The saturated red electrophosphorescence based on phenylquinoline iridium complexes with fluorenyl unit

Abstract

Novel complexes bis[2-(4-(9,9-diethylfluoren-2-yl)phenyl)-4-phenylquinolyl-C2, N] iridium, bis[2-[4-(9,9-bis(4-diphenylaminophenyl)fluoren-2-yl)phenyl]-4-phenyl- quinolyl-C2, N]iridium, bis[2-[4-(N-3,5-dimethylphenyl-N-9,9-diethylfluoren-2-yl- amino)phenyl]-4-phenylquinolyl-C2,N]iridium (with 2-picolinic acid or acetylacetonate) were prepared. The group with large steric hindrance, such as 9,9-diethylfluorenyl, triphenylaminofluorenyl or N-3,5-dimethylphenyl-N-9,9-diethylfluorenylamino, was connected to 2-phenylquinoline Ir complex to enhance the hole injection and transport ability and to restrain intermolecular interaction, which promoted luminous efficiency and tuned luminescent emission. The devices presented stable electroluminescent (EL) peaks at about 620 and 600 nm, Commission Internationale de L'Eclairage (CIE) coordinates of (0.67, 0.33) possessed maximum current (or external quantum) efficiencies of 15.4 cd/A (or 10.2%). Slow decay and high efficiency of devices indicated that the red emitters were promising. In addition, the main EL parameters of similar doped red OLEDs based on phenylquinoline Iridium acetylacetonate were briefly compared.