Solution-Processable Csp-Annulated Hosts for High-Efficiency Deep Red Phosphorescent OLEDs.

In this report, a solution-processable cohost system incorporating ,'-di(naphtalene-1-yl)-,'-diphenylbenzidine (NPB) and Csp-annulated phenylquinoline derivatives, including spiro[indeno[1,2-]quinoline-11,8'-indolo[3,2,1-de]acridine] (IAIQ), 10-phenyl-10H-spiro[acridine-9,11'-indeno[1,2-]quinoline] (PAIQ) and 3,3'-(11H-indeno[1,2-]quinoline-11,11-diyl)bis(-phenyl--(m-tolyl)aniline) (m-TPA-DPIQ), is developed for highly efficient saturated red phosphorescent organic light emitting diodes (OLEDs). IAIQ, PAIQ, and m-TPA-DPIQ, designed with the increase of molecular flexibility, are systematically investigated. Solution-processable devices based on the efficient phosphorescent emitter bis2-(3,5-dimethylphenyl)isoquinolinatoIridium [Ir(mpiq)divm] are successfully fabricated, and give electroluminescent peaks at 634-636 nm with Commission Internationale de L'Eclairage coordinates of (0.70, 0.30). Under optimized conditions, the devices incorporating IAIQ, PAIQ, and m-TPA-DPIQ exhibit high external quantum efficiency with the maximum value at 25.1%, 23.4%, and 23.3%, respectively, and all exceeding 18% at the luminance of 1000 cd/m. In application, the supersaturated red devices with excellent performance could facilitate the development of wet-made displays. The newly developed Csp-annulated host materials with their excitonic properties also showoff the tactic to construct cohost system for high-quality phosphorescent OLEDs.