  The protection of halide perovskites is important for the performance and
stability of emergent perovskite-based optoelectronic technologies. In this
work, we investigate the potential inorganic protective coating materials ZnO,
SrZrO3, and ZrO2 for the CsPbI3perovskite. The optimal interface registries are
identified with Bayesian optimization. We then use semi-local
density-functional theory (DFT) to determine the atomic structure at the
interfaces of each coating material with the clean CsI-terminated surface and
three reconstructed surface models with added PbI2and CsI complexes. For the
final structures, we explore the level alignment at the interface with hybrid
DFT calculations. Our analysis of the level alignment at the coating-substrate
interfaces reveals no detrimental mid-gap states, but substrate-dependent
valence and conduction band offsets. While ZnO and SrZrO3act as insulators on
CsPbI3, ZrO2 might be suitable as electron transport layer with the right
interface engineering.
