Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Ultrapure green organic light-emitting diodes based on highly distorted fused π-conjugated molecular design

Nature Photonics volume 17, pages 280–285 (2023)Cite this article

Subjects

Abstract

Organic light-emitting diode (OLED) technology is promising for ultrahigh-definition displays and other applications, but further improvements in efficiency and colour purity are desired. Here, we designed and synthesized an ultrapure green emitter called DBTN-2, which is organoboron based and features a highly distorted fused π-conjugated molecular design. This design concept substantially reduces the relaxation energy between the geometries of the excited and ground states, leading to a full-width at half-maximum emission of only 20 nm. Furthermore, the different excitation characters of the singlet and triplet states enhance the spin–orbit couplings leading to highly efficient operation. The introduction of the multiple carbazole moieties gives rise to a charge-resonance-type excitation feature of the triplet states, thus resulting in a high density of the triplet states and a rate of reverse intersystem crossing (kRISC) as fast as 1.7 × 105 s−1. An ultrapure green OLED exploiting DBTN-2 as an emitter without optimized cavity effects and colour filters operated with Commission Internationale de l’Eclairage coordinates of (0.19, 0.74), satisfying the requirement for a commercial green OLED display. Moreover, in combination with a photoluminescence quantum yield of near 100% and a strong horizontal dipole orientation in the doped film, an excellent external quantum efficiency of 35.2% with suppressed efficiency roll-off is simultaneously obtained.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Chemical structure and theoretical results of DBTN-2.
Fig. 2: Photophysical properties of DBTN-2.
Fig. 3: EL performance of the OLED device based on DBTN-2.

Similar content being viewed by others

Data availability

The authors declare that all relevant data are included in the paper and its Supplementary Information.

References

  1. Chen, H. W. et al. Going beyond the limit of an LCD’s color gamut. Light Sci. Appl. 6, 17043 (2017).

    Article  Google Scholar 

  2. Steckel, J. S., Ho, J. & Coe-Sullivan, S. QDs generate light for next-generation displays features. Photon. Spectra 48, 55–61 (2014).

    Google Scholar 

  3. Zhu, R., Luo, Z., Chen, H., Dong, Y. & Wu, S. T. Realizing Rec. 2020 color gamut with quantum dot displays. Opt. Express 23, 23680–23693 (2015).

    Article  ADS  Google Scholar 

  4. Liu, Y. C., Li, C. S., Ren, Z. J., Yan, S. K. & Bryce, M. R. All-organic thermally activated delayed fluorescence materials for organic light-emitting diodes. Nat. Rev. Mater. 3, 18020 (2018).

    Article  ADS  Google Scholar 

  5. Xiao, L. et al. Recent progresses on materials for electrophosphorescent organic light-emitting devices. Adv. Mater. 23, 926–952 (2011).

    Article  Google Scholar 

  6. Xu, Y., Xu, P., Hu, D. & Ma, Y. Recent progress in hot exciton materials for organic light-emitting diodes. Chem. Soc. Rev. 50, 1030–1069 (2021).

    Article  Google Scholar 

  7. Ha, J. M., Hur, S. H., Pathak, A., Jeong, J. E. & Woo, H. Y. Recent advances in organic luminescent materials with narrowband emission. NPG Asia Mater. 13, 53 (2021).

    Article  ADS  Google Scholar 

  8. Sun, Y. & Forrest, S. R. Enhanced light out-coupling of organic light-emitting devices using embedded low-index grids. Nat. Photon. 2, 483–487 (2008).

    Article  Google Scholar 

  9. Reineke, S. et al. White organic light-emitting diodes with fluorescent tube efficiency. Nature 459, 234–238 (2009).

    Article  ADS  Google Scholar 

  10. Helander, M. G. et al. Chlorinated indium tin oxide electrodes with high work function for organic device compatibility. Science 332, 944–947 (2011).

    Article  ADS  Google Scholar 

  11. Hatakeyama, T. et al. Ultrapure blue thermally activated delayed fluorescence molecules: efficient HOMO–LUMO separation by the multiple resonance effect. Adv. Mater. 28, 2777–2781 (2016).

