NEW WELL-DEFINED POLY(2,7-FLUORENE) DERIVATIVES - PHOTOLUMINESCENCE AND BASE DOPING

Well-defined poly(2,7-fluorene) derivatives have been prepared through palladium-catalyzed couplings between various 9,9-disubstituted or 9- monosubstiiuted 2,7-dibromofluorenes and thyl-1,3,2-dioxaborolan-2-yl) -9,9-dioctylfluorene. Using this versatile synthetic method, processab le polyfluorenes have been obtained in good yields. In solution, all t hese neutral yellow polymers exhibit blue emission (maximum of emissio n around 410 nm) with high quantum yields (up to 0.87). Moreover, nove l acidic polyfluorene derivatives have been synthesized (i.e., poly[2, 7'-(alkyl 9,9-dioctyl-7,2'-bifluorene-9'-carboxylate)]s) which show, u pon base doping, electrical conductivities of 10(-6)-10(-5) S/cm. This new doping method for conjugated polymers could open the way to the p reparation of air-stable electron-injecting electrodes. Both photophys ical and electrical properties of these polymers are quite promising f or the fabrication of efficient blue-light-emitting devices.