Rigid indolocarbazole as new donor moiety for highly efficient thermally activated delayed fluorescent (TADF) device

We present a study of two thermally activated delayed fluorescence (TADF) emitters based upon a new rigid donor moiety, namely, triphenyl-substituted Indolocarbazole (TPDICz). The reported TADF emitters 5-(2, 12-di-tert-butyl-5, 9-dioxa-13b-boranaphtho[3, 2, 1-de]anthracen-7-yl)-6, 11, 12-triphenyl-5, 11-dihydroindolo[3, 2-b]carbazole (TDBA-TPDICz) and 5-(4-(4, 6-diphenyl-1, 3, 5-triazin-2-yl)phenyl)-6, 11, 12-triphenyl-5, 11-dihydroindolo[3, 2-b]carbazole (TRZ-TPDICz) were synthesized and studied the device properties. These materials exhibited large steric hindrance and dihedral angle between donor and acceptor compared to the parent analog material (TRZ-pIC) due to the presence of 6, 12-phenyl substitutions. The TADF device fabricated with TDBA-TPDICz showed a deep blue color with a maximum external quantum efficiency (EQE) of 16.9%. Meanwhile, the TRZ-TPDICz emitter achieved a maximum EQE of 30.3% at green color.