Suppression of Interfacial Oxidation in Core/Shell InP Quantum Dots through Solvent Assisted Core-Etching Strategy for Efficient Green Light-Emitting Diodes

Indium phosphide (InP) quantum dots (QDs) are promising alternative heavy-metal CdSe QDs for light-emitting diode (LED) application. However, their highly reactive core surface is prone to oxidation, which reduces the photoluminescence quantum yield (PL QY) and impedes subsequent shell growth. Traditional etching methods using HF aqueous solution are problematic as water can induce reoxidation during or after etching. Herein, we present HF pyridine solution as a more effective etching reagent to enhance luminous properties of InP QDs. Pyridine molecules replace the bulky carboxyl ligand, reducing steric hindrance and allowing HF easier access to the core for removing surface oxides. This ligand exchange promotes rapid shell growth, minimizing core exposure to the reaction environment and thereby reoxidation risk. Consequently, the as-prepared core/shell QDs exhibit a high PL QY of ∼90%, and the corresponding LEDs achieve an external quantum efficiency of 15.4% along with a long operational lifetime of 6819 h, outperforming the control devices.