Dual Ligand Strategy for Efficient and Stable Ag-In-Ga-S Aqueous Quantum Dots

In recent years, Ag-In-Ga-S (AIGS) quaternary quantum dots (QDs) have garnered significant attention as a novel class of environmentally friendly and non-toxic QDs. However, the hydrothermal synthesis method for aqueous QDs has been plagued by issues such as inconsistent size, subpar crystallinity, and low photoluminescence quantum yield (PLQY). Herein, we developed a dual ligand strategy based on the hard and soft acids and bases (HSAB) theory to synthesize  aqueous AIGS QDs with an impressive PLQY of up to 64.3%, currently the highest value among hydrothermal-synthesized uncoated  I-III-VI QDs. The QDs exhibit better crystallinity, narrow size distribution (3.07 ± 0.31 nm), and remarkable stability. The mechanism underlying this dual ligand strategy was further elucidated, shedding light on the distinct influences of different ligands on the growth of QDs. The high PLQY contributes to the further application of aqueous AIGS QDs in luminescent displays and the field of biology. Meanwhile, this ligand strategy has broad reference significance for efficient preparation of other water-soluble QDs.