Fig. 3. Orientation distribution and moisture-induced degradation distribution within the perovskite film.

80 × 20 μm² (length × depth) maps of a preferred orientations of the (100) perovskite peak, and b preferred orientations and the corresponding intensity of the (100) perovskite peak. Red and purple boxes in (a) indicate preferred orientations of the (100) perovskite plane at around 35^o and 64^o. c 80 × 20 μm² (length ×  depth) intensity maps of PbI₂ (100) peak. d Overlap between the orientation map of (100) perovskite peak and the intensity map of PbI₂ (100) peak in the same scan area. The blue and yellow boxes denote the perovskite degradation occurring at the grain surface, and at the grain boundary, respectively. e Schematic diagram shows the distribution of the preferred orientation angles. f Schematic illustration of numerous small grains with different orientations close to the bottom, replaced by large grains with dominant, emergent orientations. g Magnified images of the perovskite degradation region at the grain surface (blue box), and at the grain boundary (yellow box). Schematic illustration of h moisture degradation of the perovskite film and i the grain fragmentation at the degradation region.