Interface Nucleophilic Substitution Reaction-Driven Precise Growth of Ag₂Te Quantum Dots

Surface ligands of quantum dots (QDs) play pivotal roles in determining their optical properties and stability during the growth process. The stability and continuous growth of nanocrystals are crucial to precisely tuning their properties. However, the dilemma surrounding the stability of nanocrystals and their continuous growth remains unsolved, posing a formidable challenge. Herein, we have proposed a strategy for precise tuning of Ag2Te QD growth driven by nucleophilic substitution reaction (SN2) between surface-bound thiol ligands and halogenated hydrocarbons (RX, X = Cl, Br, I), prompted by the generation of silver halide precipitate. As a result, Ag2Te QDs with emission wavelengths precisely and continuously tunable in the range of 1176–2023 nm have been successfully synthesized in one pot. As the reaction advances, the quantity of the more strongly coordinating RS– gradually diminishes, while that of the weaker coordinating dioctyl sulfide gradually increases. This dynamic process enables the growth of the QDs. The rate of the SN2 reaction can be adjusted by varying the species and concentration of RX, as well as the amount of Ag species, significantly influencing the growth rate of the QDs, a crucial factor for resolving the dilemma between the stability and tunability of the QDs. Additionally, this proposed strategy holds the potential to modulate the properties of various nanoparticles through chemical reactions at the interfaces.