Photo-induced charge transfert in Lead halide perovskites studied by Time Resolved XAS

Methylammonium Lead Iodide is a promising material due to its exceptional photovoltaic properties. These astonishing features have been overshadowed by a poor stability upon thermal and light radiation. TR- XRD and XAS have been used to unveil the main phenomena behind the long-range distortions that lead to phase degradation. Previously, Thermal- and TR- XRD have been carried out at ID09 with promising preliminary results showing a different behavior between thermal and photoinduced perturbations. This opens a window to further analyze the electronic changes induced on the sample by the elsewhere mentioned perturbations. In literature, electron transfer (from halide to lead) has been suggested as a trigger for lattice distortion (further conducting to degradation). For this purpose, TR- XRD will be performed with varying pump wavelength around the electronic gap in order to disentangle the material’s electronic response to lattice heating.

甲基碘化铅甲胺（Methylammonium Lead Iodide）因其优异的光伏性能而成为一种极具前景的材料。然而，其在热辐射与光辐射条件下稳定性较差，这一缺陷掩盖了上述卓越特性。时间分辨X射线衍射（TR-XRD）与X射线吸收光谱（XAS）已被用于揭示导致相降解的长程畸变背后的核心现象。此前，在ID09光束线开展了热XRD与TR-XRD实验，初步结果显示热扰动与光诱导扰动的行为存在差异，这一结果颇具研究前景。这为进一步分析上述扰动引发的样品电子结构变化提供了契机。文献指出，电子转移（从卤化物到铅）是晶格畸变（进而导致降解）的触发因素。为此，将在电子带隙附近改变泵浦波长进行TR-XRD实验，以厘清材料对晶格加热的电子响应机制。