Robust sky-blue aggregation-induced delayed fluorescence materials for high-performance top-emitting OLEDs and single emissive layer white OLEDs

The development of blue luminescent materials plays a crucial role in the industry of organic light-emitting diodes (OLEDs). Herein, two sky-blue luminescent materials (mCP-BP-DMAC and DCB-BP-DMAC) comprised of electron donors of 9-(3-(9H-carbazol-9-yl)phenyl, 9-(4-(9H-carbazol-9-yl)phenyl and 9,9-dimethyl-9,10-dihy-droacridine and electron acceptor of benzoyl are synthesized and characterized. They exhibit excellent thermal and electrochemical stabilities, strong aggregation-induced delayed fluorescence and bipolar carrier transport ability, and behavior efficiently in nondoped and doped bottom-emitting OLEDs with high external quantum efficiencies (eta exts) of up to 26.6% and small efficiency roll-offs. Efficient top-emitting OLEDs employing mCP-BP-DMAC and DCB-BP-DMAC as emitters are also achieved, providing sky-blue lights with high color purity and impressive eta exts over 30%. In addition, hybrid white OLEDs with stable emission color and high color rendering index are fabricated based on a single emissive layer consisting of orange-red phosphorescent Ir(MDQ)2acac dopant and sky-blue mCP-BP-DMAC and DCB-BP-DMAC hosts, furnishing excellent eta exts of up to 24.1% and small efficiency roll-offs. These results demonstrate mCP-BP-DMAC and DCB-BP-DMAC are outstanding luminescent and host materials with great application potentials in display and lighting devices.