Fig. 2: Optimization of WBG perovskite films and buried interface.

a–d Top view and cross-sectional SEM images of perovskite films deposited on control, PA-, CA-, SA-based substrates, respectively. e, f The surface KPFM results and g, h AFM images of the perovskite films deposited on control and SA-based substrates, respectively. i–l PL mapping of the perovskite films deposited on control, PA-, CA-, and SA-based substrates, respectively.