1. Simply Structured Near‐Infrared Emitters with a Multicyano Linear Acceptor for Solution‐Processed Organic Light‐Emitting Diodes.
- Author
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Zhao, Bingjie, Xie, Guohua, Wang, Huiqin, Han, Chunmiao, and Xu, Hui
- Subjects
ORGANIC light emitting diodes ,CRYSTAL structure ,SOLUTION (Chemistry) ,DELAYED fluorescence ,ELECTRON donor-acceptor complexes - Abstract
Near‐infrared (NIR) organic light‐emitting diodes (OLEDs) show great potential in a variety of applications including sensors, night vision, and information security. Despite the superiority of thermally activated delayed fluorescence (TADF) in 100 % exciton harvesting, the development of NIR TADF OLEDs is still a great challenge, especially in terms of solution‐processing technology. In this work, a multicyano acceptor of 2‐dicyanomethylene‐3‐cyano‐4,5,5‐trimethyl‐2,5‐dihydrofurance (TCF) with strong electron‐withdrawing ability was employed to construct solution‐processible NIR emitters, CzTCF and tBCzTCF, with the feature of donor–π–acceptor (D–π–A) structure. The significantly enhanced intermolecular charge transfer effects not only render the deep‐red and NIR emissions of CzTCF and tBCzTCF films, respectively, but also lead to their typical TADF characteristics. Consequently, the nondoped solution‐processed NIR OLED based on tBCzTCF was successfully demonstrated with the peak wavelength of 715 nm, which paves the way for developing NIR emitters without polycyclic aromatic cores and heavy‐metal ions. A multicyano‐substituted acceptor and styryl π‐conjugate linker were both optimized to realize efficient NIR thermally activated delayed fluorescence (TADF) emitters (CzTCF and tBCzTCF) with simple D–π–A structure. The three linearly distributed cyano groups in TCF and the longer conjugation in the styryl π‐linker effectively regulated the D–A interactions and the frontier molecular orbital distributions (see scheme). [ABSTRACT FROM AUTHOR]
- Published
- 2019
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