Self-consistent relativistic band structure of the CH3NH3PbI3 perovskite

Abstract

The perovskite material CH3NH3PbI3 is nowadays actively studied as absorber for photovoltaic applications. In this work, the electronic structure of its orthorhombic low temperature phase has been computed by means of density functional theory. Hybrid functionals have been used, including self-consistently the spin-orbit relativistic effects. Scalar relativistic effects are included in the projector augmented waves approximation. The hydrogen atoms, not resolved by crystallographic methods, have been placed in appropriate starting positions and the structure has been fully relaxed. We find that the structural parameters are well reproduced using two van-der Waals density functionals. Using this structure and two different hybrid functionals, the bandgaps obtained are 1.31 and 1.63 eV, which bracket the experimental value of 1.5 eV determined for the room temperature cubic phase[1].