Lattice-Matched Heterogeneous Nucleation Eliminates Defective Buried Interfaces in Halide Perovskites

Advancements in the formation of metal halide perovskite semiconductors have led to solar cells and light-emitting devices with efficiencies exceeding 25%. To push these performances beyond theoretical limits and achieve long-term stability, a fundamental understanding of the structural evolution at the interface between perovskites and charge-transporting materials is essential. In this study, we perform molecular dynamics simulations to investigate the atomic-scale processes involved in the nucleation and growth of cesium lead bromide perovskite on commonly used oxide interfaces. Our results reveal that the perovskite crystallizes through a heteroepitaxial mechanism, which can induce the formation of dislocations, voids, and defects at the buried interface as well as grain boundaries within the bulk crystal. From simulations, we find that the lattice-matched interfaces promote epitaxially ordered growth of the perovskite, potentially mitigating defect formation at the interface. Eliminating these defects could arguably pave the way for achieving the long-term stability required for high-efficiency perovskite solar cells and light-emitting diodes.