Fig. 3

Thin-film stability. XRD patterns of perovskite thin films before and after exposure for 24, 48, and 72 h to light-soaking (1 sun) at approximately 45 ˚C and 80% RH: a CsSn_0.5Ge_0.5I₃, b CsSnI₃, c CsPbI₃, and d MAPbI₃. e Plots of relative XRD peak intensities vs. time from a to d