Novel host materials based on phenanthroimidazole derivatives for highly efficient green phosphorescent OLEDs

Two novel host materials, 2-(4,4″-di(9H-carbazol-9-yl)-[1,1′:3′,1″-terphenyl]-5′-yl)-1-(4-(trifluoro-methyl)phenyl)-1H-phenanhro[9,10-d]imidazole (DCzBPI) and N4,N4,N4″,N4″-tetraphenyl-5′-(1-(4-(trifluoromethyl)phenyl))-1H-phenanthro-[9,10-d] (DTPABPI), were designed and synthesized. The electroluminescence (EL) characteristics by using them as host materials were investigated. Results were found both of them showed good performance, especially for DCzBPI. The maximal external quantum efficiency is up to 21.2% and the brightness is up to 63,610 cd/m2 with current efficiency of 53.8 cd A−1.