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Efficient radical-based light-emitting diodes with doublet emission

Author

Listed:
  • Xin Ai

    (College of Chemistry, Jilin University)

  • Emrys W. Evans

    (University of Cambridge)

  • Shengzhi Dong

    (College of Chemistry, Jilin University)

  • Alexander J. Gillett

    (University of Cambridge)

  • Haoqing Guo

    (College of Chemistry, Jilin University)

  • Yingxin Chen

    (College of Chemistry, Jilin University)

  • Timothy J. H. Hele

    (University of Cambridge)

  • Richard H. Friend

    (University of Cambridge)

  • Feng Li

    (College of Chemistry, Jilin University
    University of Cambridge)

Abstract

Organic light-emitting diodes (OLEDs)1–5, quantum-dot-based LEDs6–10, perovskite-based LEDs11–13 and micro-LEDs14,15 have been championed to fabricate lightweight and flexible units for next-generation displays and active lighting. Although there are already some high-end commercial products based on OLEDs, costs must decrease whilst maintaining high operational efficiencies for the technology to realise wider impact. Here we demonstrate efficient action of radical-based OLEDs16, whose emission originates from a spin doublet, rather than a singlet or triplet exciton. While the emission process is still spin-allowed in these OLEDs, the efficiency limitations imposed by triplet excitons are circumvented for doublets. Using a luminescent radical emitter, we demonstrate an OLED with maximum external quantum efficiency of 27 per cent at a wavelength of 710 nanometres—the highest reported value for deep-red and infrared LEDs. For a standard closed-shell organic semiconductor, holes and electrons occupy the highest occupied and lowest unoccupied molecular orbitals (HOMOs and LUMOs), respectively, and recombine to form singlet or triplet excitons. Radical emitters have a singly occupied molecular orbital (SOMO) in the ground state, giving an overall spin-1/2 doublet. If—as expected on energetic grounds—both electrons and holes occupy this SOMO level, recombination returns the system to the ground state, giving no light emission. However, in our very efficient OLEDs, we achieve selective hole injection into the HOMO and electron injection to the SOMO to form the fluorescent doublet excited state with near-unity internal quantum efficiency.

Suggested Citation

  • Xin Ai & Emrys W. Evans & Shengzhi Dong & Alexander J. Gillett & Haoqing Guo & Yingxin Chen & Timothy J. H. Hele & Richard H. Friend & Feng Li, 2018. "Efficient radical-based light-emitting diodes with doublet emission," Nature, Nature, vol. 563(7732), pages 536-540, November.
  • Handle: RePEc:nat:nature:v:563:y:2018:i:7732:d:10.1038_s41586-018-0695-9
    DOI: 10.1038/s41586-018-0695-9
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    Citations

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    Cited by:

    1. Xin Li & Yi-Lin Wang & Chan Chen & Yan-Yan Ren & Ying-Feng Han, 2022. "A platform for blue-luminescent carbon-centered radicals," Nature Communications, Nature, vol. 13(1), pages 1-8, December.
    2. Xiao Zhang & Mingjian Zeng & Yewen Zhang & Chenyu Zhang & Zhisheng Gao & Fei He & Xudong Xue & Huanhuan Li & Ping Li & Gaozhan Xie & Hui Li & Xin Zhang & Ningning Guo & He Cheng & Ansheng Luo & Wei Zh, 2023. "Multicolor hyperafterglow from isolated fluorescence chromophores," Nature Communications, Nature, vol. 14(1), pages 1-9, December.
    3. Xiao-Xiang Chen & Jia-Tong Li & Yu-Hui Fang & Xin-Yu Deng & Xue-Qing Wang & Guangchao Liu & Yunfei Wang & Xiaodan Gu & Shang-Da Jiang & Ting Lei, 2022. "High-mobility semiconducting polymers with different spin ground states," Nature Communications, Nature, vol. 13(1), pages 1-9, December.
    4. Cao Fang & Chang Xu & Wei Zhang & Meng Zhou & Dong Tan & Lixia Qian & Daqiao Hu & Shan Jin & Manzhou Zhu, 2024. "Dual-quartet phosphorescent emission in the open-shell M1Ag13 (M = Pt, Pd) nanoclusters," Nature Communications, Nature, vol. 15(1), pages 1-10, December.
    5. Hong Xiang & Yongfu Li & Qinglong Liao & Lei Xia & Xiaodong Wu & Huang Zhou & Chunmei Li & Xing Fan, 2024. "Recent Advances in Smart Fabric-Type Wearable Electronics toward Comfortable Wearing," Energies, MDPI, vol. 17(11), pages 1-36, May.

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