The device structures and energy level of each layer are illustrated in Figure . The devices with 30 wt% in mCP host were firstly fabricated as high ΦPL were measured for both emitters at this doping concentration. The device performance is shown in Figures As shown in Figure , the devices with 2GtBuCzCO2HDCzB and tBuCzCO2HDCzB emitted at λEL of 495 nm (FWHM =27 nm) and 496 nm (FWHM = 24 nm), producing green OLEDs with CIE coordinates of (0.08, 0.53) and CIE of (0.09, 0.53), respectively. The EL matches that of the PL, indicating that at this doping concentration there is no significant aggregation in the device (Figure ). The devices with 2GtBuCzCO2HDCzB and tBuCzCO2HDCzB both exhibited low EQE at low luminance. This EQE vs luminance behavior can be attributed to the lower packing density of the emitters in the spin-coated EMLs, which results in decreased carrier mobility and poor carrier balance. Consequently, at lower driving voltages, only a portion of the emitters are activated, leading to suboptimal exciton utilization and, ultimately, lower EQE values, this phenomenon has also been observed in many reported dendrimer emitter-based SP-OLEDs. The device with 2GtBuCzCO2HDCzB achieved a high EQEmax of 27.9% at a luminance of 2188 cd m -2 ; the EQE drops to only 27.6% at 2000 cd/m -2 . Even at 5000 cd/m 2 , the efficiency roll-off remains low at 20% (EQE5000 of 22.3%). This device performance is one of the best for solutionprocessed green TADF OLEDs, and the best amongst solution-processed green MR-TADF devices (Table and Figure ). In contrast, the device with tBuCzCO2HDCzB showed an Recognizing the benefits of the "encapsuled" structure and the high FPL of 2GtBuCzCO2HDCzB at high doping concentrations, the host-free solution-processed devices were then fabricated, where the emissive layer consisted of 70 wt% emitters plus 30wt% of the electron-transporting l,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene (OXD-7) to aid in charge balance; indeed, we have shown this EML composition to be an effective strategy in high-performance solution-processed dendrimer OLEDs. The device structure is shown in The host-free device with 2GtBuCzCO2HDCzB emits at 496 nm (FWHM of 30 nm), Figure , with associated CIE coordinates of (0.14, 0.54). The EL spectrum aligns with the PL spectrum. The device with 2GtBuCzCO2HDCzB showed an EQEmax of 24.0% (at 180 cd m -2 , Figure ), which is comparable to our previously reported non-doped SP-OLEDs with the TADF dendrimer tBuCz2m2pTRZ (EQEmax of 28.4%). Moreover, this device