Radiation damage mechanism of organic–inorganic hybrid perovskites under electron beam irradiation is currently under controversy. First-principles calculations of threshold energies show that the knock-on atomic displacement damage in CH₃NH₃PbI₃ is significant and highly energy-dependent, i.e., for the incident energy below 2.3 keV, knock-on damage is negligible; when the incident energy increases to 2.3, 26.4, 70.4, and 249.4 keV, H, C, N, and I displacements start, respectively; however, Pb does not displace even for 1 MeV incident energy. This finding explains the observation that 5 keV or higher-energy irradiation causes obvious changes in cathodoluminescence spectra while 2 keV causes only small changes. For the 300 keV high energy irradiation used in recent experiments, our results show that the H, C, N, and I knock-on displacements can cause the loss of CH₃NH₃ and I simultaneously, so the knock-on damage should play an important role in these experiments. The electron diffraction characterization cannot distinguish the CH₃NH₃ and I loss, so it might give confusing conclusions about damage processes. These results change our fundamental understandings on the radiation-damage mechanisms of CH₃NH₃PbI₃-related perovskites, laying the foundation for the transmission-electron-microscopy characterization of their microscopic structures.

中文翻译：

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电子束照射下有机-无机杂化钙钛矿的能量依赖性连锁损伤：第一性原理见解

电子束照射下有机-无机杂化钙钛矿的辐射损伤机制目前存在争议。阈值能量的第一性原理计算表明，CH ₃ NH ₃ PbI _{3 中的}原子位移破坏显着且高度依赖于能量，即对于低于 2.3 keV 的入射能量，碰撞损坏可以忽略不计；当入射能量增加到 2.3、26.4、70.4 和 249.4 keV 时，H、C、N 和 I 位移分别开始；然而，即使对于 1 MeV 的入射能量，Pb 也不会发生位移。这一发现解释了以下观察结果：5 keV 或更高能量的照射会导致阴极发光光谱发生明显变化，而 2 keV 只会引起很小的变化。对于最近实验中使用的 300 keV 高能辐照，我们的结果表明 H、C、N 和 I 的连锁位移会导致 CH ₃ NH ₃的损失和我同时进行，所以在这些实验中，连锁损伤应该起到重要作用。电子衍射表征无法区分 CH ₃ NH ₃和 I 损失，因此它可能会给出关于损伤过程的令人困惑的结论。这些结果改变了我们对 CH ₃ NH ₃ PbI ₃相关钙钛矿辐射损伤机制的基本认识，为其微观结构的透射电子显微镜表征奠定了基础。