Orange-red and saturated red thermally activated delayed fluorescent dendrimers for non-doped solution-processed OLEDs

Two thermally activated delayed fluorescence (TADF) dendritic emitters with orange-red and saturated red emission, respectively, were obtained by coupled diphenylamine-carbazole dendron groups as donor with di(pyridin-3-yl)methanone as accepter. The two TADF dendrimers of tBuDPACz-DPyM and MeODPACz-DPyM exhibited small energy gaps between the singlet and triplet excited states (0.04 vs 0.03 eV). As a consequence, the tBuDPACz-DPyM non-doped solution-processed organic light-emitting devices (OLED) exhibited high current efficiency of 2.36 cd A−1 and external quantum efficiency of 1.82% with low turn-on voltage 3.4 V as well as a lower efficiency roll-off. Moreover, Commission Internationale de L'Éclairage (CIE) coordinates of two OLED devices were (0.56, 0.43) and (0.62, 0.37) for tBuDPACz-DPyM and MeODPACz-DPyM respectively.