The OLED showed an EQEmax of 23.9% at λEL of 552 nm. Our group reported a series of DiKTa-based D-A TADF emitters using donors with different electron-donating abilities. DMAC-DiKTa, with a FPL of 76% and a ΔEST of 0.04 eV, produced the highest device performance, with an EQEmax of 23.8% at λEL of 549 nm and with a low efficiency roll-off of 16.4% at 1000 cd m -2 .