X-ray dose effects and strategies to mitigate beam damage in metal halide perovskites under high brilliance X-ray photon source

Metal halide perovskites are versatile photovoltaic and optoelectronic materials. However, they suffer from photo-structural-chemical instabilities whose intricacy requires state-of-the-art tools to investigate their properties and behavior under various conditions. In most cases, those tools strongly interact with the materials leading to undesirable transformations. This study addresses the damage caused by highly intense focused X-ray beams on hybrid organic-inorganic metal halide perovskites through a correlative multi-technique approach. Our results reveal that the damage after irradiation in the ((Cs, FAMA)Pb(Br, I)3) compound is prominent on iodine and organic components at the film surface, reducing their relative quantity. The sample morphology modifies with the formation of an excavated area, whose altered local optical properties indicate the formation of an optically inactive metal layer covering the surface. Interestingly, the bulk remains unaltered with the initial ion proportion demonstrated by the stable photoluminescence emission energy. Controlling the X-ray beam dose and environment - air, nitrogen, and cryogenic conditions - serves as a strategy to mitigate the dose harm. Hence, we combined a controlled X-ray dose with an inert N2 atmosphere to certify the conditions to probe metal halide perovskite properties while mitigating damage efficiently. Finally, we applied optimized conditions to investigate a perovskite compound using X-ray ptychography, reaching a 14-nm spatial resolution, an outcome that has never been attained so far.