Design and synthesis of efficient blue thermally activated delayed fluorescence molecules bearing triarylborane and 10,10-dimethyl-5,10-dihydrophenazasiline moieties

With the aim of tuning and generating blue emission from boron-based thermally activated delayed fluorescence (TADF) molecules, new luminescent molecules having an electron-donating 10,10-dimethyl-5,10-dihydrophenazasiline unit and an electron-accepting 10H-phenoxaborin unit (1a) or dimesitylborane unit (1b) were designed and synthesized. Compounds 1a and 1b in toluene solution showed deep blue and pure blue emissions at 296 K. The investigation of the photoluminescence properties revealed that the molecules possessed intramolecular charge transfer and TADF characteristics. Compounds 1a and 1b also exhibited high photoluminescence quantum yields of 81%.