A novel, eco‐friendly film preparation process for improving the stability of organometal halide perovskite in solar cells

A major challenge for outdoor uses of methylammonium lead halide (MAPbX3) solar cells is the poor durability of the perovskite film under humidity. This instability is due to limitations of the dipping or spin coating process in producing MAPbX3 films through a direct reaction between PbI2 and methylammonium iodide (MAI) in an organic solvent. In this study, we devised an eco‐friendly and cost‐effective method to fabricate MAPbX3 films using an aqueous solution of Pb(NO3)2 and MAI vapour. In both instances of using Pb(NO3)2 and PbI2, a perovskite layer with a tetrahedral structure was seen with a band gap of roughly 1.52‐1.54 eV. We discovered that the perovskite film grew at a slower rate with aqueous Pb(NO3)2 compared to that in PbI2 and disintegrated gradually at ambient temperature and 40% humidity. Compared to PbI2 films‐based solar cells under the same reaction time, those based on aqueous Pb(NO3)2 films showed remarkably higher durability (maintain 83% for Pb(NO3)2 films‐based, 78% for PbI2 films‐based after 720 hours) and greater photovoltaic efficiency with the photocurrent density of 10.1 mA.cm‐2, the voltage of 0.89 V, the fill factor of 0.82 and PCE of 7.4% which is higher than PbI2 cells 30%.