Radiation Tolerance of Lead Halide Perovskite Films: An in Situ X-ray Scattering Study

Lead halide perovskites, known for their excellent optoelectronic properties, have found application in solar cells, LEDs, and photodetectors. One particularly promising application of these materials is in X-ray detectors. This requires a high degree of tolerance to the effects of ionizing radiation, and one of the main drawbacks of lead halide perovskites is their instability, with respect to a wide variety of environmental stimuli. Although we know a lot about how moisture, oxygen, and visible light affect and degrade the perovskite lattice, relatively little is known about the radiation tolerance of these materials. In this work, we discuss the effect of high-energy (15.12 keV) X-ray radiation on perovskites of various compositions. We use in situ GIWAXS (grazing incidence wide-angle X-ray scattering) to follow the structural changes that occur as the result of X-ray exposure in atmospheres of varying relative humidity. Perhaps surprisingly, we find that there is a low compositional and humidity dependence on the rate of radiation damage in perovskite films. An accumulating radiation dose is associated with increasing structural disorder including the formation of ion vacancies and Schottky defects. These results are an important first step in the design of robust, radiation-tolerant, and perovskite-based X-ray detectors.