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 9′,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.