Weizmann Institute of Science, 234 Herzl Street, Rehovot, 7610001, Israel.
Department of Physics and CIMAINA, University of Milan, 16 via Celoria, Milan, 20133, Italy.
Adv Mater. 2018 Mar;30(10). doi: 10.1002/adma.201706273. Epub 2018 Jan 12.
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 (MAPbBr , FAPbBr , and CsPbBr )) 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 FAPbBr the fastest (≈1 h) and CsPbBr 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.
自修复，即一些参数的变化随着时间的推移而无需任何外部干预自动恢复，是卤化物钙钛矿的一个特别有趣的特性。虽然有许多研究表明钙钛矿具有自修复能力，但它们都是在薄膜上进行的，在薄膜中，钙钛矿与另一相（包括环境）之间的界面往往是过程中的主导和干扰因素。在这里，我们报告了钙钛矿（甲脒、甲脒、铯铅溴（MAPbBr、FAPbBr 和 CsPbBr）单晶中的自修复，使用双光子显微镜在晶体内部创建损伤（光漂白）≈110 µm，并监测损伤后光致发光的恢复。自修复发生在所有三种钙钛矿中，其中 FAPbBr 最快（≈1 h），CsPbBr 最慢（数十小时）。这种行为与表面主导的稳定性趋势不同，是典型的体相行为，强烈依赖于降解产物的定位，这些产物离损伤部位不远。自修复的机制与多溴化物的可能参与有关。它提供了一个封闭的化学循环，不一定涉及经常被提出用于解释卤化物钙钛矿可逆现象的缺陷或离子迁移现象。
