Angewandte Chemie International Edition · 2018 · 110 citations · 28 references
Mixed organolead halide perovskites (MOHPs), CH<sub>3</sub> NH<sub>3</sub> Pb(Br<sub>x</sub> I<sub>1-x</sub> )<sub>3</sub> , have been shown to undergo phase segregation into iodide-rich domains under illumination, which presents a major challenge to their development for photovoltaic and light-emitting devices. Recent work suggested that phase-segregated domains are localized at crystal boundaries, driving investigations into the role of edge structure and the growth of larger crystals with reduced surface area. Herein, a method for growing large (30×30×1 μm<sup>3</sup> ) monocrystalline MAPb(Br<sub>x</sub> I<sub>1-x</sub> )<sub>3</sub> single crystals is presented. The direct visualization of the growth of nanocluster-like I-rich domains throughout the entire crystal revealed that grain boundaries are not required for this transformation. Narrowband fluorescence imaging and time-resolved spectroscopy provided new insight into the nature of the phase-segregated domains and the collective impact on the optoelectronic properties.
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