Theoretical Characterization and Design of Triarylborane-Based Thermally Activated Delayed Fluorescent Molecules for Organic Light-Emitting Diodes

A series of novel donor (D)–acceptor (A) star-shaped triarylborane-based molecules have been designed for the applications in organic light-emitting diodes (OLEDs) devices with thermally activated delayed fluorescence (TADF) properties. Their photophysical and electronic properties have been systematically investigated by applying density functional theory (DFT) and time dependent DFT (TD-DFT) methods. The frontier molecular orbitals (FMOs) analysis has turned out that the vertical electronic transitions exhibit a strong charge transfer character. The D and A fragments are separated efficiently. Furthermore, all the designed molecules display small singlet-triplet energy gap (ΔE_ST) values, which is beneficial for TADF properties. Our results suggest that the introduction of different donors can tune the delayed fluorescence emission color effectively. The designed molecules are expected to be the promising candidates TADF materials for organic light-emitting diodes (OLEDs).