Effective Small Organic Molecule as a Defect Passivator for Highly Efficient Quasi‐2D Perovskite Light‐Emitting Diodes

The use of a small organic molecular passivator is proven to be a successful strategy for producing higher‐performing quasi‐2D perovskite light‐emitting diodes (PeLEDs). The small organic molecule can passivate defects on the grain surround and surface of perovskite crystal structures, preventing nonradiative recombination and charge trapping. In this study, a new small organic additive called 2, 8‐dibromodibenzofuran (diBDF) is reported and examines its effectiveness as a passivating agent in high‐performance green quasi‐2D PeLEDs. The oxygen atom in diBDF, acting as a Lewis base, forms coordination bonds with uncoordinated Pb2+, so enhancing the performance of the device. In addition, the inclusion of diBDF in the quasi‐2D perovskite results in a decrease in the abundance of low‐n phases, hence facilitating efficient carrier mobility. Consequently, PeLED devices with high efficiency are successfully produced, exhibiting an external quantum efficiency of 19.9% at the emission wavelength of 517 nm and a peak current efficiency of 65.0 cd A‐1. This work presents an organic small molecule additive as passivation material for PeLEDs, which reduces the defect density in the perovskite crystal hence improves the external quantum efficiency and stability of devices. This strategy effectively enhances the performance of PeLEDs.