Moisture annealing effect on CH3NH3PbI3 films deposited by solvent engineering method

Moisture has been reported to be positive for organic-inorganic halide perovskite films formation during their annealing process in several literatures. Here we report a comprehensive study of moisture effect on the annealing process of CH3NH3PbI3 films deposited by solvent engineering method. Perovskite intermediate phase films are deposited by spin coating in a glove box and then annealed in the glove box or air with different humidity. Different from previous reports, the presence of moisture dramatically deteriorates the film morphology, and too high humidity even retards the formation of the perovskite from its intermediate phase. However, the crystallinity, conductivity and optical properties of the films are greatly improved, which in turn contributes to a much better device performance. This work suggests that the effect of moisture annealing on perovskite films is closely related to the deposition method and composition, and the deterioration of surface morphology does not necessarily lead to worse device performance.