Hig-Performance Green Quasi-2D Perovskite Light-Emitting Diodes via Passivated Defects

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).