Eco-Friendly Strategy To Improve Durability and Stability of Zwitterionic Capping Ligand Colloidal CsPbBr₃ Nanocrystals

Long-chain zwitterionic ligands have been demonstrated to greatly improve the chemical durability of colloidal CsPbBr₃ nanocrystals (NCs) by the chelate effect. However, Br sources are toxic, and the reaction is so dynamic that it is hard to control the size of the crystal. We propose an eco-friendly strategy to improve the chemical durability of colloidal CsPbBr₃ NCs. Nontoxic, inexpensive, and directly available benzoyl bromine was used as the Br source, and tri-n-octylphosphine oxide was used as the adjuvant to control the reaction kinetics. Uniform, monodispersed NCs with a size of ∼11 nm were obtained. They had high photoluminescence quantum yields (PLQYs) of above 95% and, especially, showed strong stability against attack by polar solvents. The PLQY remained 80% even after 12 cycles of purification. Furthermore, after 24 h of continuous radiation by 405 nm laser, the photoluminescence (PL) intensity showed negligible decrease, and the wavelength and full width at half-maximum of PL had no significant change.