Fabricating CsPbX3-Based Type I and Type II Heterostructures by Tuning the Halide Composition of Janus CsPbX3/ZrO2 Nanocrystals

Fabricating CsPbX 3 -based heterostructures has proven to be a feasible way to tune their photophysical properties. Here, we report the successful fabrication of Janus CsPbX 3 /ZrO 2 heterostructure nanocrystals (NCs), in which each CsPbX 3 NC is partially covered by ZrO 2 . According to the band alignment, CsPbBr 3 /ZrO 2 and CsPbI 3 /ZrO 2 can be indexed as type I and type II composites, respectively. The type I composites display great enhancement in photoluminescence quantum yield (from 63 to 90%) and photoluminescence lifetime (from 12.9 to 66.1 ns) because of the charge carrier confinement and passivation effect provided by ZrO 2 . In contrast, the type II composites can be used in photocatalytic reduction of CO 2 because electrons and holes are effectively separated and accumulated in ZrO 2 and CsPbI 3, respectively, under irradiation. Janus CsPbBr 3 /ZrO 2 NCs showed a stability much higher than that of pristine CsPbBr 3 against polar solvent treatment. A stable and highly efficient light-emitting device with luminous efficiency up to 55 lm W –1 is fabricated by using CsPbBr 3 /ZrO 2 NCs as the green light source. This work may not only enrich the family of surface-passivated perovskite materials but also provide a good example for the rational design of specific composites in the metal halide perovskite field.