Deliquescence Thresholds of Halide Perovskite Precursor Salts Govern Moisture Sensitivity

Abstract

Lead halide perovskite precursor salts exhibit deliquescence, where water spontaneously condenses from the air above a discrete onset relative humidity to form a saturated aqueous salt solution. FABr salts exhibit the lowest deliquescence relative humidity (DRH), followed by MABr, MAI/FAI, and finally the inorganic PbBr2/PbI2 and perovskite MAPbBr3, identifying deliquescence as a threshold process that may accelerate moisture-induced degradation at organohalide-rich, lead-deficient perovskite surfaces.