Self‐healing, where a modification in some parameter is reversed with time without any external intervention, is one of the particularly interesting properties of halide perovskites. While there are a number of studies showing such self‐healing in perovskites, they all are carried out on thin films, where the interface between the perovskite and another phase (including the ambient) is often a dominating and interfering factor in the process. Here, self‐healing in perovskite (methylammonium, formamidinium, and cesium lead bromide (MAPbBr₃, FAPbBr₃, and CsPbBr₃)) single crystals is reported, using two‐photon microscopy to create damage (photobleaching) ≈110 µm inside the crystals and to monitor the recovery of photoluminescence after the damage. Self‐healing occurs in all three perovskites with FAPbBr₃ the fastest (≈1 h) and CsPbBr₃ the slowest (tens of hours) to recover. This behavior, different from surface‐dominated stability trends, is typical of the bulk and is strongly dependent on the localization of degradation products not far from the site of the damage. The mechanism of self‐healing is discussed with the possible participation of polybromide species. It provides a closed chemical cycle and does not necessarily involve defect or ion migration phenomena that are often proposed to explain reversible phenomena in halide perovskites.

中文翻译：

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APbBr3卤化物钙钛矿晶体内部的自我修复

自我修复是卤化钙钛矿特别令人感兴趣的特性之一，其中某些参数的修改会随时间逆转而无需任何外部干预。尽管有许多研究表明钙钛矿具有这种自我修复功能，但它们都是在薄膜上进行的，钙钛矿与另一相（包括周围环境）之间的界面通常是该过程中的主要和干扰因素。在这里，钙钛矿（甲基铵，甲ami和溴化铯（MAPbBr ₃，FAPbBr ₃和CsPbBr ₃））报告了单晶，使用双光子显微镜在晶体内部造成了约110 µm的损伤（光致漂白），并监测了损伤后光致发光的恢复。三种钙钛矿中均发生自我修复，其中FAPbBr ₃最快（约1小时），CsPbBr ₃最快（数十小时）恢复。这种行为不同于以表面为主的稳定性趋势，这是整体的典型现象，并且强烈依赖于降解产物在损伤部位附近的定位。讨论了多溴联苯物种可能参与的自我修复机制。它提供了一个封闭的化学循环，并不一定涉及通常建议用来解释卤化物钙钛矿中可逆现象的缺陷或离子迁移现象。