Impact of Moisture on Mobility in Methylammonium Lead Iodide and Formamidinium Lead Iodide

The greatest remaining barrier to the commercialization of perovskite solar cells is their instability to ambient environmental conditions. While most studies of the electronic stability of perovskites employ finished devices, we here exploit the contactless characterization technique time-resolved microwave conductivity to probe electronic properties in the absence of encapsulation and interface effects. By tracking the mobility of charge carriers in two archetypal perovskite compounds, methylammonium lead iodide (MAPbI₃) and formamidinium lead iodide (FAPbI₃) under various conditions, we are able to make decisive statements about the role of water in the electronic performance of perovskites. Overall, we observe a strong negative correlation between hydration and mobility in MAPbI₃, but not in FAPbI₃. We anticipate that the data presented herein will serve as a valuable resource in future stability studies in perovskite solar cells and, ultimately, lead to more stable devices.