Bifunctional Molecule for Highly Efficient Green Perovskite Light‐Emitting Diodes

Abstract 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.