In this study, two MR-TADF compounds, PhDPA-DiKTa and MeODPA-DiKTa, respectively, were developed containing DiKTa as a core that is decorated by two different DPA derivative donors. These molecules exhibited orange-to-red emission in toluene, with lPL of 592 nm and 633 nm, correlated to the increase in donor strength of the substituent from PhDPA to MeODPA. PhDPA-DiKTa has a higher FPL of 69% at lPL of 617 nm, while MeODPA-DiKTa has a deeper red emission at 655 nm but a lower FPL of 27% in 5 wt% doped films in mCP. The DEST decreases from 0.16 to 0.12 eV from PhDPA-DiKTa to MeODPA-DiKTa, while the delayed lifetime shortens from 658.4 to 249.2 µs.