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.金属卤化物钙钛矿半导体（metal halide perovskite semiconductors）的合成工艺进展，已使得太阳能电池与发光器件的效率突破25%。为将此类器件的性能推至理论极限之外，并实现长期稳定性，阐明钙钛矿与电荷传输材料（charge-transporting materials）界面处的结构演化机制至关重要。本研究通过分子动力学模拟（molecular dynamics simulations），探究溴化铯铅钙钛矿（cesium lead bromide perovskite）在常用氧化物界面（oxide interfaces）上的成核与生长的原子尺度过程。研究结果表明，该钙钛矿通过异质外延机制（heteroepitaxial mechanism）结晶，该机制会在掩埋界面处引发位错、空洞与缺陷，同时在体相晶体内部形成晶界（grain boundaries）。模拟结果显示，晶格匹配的界面可促进钙钛矿的外延有序生长，有望缓解界面处的缺陷形成。消除此类缺陷，无疑将为实现高效钙钛矿太阳能电池与发光二极管（light-emitting diodes）所需的长期稳定性铺平道路。