Revealing the structural, electronic and optical properties of lead-free perovskite derivatives of Rb2SnX6(X = Cl, Br and I): A theory calculation

Abstract Over the past few years, the excellent photoelectric properties of perovskite materials have stimulated the interests of researchers to search for new perovskites and derivatives, possessing the properties of environment-friendly and good stability, as promising solar light harvester. In this work, we have mainly studied the geometric structures, electronic and optical properties of the three stable lead-free perovskite derivatives Rb2SnX6(X = Cl, Br and I) by employing the first principles method based on the Density Functional Theory. The consequences reveal that all the three compounds possess direct band gap. Thereinto, Rb2SnX6 exhibits superior photovoltaic performance in terms of high optical absorption coefficients compared with Cs2SnI6 and CH3NH3PbI3, which reach over 105 cm−1. Particularly, Rb2SnI6 exhibits an appropriate band gap of 1.1 eV and small effective mass. These results demonstrated that perovskite derivatives Rb2SnX6 may be potential candidate for excellent light absorbing material.