Study of the Impact of Strain on the Physical Properties of the Li₂SnI₆ Compound

Perovskites represent distinctive materials suitable for both transport and optoelectronic applications, harnessing renewable resources to produce energy. In this study, the perovskite Li₂SnI₆ has been explored, focusing on a comprehensive analysis of its physical properties under strain. The encompassed investigation of the structural, elastic, electronic, optical, and thermoelectric characteristics of the studied compound. Utilizing density functional theory (DFT) implemented in the Wien2k package, we employed the LSDA+mBJ approximation to determine the exchange-correlation potential. The elastic constants and related parameters have been reported such as bulk modulus, shear modulus, Young’s modulus, anisotropy factor, Poisson’s ratio, and internal strain parameter for Li₂SnI₆ in its cubic structure. The electronic part reveals the semiconductor behavior of the studied compound and a decrease in gap energy with increasing pressure, reaching E_g = 0.2 eV for P = 12 GPa. Additionally, the absorption of optical factors lies in the ultra-violet (UV) region, noted at P = 12 GPa, with an intensity of 230 × 10⁴ cm⁻¹, which makes this material suitable for photovoltaic devices. Furthermore, we delved into the electrical conductivity, Seebeck coefficient, and electronic part of thermal conductivity. The results indicated that the compound demonstrates p-type behavior, as evidenced by positive values for the Seebeck coefficient with the highest value of 240 µV/K observed for P = 4 GPa. The analysis of thermoelectric and optical properties suggests that the studied perovskite is well-suited for applications in renewable energy.