Electronic and Optical Properties of Organic-Inorganic MASn1-xGexI3 Perovskites: A First-Principles Study

In recent years, the search of lead-free perovskites have been investigated to obtain better structural stability and photovoltaic performance compared with the corresponding lead-based hybrid perovskites. In this work, we calculated the structural stabilities, electronic and optical properites of the mixed MASn(1-x)Ge(x)I(3) perovskites using the HSE06 functional. The results indicate that our predicted mixed Sn-Ge perovskites are stable, but they are weaken than that of MASnI(3). The calculated results show that these mixed perovskites possess direct band gaps from 1.22 to 1.74 eV. The calculated band gaps of the mixed Sn-Ge perovskites are in the suitable ranges for single-junction solar cell. The mixed MASn(1-x)Ge(x)I(3) perovskites also possess strong optical absorption abilities in the visible light region. Based on our calculated results, these mixed Sn-Ge perovskites are potential candidates for photovoltaic applications. We expect that this work can provide a insight for further research on lead-free perovskite solar cells.