    Article  Google Scholar 

  12. Kondo, Y. et al. Narrowband deep-blue organic light-emitting diode featuring an organoboron-based emitter. Nat. Photon. 13, 678–683 (2019).

    Article  ADS  Google Scholar 

  13. Wei, J. et al. Indolo[3,2,1-jk]carbazole embedded multiple-resonance fluorophors for narrowband deep-blue electroluminescence with EQE ≈ 34.7% and CIEy ≈ 0.085. Angew. Chem. Int. Ed. 60, 12269–12273 (2021).

    Article  Google Scholar 

  14. Yang, M., Park, I. S. & Yasuda, T. Full-color, narrowband, and high-efficiency electroluminescence from boron and carbazole embedded polycyclic heteroaromatics. J. Am. Chem. Soc. 142, 19468–19472 (2020).

    Article  Google Scholar 

  15. Zhang, Y. et al. Multi-resonance deep-red emitters with shallow potential-energy surfaces to surpass energy-gap law. Angew. Chem. Int. Ed. 60, 20498–20503 (2021).

    Article  ADS  Google Scholar 

  16. Chan, C.-Y. et al. Stable pure-blue hyperfluorescence organic light-emitting diodes with high-efficiency and narrow emission. Nat. Photon. 15, 203–207 (2021).

    Article  ADS  Google Scholar 

  17. Jeon, S. O. et al. High-efficiency, long-lifetime deep-blue organic light-emitting diodes. Nat. Photon. 15, 208–215 (2021).

    Article  ADS  Google Scholar 

  18. Yang, M. et al. Wide-range color tuning of narrowband emission in multi-resonance organoboron delayed fluorescence materials through rational imine/amine functionalization. Angew. Chem. Int. Ed. 60, 23142–23147 (2021).

    Article  Google Scholar 

  19. Zhang, Y. et al. Achieving pure green electroluminescence with CIEy of 0.69 and EQE of 28.2% from an aza-fused multi-resonance emitter. Angew. Chem. Int. Ed. 59, 17499–17503 (2020).

    Article  Google Scholar 

  20. Ikeda, N. et al. Solution-processable pure green thermally activated delayed fluorescence emitter based on the multiple resonance effect. Adv. Mater. 32, 2004072 (2020).

    Article  Google Scholar 

  21. Cai, X. et al. Achieving 37.1% green electroluminescent efficiency and 0.09 eV full width at half maximum based on a ternary boron–oxygen–nitrogen embedded polycyclic aromatic system. Angew. Chem. Int. Ed. 61, e202200337 (2022).

  22. Pershin, A. et al. Highly emissive excitons with reduced exchange energy in thermally activated delayed fluorescent molecules. Nat. Commun. 10, 597 (2019).

    Article  ADS  Google Scholar 

  23. Baronas, P. et al. Helical molecular orbitals to induce spin–orbit coupling in oligoyne-bridged bifluorenes. J. Phys. Chem. Lett. 12, 6827–6833 (2021).

    Article  Google Scholar 

  24. Saltiel, J. & Kumar, V. K. Photophysics of diphenylacetylene: light from the “dark state”. J. Phys. Chem. A 116, 10548–10558 (2012).

    Article  Google Scholar 

  25. Bulashevich, K. A., Kulik, A. V. & Karpov, S. Y. Optimal ways of colour mixing for high-quality white-light LED sources. Phys. Status Solidi A 212, 914–919 (2015).

    Article  ADS  Google Scholar 

  26. Cui, L.-S. et al. Fast spin-flip enables efficient and stable organic electroluminescence from charge-transfer states. Nat. Photon. 14, 636–642 (2020).

    Article  MathSciNet  ADS  Google Scholar 

  27. Noda, H. et al. Critical role of intermediate electronic states for spin-flip processes in charge-transfer-type organic molecules with multiple donors and acceptors. Nat. Mater. 18, 1084–1090 (2019).

    Article  ADS  Google Scholar 

  28. Chen, X. K., Coropceanu, V. & Bredas, J. L. Assessing the nature of the charge-transfer electronic states in organic solar cells. Nat. Commun. 9, 5295 (2018).

