Dimethyl modified terphenyl core based compounds as hosts of blue phosphorescent emitters

High triplet energy materials were derived from dimethyl modified terphenyl core structure in order to apply them as the host materials of blue-emitting phosphors. The dimethyl modification was effective to increase the triplet energy of the terphenyl and carbazole based host materials and enabled application of the host materials in blue phosphorescent organic light-emitting diodes. Four hosts based on the dimethyl modified terphenyl and carbazole derived charge transport units were synthesized and the hosts with the carbazole functionalized backbone structure performed effectively as the host materials of phenylpyridine type Ir emitter. An external quantum efficiency of 18.2% was achieved in the blue phosphorescent organic light-emitting diodes using the new host developed in this work.