Enhancement and recovery of photoluminescence and stability by multifunctional etching ligands treatment for perovskite nanocrystals

Multifunctional etching ligands cycle acid (CA) is introduced to improve the photoluminescence quantum yields, recover the luminescence emission, and enhance stabilities for perovskite nanocrystals (PNCs) and the white light-emitting diodes. Perovskite nanocrystals (PNCs) have recently become promising optoelectronic materials due to their excellent photophysical properties. However, the highly dynamic binding state between ligands and the surface of PNCs has severely restricted their luminescent properties and stabilities. In this work, 1,3-bisbenzyl-2-oxoimidazolidine-4,5-dicarboxylic acid (cycle acid, CA) is introduced as both an etchant and a ligand upon post-synthetic surface treatment of PNCs. By removing the imperfect octahedrons [PbX 6 ] 4− and passivating the surface defects synergistically, this treatment improves photoluminescence quantum yields from 76% to 95% and enhances the stability of PNCs against polar solvent, moisture, heat, and illumination. Meanwhile, CA can effectively and instantly recover the luminescence emission for aged PNCs. As a result, the CA-CsPbBr 3 PNCs and CA-CsPbI x Br 3− x PNCs are applied as color-converting layers on a blue LED chip for warm white light-emitting diodes (WLEDs) with a color coordinate of (0.41, 0.40). Importantly, the CA-based WLED device exhibits superior stability in operational conditions.