Thermally Activated Delayed Fluorescence Materials Based on Carbazole/Sulfone

A series of bipolar materials for thermally activated delayed fluorescence (TADF) based on carbazole and diphenylsulfone, is synthesized by Ulmann and Suzuki coupling reactions. In these materials, the 3,6-di-tert-butylcarbazole and N-phenylcarbazole group as donors are linked at the 3-, 4-position of diphenyl sulfone. The electronic, photophysical and electrochemical properties of these materials are studied by extensive UV-vis, fluorescence spectroscopic measurements, cyclic voltammetry as well as theoretical calculations. The energy gap between singlet and triplet (△E ST ) in these materials is tuned from 0.99 eV to 0.24 eV by changing the donor units and the positions of substitution.