Surface ligand engineering involving fluorophenethyl ammonium for stable and strong emission CsPbBr3 quantum dots and high-performance QLEDs

Abstract

All-inorganic CsPbBr₃ perovskite quantum dots (CsPbBr₃ QDs) have become one of the most promising materials in the field of optoelectronics. However, the poor stability and low photoluminescence quantum yield (PLQY) of CsPbBr₃ QDs hinder their further applications. Herein, fluorinated aromatic ammonium bromide (fluorophenethyl ammonium bromide, FPEABr) is introduced in the synthesis of CsPbBr₃ QDs. The influence of the fluorination position (ortho, meta, and para) at the benzene ring on the optical properties and stability of CsPbBr₃ is systematically evaluated. The results indicate that the short fluorinated aromatic alkyl ammonium chain has been successfully adsorbed onto the surface of CsPbBr₃ QDs, and the bromine vacancy defects have been significantly reduced. Eventually, stable CsPbBr₃ QDs with a high PLQY (>90%) are achieved with the use of pFPEABr. Furthermore, the short chains of the ligand improved the carrier transport in the CsPbBr₃ QD film, and thus the surface treatment increases the maximum luminance of the corresponding perovskite quantum dot light-emitting diodes (QLEDs) from 531 to 1278 cd m⁻². The surface ligand engineering strategy involving the FPEABr ligand, in particular pFPEABr, actually provides a new direction for the future development of high-performance QLEDs.