Stabilization and Self-Passivation of Grain Boundaries in Halide Perovskite by Rigid Body Translation

The physical properties of grain boundaries in halide perovskites, especially their atomic structure, have not been fully understood yet. We report that Σ5 [130] symmetrical tilt grain boundaries can be stabilized by rigid body translation which is moving one side of the grain parallel with respect to the adjacent grain. Such reconstruction passivates grain boundaries by removing Pb-Pb and I-I interactions that introduce shallow defect states in the band gap. Rigid body translation also stabilizes the [110] antiphase boundary as well in both CsPbI₃ and CsPbBr₃.