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Diboron compound-based organic light-emitting diodes with high efficiency and reduced efficiency roll-off

Nature Photonics volume 12, pages 235–240 (2018)Cite this article

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Abstract

Organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) materials are promising for the realization of highly efficient light emitters. However, such devices have so far suffered from efficiency roll-off at high luminance. Here, we report the design and synthesis of two diboron-based molecules, CzDBA and tBuCzDBA, which show excellent TADF properties and yield efficient OLEDs with very low efficiency roll-off. These donor–acceptor–donor (D–A–D) type and rod-like compounds concurrently generate TADF with a photoluminescence quantum yield of ~100% and an 84% horizontal dipole ratio in the thin film. A green OLED based on CzDBA exhibits a high external quantum efficiency of 37.8 ± 0.6%, a current efficiency of 139.6 ± 2.8 cd A−1 and a power efficiency of 121.6 ± 3.1 lm W−1 with an efficiency roll-off of only 0.3% at 1,000 cd m−2. The device has a peak emission wavelength of 528 nm and colour coordinates of the Commission International de l´Eclairage (CIE) of (0.31, 0.61), making it attractive for colour-display applications.

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Fig. 1: Synthetic route and theoretical results of DBA compounds.
Fig. 2: Photophysical properties of the DBA derivatives.
Fig. 3: Performance of optimized diboron-based OLEDs and measurement of molecular orientation.

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Acknowledgements

The authors gratefully acknowledge the financial support of the Ministry of Science and Technology (MOST 105-2633-M-007-003; MOST 106-2119-M-007-020; MOST 106-2745-M-007-001) and the Ministry of Education, Taiwan, and also thank the National Center for High-Performance Computing (Account number: u32chc04) of Taiwan for providing the computing time.

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Authors and Affiliations

  1. Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan

    Tien-Lin Wu, Min-Jie Huang, Chih-Chun Lin, Pei-Yun Huang, Rai-Shung Liu & Chien-Hong Cheng

  2. Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan

    Tsu-Yu Chou, Ren-Wu Chen-Cheng & Hao-Wu Lin

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Contributions

T.-L.W. and C.-H.C. contributed to the manuscript writing. T.-L.W. designed, synthesized and characterized the organoboron molecules, then measured and analysed their chemical and photophysical properties. M.-J.H. developed the theoretical calculation and performed the computational experiments. C.-C.L. designed the optimized OLED configuration, P.-Y.H. fabricated all of the OLED devices, measured the electroluminescence and prepared thin films. T.-Y.C. conducted the transient PL and low-temperature measurements, R.-W.C.-C. determined molecular emitting dipole orientations. H.-W.L. provided experimental methods and analysed the optical data. R.-S.L. and C.-H.C. provided the synthetic supports and suggestions. All authors discussed the progress of research and reviewed the manuscript.

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Correspondence to Hao-Wu Lin, Rai-Shung Liu or Chien-Hong Cheng.

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Wu, TL., Huang, MJ., Lin, CC. et al. Diboron compound-based organic light-emitting diodes with high efficiency and reduced efficiency roll-off. Nature Photon 12, 235–240 (2018). https://doi.org/10.1038/s41566-018-0112-9

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