Boosting the Efficiency of NiO<sub><i>x</i></sub>-Based Perovskite Light-Emitting Diodes by Interface Engineering
Haoran Wang, Hao Yuan, Jiahao Yu, Chen Zhang, Kang Li, Mengqing You, Wenqiang Li, Jian Shao, Jun Wei, Xiaoyu Zhang, Rui Chen, Xuyong Yang, Weiwei Zhao
Abstract
Nickel oxide (NiOx) is a promising hole-transporting material for perovskite light-emitting diodes (PeLEDs) because of its low cost, excellent stability, and simple fabrication process. However, the electroluminescence efficiencies of NiOx-based PeLEDs are greatly limited by inefficient hole injection and exciton quenching at the NiOx–perovskite interfaces. Here, a novel interfacial engineering method with sodium dodecyl sulfate-oxygen plasma (SDS-OP) is demonstrated to simultaneously overcome the aforementioned issues. Experimental results reveal that a short OP treatment on the top of the SDS-coated NiOx significantly deepens the NiOx work function (from 4.23 to 4.85 eV) because of the formation of a large surface dipole, allowing for efficient hole injection. Moreover, the SDS-OP layer passivates the electronic surface trap states of perovskite films and suppresses the exciton quenching by NiOx. These improvements inhibit the nonradiative decays at the NiOx–perovskite interface. As a result, the external quantum efficiency of CsPbBr3 LEDs is increased from 0.052 to 2.5%; that of FAPbBr3 nanocrystals LEDs is increased from 5.6 to 7.6%.