For efficient white organic light-emitting diodes (OLEDs), it's needed to cover a wide range of visible light area. For these needs, we synthesized new types of yellowish green phosphorescent iridium (III) complexes that have 4-(1-Naphtyl)thieno[3,2-c]pyridine (1-NTP), 4-(2-Naphthyl)thieno[3,2-c]pyridine (2-NTP) or 4-(p-biphenyl)thieno[3,2-c]pyridine (BTP) as main ligands, in addition to chelation with acetylacetonate (acac) as an ancillary ligand. We characterized these phosphors with H-1 NMR, mass spectrometer and UV-Vis spectra. The photoluminescence (PL) maxima of iridium(III) complexes appeared at 514, 508 and 512 nm, respectively. Also, these complexes showed shoulder peaks in PL spectra at 550 to 560 nm. The overall luminescent ranges were about 50 nm of FWHM (full width at half maximum). As a result, emission colors of these complexes are closer to yellowish green, and consequently these complexes are good for application of white OLEDs. We also studied their HOMO and LUMO level with cyclic voltammetry (CV). The electroluminescence (EL) study of these complexes is in progress for the applications to white OLEDs.