Synthesis and characterization of novel polymers containing aminophenylsilole

A series of conjugated copolymers consisting of 9,9-dioctylfluorene units and 1,1-bis(4'-N,N-dimethylaniline)-tetraphenylsilole units (APh-TPS) were designed and synthesized by a palladium-catalyzed Suzuki coupling reaction. The chemical structures, electrochemical properties and optoelectronic properties, including the absorption, photoluminescence and electroluminescence (EL), of these copolymers were successfully characterized. EL devices were fabricated in three different configurations: indium tin oxide (ITO)/poly-(3,4-ethylenedioxythiophene): poly(styrenesulfonic acid; PEDOT:PSS) (50 nm)/polyfluorene (PF)-APh-TPS (80 nm)/Al (device A), ITO/PEDOT:PSS (50 nm)/PF-APh-TPS (80 nm)/Ba/Al (device B) and ITO/PEDOT:PSS (50 nm)/PF-APh-TPS (80 nm)/1,3,5-tris (2-N-phenylbenzimidazolyl) benzene (TPBI) (30 nm)/Ba/Al (device C). The EL properties of PF-APh-TPS were clearly improved compared with those of previously reported silole-containing PFs because of the introduction of N,N-dimethylaniline. The insertion of a TPBI hole-blocking layer not only elevated the luminous and external quantum efficiencies but also improved the color purity by separating the light-emitting layer from the cathode.