Aromatic Lewis-Base-Assisted Ligand Cleaning Strategy Enables Suppression of Nonradiative Recombination in Blue...

Currently, blue perovskite quantum dot light-emitting diodes (PQLEDs) significantly underperform compared to their red and green counterparts. The development of efficient blue PQLEDs remains a critical challenge for full-color display applications. One major obstacle associated with blue-emitting CsPbBr_xCl_3-x PQDs resides in their ligand purification procedure required for eliminating insulating ligands, since this process often introduces additional surface defects and aggravates nonradiative recombination. Here, a Lewis-base-assisted purification strategy employing short-chain aromatic phenylmethylsulfonyl fluoride or benzyl thiocyanate is developed. These strongly electron-donating molecules passivate surface defects and enhance optoelectronic properties by coordinating with the unsaturated Pb²⁺ exposed as the desorption of inherent long-chain insulating ligands during the purification process. Resultantly, blue PQDs with a near-unity photoluminescence quantum yield are achieved, and the external quantum efficiency of corresponding PQLEDs increases from 5.75% to 13.80%. This work provides an effective ligand management strategy for high-performance blue PQLEDs and advances their application in full-color displays.