DFT combined to Boltzmann transport theory for optoelectronic and thermoelectric properties investigations for Se (4 & 8 (at.%)) doped Li₂SnS₃

Abstract

Cubic Li2SnS3 emerges as a noteworthy ionic conductor and a viable electrode material for lithium secondary batteries. Its application extends to solar cell technologies, owing to its commendable optoelectronic properties and high-power conversion efficiency. In this study, we present density functional theory (DFT)-based first principles calculations for Li2SnS3-xSex (x = 0, 4, and 8% (atomic percent (at.%)) utilizing the modified Becke Johnson (mBJ) approximations, proposing a compelling alternative. Our investigation reveals significant optical absorption in the ultraviolet region for Li2SnS3-xSex (x = 0, 4, and 8%), accompanied by modest effective mass and indirect band gaps of 2.18 eV for the pristine material. Conversely, doped materials exhibit direct band gaps, with values of 2.113 eV for 4% and 2.026 eV for 8%. Furthermore, the calculated thermoelectric power factor underscores the potential and efficacy of Li2SnS3-xSex in thermoelectric energy devices. The findings not only highlight the material’s promise for solar applications but also underscore its candidacy as a novel solid-state electrolyte for lithium-ion batteries. This stems from its robust thermal stability and notable lithium-ion conductivity, positioning Li2SnS3 as a compelling candidate for advanced energy storage technologies.