Calix[4]resorcinarene-based hyper-structured molecular thermally activated delayed fluorescence yellow-green emitters for non-doped OLEDs

A series of novel hyper-structured molecular (HSM) thermally activated delayed fluorescent (TADF) emitters, in which the TADF units and host units are bound together into one inactive core through flexible linkages, were designed. Phenoxazine-triphenyltriazine (PXZ-Trz), 1,3-bis(9H-carbazol-9-yl)benzene (mCP) and calix[4]resorcinarene (CRA) were chosen as the TADF unit, the host unit and the core, respectively. A series of CRA-based HSM emitters, CRA-PXZ-Trz((X))-mCP((100-X)) (X = 0, 12.5, 25, 50, 75, 87.5 or 100) were successfully synthesized by a two-step click reaction. Upon using non-doped CRA-PXZ-Trz((87.5))-mCP((12.5)) as the light-emitting layer, the solution-processable OLEDs emitted yellow-green light, and displayed an external quantum efficiency of 16.7% at 100 cd m(-2).