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

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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.

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Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (Nos. 91833303, 51911530155, 91733302, 22001187, and 52062019), the Key Research and Development Program of Zhejiang Province (No. 2020C01001) and the Natural Science Research Foundation of Jiangsu Higher Education Institutions (No. 20KJB150032).

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

Authors and Affiliations

  1. Zhejiang Key Laboratory for Excited-State Materials, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou, 310027, China

    Maopeng Xu, Desui Chen, Xiuyuan Lu, Yunzhou Deng, Siyu He, Xitong Zhu, Wangxiao Jin & Yizheng Jin

  2. School of Materials Science and Engineering, Suzhou University of Science and Technology, Suzhou, 215009, China

    Jian Lin

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  1. Maopeng Xu
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  2. Desui Chen
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Correspondence to Yizheng Jin.

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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 Res. 15, 7453–7459 (2022). https://doi.org/10.1007/s12274-022-4260-3

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