Role of an external electric field on hybrid halide perovskite CH3NH3PbI3 band gaps

Abstract

Abstract The organic-inorganic perovskite CH 3 NH 3 PbI 3 has attracted much attention due to their power conversion efficiency as a potential photovoltaic material, but the role of an external electric field has not been well understood. Based on first-principles calculations, the effects of an external electric field ( E ) applied along the [111] direction of the orthorhombic perovskite, CH 3 NH 3 PbI 3 , on its electronic structure and optical properties are investigated. Our results indicate that the electric field strength affects the band gap ( E g ) of CH 3 NH 3 PbI 3 (MAPbI 3 , MA = CH 3 NH 3 ). The energy difference between the two peaks closest to the Fermi level in the density of states diagram decreases with increasing applied electric field strength along the [111] direction, indicating that the covalent character increases between A-sites cations and I-sites anions. Both the cell volume and the final energy show the same increasing trend. The absorption peaks move toward the visible-frequency range, with the optimal band gap of 1.1–1.45 eV and E = 0.04–0.06 eV/Å/e. In particular, the non-linear change of the second-order Stark effect causes a non-linear change in the band gap.