Etching-Assisted Double-End Anchoring of Ligands for High-Performance CsPbBr3 Light-Emitting Diodes.

Perovskite nanocrystals (NCs) have emerged as highly promising emitters for light-emitting diodes (LEDs) owing to their outstanding luminescence properties, broadly tunable band structures, and intrinsically high color purity. Surface ligand engineering plays a crucial role in regulating the electroluminescent performance and device stability of perovskite NCs. Here, we develop a cooperative 2-(4-(methylsulfonyl)phenyl)ethylamine (MSPE)-hydrogen halide (HX, X = Br, I) ligand-exchange strategy that enables surface reconfiguration and robust passivation of perovskite NCs. In this approach, HX assists in removing insulating long-chain ligands (oleic acid and oleylamine), thereby exposing additional undercoordinated surface sites and promoting firm double-end anchoring of in situ protonated MSPE through bidentate interactions. Spectroscopic and electrical analyses reveal that the strengthened ligand-nanocrystal interface effectively suppresses trap-assisted nonradiative recombination, increases the exciton binding energy from 97.7 to 168.9 meV, prolongs the lifetime from 9.5 to 12.3 ns, and reduces trap densities in CsPbBr3 NC films. As a result, the photoluminescence quantum yield of CsPbBr3 NCs after MSPE-HBr treatment is enhanced to 96.1%, and LEDs fabricated with MSPE-HBr-treated NCs deliver a peak external quantum efficiency of 25.2% and display excellent device-to-device reproducibility. This cooperative ligand-exchange strategy provides an effective pathway for achieving high surface coverage of robust multidentate ligands, offering a promising route toward highly efficient and stable perovskite LEDs.