Cu-Catalyzed Synthesis of CdZnSe–CdZnS Alloy Quantum Dots with Highly Tunable Emission

Fabrication of quantum dots (QDs) with emission covering a wide spectral region has been persistently intriguing because of their potentials in a range of practical applications such as biological labeling and imaging, solar cells, light-emitting diodes, and next-generation displays. In this work, we report the synthesis of CdZnSe–CdZnS core–shell alloy QDs through a Cu-catalyzed solid solution alloying strategy starting from CdSe–CdS core–shell QDs. The resulting CdZnSe–CdZnS alloy QDs exhibit emission profiles covering a wide wavelength range of 470–650 nm while maintaining high photoluminescence quantum yields. In addition, high morphological uniformity of the starting CdSe–CdS QDs can be largely retained in the final alloy QDs. We attribute this alloying process to the high mobility nature of Cu cations in Cd-chalcogenide crystals at elevated reaction temperatures, which allows Cu cations to act as transporting agents to transfer a Zn component into the CdSe–CdS QDs while maintaining the particle integrity. We show that this unique alloying strategy is independent of the shape of the starting QDs and can also be applied to the synthesis of CdZnSe–CdZnS nanorods. We anticipate that our study will instigate the synthesis of various high-quality alloy QDs and other alloy nanocrystals beyond what can be achieved currently.