Carbazole-Based DABNA Analogues as Highly Efficient Thermally Activated Delayed Fluorescence Materials for Narrowband Organic Light-Emitting Diodes.

Carbazole-based DABNA analogues (CzDABNAs) were synthesized from triarylamine by regioselective one-shot single and double borylation. The reaction proceeded selectively at the ortho position of the carbazolyl group, where the highest occupied molecular orbital is mainly localized owing to the difference in the electron-donating abilities of the diarylamino and carbazolyl groups. The facile and scalable method enabled synthesis of CzDABNAs, exhibiting narrowband thermally activated delayed fluorescence with emission spectra ranging from deep blue to green. The organic light-emitting diode devices employing these products as emitters exhibited deep-blue, sky-blue, and green emission with high external quantum efficiencies of 19.5, 21.8, and 26.7 %, respectively.