Improved Efficiency of All-Inorganic Quantum-Dot Light-Emitting Diodes via Interface Engineering

Qiulei Xu; Xinyu Li; Qingli Lin; Huaibin Shen; Hongzhe Wang; Zuliang Du

doi:10.3389/fchem.2020.00265

Improved Efficiency of All-Inorganic Quantum-Dot Light-Emitting Diodes via Interface Engineering

Front Chem. 2020 Apr 23:8:265. doi: 10.3389/fchem.2020.00265. eCollection 2020.

Authors

Qiulei Xu¹, Xinyu Li¹, Qingli Lin¹, Huaibin Shen¹, Hongzhe Wang¹, Zuliang Du¹

Affiliation

¹ Key Lab for Special Functional Materials, Ministry of Education, National and Local Joint Engineering Research Center for High-Efficiency Display and Lighting Technology, Collaborative Innovation Center of Nano Functional Materials and Applications, School of Materials Science and Engineering, Henan University, Kaifeng, China.

Abstract

As the charge transport layer of quantum dot (QD) light-emitting diodes (QLEDs), metal oxides are expected to be more stable compared with organic materials. However, the efficiency of metal oxide-based all-inorganic QLEDs is still far behind that of organic-inorganic hybrid ones. The main reason is the strong interaction between metal oxide and QDs leading to the emission quenching of QDs. Here, we demonstrated nickel oxide (NiO_x)-based all-inorganic QLEDs with a maximum current efficiency of 20.4 cd A^-1 and external quantum efficiency (EQE) of 5.5%, which is among the most efficient all-inorganic QLEDs. The high efficiency is mainly attributed to the aluminum oxide (Al₂O₃) deposited at the NiO_x/QDs interface to suppress the strong quenching effect of NiO_x on the QD emission, together with the molybdenum oxide (MoO_x) that reduced the leakage current and facilitated hole injection, more than 300% enhancement was achieved compared with the pristine NiO_x-based QLEDs. Our study confirmed the effect of decorating the NiO_x/QDs interface on the performance enhancement of the all-inorganic QLEDs.

Keywords: NiOx; all-inorganic; high efficiency; light-emitting devices; quantum dots.