DOBNA-OAr, featuring an oxygen-bridged triaryl-boron 5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracene (DOBNA) electron acceptor core, is a MR-TADF host material for highly efficient TADF and hyperfluorescence (HF) OLED devices. DOBNA-OAr shows MR-TADF characteristics in the violet region with emission at 388 nm and a FWHM of 34 nm in toluene.
Due to the suppression of nonradiative decay processes by engaging DOBNA-OAr as the MR-TADF host, the photoluminescence quantum yield (PLQY) of n-DABNA (1 wt.%) in the doped film reaches to 90%. The TADF-OLED based on n-DABNA as the guest emitter and DOBNA-OAr as the host shows deep-blue electroluminescence (469 nm) with CIE coordinates of (0.12, 0.11), and FWHM of 18 nm . Moreover, the n-DABNA-based device achieves a notably high EQEmax of 34.4% along with suppressed efficiency roll-off, 26.0% at 1,000 cd m–2. n-DABNA currently is the bench-mark for blue MR-TADF materials and as the terminal emitter in state-of-the-art HF-TADF devices.