New Insight into the Formation of Hybrid Perovskite Nanowires via Structure Directing Adducts

We report a facile preparation approach of MAPbBr3, MAPbCl3, or FAPbBr3 (where MA = CH3NH3+ and FA = CH(NH2)2+) perovskite nanowires via sequential synthesis of MAPbI3 and FAPbI3 nanowires with chemically controlled composition and morphologies followed by an exchange of halide anions. The nanowires formation sequence includes intermediate phases such as MAI-PbI2-DMF and FAI-PbI2-DMF (DMF = dimethylformamide) acting as structure directing agent. The 1D shape of the adduct is preserved during the conversion to perovskite. The adducts play the role of key precursors controlling the final product morphology. Systematic investigations of the observed phase transformations and morphology features on multiple length scales revealed the effectiveness of the suggested synthetic route utilizing an original pseudomorph formation mechanism of the 1D structures to produce partly oriented films and textured layers of the nanowires via only a few experimental steps.