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Highly Efficient Blue Organic Light-Emitting Diodes from Pyrimidine-Based Thermally Activated Delayed Fluorescence Emitters

Article excerpt is from:Bowen Li, Zhiyi Li, Taiping Hu, Yong Zhang, Ying Wang, Yuanping Yi, Fengyun Guo, Liancheng Zhao
 
J. Mater. Chem. C, 2018 in press

Three highly efficient blue thermally activated delayed fluorescence (TADF) emitters,2SPAc-HPM, 2SPAc-MPM and 2SPAc-PPM, have been synthesised based on pyrimidine(PM), 2-methylpyrimidine (MPM) and 2-phenylpyrimidine (PPM) as the acceptor and 10Hspiro[acridan-9,9'-fluorene] (2SPAc) as the donor moiety, respectively. With the appropriatemolecular design, these emitters successfully achieve small singlet-triplet splitting energies for efficient reverse intersystem crossing, and exhibit high photoluminescence quantum yields. As a result, the TADF OLEDs based on 2SPAc-HPM, 2SPAc-MPM and 2SPAc-PPM emit blue light peaking at 479-489 nm and generate the very high the external quantum efficiency of 25.56%, 24.34% and 31.45%, respectively. The 2SPAc-PPM based TADF OLEDs also is one of the very few blue TADF emitters with the external quantum efficiency of more than 30% and is the best OLED performance among the pyrimidine-based TADF emitters.