Interfacial Synthesis of Ag₂S/ZnS Core/Shell Quantum Dots in a Droplet Microreactor

Coating a shell outside the silver chalcogenide quantum dots (QDs) is still difficult due to the large lattice mismatch between the core and the shell. In this work, benefited from the huge specific surface area of the droplets and the adsorption of nanoparticles (NPs) at the interface in a droplet microreactor, the problem was successfully solved. The Ag2S/ZnS core/shell QDs were rapidly synthesized by interfacial reaction for the first time in a droplet microreactor. By adjusting the concentration of precursors, the control of the shell thickness became workable. In addition, the quantum yield (QY) was improved approximately 20 times after growing a ZnS shell outside the Ag2S core. Besides, the effect of shell thickness on fluorescence was further studied, and it was found that only appropriate shell thickness could effectively improve fluorescence. The proposed method is novel, non-toxic and controllable, providing a new way for the synthesis of core/shell QDs.