Yamamoto et al. showed how substitution about the periphery of the donor dendron in Although the EQEmax of the OLED based on tBuG2TAZ improved to 9.5%, this performance is still not comparable to the efficiencies reported for non-doped vacuum-deposited devices based on small molecule TADF emitters. This is due to the low FPL (<50%) in the neat film that results from concentration quenching. To solve the problem and further improve the device performance, Yamamoto et al. developed two carbazole-based dendrimers (G3Ph and G4Ph as shown in Figure ) as host materials to suppress the observed concentration quenching of tBuG2TAZ (λPL: 500 nm; FPL: 76%; ΔEST: 0.07 eV; 15 wt% in G3Ph). The doping concentration of 15% was chosen to optimize the FPL in the blended film. The emission spectra remain unchanged at 500 nm between the neat film and the films doped in G3Ph and G4Ph.