Degradation and Self‐Healing of FAPbBr3 Perovskite under Soft‐X‐Ray Irradiation

Abstract The extensive use of perovskites as light absorbers calls for a deeper understanding of the interaction of these materials with light. Here, the evolution of the chemical and optoelectronic properties of formamidinium lead tri‐bromide (FAPbBr 3 ) films is tracked under the soft X‐ray beam of a high‐brilliance synchrotron source by photoemission spectroscopy and micro‐photoluminescence. Two contrasting processes are at play during the irradiation. The degradation of the material manifests with the formation of Pb 0 metallic clusters, loss of gaseous Br 2 , decrease and shift of the photoluminescence emission. The recovery of the photoluminescence signal for prolonged beam exposure times is ascribed to self‐healing of FAPbBr 3 , thanks to the re‐oxidation of Pb 0 and migration of FA + and Br − ions. This scenario is validated on FAPbBr 3 films treated by Ar + ion sputtering. The degradation/self‐healing effect, which is previously reported for irradiation up to the ultraviolet regime, has the potential of extending the lifetime of X‐ray detectors based on perovskites.