First-Principles Evaluation of the Structural, Electronic, Optical, and Thermodynamic Properties of LiSnI3

Abstract

This study presents a comprehensive first-principles (DFT) investigation of the structural, electronic, optical, and thermodynamic properties of the LiSnI3 perovskite. Structural optimization confirms a stable cubic LiSnI3 perovskite phase with a lattice constant of 6.22 A & ring; and a bulk modulus of 16.77 GPa, supported by a negative formation energy (-1.35 eV/atom). Electronic structure calculations show that LiSnI3 is a direct-band-gap semiconductor, with band gaps of 0.33 eV (GGA-PBE) and 0.76 eV (HSE06). The optical properties of LiSnI3 reveal a strong static dielectric response (epsilon 1 (0) = 8.08), a high refractive index (n (0) = 2.84), and a pronounced absorption edge at 0.81 eV, demonstrating suitability for infrared and UV optoelectronic applications. Thermodynamic results, combined with ab initio molecular dynamics simulations, confirm that the LiSnI3 perovskite remains dynamically and thermally stable across broad pressure and temperature ranges. The combined findings highlight LiSnI3 as a promising lead-free perovskite material for advanced optoelectronic and energy-related applications.