Exploring Efficient Blue Thermally Activated Delayed Fluorescence Emitters by Constructing Intramolecular Hydrogen Bonds

Efficient blue organic luminescent materials are highly desired for full-color displays and white lighting based on the organic light-emitting diode (OLED) technique, but the exploration of robust blue emitters remains challenging. In this work, a series of efficient blue thermally activated delayed fluorescence materials comprised of a benzonitrile acceptor, pyridine bridge, and carbazole-based donors is designed and synthesized. Intramolecular hydrogen bonds are formed in these molecules, which improve molecular planarity and rigidity. These molecules exhibit excellent thermal stability, high photoluminescence quantum yields, and large horizontal dipole ratios. Highly efficient non-doped and doped OLEDs are fabricated using these molecules as emitters, providing deep-blue to sky-blue lights with outstanding maximum external quantum efficiencies and good operational device lifetime. These results indicate that building intramolecular hydrogen bonds can be an effective strategy for the construction of efficient and robust blue emitters for OLED applications.