Synthesis of Red Cesium Lead Bromoiodide Nanocrystals Chelating Phenylated Phosphine Ligands with Enhanced Stability

Two new phosphine ligands diphenylmethylphosphine (DPMP) and triphenylphosphine (TPP) were introduced onto cesium lead bromoiodide nanocrystals (CsPbBrI2 NCs) to improve air stability in the ambient atmosphere. Incorporating DPMP or TPP ligands can also enhance film-forming and optoelectronic properties of the CsPbBrI2 NCs. The results reveal that DPMP is a better ligand to stabilize the emission of CsPbBrI2 NCs than TPP after 21 days storage. The increased carrier lifetime and PLQY of perovskite NCs is due to the surface passivation by DPMP or TPP ligands, which reduces non-radiative recombination at the trap sites. The DPMP and TPP-treated CsPbBrI2 NCs were successfully utilized as the red emitter for fabricating perovskite light emitting diodes with enhanced performance and prolonged device lifetime relative to the pristine one.