Photon-Induced Reshaping in Perovskite Material Yields of Nanocrystals with Accurate Control of Size and Morphology.

Benefiting from morphology-/size-tunable optical features, nanocrystals have been considered promising candidates for display or lighting applications. To achieve selective characteristic emission, precise control in size and morphology is thus a prerequisite. Herein, we report that the nanosecond-pulsed laser irradiation induces CsPbBr reshaping, yielding precise control of size and morphology. Under 532 and 355 nm laser irradiation, polydisperse CsPbBr nanocrystals or raw micron powders can be reshaped into uniform sizes of 12 and 6 nm, respectively. Moreover, by tuning ligand composition, the morphology of reshaped nanocrystals can be manipulated, such as nanocubes, nanorods, or nanosheets. Results reveal that the reshaping process relies on striving for a delicate balance between energy deposition and heat dissipation under irradiation. A low dissipation rate leads to temperature rising and lattice breaking, which turn out to be the driving forces for reshaping. This feasible method provides a reliable, and scalable route toward preparation of perovskite functional nanocrystals.