Figure 1.

Illustrations of possible phase transition processes in hybrid perovskite films via different annealing methods. a) The hotplate‐annealing process leads to a nonuniform temperature distribution from bottom to top, which makes the inhomogeneous nucleation of perovskite polycrystals, in meanwhile, long annealing period induces the formation of miscellaneous phases. b) The microwave‐annealing process can provide uniform annealing environment all‐around perovskite film, benefitting to accelerate processing duration and achieve fine‐quality perovskite film without miscellaneous phases.