We investigated the electroluminescent characteristics of three devices which were fabricated with a green phosphorescent emitter bis[2-(o-terphen-3-yl)pyridinato-C,N] iridium(III) (acetylacetonate) [(tppy)(2)Ir(acac)] doped in triphenylsilane-based host materials, such as 4,4'-bis(triphenylsilyl) biphenyl (BSB), 9,9'-spirobifluorene-2-yltriphenylsilane (SFS) and (4-(10-(naphthalene-2-yl)anthracen-9-yl)phenyl)-triphenylsilane (ANPTPS), which have the different the triplet energy levels (ET) of 2.61 eV, 2.64 eV and <1.91 eV, respectively. Among those, two devices using BSB and SFS hosts with the suitable ET energy levels to green phosphorescent dopant exhibited the highly efficient green electrophosphorescence with the maximum luminous efficiencies of 51.3 cd/A and 46.6 cd/A, respectively, and the maximum quantum efficiencies of 13.9% and 12.4%, respectively.