    Article  ADS  Google Scholar 

  29. Huang, Y., Hsiang, E. L., Deng, M. Y. & Wu, S. T. Mini-LED, micro-LED and OLED displays: present status and future perspectives. Light Sci. Appl. 9, 105 (2020).

    Article  ADS  Google Scholar 

  30. Hsiang, E. L., Yang, Z., Yang, Q., Lan, Y. F. & Wu, S. T. Prospects and challenges of mini‐LED, OLED, and micro‐LED displays. J. Soc. Inf. Disp. 29, 446–465 (2021).

    Article  Google Scholar 

  31. Frisch, M. J. et al. Gaussian 16, revision C.01 (Gaussian, Inc., 2016).

  32. Neese, F., Wennmohs, F., Becker, U. & Riplinger, C. The ORCA quantum chemistry program package. J. Chem. Phys. 152, 224108 (2020).

    Article  ADS  Google Scholar 

Download references

Acknowledgements

This work was supported by the National Natural Science Foundation of China (grant numbers 52130304 (X.-H.Z.), 51821002 (X.-H.Z.), 52003185 (K.W.) and 52003186 (Y.-Z.S.)), the National Key Research and Development Program of China (grant numbers 2020YFA0714601 (K.W.) and 2020YFA0714604 (K.W.)), and Suzhou Key Laboratory of Functional Nano and Soft Materials, Collaborative Innovation Center of Suzhou Nano Science and Technology, the 111 Project (X.-H.Z.). X.-K.C. acknowledges the New Faculty Start-up Grant of the City University of Hong Kong (7200709 and 9610547), and the financial support from the Kyulux Inc.

Author information

Authors and Affiliations

  1. Institute of Functional Nano and Soft Materials (FUNSOM), Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, P. R. China

    Xiao-Chun Fan, Kai Wang, Ying-Chun Cheng, Jia Yu, Xian-Kai Chen & Xiao-Hong Zhang

  2. Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou, P. R. China

    Xiao-Chun Fan & Xiao-Hong Zhang

  3. Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, P. R. China

    Kai Wang

  4. School of Materials Science and Engineering, Suzhou University of Science and Technology, Suzhou, P. R. China

    Yi-Zhong Shi

  5. Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, Fukuoka, Japan

    Yi-Ting Lee & Chihaya Adachi

  6. Department of Chemistry, Department of Materials Science and Engineering, and Hong Kong Institute for Advanced Study, City University of Hong Kong, Hong Kong SAR, P. R. China

    Xian-Kai Chen

  7. International Institute for Carbon-Neutral Energy Research (I2CNER), Kyushu University, Fukuoka, Japan

    Chihaya Adachi

Authors
  1. Xiao-Chun Fan
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Kai Wang
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Yi-Zhong Shi
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Ying-Chun Cheng
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Yi-Ting Lee
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Jia Yu
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Xian-Kai Chen
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Chihaya Adachi
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Xiao-Hong Zhang
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

K.W., X.-K.C., C.A. and X.-H.Z. conceived the project. X.-K.C. carried out all of the theoretical simulations, and proposed the molecular-design concept. K.W. and X.-C.F. designed the compound and devices. X.-C.F. synthesized and characterized the organic compound with the help of Y.-Z.S. and Y.-C.C.; X.-C.F. performed the photophysical measurements and fabricated the OLED devices. Y.-T.L. measured the molecular orientation in the thin films. X.-C.F., K.W., X.-K.C., C.A. and X.-H.Z. wrote the manuscript. X.-H.Z. supervised the project. J.Y. commented on the manuscript. All authors discussed the results and commented on the final manuscript.

Corresponding authors

Correspondence to Kai Wang, Xian-Kai Chen, Chihaya Adachi or Xiao-Hong Zhang.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature Photonics thanks the anonymous reviewers for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figs. 1–16 and Tables 1–3.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Fan, XC., Wang, K., Shi, YZ. et al. Ultrapure green organic light-emitting diodes based on highly distorted fused π-conjugated molecular design. Nat. Photon. 17, 280–285 (2023). https://doi.org/10.1038/s41566-022-01106-8

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41566-022-01106-8

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing