Design and Synthesis of Highly Efficient Blue Thermally Activated Delayed Fluorescence Molecules Based on Carbazole and 1,3,5-Triazine Units through Position Engineering

Using carbazole as the donor motif, triazine as the acceptor motif, two thermally activated delayed fluorescence (TADF) molecules of m-CzTri and p-CzTri were designed and synthesized through efficient combination and position regulation.Both materials emit bright blue fluorescence with very small singlet-triplet splitting energy.Computational simulations show that the donor and acceptor groups are well separated from the highest occupied orbit (HOMO) and the lowest unoccupied orbit (LUMO).In addition, their thermal, electrochemical, photophysical, and device properties were tested.Among them, the color coordinates of organic light emitting diode (OLED) devices with m-CzTri as the emitter were (0.15, 0.25), and the external quantum efficiency was as high as 18%.