High‐Performance Green Quasi‐2D Perovskite Light‐Emitting Diodes via Passivated Defects

Abstract In next generation semiconductors, metal halide perovskite materials would replace traditional light‐emitting materials since their exceptional photoelectronic characteristics. The future development of perovskite light‐emitting diodes have generated challenges such as abundant surface or interfacial defects and exciton quenching. To overcome these challenges, the light‐emitting layer is modified utilizing benzimidazole/phosphine oxide hybrid 1,3,5‐tris(1‐(4‐(diphenylphenylphosphoryl)phenyl)‐1H‐benzo[d]imidazol‐2‐yl)benzene (TPOB) and 1,3,5‐tris(diphenylphosphoryl)benzene (TPO) with high triple energy state. It is demonstrated by X‐ray photoelectron spectroscopy results that the oxygen atoms in the P = O functional group of TPOB and TPO provided lone electron pairs coordinate to the unsaturated Pb²⁺ in turn led to a decrease in the electron cloud density of Pb²⁺ and Br‐, which can suppress defects. Additionally, this technique improved the morphology of film, reduced surface roughness, and facilitated carrier transport, all of which are crucial for achieving high‐emission efficiency. As a result, the optimal devices has EQEs of 16.20 (TPOB) and 20.48% (TPO), respectively. Furthermore, the devices demonstrated excellent reproducibility. Excitingly, the champion EQE value for the optimal device is 22.64%. Simultaneously, it can increase the stability of the devices and the lifetimes are increased from 1231 s (Pristine) to 5421 (TPOB) and 5631 s (TPO).