Novel polyfluorene copolymers containing porphyrin and thiophene moieties with broad absorption and efficient charge transfer and separation

A novel series of soluble conjugated polyfluorene copolymers comprised of porphyrin and thiophene moieties were synthesized by palladium-catalyzed Suzuki coupling reactions with various feed ratios. Chemical structures of the copolymers were characterized by H-1 NMR and IR. All of the polyfluorene copolymers demonstrated good thermal stability, relatively high glass transition temperatures, and strong absorption over 600 nm and nearly cover 400 similar to 700 nm visible region. It was revealed by cyclic voltammetry that the bandgaps of copolymers were between 1.96 and 2.03 eV. And the polymer:TiO2 bulk-heterojunction films were made from mixtures of polymer and titanium isopropoxide (Ti(OC3H7)(4)) via hydrolysis in air. The photoluminescence (PL) at 380 similar to 800 nm of the blend film of PT-TPP20:TiO2 bulk-heterojunction in the 20% Ti(OC3H7)(4) blend film was decreased compared to that of a pristine copolymer film. PL was significantly quenched in the 50% Ti(OC3H7)(4) blend film, indicative of rapid and efficient separation of photoinduced electron-hole pairs with electrons on the TiO2 and holes on the polymer.