To evaluate the role of planar defects in lead‐halide perovskites—cheap, versatile semiconducting materials—it is critical to examine their structure, including defects, at the atomic scale and develop a detailed understanding of their impact on electronic properties. In this study, postsynthesis nanocrystal fusion, aberration‐corrected scanning transmission electron microscopy, and first‐principles calculations are combined to study the nature of different planar defects formed in CsPbBr₃ nanocrystals. Two types of prevalent planar defects from atomic resolution imaging are observed: previously unreported Br‐rich [001](210)∑5 grain boundaries (GBs) and Ruddlesden–Popper (RP) planar faults. The first‐principles calculations reveal that neither of these planar faults induce deep defect levels, but their Br‐deficient counterparts do. It is found that the ∑5 GB repels electrons and attracts holes, similar to an n–p–n junction, and the RP planar defects repel both electrons and holes, similar to a semiconductor–insulator–semiconductor junction. Finally, the potential applications of these findings and their implications to understand the planar defects in organic–inorganic lead‐halide perovskites that have led to solar cells with extremely high photoconversion efficiencies are discussed.

中文翻译：

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溴化铯铅钙钛矿中晶界和Ruddlesden-Pop断层的原子结构和电活动

要评估平面缺陷在卤化钙钛矿（廉价的通用半导体材料）中的作用，至关重要的是在原子尺度上检查其结构（包括缺陷），并详细了解其对电子性能的影响。在这项研究中，合成后的纳米晶体融合，像差校正的扫描透射电子显微镜和第一性原理计算相结合，以研究CsPbBr _3中形成的不同平面缺陷的性质。纳米晶体。从原子分辨率成像中观察到两种类型的普遍平面缺陷：先前未报告的富Br [001]（210）∑5晶界（GBs）和Ruddlesden-Popper（RP）平面缺陷。第一性原理计算结果表明，这些平面断层均未引起深层缺陷，而它们的含溴缺陷断层却没有。发现∑5 GB排斥电子并吸引空穴，类似于n–p–n结，而RP平面缺陷排斥电子和空穴，类似于半导体-绝缘体-半导体的结。最后，讨论了这些发现的潜在应用及其对理解有机-无机卤化铅钙钛矿中平面缺陷的意义，这些缺陷导致了太阳能电池具有极高的光转换效率。