The Photochemical Stability of PbI2 and PbBr2: Optical and XPS and DFT Studies

We investigated the photochemical stability of PbX2 (X = I and Br) halides by optical X-ray photoelectron spectroscopy (XPS). The absorbance displayed a strong reduction for PbI2 with light soaking permanent behavior PbBr2. XPS survey spectra showed sharp drop in I:Pb ratio from 1.63 to 1.14 exposure time 0 1000 h while PbBr2, it remains practically unchanged (1.59–1.55). measurements Pb 4f 5d have shown partial photolysis release metallic lead whereas PbBr2 demonstrated remarkable stability. According density functional theory (DFT), calculations metal iodide vacancy formation energies are higher than which confirms better soaking. high means that can be used as excess under MAPbBr3 perovskite synthesis improve not only power conversion efficiency but also