Fig. 5: Mechanism exploration.

a Depth profile of N 1s peak in XPS spectra and b relative integral area of the MA signal peak in different etching time of pristine MAPbI3 and champion films. c Schematic illustration for the crystallization of MAPbI3 under the dual action of BHT and water. d 1H NMR spectra of MAPbI3+4% BHT and champion films. e Ratio of the relative integral area of H2O and DMSO-d6 from NMR results at different moisture-treated time