Abstract:
Organic light emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) emitters have attracted much interest in recent years for their great potential in full exciton utilization. However, the lack of electron-donor candidates limits further development of TADF emitters. In this study, a novel electron-donor segment 13,13-dimethyl-5-phenyl-11,13-dihydro-5-indolo[2,3-]acridine (IDAC) is newly developed to construct TADF emitters. Due to the suitable steric hindrance and large planar rigid structures, IDAC derivatives could easily obtain small energy differences (Δs) between the lowest singlet and triplet excited states for effective TADF characteristics as well as high photoluminance quantum yields. Two novel TADF emitters, 6-(13,13-dimethyl-5-phenyl-5,13-dihydro-11-indolo[2,3-] acridin-11-yl)-3-methyl-1H-isochromen-1-one (IDAC-MCO) and 11-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-13,13-dimethyl-5-phenyl-11,13-dihydro-5-indolo[2,3-]acridine (IDAC-Trz), are accordingly designed and synthesized, and both exhibit evident TADF characteristics with small Δs of ingly designed and synthesized, and both exhibit evident TADF characteristics with small△Ests of 0.09 and 0.02 eV and high photoluminance quantum yields of 81% and 90%, respectively. The OLEDs using IDAC-MCO and IDAC-Trz as emitters respectively achieve high external quantum efficiencies of 18.0% and 20.5% with remarkable low efficiency roll-offs. These results demonstrate the capacity of IDAC segment as an ideal electron-donor to construct efficient TADF emitters.
链接：http://www.sciencedirect.com/science/article/pii/S1566119918301307
