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

Abstract 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.