Cascade Effect of a Dimerized Thermally Activated Delayed Fluorescence Dendrimer

Thermally activated delayed fluorescence (TADF) emitters with a high horizontal orientation are highly essential for improving the external quantum efficiency (EQE) of organic light-emitting diodes; however, pivotal molecular design strategies to improve the horizontal orientation of solution-processable TADF emitters are still scarce and challenging. Herein, a phenyl bridge is adopted to connect the double TADF units, and generate a dimerized TADF dendrimer, D4CzBNPh-SF. Compared to its counterpart with a single TADF unit, the proof-of-the-concept molecule not only exhibits an improved horizontal dipole ratio (78 %) due to the π-delocalization-induced extended molecular conjugation, but also displays a faster reversed intersystem crossing rate constant (6.08×10