How Methylammonium Iodide Reactant Size Affects Morphology and Defect Properties of Mechanochemically Synthesized MAPbI3 Powder

Methylammonium iodide (MAI) of different sizes is used to mechanochemically synthesize MAPbI₃ powder by planetary ball milling. Morphology and structural characterization reveal a clear trend of an increasing particle size and decreasing defect density in the perovskite powder with increasing MAI reactant size, which also affects the optoelectronic properties.

Abstract

Here, we investigate in detail the impact of the size of the methylammonium iodide (MAI) reactants in the mechanochemical powder synthesis of the halide perovskite methylammonium lead iodide (MAPbI₃). Morphology and structural characterizations by scanning electron microscopy and X-ray diffraction reveal that with increasing MAI reactant size, the particle size of the perovskite powder increases, while its defect density decreases, as suggested by nuclear quadrupole resonance spectroscopy and photoluminescence investigations. The reason for this behavior seems to be associated to the sensitive influence of the MAI size on the time durations of MAPbI₃ synthesis and delayed MAPbI₃ crushing stage during ball milling. Thus, our results emphasize the high importance the reactant properties have on the mechanochemical synthesis of halide perovskites and will contribute to enhance the reproducibility and control of the fabrication of halide perovskites in powder form.

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