In lieu of an indolocarbazole donor, compound CC2TA (λPL: 490 nm; τd: FPL: 60.5%; 6 wt% in DPEPO), each containing only one functionalized carbazole donor, were also prepared by Adachi and co-workers. These two compounds are randomly oriented in the neat films; however, the orientation of the TDMs (orientation order parameter q: -0.18 for DTDC; -0.12 for BDTC) of these two TADF emitters is significantly more horizontally aligned when they are dispersed in the DPEPO matrix. The best OLEDs showed comparable efficiencies to that of the CC2TA device with EQEmax values of 10.3% and 11.6% for the DTDC and BDTC devices, respectively.