In most mixed-ligand iridium complexes Ir(C^N)2(LX), density functional theory calculations indicate that the HOMO is largely metal-centered, whereas the LUMO is primarily localized on the heterocyclic rings of the cyclometalated ligands.The ancillary ligand is therefore not directly involved in the lowest excited state.However, it can alter the energy of the excited state by modifying the electron density at the metal center [1].Thus, the photophysical and electrochemical properties of Ir(Ⅲ) complexes can be tuned through controlled functionalization of both the cyclometalated and ancillary ligands.The popular ancillary ligands are acac (acetylacetone) and pie (picolinate), etc.