Liquid water-induced growth of the 1D morphology of CH3NH3PbI3 hybrid perovskites†
We observed an in situ decomposition–recrystallization process of CH3NH3PbI3 from cuboid (3D) to needle-shaped (1D) morphology induced by liquid water interactions. All the reversible processes from dry to increasing the relative humidity to water condensation and to dry again lasted for a few minutes and occurred at T = 1 °C. The water-induced crystallization process occurred slowly and at ambient conditions by dropping the solution on a substrate; subsequently, a very long monohydrate microwire having a 1D crystal structure was formed, which fully and quickly reversed to a 3D perovskite structure. The growth driving force in the droplet involved a meniscus moving from the outward direction to the inward direction in the droplet, which incorporated an 1D assembly of [PbI6]4− octahedra intercalated with (CH3NH3·H2O)+ cations.