Organometal halide perovskites of general composition CH3NH3PbX3 (X = I, Br, Cl) have drawn great attention as photovoltaic materials as well as fluorophores due to their low cost and unique photophysical properties. Compositional substitution and dimensional manipulation can enhance the stability of perovskite crystals against moisture, heat and light, which in turn promotes their performance in optoelectronic devices. In this study, we combine composition-control with dimensionality-control of organometal halide perovskite crystals by tuning halide-incorporation and exploiting bulky alkylammonium cations as capping ligands. We demonstrate a systematic synthesis of all the series of mixed halide perovskite polycrystals and their low dimensional analogues. Both structural and optical properties exhibit a non-linear relationship between synthetic loadings vs. compositions, which to our knowledge has not been reported yet. We speculate this non-linear behavior is caused by the differences in structure phases, halide radii, precursor reactivities, lattice entropies and precursor solubilities. Also, by optimizing synthetic conditions, we are able to inhibit the appearance of a reversible photoinduced PL peak derived from surface traps.

Mixed halide organolead perovskites: Dimensionality control and role of excess precursor on photoluminescence stability

251st National Meeting (2016)

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