4TCzBN is another family member of carbazolyl benzonitrile derivatives which are widely used in either white or blue highly efficient TADF-OLED devices.
The carbazolyl groups are electron donating and nitrile group is electron withdrawing while the extended tert-butyl units can serve as an encapsulation shell to the luminophore in 4TCzBN. It is believed that the introduction of the tert-butyl units can effectively separate molecules thus reduce the chance of triplet-polaron annihilation (TPA) to greatly improve the device efficiency and stability.