p‑π Conjugated L‑Type Ligand for Pure-Red Perovskite Light-Emitting Diodes

High-performance pure-red perovskite light-emitting diodes (PeLEDs) with luminescence peaks around 630 nm are desirable for displays, yet the brightness and operational stability remain critical factors limiting their applications. Here, we report the high-luminance and long-life pure-red PeLEDs achieved by 4-fluorobenzenesulfonamide (4-FBSA) anchored CsPb­(Br/I)₃ nanocrystals (NCs). Theoretical simulation and experimental results confirm the p-π conjugated moiety, and electronegative atoms weaken the capability of nitrogen atoms to accept foreign protons, allowing 4-FBSA to act as an L-type ligand under the acid-amine circumstance and strongly coordinate with NC surface. The firmly bonded 4-FBSA not only passivates the surface defects but also enhances the luminescence stability of NCs. The resultant device exhibits a remarkable luminance of 21 590 cd m^–2, a peak efficiency of 21.8%, and an extended half-lifetime of 11.7 h with negligible spectral shifting and broadening during operation, signifying the advancement of the Rec.2020 pure-red PeLEDs with mix-halide perovskite emitters toward display applications.