In order to improve luminescence efficiency, it is necessary to design a phosphorescent material which is capable of transferring the excited energy without triplet-triplet (T-T) annihilation. For this purpose, new types of metal complexes were designed with different species of (CN) ligands. Herein, Ir(ppy)(2)(piq), Ir(ppy)(2)(piq-F) and Ir(ppy)(2)(piq-CF3) were designed and prepared, where ppy, piq, piq-F and piq-CF3 represent 2-phenylpyridine, 1-(phenyl)isoquinoline, 1-(4'-fluorophenyl)isoquinoline and 1-(4'-trifluoromethylphenyl)isoquinoline, respectively. These Ir(III) complexes having two different ligands (hetero-Ir complexes) are expected to have a high luminescence efficiency by intramolecular energy transfer from the energy absorbing ligand to the luminescent ligand leading to a decrease in quenching or energy deactivation. To compare luminescent characteristics of these hetero-Ir complexes, homo-Ir complexes Ir(ppy)(3), Ir(piq)(3), Ir(piq-F)(3) and Ir(piq-CF3)(3) were prepared and investigated photophysically. (c) 2006 Elsevier B.V. All rights reserved.