Sensitized organic light-emitting diodes: towards high efficiency and long lifetimes

Sensitized organic light-emitting diodes (OLEDs) have received extensive attention in recent years owing to their exciton utilization improvement. Along with the advances in fluorescent, phosphorescent, and thermally activated delayed fluorescent (TADF) OLEDs, a series of highly efficient sensitizers have been designed or selected to match them. Sensitized OLEDs realize dual improvements in efficiency and lifetime with the combination of high exciton utilization sensitizers and high-performance emitters. In this review, we systematically summarize the mechanisms of sensitized OLEDs, including phosphorescent, TADF, and exciplex sensitizers. On the basis of this classification, we further introduce the functions and selection criteria of sensitizers for phosphorescent, TADF, and exciplex-sensitized OLEDs. Finally, we hope that such a review will help researchers to design highly efficient and long lifetime sensitized OLEDs.