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Unconventional Three-armed Luminogens Exhibiting Both Aggregation-Induced Emission and Thermally Activated Delayed Fluorescence Resulting in High-Performing Solution-Processed OLEDs

Article excerpt is from:Seo Yeon Park, Suna Choi, Gi Eun Park, Hyung Jong Kim, Chiho Lee, Ji Su Moon, Si Woo Kim, Sungnam Park, Jang Hyuk Kwon, Min Ju Cho, and Dong Hoon Choi
ACS Appl. Mater. Interfaces, Just Accepted Manuscript

In this work, three-armed luminogens IAcTr-out and IAcTr-in were synthesized and used as emitters bearing triazine and indenoacridine moieties in thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs). These molecules could form a uniform thin film via the solution process, and also allowed the subsequent deposition of an electron transporting layer either by vacuum deposition or by an all-solution coating method. Intriguingly, the new luminogens displayed aggregation-induced emission (AIE), which is a unique photophysical phenomenon. As a non-doped emitting layer, IAcTr-in showed external quantum efficiencies (EQEs) of 11.8% for hybrid-solution processed OLED and 10.9% for all-solution processed OLED with a low efficiency roll-off. This was evident by the higher photoluminescence quantum yield and higher rate constant of reverse intersystem crossing of IAcTr-in, as compared to IAcTr-out. These AIE luminogens were used as dopants and mixed with the well-known host material 1,3-bis(Ncarbazolyl) benzene (mCP) to produce a high-efficiency OLED with a two-component emitting layer (EML). The maximum EQE of 17.5% was obtained when using EML with IAcTr-out doping (25 wt%) into mCP, and the OLED with EML bearing IAcTr-in and mCP showed a higher maximum EQE of 18.4% as in the case of the non-doped EML-based device.