First-Principles Investigation of Semiconducting Cu2ZnSnX4 (X = S, Se) Eco-Friendly Materials for the Next Generation of Photovoltaic Applications

The quaternary general form A2BCX4-based semiconducting materials with Kesterite-type structures are promising candidates for thin film-based solar cell devices. We examined the structural, electrical, optical, elastic, thermodynamic, and thermoelectric characteristics of Cu2ZnSnX4 (X = S, Se) using the FP-LAPW technique with an implanted Wien2k code. The Burke-Ernzerhof-generalized gradient approach (PBE-GGA) and Trans-Blaha modified Becke-johnson (TB-mBJ) are used to manage the exchange and correlation potentials. The results shows that Cu2ZnSnS4 and Cu2ZnSnSe4 compounds have stable structures with direct bands at 1.51 eV and 1.29 eV, respectively. The optical characteristics of these compounds were estimated using the dielectric function, allowing for an analysis of their reflectivity, refractive index, and absorption. Elastic parameters such as the Bulk, Young, Pugh, and Poisson ratios demonstrate that they are ductile and can be formed as thin films, a significant characteristic of Photovoltaic applications. Furthermore, we calculated various thermodynamic parameters entropy, and constant volume under pressure and temperature. We also determined the Cu2ZnSnX4 (X = S, Se) exhibits good thermoelectric performance concerning the figure of merit at 300K which is nearly unity. According to our findings, these materials are viable candidates for future clean green solar energy applications.