Preliminary study on alternating thienylene/phenylene copolymers functionalized with an electron-donating or -withdrawing group

Three novel regioregular polymers substituted with electron-donating or -wi thdrawing groups, poly[1,4-bis(3-X-2,5-thienylene)phenylene-alt-2,5-dioctyl -1,4-phenylene] [PBT(X), X = OMe, H, CN], were synthesized and characterize d. They are highly fluorescent, but the absorption wavelength of PBT(CN) an d PBT(OMe) are shifted toward the blue and red regions, respectively, with reference to PBT(H). The onset reduction potential of PBT(CN) is -1.11 V ve rsus SCE (saturated calomel electrode), which is higher than that of the cy ano derivative of poly(phenylene vinylene), indicating it be a good candida te as electron transport layer. The onset oxidation and reduction potential s of PBT(OMe) (0.96 and -1.28 V versus SCE respectively) suggest it: would perform well as emissive layer in light-emitting display applications.