Synthesis and properties of novel poly(p-phenylenevinylene) copolymers for near-infrared emitting diodes

A series of novel near-infrared (NIR) electroluminescence (EL) copolymers based on a host poly(p-phenylenevinylene) (PPV) derivative of poly(2-methoxy-5-octyloxy-p-phenylenevinylene) (PMOPV) with different content of narrow band-gap (NBG) unit 4,7-bis(2-thienyl)-2,1,3-benzothiadiazolevinylene (DBTV) or 4,7-bis(2-thienyl)-2,1,3-benzoselenadiazolevinylene (TBSV) was prepared by Stille coupling reaction. All the copolymers are soluble in common organic solvents, most of which emit NIR light accompanied by gradually red-shifting with increasing the content of the NBG units. The peak EL emission of the copolymers with around 30% TBSV content is at about 800 nm.