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.