Characterization of the Σ5(210) / [001] Grain Boundary of Methyl-Ammonium Lead Triiodide Perovskite using Density Functional Theory

Abstract

The Σ5(210)/[001] grain boundary (GB) of methyl-ammonium lead triiodide (MAPbI₃) perovskite, one of the high-symmetry coincident site boundaries, is characterized by density functional theory. We searched for the lowest energy GB structure through ab-initio atomistic relaxation of symmetric twin boundaries with and without translational shifts relative to the GB plane. We confirmed that the symmetric Σ5(210)/[001] GB of MAPbI₃ perovskite is the most stable among all the structures examined. The electronic density of states of the GB structure reveals no gap states. The electronic states of the valence-band maximum and conduction-band minimum are mainly p orbitals of I and Pb atoms, respectively.