Promoting Energy Transfer Between Quasi‐2D Perovskite Layers Toward Highly Efficient Red Light‐Emitting Diodes
Xiangfei Liang, Zhe Liu, Jibin Zhang, Hongting Chen, Qing Gu, Wei Zhang, Chao Shen, Zijie Xiao, Yufei Wang, Ji-Hai Liao, Xuemiao Wen, Jianing Xie, Lijun Yao, Wanzhu Cai, Yueqi Mo, Jian Qing, Shi‐Jian Su, Lintao Hou
Abstract
Abstract Although tremendous progress has recently been made in quasi‐2D perovskite light‐emitting diodes (PeLEDs), the performance of red PeLEDs emitting at ≈650–660 nm, which have wide prospects for application in photodynamic therapy, is still limited by an inefficient energy transfer process between the quasi‐2D perovskite layers. Herein, a symmetric molecule of 3,3′‐(9H‐fluorene‐9,9‐diyl)dipropanamide (FDPA) is designed and developed with two functional acylamino groups and incorporated into the quasi‐2D perovskites as the additive for achieving high‐performance red PeLEDs. It is demonstrated that the agent can simultaneously diminish the van der Waals gaps between individual perovskite layers and passivate uncoordinated Pb 2+ related defects at the surface and grain boundaries of the quasi‐2D perovskites, which truly results in an efficient energy transfer in the quasi‐2D perovskite films. Consequently, the red PeLEDs emitting at 653 nm with a peak external quantum efficiency of 18.5% and a maximum luminance of 2545 cd m −2 are achieved, which is among the best performing red quasi‐2D PeLEDs emitting at ≈650–660 nm. This work opens a way to further improve the electroluminescence performance of red PeLEDs.