽  
Lead Halide

Controlling the grain size of the organic–inorganic perovskite thin films using thiourea additives now crossing 2 μm size with >20% power conversion efficiency.

Stability Investigation in the Optical Properties of Thermally Evaporated Ge5Se95-x Znx Thin Films

2015 ◽  
Vol 7 (3) ◽  
pp. 1923-1930
Author(s):  
Austine Amukayia Mulama ◽  
Julius Mwakondo Mwabora ◽  
Andrew Odhiambo Oduor ◽  
Cosmas Mulwa Muiva ◽  
Boniface Muthoka ◽  
...  
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Optical Band Gap ◽  
Thermal Evaporation ◽  
Optical Transition ◽  
Bulk Material ◽  
Band Gap Energy ◽  
Optical Absorbance ◽  
Gap Energy ◽  
Constituent Elements

 Selenium-based chalcogenides are useful in telecommunication devices like infrared optics and threshold switching devices. The investigated system of Ge5Se95-xZnx (0.0 ≤ x ≤ 4 at.%) has been prepared from high purity constituent elements. Thin films from the bulk material were deposited by vacuum thermal evaporation. Optical absorbance measurements have been performed on the as-deposited thin films using transmission spectra. The allowed optical transition was found to be indirect and the corresponding band gap energy determined. The variation of optical band gap energy with the average coordination number has also been investigated based on the chemical bonding between the constituents and the rigidity behaviour of the system’s network.

Wide Band-Gap Kesterite Thin Films for Photovoltaic Applications

2018 ◽  
Author(s):  
Raquel Caballero ◽  
Leonor de la Cueva ◽  
Andrea Ruiz-Perona ◽  
Yudenia Sánchez ◽  
Markus Neuschitzer ◽  
...  
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Wide Band ◽  
Wide Band Gap ◽  
Photovoltaic Applications
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