BF4⁻ surface treatment enhancing stability of CsPbBr3 nanocrystals for Rec. 2020 ultra-wide color gamut green perovskite LEDs

Surface treatment with NaBF 4 effectively reduces surface defects of CsPbBr 3 nanocrystals. • Anions in NaBF 4 replace original carboxylate ligands via strong coordination with surface cations. • NaBF 4 -treated CsPbBr 3 nanocrystals achieve high PLQY of 93.71% and good stability. • NaBF 4 -treated PeLEDs show CIE coordinates of (0.10, 0.73), meeting Rec.2020 standard. Surface defect passivation is critical for improving the luminescence performance and stability of CsPbBr 3 perovskite nanocrystals (NCs) toward high-performance perovskite light-emitting diodes. Herein, a facile and efficient room-temperature surface treatment strategy using NaBF 4 is proposed to synergistically enhance the optical properties and environmental stability of CsPbBr 3 NCs prepared via a modified ligand-assisted reprecipitation method. Through the strong coordination interaction between F atoms in BF 4 − anions and surface Pb 2+ ions, the weakly bound carboxylate ligands are replaced, effectively passivating surface defects without altering the cubic perovskite crystal structure. Consequently, the photoluminescence quantum yield is remarkably improved from 72.44% to 93.71%. Moreover, the treated NCs exhibit significantly enhanced thermal stability with PL intensity retention of 65.55% at 350 K, ethanol tolerance with 89.51% retention after 360 min, and photostability under continuous UV irradiation. PeLED devices based on the treated NCs achieve a maximum brightness of 7536 cd/m 2 and an external quantum efficiency of 6.50%, with emission centered at 514 nm and CIE coordinates of (0.10, 0.73) satisfying the Rec. 2020 ultra-wide color gamut standard. This work demonstrates that NaBF 4 surface treatment provides a practical and viable pathway toward high-performance and long-lifetime PeLEDs. Download: Download high-res image (148KB) Download: Download full-size image