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Research Article

Quantum-dot light-emitting diodes with Fermi-level pinning at the hole-injection/hole-transporting interfaces

Maopeng Xu1,§, Desui Chen1,§, Jian Lin2,§, Xiuyuan Lu1, Yunzhou Deng1, Siyu He1, Xitong Zhu1, Wangxiao Jin1, Yizheng Jin1( )
Zhejiang Key Laboratory for Excited-State Materials, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
School of Materials Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China

§ Maopeng Xu, Desui Chen, and Jian Lin contributed equally to this work.

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Graphical Abstract

For the quantum-dot light-emitting diodes (QLEDs) with Fermi-level pinning at the holeinjection/hole-transporting interface, despite the same hole-injection barriers, hole-injection layers (HILs) with higher work functions are beneficial for improving device performance.

Abstract

Quantum-dot light-emitting diodes (QLEDs) are multilayer electroluminescent devices promising for next-generation display and solid-state-lighting technologies. In the state-of-the-art QLEDs, hole-injection layers (HILs) with high work functions are generally used to achieve efficient hole injection. In these devices, Fermi-level pinning, a phenomenon often observed in heterojunctions involving organic semiconductors, can take place in the hole-injection/hole-transporting interfaces. However, an in-depth understanding of the impacts of Fermi-level pinning at the hole-injection/hole-transporting interfaces on the operation and performance of QLEDs is still lacking. Here, we develop a set of NiOx HILs with controlled work functions of 5.2–5.9 eV to investigate QLEDs with Fermi-level pinning at the hole-injection/hole-transporting interfaces. The results show that despite that Fermi-level pinning induces identical apparent hole-injection barriers, the red QLEDs using HILs with higher work functions show improved efficiency roll-off and better operational stability. Remarkably, the devices using the NiOx HILs with a work function of 5.9 eV demonstrate a peak external quantum efficiency of ~ 18.0% and a long T95 operational lifetime of 8,800 h at 1,000 cd·m−2, representing the best-performing QLEDs with inorganic HILs. Our work provides a key design principle for future developments of the hole-injection/hole-transporting interfaces of QLEDs.

Keywords

quantum-dot light-emitting diodesFermi-level pinninghole-injection/hole-transporting interfaceswork functionperformance

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Nano Research
Volume 15 Issue 8,
August 2022
Pages 7453-7459
DOI: 10.1007/s12274-022-4260-3
Cite this article:
Xu M, Chen D, Lin J, et al. Quantum-dot light-emitting diodes with Fermi-level pinning at the hole-injection/hole-transporting interfaces. Nano Research, 2022, 15(8): 7453-7459. https://doi.org/10.1007/s12274-022-4260-3
Topics:
QuantumLight emitting diodes

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Received: 30 November 2021
Revised: 03 February 2022
Accepted: 18 February 2022
Published: 04 April 2022
© Tsinghua University Press 2022
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