3-Cyano Imidazopyridine Acceptor-based Bipolar and n-type Host Materials for Phosphorescent Organic Light-Emitting Diodes

Two host materials named 8-(3-(9H-carbazol-9-yl)phenyl)-2-phenylimidazo[1,2-a]pyridine-3-carbonitrile (mCzImPy) and 8,8′-(1,3-phenylene)bis(2-phenylimidazo[1,2-a]pyridine-3-carbonitrile) (mBisImPy) were synthesized as a bipolar host and a n-type host, respectively, from the herocyclic imidazopyridine unit through its 3-position CN modification. They worked as the hosts of yellow phosphorescent emitter and the mCzImPy host achieved high quantum efficiency of 18.2% in the yellow phosphorescent devices. Therefore, the 3-cyanoimidazopyridine showed potential as an electron transport unit of host design.