Department of Earth Sciences, University of Firenze, Via G. La Pira 4, 50121 Firenze, Italy.
Department of Physics, Chalmers University of Technology, 412 96 Goteborg, Sweden.
J Phys Chem Lett. 2023 Mar 2;14(8):2178-2186. doi: 10.1021/acs.jpclett.3c00105. Epub 2023 Feb 21.
Tin-based metal halide perovskites with a composition of ASnX (where A= MA or FA and X = I or Br) have been investigated by means of X-ray total scattering techniques coupled to pair distribution function (PDF) analysis. These studies revealed that that none of the four perovskites has a cubic symmetry at the local scale and that a degree of increasing distortion is always present, in particular when the cation size is increased, i.e., from MA to FA, and the hardness of the anion is increased, i.e., from Br to I. Electronic structure calculations provided good agreement with experimental band gaps for the four perovskites when local dynamical distortions were included in the calculations. The averaged structure obtained from molecular dynamics simulations was consistent with experimental local structures determined via X-ray PDF, thus highlighting the robustness of computational modeling and strengthening the correlation between experimental and computational results.
采用 X 射线全散射技术结合配对分布函数（PDF）分析研究了组成式为 ASnX（其中 A=MA 或 FA，X=I 或 Br）的锡基卤化物钙钛矿。这些研究表明，在局部尺度上，这四种钙钛矿都没有立方对称性，而且总是存在一定程度的扭曲，特别是当阳离子尺寸增大，即从 MA 变为 FA，以及阴离子的硬度增大，即从 Br 变为 I 时。当计算中包含局部动力学扭曲时，电子结构计算与四种钙钛矿的实验能带隙吻合得很好。通过分子动力学模拟得到的平均结构与通过 X 射线 PDF 确定的实验局部结构一致，从而突出了计算建模的稳健性，并加强了实验和计算结果之间的相关性。
