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 (NaPF6) is proposed. The introduction of PF6- 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 PF6- anions can pair with the uncoordinated Pb2+ cations of perovskites to passivate defects. As a result, the champion green PeLED modified with NaPF6 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. A passivation strategy using the bifunctional additive sodium hexafluorophosphate (NaPF6) is proposed. By adjusting the phase distribution and passivating the defect in the quasi-2D perovskite film, the champion green perovskite light-emitting diodes (PeLED) modified with NaPF6 exhibits a remarkable external quantum efficiency (EQE) of 20.13%, which represents a significant improvement compared with the 11.26% EQE of the control sample. image