Oriented assembly of CdS nanocrystals via dynamic surface modification-tailored particle interaction.

The controlled assembly of quantum dots (QDs) remains a challenge due to the lack of in-depth understanding of the roles of ligand dynamics. In this study, tripods, particles, nanorods and nanoflowers of CdS with yellow, red and cyan PL emissions, respectively, were achieved through the coarsening of thioglycolic acid (TGA)-capped CdS QDs with a novel hydroxyl-TGA exchange procedure. Dynamic hydroxyl modification-induced aggregation and coalescence can help to describe the defects and the corresponding photoluminescence characteristics of these nanocrystals. A crystal growth model involving assembly and coalescence was developed to describe the crystal growth and the corresponding PL properties, where hydroxyl-motivated hydrogen-bonding interaction was used to explain the oriented assembly of CdS QDs.