First-principles study of the optoelectronic and thermoelectric properties of lead-free ASnI3 (A = K, Rb, and Cs) novel halide perovskites

Abstract

In this work, we investigated the optoelectronic and thermoelectric properties of novel lead-free ASnI3 (A = K, Rb, and Cs) perovskite materials employing density functional theory calculations with the most accurate modified TB-mBJ potential. The three studied materials are similar in terms of their computed band profiles. The presence of an energy bandgap between the valence and conduction bands confirms the materials to be semiconductors with an indirect band-type nature. The CsSnI3 with a small gap value compared to the other two materials follows that it would require less energy for excitation. The calculated density of states and their actual electronic orbital contributions are also examined. The projected total density of states shows a successive variation along the energy value. Moreover, the linear optical characteristics are computed and investigated for their possible use in optoelectronic devices. The polarizability of KSnI3 is higher than the other two materials. The studied materials can be potential as an anti-reflecting coating material against UV rays as confirmed by the sharp peaks in the reflectivity spectra. The positive value of RH was consistent with the p-type nature of these materials as also revealed by the Seebeck coefficient and electronic characteristics. The materials seem to be prospective for use in thermoelectric devices supported by the predicted thermoelectric parameters.