High-Performance Quantum Dots with Synergistic Doping and Oxide Shell Protection Synthesized by Cation Exchange Conversion of Ternary-Composition Nanoparticles

The insertion of cation impurities into quantum dots (QDs) as a dopant has been proved to be an efficient way to tailor their optical, electronic, and magnetic properties; however, the low quantum yield (QY) and poor photostability strongly limit their further applications. We report a strategy to coat a thin oxide shell around the heterovalent doped QDs to enhance their QYs and photostabilities simultaneously. In the case of Ag⁺-doped CdS QDs, the controlled cation exchange reaction between Cd²⁺ and ternary Ag₃SbS₃ nanoparticles not only realizes the Ag⁺ doping in CdS QDs but also generates a thin Sb₂O₃ shell around the surface of the QDs. Enabled by such, as-prepared CdS:Ag@Sb₂O₃ QDs exhibited enhanced photostability and high QY of 66.5%. We envision that the findings presented here will inspire more novel protocols for advancing the practical applications of doped QDs.