Zhao Bingjie, Xie Guohua, Wang Huiqin, Han Chunmiao, Xu Hui
Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, School of Chemistry and Materials, Heilongjiang University, 74 Xuefu Road, Harbin, 150080, P.R. China.
Hubei Collaborative Innovation Centre for, Advanced Organic Chemical Materials &, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan, 430072, P.R. China.
Chemistry. 2019 Jan 18;25(4):1010-1017. doi: 10.1002/chem.201805201. Epub 2019 Jan 2.
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.
近红外（NIR）有机发光二极管（OLED）在包括传感器、夜视和信息安全在内的各种应用中显示出巨大潜力。尽管热激活延迟荧光（TADF）在100%激子收集方面具有优势，但近红外TADF OLED的发展仍然是一个巨大挑战，特别是在溶液处理技术方面。在这项工作中，采用具有强吸电子能力的多氰基受体2-二氰基亚甲基-3-氰基-4,5,5-三甲基-2,5-二氢呋喃（TCF）构建具有供体-π-受体（D-π-A）结构特征的可溶液处理的近红外发光体CzTCF和tBCzTCF。显著增强的分子间电荷转移效应不仅分别使CzTCF和tBCzTCF薄膜发出深红色和近红外光，还导致它们具有典型的TADF特性。因此，成功展示了基于tBCzTCF的非掺杂溶液处理近红外OLED，其峰值波长为715 nm，为开发不含多环芳香核和重金属离子的近红外发光体铺平了道路。
