Optoelectronic and Thermoelectric Properties of the Perovskites: NaSnX3 (X = Br or I)—A DFT Study

This paper explores the photovoltaic and thermoelectric properties of composites consisting of NaSnX3 (X = Br or I). The study uses density functional theory in conjunction with the Boltzmann Transport Theory. Initially, the structural, electronic, and optical properties of the materials are inspected using the generalized gradient approximation (GGA) based on the Perdew–Burke–Ernzerhof approximation (GGA-PBE) with consideration of the cross-correlation potential. The findings reveal that the studied compounds exhibit a p-type semiconductor character along with intriguing optical properties. Afterward, the thermoelectric properties of the materials are examined and discussed in the second part of the study. This analysis includes the Seebeck coefficient, electrical and thermal conductivities, the figure of merit, and the power factor. It is observed that the Seebeck coefficient demonstrates positive values, confirming the p-type semiconducting properties of the two materials under study. Additionally, these compounds exhibit significant values of the figure of merit (ZT) values when compared to existing thermoelectric materials. Especially, the large ZT values are achieved at both low and high-temperature ranges. Generally, these materials hold potential for applications in photovoltaic and/or thermoelectric fields.