Figure 3: SEM of the thin films.

(a) The PbI₂ film. (b) HPbI₃ film. (c) Controlled perovskite film by one-step method. (d–f) NABR prepared perovskite films with increasing amounts of CH₃NH₂: 0.3 ml (d), 0.35 ml (e) and 0.4 ml (f) MA in 1.5 M 1 ml HPbI₃. Scale bar, 5 μm (a), 10 μm (b–f).