光活性卤化物钙钛矿中晶界、位错及相关应变的原子结构
Atomic Structure of Grain Boundaries, Dislocations and Associated Strain in Templated Co-evaporated Photoactive Halide Perovskites
AI总结：
研究通过低剂量电子显微镜技术揭示了模板化FA0.9Cs0.1PbI3-xClx薄膜的原子结构，发现其具有<001>轴的优先晶向取向，并揭示了高角和低角晶界、位错及应变场的特性，为理解缺陷对光伏器件性能的影响提供原子级见解。
摘要：
结构缺陷，特别是晶界，在决定金属卤化物钙钛矿的电荷输运和光电子性质中起关键作用，从而限制了器件性能。掺杂FA0.9Cs0.1PbI3-xClx的太阳能电池表现出显著的晶粒取向和稳态功率转换效率提升；然而，其内在机制仍不清楚。在本研究中，我们采用一系列定制化的低剂量电子显微镜技术来研究模板化FA0.9Cs0.1PbI3-xClx薄膜，发现其沿<001>轴具有优先的晶向取向，具有围绕该轴的任意晶粒旋转，表明Volmer-Weber生长机制。我们确定了所得到的高角度和低角度晶界的原子结构。我们还揭示了边缘位错及其相关应变场的存在，显示位错核心一侧的压缩应变和另一侧的拉伸应变。此外，我们发现与堆垛故障相关的位错。这些原子级的见解揭示了哪些晶界和晶内缺陷可能作为复合中心或修改带隙，这对于理解哪些缺陷影响钙钛矿太阳能电池器件性能至关重要。
英文摘要：
Structural defects, particularly grain boundaries, play a crucial role in governing charge transport and the optoelectronic properties of metal halide perovskites, thereby limiting the performance of devices. Solar cells incorporating templated FA0.9Cs0.1PbI3-xClx show significant improvements in grain orientation and steady-state power conversion efficiency; however, the underlying mechanisms remain unclear. In this study, we address this gap by employing a suite of tailored low-dose electron microscopy techniques to investigate the templated FA0.9Cs0.1PbI3-xClx film, revealing that it exhibits a preferred crystallographic orientation along the <001> zone axis, with arbitrary grain rotations about that axis, indicative of a Volmer-Weber growth mechanism. We determine the atomic structure of the resulting high-angle and low-angle grain boundaries. We also reveal the presence of edge dislocations and their associated strain fields, demonstrating the compressive strain on one side of the dislocation core and tensile strain on the opposite side. Furthermore, we find dislocations associated with stacking faults. These atomic-level insights uncover which grain boundaries and intra-grain defects are likely to act as recombination centres or modify band gaps, crucial for understanding which defects influence the performance of perovskite solar cell devices.
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