LIGHT-EMITTING-DIODES BASED ON POLY(METHACRYLATES) WITH DISTYRYLBENZENE AND OXADIAZOLE SIDE-CHAINS

We report investigations on the use of singly and doubly functionalise d poly(methacrylates) (PMA) for the fabrication of polymeric light-emi tting diodes (LEDs). The functional groups we used were distyrylbenzen e (DSB) as blue chromophore and 1-phenyl-5-phenyl-1,3,4-oxadiazole (PP D) or 2-phenyl-5-biphenyl-1,3,4-oxadiazole (PBD) as charge-transport g roups to produce three homopolymers (with one functional group only) a nd a copolymer bearing both DSB and PBD groups (PMA-DSB-PBD). The poly mers have been used alone or blended together in single-layer devices or in double-layer devices, for which a thin poly(p-phenylene vinylene ) (PPV) layer was used as a hole-transporting material. Despite the hi gh photoluminescence yield of these DSB-based materials, successful fa brication of blue-emitting LEDs has only been achieved by using the co polymer, both in single- and double-layer devices.