Long‐Lived and Highly Efficient TADF‐PhOLED with "(A)n–D–(A)n" Structured Terpyridine Electron‐Transporting Material. (2nd May 2018)

• Record Type: Journal Article
• Authors: Bian, Mengying; Zhang, Dongdong; Wang, Yuanxun; Chung, Yao‐Hsien; Liu, Yang; Ting, Hungkit; Duan, Lian; Chen, Zhijian; Bian, Zuqiang; Liu, Zhiwei; Xiao, Lixin
• Is Part Of: Advanced functional materials. Volume 28:Number 28(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-05-02
• Subjects: electron‐transporting -- long lifetime -- organic light‐emitting diodes -- phosphorescence -- terpyridine -- thermally activated delayed fluorescence; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201800429
• Languages: English
• ISSNs: 1616-301X

Abstract

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 ( T 1 = 2.5 eV) as well as enhances glass transition temperature ( T g = 195 °C) for better stability. By using tris[2‐( 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)2 tmd) 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. Abstract : A novel electron‐transporting material 27‐TPSF with a "(A)n –D–(A)n " structure is synthesized by combining electron‐withdrawing terpyridine moieties and rigid twisted spirobifluorene for achieving highly efficient and long lifetime (a half‐life of 6804 and 382 636 h at initial luminance of 1000 and 100 cd m −2, respectively) green thermally activated delayed fluorescence‐phosphorescent devices.