Bifunctional Molecule for Highly Efficient Green Perovskite Light-Emitting Diodes

Quasi-2D perovskites have emerged as a promising material for the fabrication of perovskite light-emitting diodes (PeLEDs) owing to their excellent photoelectronic properties. The realization of efficient PeLEDs relies critically on the effective energy transfer and radiation recombination in quasi-2D perovskites. However, the performance of PeLEDs is hindered by the disordered distribution of n-values and a large number of surface defects in quasi-2D perovskites, which significantly impacts their practical application and further development. Herein, a passivation strategy utilizing the bifunctional additive sodium hexafluorophosphate (NaPF 6 ) is proposed. The introduction of PF 6 − anions substantially inhibits the formation of low-n phases, which can accelerate the effective energy transfer within the quasi-2D perovskites. Furthermore, the lone electron pairs in PF 6 − anions can pair with the uncoordinated Pb 2+ cations of perovskites to passivate defects. As a result, the champion green PeLED modified with NaPF 6 exhibits a remarkable external quantum efficiency (EQE) of 20.13% and a current efficiency (CE) of 67.54 cd A −1 , which represents a significant improvement compared with the 11.26% EQE and the CE of 37.38 cd A −1 of the control sample.