Electronic Consequences of the Formation of Local Tilting in Halide Perovskites.

Complex structural dynamics in halide perovskites have attracted researchers in the field of perovskite optoelectronics. Although state-of-the-art experimental and theoretical techniques have disclosed the dynamic nature of local tilting in halide perovskites, how such local tilting influences the physical properties of these materials is still poorly understood. In this study, we model confined local tilting within a cubic halide perovskite CsPbBr and reveal the electronic consequences of the local tilting, employing density functional theory. Our calculations confirm that the locally tilted layers have larger band gaps than the host cubic lattice, where no charge trapping levels are introduced by them. The degree of local band gap fluctuation is predicted to depend significantly on the geometry of the locally tilted domains. We conclude that local tilting will act as dynamic charge-blocking barriers, which impact carrier dynamics in perovskite optoelectronic devices.