Long‐Lived and Highly Efficient TADF‐PhOLED with “(A)n–D–(A)n” Structured Terpyridine Electron‐Transporting Material |
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| Authors: | Mengying Bian Dongdong Zhang Yuanxun Wang Yao‐Hsien Chung Yang Liu Hungkit Ting Lian Duan Zhijian Chen Zuqiang Bian Zhiwei Liu Lixin Xiao |
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| Affiliation: | 1. State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing, P. R. China;2. Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, P. R. China;3. Valiant Corporation, Shandong, P. R. China;4. Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing, P. R. China;5. College of Physics and Electronics Engineering, Hengyang Normal University, Hengyang, P. R. China |
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| Abstract: | The electron‐transporting material (ETM) is one of the key factors to determine the efficiency and stability of organic light‐emitting diodes (OLEDs). A novel ETM with a “(Acceptor)n–Donor–(Acceptor)n” (“(A)n–D–(A)n”) structure, 2,7‐di(2,2′:6′,2″‐terpyridin]‐4′‐yl)‐9,9′‐spirobifluorene (27‐TPSF), is synthesized by combining electron‐withdrawing terpyridine (TPY) moieties and rigid twisted spirobifluorene, in which the TPY moieties facilitate electron transport and injection while the spirobifluorene moiety ensures high triplet energy (T1 = 2.5 eV) as well as enhances glass transition temperature (Tg = 195 °C) for better stability. By using tris2‐(p‐tolyl)pyridine]iridium(III) (Ir(mppy)3) as the emitter, the 27‐TPSF‐based device exhibits a maximum external quantum efficiency (ηext, max) of 24.5%, and a half‐life (T50) of 121, 6804, and 382 636 h at an initial luminance of 10 000, 1000, and 100 cd m?2, respectively, which are much better than the commercialized ETM of 9,10‐bis(6‐phenylpyridin‐3‐yl)anthracene (DPPyA). Furthermore, a higher efficiency, a ηext, max of 28.2% and a maximum power efficiency (ηPE, max) of 129.3 lm W?1, can be achieved by adopting bis(2‐phenylpyridine)iridium(III)(2,2,6,6‐tetramethylheptane‐3,5‐diketonate) (Ir(ppy)2tmd) as the emitter and 27‐TPSF as the ETM. These results indicate that the derivative of TPY to form “(A)n–D–(A)n” structure is a promising way to design an ETM with good comprehensive properties for OLEDs. |
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| Keywords: | electron‐transporting long lifetime organic light‐emitting diodes phosphorescence terpyridine thermally activated delayed fluorescence |
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