Blue thermally activated delayed fluorescent (TADF) emitters were developed by linking a donor moiety to a triazine core via the ortho-position of an aromatic moiety. Three phenylcarbazole derivatives with different substituents were incorporated into the 4,6-diphenyltriazine core to prepare the blue TADF emitters. The photophysical properties and device performance of the blue TADF emitters were investigated, and the blue TADF emitters with 3,6-dimethyl-9-phenylcarbazole as the donor moiety showed a high quantum efficiency of 14.7%. Display omitted •Distorted ortho-linkage trazine core dopant materials were prepared.•CzTrz displayed delayed emission with a decay time of 3.9 μs at 300 K.•Sky-blue TADF OLEDs with a color purity of (0.15, 0.22) were developed.•The OLED shows a singlet-triplet energy gap less than 0.1 eV and high EQE of 14.7%.