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Design,synthesis, and properties of polystyrene-based through-space charge transfer polymers: Effect of triplet energy level of electron donor moiety on delayed fluorescence and electroluminescence performance |
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| Authors: | Jun Hu Yufei Chang Fan Chen Qingqing Yang Shiyang Shao Lixiang Wang |
| Institution: | 1. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of sciences, Changchun, P. R. China
School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, P. R. China Contribution: Investigation (lead);2. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of sciences, Changchun, P. R. China School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, P. R. China Contribution: Methodology (lead);3. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of sciences, Changchun, P. R. China School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, P. R. China Contribution: Investigation (supporting);4. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of sciences, Changchun, P. R. China Contribution: Methodology (supporting);5. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of sciences, Changchun, P. R. China |
| Abstract: | Two kinds of polystyrene-based through-space charge transfer (TSCT) polymers consisting of spatially-separated acridan donor moieties bearing phenyl or naphthyl substituents and triazine acceptor moieties are designed and synthesized. It is found that TSCT polymers containing phenyl-substituted acridan donors exhibit high-lying singlet (S1) and triplet (T1) states with small singlet-triplet energy splitting (∆EST) of 0.04–0.05 eV, resulting in thermally activated delayed fluorescence (TADF) with reverse intersystem crossing rate constants of 1.1–1.2 × 106 s−1. In contrast, polymers bearing naphthyl-substituted acridan donors, although still having TSCT emission, exhibit no TADF effect because of the large ∆EST of 0.30–0.33 eV induced by low-lying locally excited T1 state of naphthyl donor moiety. Solution-processed organic light-emitting diodes using TSCT polymers containing phenyl-substituted acridan donors reveal sky-blue emission at 483 nm together with maximum external quantum efficiency (EQE) of 11.3%, which is about 30 times that of naphthyl-substituted counterpart with maximum EQE of 0.38%, shedding light on the importance of high triplet energy level of donor moiety on realizing TADF effect and high device efficiency for through-space charge transfer polymer. |
| Keywords: | delayed fluorescence donor-acceptor structure reverse intersystem crossing through-space charge transfer triplet energy level |