Version 1
: Received: 29 October 2023 / Approved: 30 October 2023 / Online: 30 October 2023 (08:48:15 CET)
How to cite:
Nematov, D.; Burhonzoda, A.; Kurboniyon, M.; Umar, Z.; Kholmurodov, K.; Yamamoto, T.; Shokir, F. The Effect of Structural Phase Changes on Fermi Level Shifts and Optoelectronic Properties of Lead-Free CsSnI3 Perovskites. Preprints2023, 2023101877. https://doi.org/10.20944/preprints202310.1877.v1
Nematov, D.; Burhonzoda, A.; Kurboniyon, M.; Umar, Z.; Kholmurodov, K.; Yamamoto, T.; Shokir, F. The Effect of Structural Phase Changes on Fermi Level Shifts and Optoelectronic Properties of Lead-Free CsSnI3 Perovskites. Preprints 2023, 2023101877. https://doi.org/10.20944/preprints202310.1877.v1
Nematov, D.; Burhonzoda, A.; Kurboniyon, M.; Umar, Z.; Kholmurodov, K.; Yamamoto, T.; Shokir, F. The Effect of Structural Phase Changes on Fermi Level Shifts and Optoelectronic Properties of Lead-Free CsSnI3 Perovskites. Preprints2023, 2023101877. https://doi.org/10.20944/preprints202310.1877.v1
APA Style
Nematov, D., Burhonzoda, A., Kurboniyon, M., Umar, Z., Kholmurodov, K., Yamamoto, T., & Shokir, F. (2023). <strong></strong>The Effect of Structural Phase Changes on Fermi Level Shifts and Optoelectronic Properties of Lead-Free CsSnI<sub>3</sub> Perovskites. Preprints. https://doi.org/10.20944/preprints202310.1877.v1
Chicago/Turabian Style
Nematov, D., Tomoyuki Yamamoto and Farhod Shokir. 2023 "<strong></strong>The Effect of Structural Phase Changes on Fermi Level Shifts and Optoelectronic Properties of Lead-Free CsSnI<sub>3</sub> Perovskites" Preprints. https://doi.org/10.20944/preprints202310.1877.v1
Abstract
The work carried out first-principles calculations within the framework of density functional theory to study the structural stability of the CsSnI3 compound and the influence of phase transitions on their electronic and optical properties. Using the GGA and SCAN functionals, the relaxed structures of the CsSnI3 phases were obtained and their geometric characteristics were assessed. Using the Phonopy code based on VASP, calculations of phonon and thermodynamic properties were performed, and the temperatures of phase transitions of CsSnI3 were determined. The temperature dependences of the thermodynamic parameters α-, β-, γ- and δ-phases of CsSnI3 were analyzed. The trends in free energy, entropy, enthalpy, heat of formation energy and heat capacity were justified in terms of the pattern of changes in the total energy of the four phases of CsSnI3 from VASP calculations. It is shown that at 0 K the non-perovskite structure of the CsSnI3 compound (δ-CsSnI3) is the most stable (followed by γ-CsSnI3), and the tetragonal phase (β) is quite unstable, having the highest energy among the perovskite phases. It was revealed that at temperatures above 450 K the tetragonal phase becomes stable, and when the temperature drops, it transforms into the cubic phase (α-CsSnI3). The phase transition between the β and γ phase of perovskite occurs in the range of 300-320 K, and at 320 K a black-yellow transformation of CsSnI3 occurs in which the cubic phase (black perovskite) undergoes a phase transition to a non-perovskite conformation (yellow phase). The presence of temperature phase transitions between two orthorhombic phases of CsSnI3 at 360 K was discovered, although direct transitions of the α⟷γ and γ⟷δ types have not yet been reported in any experiment, except for γ→δ transitions under the influence of moisture. Based on well-relaxed structures (from the SCAN calculations), the band gap widths for four CsSnI3 phases were calculated and compared with experimental measurements. Electronic properties and Fermi level shifts as a result of phase transformations of CsSnI3 were assessed using the HSE06 functional and machine learning prediction. The values of the complex dielectric constant and the refractive index of all phases of the CsSnI3 were determined.
Keywords
lead-free perovskites; instability; phase transitions; thermodynamic characteristics; Fermi level shift; electronic and optical properties; density function theory; phonopy calculations; photovoltaic applications
Subject
Physical Sciences, Condensed Matter Physics
Copyright:
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