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High efficiency warm-white light-emitting diodes based on copper–iodide clusters

Nature Photonics volume 18, pages 200–206 (2024)Cite this article

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Abstract

Solution-processed light-emitting diodes (LEDs) based on copper–iodide clusters are promising candidates for solid state lightings due to their abundance, environmental friendliness and high luminescent efficiency. However, the development of this class of LEDs is hampered by the instability of the clusters, poor solution compatibility and low film quality, resulting in poor device performances. Here we report a new type of copper–iodide cluster hybrids with functional groups that facilitate both solubility and stability of the clusters. The hybrid clusters exhibit high structural stability in solvents, enabling smooth solution-processed thin films with low surface roughness of 0.22 nm and high photoluminescence quantum yields of over 70%. We employ the high-quality thin film as an emissive layer in warm-white LEDs, showing a maximum external quantum efficiency of 19.1%, maximum high brightness of over 40,000 cd m−2 and a good operational lifetime of 232 h (T50 at an initial luminance of 100 cd m−2). We also demonstrate a large-area LED with brightnesses of up to ~60,000 cd m−2 through blade-coating and a series of colour-tunable LEDs based on ligand modifications. Our results suggest great potential of copper–iodide cluster-based LEDs for practical applications in panel display and solid-state lighting.

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Fig. 1: Fabrication process and characteristics of the CuI-Pyrphos LED.
Fig. 2: Solubility and stability of CuI-Pyrphos in DMF.
Fig. 3: Characterizations of CuI-Pyrphos thin film and large-area solution-processed CuI-Pyrphos LED.
Fig. 4: The extended colour tunable CuI-ligand thin film and devices.

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Data availability

The data that support the findings of this study are available from the corresponding author on reasonable request. The X-ray crystallography data for CuI-Pyrphos structure have been deposited in Cambridge Crystallographic Data Centre (CCDC) under accession no. CCDC-2266353. The data can be obtained free of charge from the CCDC via http://www.ccdc.cam.ac.uk/data_request/cif.

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Acknowledgements

We acknowledge the financial support from the National Key Research and Development Program of China (grant no. 2022YFA1204800 to H.-B.Y.), the National Natural Science Foundation of China (grant nos. 22325505, 52073271, 22161142004 to H.-B.Y.; 62175226, 62234004 to Z.X.; and 52272167 to F.F.), the USTC Research Funds of the Double First-Class Initiative (grant no. YD2060002034 to H.-B.Y.), the Collaborative Innovation Program of Hefei Science Center, CAS (grant no. 2022HSC-CIP018 to H.-B.Y.) and Innovation Program for Quantum Science and Technology (grant no.2021ZD0301603 to F.F.). We thank J. Wang for helping us collect in situ PL/UV spectra and X. Chen for helping us test temperature dependent PLQY. We thank the support from the USTC Center for Micro and Nanoscale Research and Fabrication. We also thank the support from the USTC Supercomputing Center the computing resource and the National Synchrotron Radiation Laboratory (NSRL) in Hefei.

Author information

Author notes

  1. These authors contributed equally: Jing-Jing Wang, Li-Zhe Feng, Guangyi Shi, Jun-Nan Yang.

Authors and Affiliations

  1. Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, China

    Jing-Jing Wang, Li-Zhe Feng, Jun-Nan Yang, Kuang-Hui Song, Tian Chen & Hong-Bin Yao

  2. Department of Applied Chemistry, Hefei Science Center of Chinese Academy of Sciences, University of Science and Technology of China, Hefei, China

    Jing-Jing Wang, Li-Zhe Feng, Jun-Nan Yang, Yi-Da Zhang, Kuang-Hui Song, Tian Chen & Hong-Bin Yao

  3. School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou, China

    Jing-Jing Wang & Jun-Nan Yang

  4. CAS Key Laboratory of Strongly-coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, China

    Guangyi Shi & Zhengguo Xiao

  5. National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, China

    Yi-Da Zhang & Xu-Sheng Zheng

  6. CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei, China

    Huaiyu Xu & Fengjia Fan

  7. Hefei National Laboratory, University of Science and Technology of China, Hefei, China

    Huaiyu Xu & Fengjia Fan

  8. Hefei National Research Center for Physical Sciences at the Microscale, School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, China

    Guozhen Zhang

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Contributions

H.-B.Y. and J.-J.W. conceived the idea, designed the experiment, and analysed the data. J.-J.W. and L.-Z.F. synthesized the materials, performed characterizations and analysed the data. G.S., J.-N.Y. and Z.X. participated in the fabrication of LED devices and performed the performance tests. Y.-D.Z. and X.-S.Z. performed the XAS characterizations and analysed the data. H.X. and F.F. conducted the optical simulation for theoretical limit on outcoupling efficiency and maximum EQE. K.-H.S. and T.C. performed TEM and AFM characterizations and discussed the results. G.Z. performed DFT and TDDFT calculations and analysed the computational results. J.-J.W., L.-Z.F., G.S., J.-N.Y., G.Z. and H.-B.Y. co-wrote the manuscript. H.-B.Y. directed and supervised the project. All authors contributed to discussions and finalizing the manuscript.

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Correspondence to Hong-Bin Yao.

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Nature Photonics thanks Yizheng Jin, Tae-Woo Lee and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Figs. 1–21, Tables 1–5, references and experimental section.

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Wang, JJ., Feng, LZ., Shi, G. et al. High efficiency warm-white light-emitting diodes based on copper–iodide clusters. Nat. Photon. 18, 200–206 (2024). https://doi.org/10.1038/s41566-023-01340-8

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