Study of the role of iodine in the degradation mechanism of hybrid perovskite crystals upon exposure to light and humidity

The Near edge x-ray absorption helps to identify fine structural changes, which are difficult to observe with a normal x-ray diffractometer. We have recently developed a new strategy to prepare hybrid perovskite (HPV) with improved optoelectronic properties and charge carrier lifetime. We hypothesize that these improvements originate from the high quality of the perovskite crystals. Specifically, we presume that improving the crystallinity of the HPV prevents the photoreduction of Pb2+ to Pb0 and protects the HPV layer from further degradation. To verify this hypothesis, this proposal aims to investigate (1) the coordination environment of Pb and I as well as their oxidation state using XAS and (2) the crystallinity of the HPV thin films upon moisture and light exposure using GIWAXS.