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The role of host–guest interactions in organic emitters employing MR-TADF

Nature Photonics volume 15, pages 780–786 (2021)Cite this article

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Abstract

Research into organic light emitters employing multiple resonance-induced thermally activated delayed fluorescence (MR-TADF) materials is presently attracting a great deal of attention due to the potential for efficient deep-blue emission. However, the origins and mechanisms of successful TADF are unclear, as many MR-TADF materials do not show TADF behaviour in solution, but only as particular pure solids. Here, an investigation into a well-known MR-TADF material, DABNA-1, together with other new MR materials (9H-quinolino[3,2,1-kl]phenothiazin-9-one (QPO) and 9H-quinolino-[3,2,1-kl]-phenothiazin-9-one 5,5-dioxide (QP3O)), yields new insights regarding the origin of TADF. Although a material system may support the concept of MR, inefficiency in both forward and reverse intersystem crossings forbids TADF unless a suitable host material allows an exciplex-like host–emitter interaction that boosts TADF. This boosted-TADF mechanism can be generalized to any fluorescence dye that lacks TADF in the photoluminescence measurement but has a thermally accessible S1–T1 energy gap, opening the way to high-performance organic light-emitting diodes.

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Fig. 1: The molecular structures of the MR-TADF materials in this study.
Fig. 2: Probing the transient interaction between host and DABNA-1 through pump–probe step-scan Fourier-transform UV–vis spectroscopy.
Fig. 3: Energy alignment and proposed interaction for DABNA-1 and mCBP.
Fig. 4: Energy alignment and proposed interaction for DABNA-1 and DPEPO.
Fig. 5: Schematic of state energy alignment.

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Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

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Acknowledgements

X.W., D.L., M.Z. and W.Z. acknowledge financial support from the National Natural Science Foundation of China (U1663229, 52073035), the Natural Science Foundation of Jiangsu Province (SBK2021020897), the Science and Technology Project of Changzhou University (ZMF20020429), Jiangsu Provincial Talents Project of High-Level Innovation and Entrepreneurship, the Top-notch Academic Programs Project (TAPP) for Polymeric Materials Science and Technology, and The Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions, Brand Specialty & Preponderant Discipline Construction Projects of Jiangsu Higher Education Institutions. B.-K.S., D.-G.C., C.-C.W., Z.-X.H., T.-C.L., C.-H.W., E.Y.L., W.-Y.H. and P.-T.C. acknowledge financial support from Ministry of Science and Technology (MOST), Taiwan.

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Author notes

  1. These authors contributed equally: Xiugang Wu, Bo-Kang Su.

Authors and Affiliations

  1. School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, Jiangsu Engineering Laboratory of Light-Electricity-Heat Energy-Converting Materials and Applications, Jiangsu Key Laboratories of Environment-Friendly Polymers, National Experimental Demonstration Center for Materials Science and Engineering, Changzhou University, Changzhou, China

    Xiugang Wu, Denghui Liu, Mengbing Zhu & Weiguo Zhu

  2. Department of Chemistry, National Taiwan University, Taipei, Taiwan

    Bo-Kang Su, Deng-Gao Chen, Zhi-Xuan Huang, Ta-Chun Lin, Cheng-Ham Wu & Pi-Tai Chou

  3. Department of Chemistry, National Normal Taiwan University, Taipei, Taiwan

    Chi-Chi Wu & Elise Y. Li

  4. Department of Optoelectronics and Materials Technology and Center of Excellence for Ocean Engineering, National Taiwan Ocean University, Keelung, Taiwan

    Wen-Yi Hung

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Contributions

W.-Y.H., W.Z. and P.-T.C. conceived the project. X.W., B.-K.S. and D.-G.C. conducted the experiments, analysed the data and wrote the manuscript. W.-Y.H. helped with fabrication of the vacuum-deposited films. D.L., C.-C.W., Z.-X.H., T.-C.L., C.-H.W, M.Z., E.Y.L. and W.-Y.H. assisted in the characterization of the structure and provided helpful discussions. All authors commented on the paper.

Corresponding authors

Correspondence to Wen-Yi Hung, Weiguo Zhu or Pi-Tai Chou.

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Additional information

Peer review information Nature Photonics thanks Fernando Dias and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–37 and Tables 1–6.

Supplementary Data 1

Crystal structure of QPO.

Supplementary Data 2

Crystallographic data of QPO.

Supplementary Data 3

Crystal structure A of QP3O.

Supplementary Data 4

Crystallographic data A of QP3O.

Supplementary Data 5

Crystal structure B of QP3O.

Supplementary Data 6

Crystallographic data B of QP3O.

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Wu, X., Su, BK., Chen, DG. et al. The role of host–guest interactions in organic emitters employing MR-TADF. Nat. Photon. 15, 780–786 (2021). https://doi.org/10.1038/s41566-021-00870-3

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