A new functionalized heteroleptie iridium complex coordinated with l-phenylisoquinoline (l-piq) and a functionalized β-diketone (GI), Ir(l-piq)2G1, was synthesized and characterized by 1H-NMR, mass spectrometry and elemental analysis. The larger conjugation of the replacement of aeetylacetone (acac) by a functionalized β-diketonate iigand led to a significant decrease in the HOMO level toward vacuum level, while Ir(1-piq）2G 1 and Ir(l-piq）2(acac) showed red phosphorescent emissions of about 620 um in dichloromethane solution. The phosphorescent polymer light-emitting devices were achieved, with the complexes incorporated with polyfluorene (PFO) as a host polymer doped with 30% of 5-(4-biphenylyl)-2-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD) as electron transport material. The energy transfer mechanism of the devices was also discussed. The lower EL performance of Ir(1-piq）2G 1 is ascribed to the inter-ligand energy transfer, indicating that it is important to control the energy level of the cyclometalated and ancillary ligands.