The Effect of Structural Phase Changes on Fermi Level Shifts and Optoelectronic Properties of Lead-Free CsSnI3 Perovskites

TL;DR

This study uses first-principles calculations to explore how structural phase transitions in lead-free CsSnI3 perovskites affect their electronic and optical properties, including Fermi level shifts and dielectric constants.

Contribution

It provides a comprehensive analysis of phase transition effects on CsSnI3's properties using advanced computational methods and machine learning predictions.

Findings

Phase transitions influence Fermi level positions.

Optical properties vary significantly across phases.

Thermodynamic stability of phases was established.

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. 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.