We next explored the potential of DtCzBN-CNBT1 and DtCzBN-CNBT2 as emitters in vacuumdeposited OLEDs (VD-OLEDs), fabricated using the following stack: ITO/HATCN (5 nm)/TAPC (30 nm)/TCTA (10 nm)/mCBP (10 nm)/emitter:PhCzBCz X wt% (20 nm)/TmPyPB (40 nm)/LiF (1 nm)/Al (100 nm). For comparison, we also fabricated solution-processed OLEDs (SP-OLEDs) using the device architecture of ITO/PEDOT:PSS (35 nm)/emitter: PhCzBCz X wt% (25 nm)/TmPyPB (40 nm)/LiF (1 nm)/Al (100 nm), (Table & Figure ). For the VD-OLEDs, HATCN acts as the hole injection layer, TAPC and TCTA are used as hole transporting layers, mCBP is the exciton blocking layer, and TmPyPB is the electron-transport material. PhCzBCz was selected as the host material, and to obtain optimal device performance, the doping concentrations of DtCzBN-CNBT1 and DtCzBN-CNBT2 were investigated from 5 to 30 wt%. The device results are summarized in Table . Similar to their PL behavior, the electroluminescent maxima, λEL, of the devices with DtCzBN-CNBT1 and DtCzBN-CNBT2 do not significantly change as the doping concentration increases from 5 to 30 wt%, slightly bathochromically shifting from 504 to 510 nm, while the FWHM stays approximately at 38 nm. The maximum EQE (EQEmax) for the device with DtCzBN-CNBT2 remained over 30.0% across all investigated doping concentrations, and the highest EQEmax of 40.2% was achieved at a concentration of 15 wt% (Figure , Figure ) with CIE coordinates of (0.17, 0.67). Although there are emitters with CIEy of over 0.70, it is challenge to produce devices that simultaneously achieve high EQEmax (over 40%) and pure green emission that matches the BT 2020. standard [CIE of (0.17, 0.80), Figure & 6a]. For the device with DtCzBN-CNBT1, the highest EQEmax of 37.1% (Figure , Figure ) was also achieved at this same doping concentration, with CIE coordinates of (0.17, 0.66). Moreover, thanks to its faster kRISC, the devices with DtCzBN-CNBT2 showed a decreased efficiency roll-off of 48% at a brightness of 1000 cd m -2 at doping concentrations varying from 10 to 25 wt%, while the devices with DtCzBN-CNBT1 all showed more severe efficiency roll-off of 68% at 1000 cd m -2 . The high EQEmax and moderate efficiency roll-off, plus the CIEy of 0.67, make the OLEDs with DtCzBN-CNBT2 one of the best performing green-emissive MR-TADF devices (Figure ) to date; gratifyingly, there is no need to employ a bespoke TADF host or TADF assistant (Table ), which would be more desirable for industry application. These results also demonstrate the attractive value of our emitter design, which decorates a high-energy TADF moiety onto the MR-TADF emitter to simultaneously mitigate aggregation-caused quenching and red-shifting of the emission, and to provide multiple RISC channels that reduce efficiency roll-off at high brightness.