Intermolecular Charge-Transfer Transition Emitter Showing Thermally Activated Delayed Fluorescence for Efficient Non-Doped OLEDs
Yi-Zhong Shi,1 Kai Wang, 1* Xing Li,1 Gao-Le Dai,1 Wei Liu,1 Ke Ke,2 Ming Zhang,2 Si-Lu Tao,2 Cai-Jun Zheng, 2* Xue-Mei Ou,1 and Xiao-Hong Zhang1*
1Institute of Functional Nano & Soft Materials (FUNSOM) and Jiangsu, Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, P. R. China
2School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu, Sichuan 610054, P. R. China
A novel molecular model of connecting electron-donating (D) and electron-withdrawing (A) moieties via a space-enough and conjugation-forbidden linkage (D-Spacer-A) is proposed to develop efficient non-doped thermally activated delayed fluorescence (TADF) emitters. 10-(4-(4-(4,6-diphenyl-1,3,5-triazin-2-yl) phenoxy) phenyl)-9,9-dimethyl-9,10-dihydroacridine (DMAC-o-TRZ) was designed and synthesized accordingly. As expected, it exhibits local excited properties in single-molecule state as D-Spacer-A molecular backbone strongly suppress the intramolecular charge-transfer (CT) transition. And intermolecular CT transition acted as the vital radiation channel for neat DMAC-o-TRZ film. As in return, the non-doped device exhibits a remarkable maximum external quantum efficiency (EQE) of 14.7%. These results prove the feasibility of D-Spacer-A molecules to develop intermolecular CT transition TADF emitters for efficient non-doped OLEDs.