Synthesis and properties of ipsilateral double substituted diphenylsulfone thermally activated delayed fluorescent materials

Two novel donor-acceptor (D-A) type thermally activated delayed fluorescent (TADF) materials 2PXZDPS and 2DMACDPS are synthesized by attaching two donors phenoxazine (PXZ) or 9,9-dimethyl-9,10-dihydroacridine (DMAC) to the ipsilateral side of the acceptor diphenylsulfone group. The two materials show high yield, good thermal properties, suitable photophysical properties, high triplet energy and small energy difference between singlet and triplet states, leading to feasible thermally activated delayed fluorescence (TADF) organic light emitting diodes (OLEDs). Both 2PXZDPS and 2DMACDPS show excellent performance in OLED. 2PXZDPS based OLED give the maximum external quantum efficiency (EQE(max)) of 20.7% and low turn-on voltage of 2.2 V.