Fig. 5

Surface scanning electron microscopy (SEM) images at different loading times for a the low concentration of 0.038 M and b the high concentration of 0.063 M MAI solutions. Insets show photographs of the samples used for SEM measurement. Scale bars 500 nm. c Schematic of the perovskite solar cell configuration based on surface and cross-sectional SEM images, where large cuboid MAPbI₃ was formed on top of the mesoporous TiO₂ layer. Scale bar (SEM image), 1 μm. Reprinted with permission from Ref. [34]