Two emitters (DtCzBN-CNBT1 and DtCzBN-CNBT2) possessing, respectively, non-TADF or TADF D-A moieties connected to the same MR-TADF emitting core DtCzBN were rationally designed, modelled, synthesized, and characterized. The objective of the design strategy aimed to increase kRISC, improve triplet exciton harvesting, maintain the high FPL, while simplifying the device fabrication for MR-TADF emitters by removing the need for an external TADF sensitizer in order to achieve highperformance devices. Thanks to the presence of the D-A TADF moiety, DtCzBN-CNBT2 demonstrated a shorter τd of 15.3 µs, a faster kRISC of 1.1 × 10 5 s -1 , and a higher ΦPL of 97% in a 15 wt% doped film in PhCzBCz than DtCzBN-CNBT1, which although having a similarly high ΦPL of 92%, has a much longer τd of 75.5 µs and slower kRISC of 2.0 × 10 4 s -1 . Sensitizer-free OLEDs containing 15 wt% DtCzBN-CNBT2 in PhCzBCz emitted green light with CIE coordinates of (0.16, 0.67) and achieved a record-high average EQEmax of 40.2%, with an EQE of 20.7% at 1000 cd m -2 . The device with DtCzBN-BT1CN showed a similarly high average EQEmax of 37.1% and emitted with comparable CIE coordinates of (0.17, 0.66); however, the device experienced a significant efficiency roll-off, with the EQE at 1000 cd m -2 dropping to 11.9% due to the slower kRISC of the emitter. Solution-processed OLEDs with DtCzBN-CNBT2 emitting at the same color point as the vacuum-deposited analogs, showed lower efficiencies and stronger efficiency roll-off, with an EQEmax of 24.4% and EQE1000 of 5.6%, while devices with DtCzBN-CNBT1 performed slightly worse (EQEmax of 22.3% and EQE1000 of 4.8%). The impressive vacuum-deposited device performance using DtCzBN-CNBT2 validates the emitter design of integrating high-energy TADF moieties as peripheral moieties decorating MR-TADF emitting cores to enhance kRISC without compromising the attractive photophysical properties endemic to MR-TADF materials.