Xie Feng-Ming, Li Hao-Ze, Dai Guo-Liang, Li Yan-Qing, Cheng Tao, Xie Miao, Tang Jian-Xin, Zhao Xin
College of Chemistry, Biology and Material Engineering , Suzhou University of Science and Technology , Suzhou 215009 , P. R. China.
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices , Soochow University , Suzhou 215123 , P. R. China.
ACS Appl Mater Interfaces. 2019 Jul 24;11(29):26144-26151. doi: 10.1021/acsami.9b06401. Epub 2019 Jul 12.
The design and synthesis of highly efficient thermally activated delayed fluorescence (TADF) emitters with an electroluminescence wavelength beyond 600 nm remains a great challenge for organic light-emitting diodes (OLEDs). To solve this issue, three TADF molecules, DMAC-BP ( = 1, 2, 3), are developed in combination with the rigid planar dibenzo[,]phenazine (BP) acceptor core and different numbers of 9,9-dimethylacridan (DMAC) donors. All these emitters possess stable internal charge transfer and a large dihedral angle between the donors and planar BP core. The emission wavelength can be regulated from 541 to 605 nm by increasing the number of the donor DMAC units because of the controllable tuning of the intramolecular charge transfer effect and the molecular geometrical structure. The photoluminescence quantum yields of these emitters are improved from 42 to 89% with the increase in the number of DMAC units. The orange-red OLEDs employing the DMAC-BP emitters exhibit maximum external quantum efficiency (EQE) of 22.0% at 606 nm, which is the highest EQE of the previously reported TADF OLEDs exceeding 600 nm.
设计和合成电致发光波长超过600 nm的高效热激活延迟荧光（TADF）发光体对有机发光二极管（OLED）来说仍然是一个巨大的挑战。为了解决这个问题，结合刚性平面二苯并[,]吩嗪（BP）受体核和不同数量的9,9-二甲基吖啶（DMAC）供体，开发了三种TADF分子DMAC-BP（ = 1, 2, 3）。所有这些发光体都具有稳定的内电荷转移以及供体与平面BP核之间的大的二面角。由于分子内电荷转移效应和分子几何结构的可控调节，通过增加供体DMAC单元的数量，发射波长可以从541调节到605 nm。随着DMAC单元数量的增加，这些发光体的光致发光量子产率从42%提高到89%。采用DMAC-BP发光体的橙红色OLED在606 nm处表现出22.0%的最大外量子效率（EQE），这是先前报道的超过600 nm的TADF OLED的最高EQE。
