Density functional theory analysis of electronic and optical properties of orthorhombic perovskite CH3NH3SnX3 (X = Br, I)

Abstract The electronic and optical properties of hybrid perovskites CH3NH3SnX3 (X = Br, I) are investigated by first-principles calculations. Our results show that consideration of the weak van der Waals interactions is important for theoretical investigations of Sn-based hybrid materials. During light harvesting, the electron transition will occur between the p states of halogen at the valence band maximum (VBM) and the Sn 5p states at the conduction band minimum (CBM). Comparing with the energy distribution of solar spectra, CH3NH3SnI3 has better absorption characteristics in the visible region than CH3NH3PbI3, which shows promising prospects in realizing lead-free, highly efficient solar cells.