Sulfonic Acid Ligands Promote Surface Reconstruction of Perovskite Quantum Dots for High-Performance Light-Emitting Diodes

Perovskite quantum dots (PQDs) have emerged as promising candidates for next-generation high-quality lighting and high-definition displays due to their outstanding luminescence properties, characterized by a narrow emission spectrum and tunable color. However, during the purification process involving polar solvents, ligand detachment from the quantum dot surface often induces crystal defects, thereby compromising their long-term stability. Herein, the effects of various post-processing strategies on PQD performance are systematically explored, including the use of oleic acid (OA), didodecyldimethylammonium bromide (DDAB), and their combinations, alongside OA-assisted synthesis. Furthermore, a synergistic post-processing strategy based on DDAB-NaMeS (sodium methanesulfonate) is proposed to elucidate the mechanism of ligand reconstruction on the quantum dot surface during purification. The resulting PQDs demonstrated excellent stability over a storage period exceeding one month, and the corresponding Quantum Dots Light-Emitting Diodes (QLEDs) achieved a peak external quantum efficiency (EQE) of 9.82%, representing a 1.91-fold improvement over standard devices. These QLEDs exhibited exceptional optoelectronic performance, underscoring their potential for application in other sulfonic acid ligands and perovskite-based materials.