Efficient green phosphorescent Ir( iii ) complexes with β-diketonate ancillary ligands

Three new iridium complexes containing 3-(pyridine-2-yl)coumarin as the cyclometalated ligand ( L ) and 1-(3,5-bis(trifluoromethyl)phenyl)-3-(4-methoxyphenyl)propane-1,3-dione ( 1L ), 1-(furan-2-yl)-4,4-dimethylpentane-1,3-dione ( 2L ) and 1-(3,4-dimethoxyphenyl)-4,4-dimethylpentane-1,3-dione ( 3L ) as the ancillary ligands, respectively, were synthesized as emissive materials for organic light-emitting devices. Among them, the crystal structure of the Ir( iii ) complex based on the ancillary ligand 1L was characterized by single crystal X-ray diffraction. The photophysical and electrochemical properties and thermal stabilities of the Ir( iii ) complexes were systematically investigated. The results showed that all the Ir( iii ) complexes not only exhibit excellent thermal stabilities but also emit strong green emissions. Furthermore, based on these Ir( iii ) complexes, solution-processed green organic light-emitting devices with a configuration of ITO/PEDOT:PSS/PVK:PBD (7 : 3, wt%):Ir( iii ) complex ( x wt%, 30 nm)/TPBi (50 nm)/Liq (2 nm)/Al (150 nm) have been successfully fabricated, in which the devices fabricated from the Ir( iii ) complex based on the ancillary ligand 3L exhibited the best electroluminescence performance with a maximum brightness of 9275 cd m −2 and a maximum luminous efficiency of 19.38 cd A −1 and a maximum external quantum efficiency (EQE) of 5.37%.