Visible Light-Driven Luminescence Evolution of CsPbBr3 Quantum Dots via Surface Reconstruction

Ligand exchange has been demonstrated as an efficient strategy to improve the photoluminescence quantum yield (PLQY) and stability of quantum dots (QDs). Long-term illumination can considerably accelerate the ligand desorption after ligand exchange because of the weak bonding between the ligand and QDs. Here, a novel light-driven luminescence evolution strategy in combination with ligand exchange is devised by using N-acetyl-l-cysteine (NAC) as a ligand. NAC is expected to coordinate with the uncoordinated Pb2+ to improve the bonding between NAC and QDs. Light illumination is employed to accelerate the digestive ripening process and realize the uniform distribution of QDs. On the basis of the synergistic effect of NAC ligand exchange and light illumination, the CsPbBr3 QDs show reduced surface defects with nearly 100% PLQY and remarkable stability in polar solvents. Furthermore, a white light-emitting diode is demonstrated with a high rendering index of 80.7 and color temperature of 5595 K.