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

• Published in: Optical materials Vol. 132; p. 112870
• Main Authors: Zhang, Wenguan, Chen, Yinjie, He, Zhiqun, Wang, Yongsheng
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2022
• Subjects: Fluorene; Iridium complex; Large steric hindrance; Phenylquinoline; Saturated red emission; Stable electrophosphorescence; Phenylquinoline; Iridium complex; Fluorene; Stable electrophosphorescence; Large steric hindrance; Saturated red emission
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2022.112870

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. •>2-(para-substituted)phenylquinoline iridium complexes with fluorenyl unit.•>The devices exhibited stable electroluminescent (EL) peaks at about 620 and 600 nm.•>The device showed CIE coordinate of (0.67, 0.33) with efficiencies of 15.4 cd/A and 10.2%.•>Large steric hindrance was introduced to improve luminous efficiency and to tune emission.•>High efficiency and PL peak from the segment of (PPQ)2Ir(acac) in iridium complexes were maintained.