Water-induced dimensionality conversion from 3D perovskites to microwires and 2D hybrid halide perovskites

Important applications of hybrid organic-inorganic halide perovskites are closely related to their crystal organization leading to different electronic structures. Adapting the dimensionality in lead halide perovskites along with inherent quantum confinement effects in the building blocks of n layers of [MX6](4-) octahedral sheets can further influence the optoelectronic properties. The [MX6](4-) octahedral array defining the dimensionality is crucial for stability, exciton dynamics, bandgap energy, and charge transport. Here, we demonstrate the water-assisted formation of both microwires and 2D layered morphologies from 3D MAPbBr(3) microcubes through a dissociation-recrystallization process. Besides the systematic changes in the bandgap energy, our study reveals an effect on trap- and excito-assisted recombination life-times due to the changes in exciton binding energy along with a dependence on the structural confinement. We show the role and the importance of controlling the water and organic molecules in a precursor ionic solution which can induce and/or inhibit the growth confining the charge in one or two directions, leading to a change in the optical properties and exciton dynamics.