Phenothiazine dioxide based high triplet energy host materials for blue phosphorescent organic light-emitting diodes

Donor–acceptor type high triplet energy host materials were derived from a phenothiazine dioxide based electron transport moiety and a carbazole based hole transport moiety. Three phenothiazine dioxide type materials, 10-(3,5-di(9H-carbazol-9-yl)phenyl)-10H-phenothiazine 5,5-dioxide (DCzPO), 10-(3′,5′-di(9H-carbazol-9-yl)-[1,1′-biphenyl]-3-yl)-10H-phenothiazine 5,5-dioxide (DCzmPPO), and 10-(3′,5′-di(9H-carbazol-9-yl)-[1,1′-biphenyl]-4-yl)-10H-phenothiazine 5,5-dioxide (DCzpPPO), could transport both holes and electrons effectively and showed high triplet energy for use in blue phosphorescent organic light-emitting diodes. Device optimization of the DCzPO, DCzmPPO, and DCzpPPO host based blue devices could realize high EQE of 24.3%.