Muon Studies of Ion Diffusion in Single-Crystal Photovoltaic Materials Under Illumination

In recent years, the family of lead halide perovskite materials (e.g. MAPbI3) has attracted substantial interest due to their unique combination of properties and potential solar cell, light emitting diode, and laser applications. One of the issues with these materials is to keep high efficiency during operation i.e. life-time problems. One of the main reasons behind such degradation has been identified as ion-diffusion causing inhomogeneities in the chemical composition, especially at surfaces and interfaces within the device. This proposed project aims to study the true intrinsic Clrorine and Bromine ion diffusion process in high-quality single crystalline samples of MAPbI3 and MAPbBr3 using our own developed muon spin rotation (muSR) technique. We will study the Iodine and Bromide ion diffusion in operando (under light illumination) on these single crystal samples.