A Facile Heat-Up Strategy for Synthesizing InP/ZnSe/ZnS Quantum Dots

Colloidal InP/ZnSe/ZnS core/shell/shell quantum dots (QDs) have emerged as a leading alternative to Cd-based QDs. However, their synthesis is more complex because of the susceptibility of InP QDs to oxidation and surface defects. This necessitates a multistep, labor-intensive, layer-by-layer shell growth approach with intermediate surface treatment or etching steps to maintain interface quality and optical performance. Here, we present a simplified approach to the synthesis of InP/ZnSe/ZnS QDs, wherein all zinc precursors are introduced at the beginning along with InP QDs, followed by the sequential addition of chalcogenide precursors. It is demonstrated that heterogeneous shell growth is achieved via the consumption of monomers by the cores. Such a simplified strategy eliminates the need for successive zinc precursor injection during shell growth and yields highly photoluminescent (PL) green QDs (PL quantum yield = 75%, peak at 532 nm) with a narrow full width at half maximum (41 nm). The synthesized InP/ZnSe/ZnSeS/ZnS QDs exhibited stable multiexciton performance under high excitation fluence. We expect that, by simplifying the workflow and improving reproducibility, this strategy could become broadly applicable across InP-based and other core/shell chalcogenide systems.