A computational study of the electronic and thermoelectric properties of metal halide cubic perovskites CsBX3 (B = Ge, Sn, Pb and X = Cl, Br, I)

Metal halide perovskites have received a tremendous interest recently in new applications. Photovoltaic, diverse photonic and optoelectronic applications of these materials are in full expansion, but thermoelectricity also instigates a great interest. In this work, we will focus on the thermoelectric properties of a particular material family of metal halide cubic perovskites CsBX3 (B = Ge, Sn, Pb and X = Cl, Br, I). The structural and electronic properties of CsBX3 are computed using first-principles calculations based on the density functional theory which allows calculating equilibrium lattice parameters, band structures, the nature (direct/indirect) and value of the band gap. These studied compounds are semiconductors with direct band gap energy. We have also detected the effect of replacement of halogen and metal cation atoms with other halogen and metal cation atoms on electronic and thermoelectric properties. Boltzmann transport calculations are carried out to explore their thermoelectric properties like the Seebeck coefficient, electrical conductivity and power factor. Large values of the Seebeck coefficient and the power factor obtained for these compounds indicate that these compounds can be used for thermoelectric devices. Our theoretical analysis of the electronic and thermoelectric properties of these compounds suggests that CsSnBr3 and CsGeBr3 are the best Pb-free inorganic metal halide semiconductor for a high thermoelectric performance.