Liquid-like Interfaces Mediate Structural Phase Transitions in Lead Halide Perovskites
Liquid-like Interfaces Mediate Structural Phase Transitions in Lead Halide Perovskites
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DOI：
10.1016/j.matt.2020.07.015
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发表时间：
2020-08-05
期刊：
影响因子：
18.9
通讯作者：
Ginsberg, Naomi S.
中科院分区：
文献类型：
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作者：
Bischak, Connor G.;Lai, Minliang;Ginsberg, Naomi S.
金属卤化物钙钛矿中结构相变的微观途径难以探测，因为它们发生在不同的时间和长度尺度上，并且因为通常用于直接探测相变的纳米级动力学的基于电子的显微镜经常损坏金属卤化物钙钛矿材料。使用原位纳米级阴极发光显微镜与低电子束曝光，我们可视化成核和生长的热驱动过渡到钙钛矿相在数百个非钙钛矿相纳米线。结合分子动力学模拟，我们发现，转换并不遵循一个简单的马氏体机制，但尽管通过离子扩散通过两个结构之间的液体状界面的实质性的能量障碍进行。虽然阳离子是无序的，在这个液体状的区域，卤素离子保持实质性的空间相关性。这幅详细的图片不仅揭示了不同结构之间的相变是如何进行的，而且还提供了控制这些过程的可能性。
Microscopic pathways of structural phase transitions inmetal halide perovskites are difficult to probe because they occur over disparate time and length scales and because electron-based microscopies typically used to directly probe nanoscale dynamics of phase transitions often damage metal halide perovskite materials. Using in situ nanoscale cathodoluminescence microscopy with low electron beam exposure, we visualize nucleation and growth in the thermally driven transition to the perovskite phase in hundreds of non-perovskite phase nanowires. In combination with molecular dynamics simulations, we reveal that the transformation does not follow a simple martensitic mechanism, but proceeds despite a substantial energy barrier via ion diffusion through a liquid-like interface between the two structures. While cations are disordered in this liquid-like region, the halide ions retain substantial spatial correlations. This detailed picture not only reveals how phase transitions between disparate structures can proceed, but also opens the possibility to control such processes.