Complete Suppression of Phase Segregation in Mixed-Halide Perovskite Nanocrystals under Periodic Heating

Under continuous light illumination, it is known that localized domains with segregated halide compositions form in semiconducting mixed-halide perovskites, thus severely limiting their optoelectronic applications due to the negative changes in bandgap energies and charge-carrier characteristics. Here mixed-halide perovskite CsPbBr1.2I1.8 nanocrystals are deposited onto an indium tin oxide substrate, whose temperature can be rapidly changed by approximate to 10 degrees C in a few seconds by applying or removing an external voltage. Such a sudden temperature change induces a temporary transition of CsPbBr1.2I1.8 nanocrystals from the segregated phase to the mixed phase, the latter of which can be permanently maintained when the light illumination is coupled with periodic heating cycles. These findings mark the emergence of a practical solution to the detrimental phase-segregation problem, given that a small temperature modulation is readily available in various fundamental studies and practical devices of mixed-halide perovskites. When mixed-halide CsPbBr1.2I1.8 nanocrystals are periodically heated with a temperature change of approximate to 10 degrees C, the phase-segregation effect can be completely suppressed even under strong light illumination. The above finding marks the emergence of a practical solution to the detrimental phase-segregation problem, given that a small temperature modulation is readily available in various fundamental and practical studies of mixed-halide perovskite nanocrystals.image