Blue thermally activated delayed fluorescent emitters having a bicarbazole donor moiety

Bis(4-(9'-phenyl-9H, 9'H-[ 3,3'-bicarbazol]-9-yl) phenyl) methanone (BPBCz) and 90,9 '''-((6-phenyl-1,3,5-triazine-2,4-diyl) bis(4,1-phenylene)) bis(9-phenyl-9H, 9'-H-3,3'-bicarbazole) (TrzBCz) were investigated as thermally activated delayed fluorescent (TADF) emitters to exhibit blue emission color. A 3,3'-bicarbazole was a donor in the two TADF emitters, and benzophenone and triazine were acceptors of BPBCz and TrzBCz, respectively. Both BPBCz and TrzBCz behaved as high efficiency TADF emitters through a small singlet-triplet energy gap for the activation of delayed fluorescence. The BPBCz and TrzBCz TADF emitters offered high quantum efficiencies of 23.3% and 23.6% in the blue TADF devices.