Unraveling the Role of Ligands Adsorption/Desorption on Photoluminescence Blinking in Single Water-Soluble InP-Based Quantum Dots

Water-soluble quantum dots (QDs) face the challenges of photoluminescence (PL) blinking accompanied by photodegradation due to ligand desorption, which pose barriers to the implementation of QDs in their optical and optoelectronic applications. Here, we demonstrate the critical role of ligand adsorption/desorption dynamics in modulating PL blinking behaviors and photostability of water-soluble InP-based QDs at the single-dot level. Pre-adding excess ligands to water-soluble QDs can redirect ligand adsorption/desorption dynamics toward adsorption dominance and effectively passivate surface traps induced by dilution, converting PL blinking types from band-edge carrier blinking (BC-blinking) to Auger-blinking dominance. With increasing extra ligand concentration, the average on-fraction of single water-soluble QD elevates from 17.6% to 91.3%, achieving impressive nonblinking emission. Notably, single water-soluble InP-based QDs with unprecedented photostability under continuous irradiation have been achieved with extra ligands. Our results provide insights into ligand-regulated exciton dynamics in aqueous ecofriendly QDs and inspire promising developments in applications of single-molecule detection and single-photon sources.