Dual-Ligand Synergistic Passivation Strategy for High-Brightness Perovskite Quantum Dot Light-Emitting Diodes

Although high-efficiency perovskite quantum dots (PQDs)-based light-emitting diodes (PQLEDs) have been achieved, their brightness is still limited due to halogen element loss and surface ligand mismatch in PQDs. Here, to passivate surface vacancies and defects of CsPbBr3-based PQDs, we proposed a dual-ligand synergistic passivation (DSP) strategy, in which the alkaline metal ion Na+ was employed to couple with halogen ions, and the long-chain ligand oleic acid was utilized for in situ ligand compensation. By using this DSP strategy, the bromine vacancies (VBr) and defects on the surface of CsPbBr3-based PQDs were successfully passivated, leading to the PQDs showing a higher photoluminescence quantum yield, faster radiative recombination rate, and longer exciton lifetime than the unpassivated ones. As a result, the obtained CsPbBr3-based PQLEDs exhibited an impressive brightness of 160,900 cd m–2, which was 2.89 times higher than those of the unpassivated devices. To the best of our knowledge, this is the highest brightness ever reported for the PQLEDs. We believe that the demonstrated high-brightness PQLEDs may open a path for the design of higher-brightness PQLEDs.