Highly bright and low turn-on voltage CsPbBr3 quantum dot LEDs via conjugation molecular ligand exchange

摘要

All-inorganic CsPbBr3 perovskite quantum dots (QDs) hold great promise as candidate materials for next-generation electroluminescent displays owing to their excellent optoelectronic properties.However,the long insulating ligands on the surface of CsPbBr3 QDs originating from the synthesis process hinder the fabrication of high-performance optoelectronic devices.Herein,an efficient ligand-exchange route is proposed with the use of perovskite-precursor-based halide ligands,including a series of phenalkylammonium bromides with a π-conjugation benzene ring and different branch lengths.Based on the ligand-exchange method,the conductivity of the CsPbBr3 QD layer is significantly improved owing to ligand shortening and the insertion of the π-conjugation benzene ring.As a result,high brightness (up to 12,650 cd/m2)and low tum-on voltage (as low as 2.66 V) can be realized in CsPbBr3 QD light-emitting diodes (QLEDs),leading to dramatic improvements in device performance with a current efficiency of 13.43 cd/A,power efficiency of 12.05 lm/W,and external quantum efficiency of 4.33％.