Regulating the Growth of Cesium Lead Bromide Quantum Dots at a Liquid/Liquid Interface Constrained in a Micropipette

Abstract Colloidal all‐inorganic lead halide perovskite quantum dots (QDs) are high‐performance light‐emitting materials with size‐dependent optical properties and can be readily synthesized by mixing ionic precursors. However, the low formation energy of the perovskite lattice makes their growth too fast to control under regular reaction conditions. Diffusion‐regulated CsPbBr 3 perovskite QD growth is reported on a nanometer‐sized liquid/liquid (L/L) interface supported in a micropipette tip without long‐chain organic ligands. The precursors are divided into two immiscible solutions across the L/L interface to avoid additional nucleation, and the QD growth kinetics are regulated by the constrained cationic diffusion field depending on the size of the micropipette tip. QDs with unprecedentedly small sizes (2.7 nm) are obtained due to the slowed‐down growth rates. The synthesis approach demonstrates the potential of micro‐controlled colloidal QD synthesis for mechanistic studies and micro‐fabrications.