牛津大学Laura M. Herz团队通过原子分辨率扫描透射电子显微镜获得了金属卤化物钙钛矿材料的原子尺度微观结构。 这一研究成果于2020年10月30日发表在《科学》上。

原子分辨率扫描透射电子显微镜为许多晶态太阳能电池材料提供了非常有价值的见解，因此课题组成功地用这一方法以低剂量的电子辐照对甲脒铅碘[CH(NH₂)₂PbI₃]薄膜进行了成像。这些图片揭示了具有锐利晶界和连贯的钙钛矿/ PbI₂界面的高度有序的原子排列，令人印象深刻的是，在晶体中没有观察到长程无序性。

研究人员还发现，电子束诱导的钙钛矿降解导致甲脒[CH(NH₂)₂]离子的初始损失，留下了部分未填充的钙钛矿晶格，这解释了这些材料与众不同的再生特性。他们还观察到排成一列的点缺陷和攀移位错。他们的发现为工业中重要的卤化物钙钛矿提供了原子级别的理解。

据了解，有机-无机杂化钙钛矿是一种很有潜力的太阳能材料，但人们对其微观性质仍知之甚少。

附：英文原文

Title: Atomic-scale microstructure of metal halide perovskite

Author: Mathias Uller Rothmann, Judy S. Kim, Juliane Borchert, Kilian B. Lohmann, Colum M. O’Leary, Alex A. Sheader, Laura Clark, Henry J. Snaith, Michael B. Johnston, Peter D. Nellist, Laura M. Herz

Issue&Volume: 2020/10/30

Abstract: Hybrid organic-inorganic perovskites have high potential as materials for solar energy applications, but their microscopic properties are still not well understood. Atomic-resolution scanning transmission electron microscopy has provided invaluable insights for many crystalline solar cell materials, and we used this method to successfully image formamidinium lead triiodide [CH(NH2)2PbI3] thin films with a low dose of electron irradiation. Such images reveal a highly ordered atomic arrangement of sharp grain boundaries and coherent perovskite/PbI2 interfaces, with a striking absence of long-range disorder in the crystal. We found that beam-induced degradation of the perovskite leads to an initial loss of formamidinium [CH(NH2)2+] ions, leaving behind a partially unoccupied perovskite lattice, which explains the unusual regenerative properties of these materials. We further observed aligned point defects and climb-dissociated dislocations. Our findings thus provide an atomic-level understanding of technologically important lead halide perovskites.

DOI: 10.1126/science.abb5940

Source: https://science.sciencemag.org/content/370/6516/eabb5940