Synthesis and properties of polyfluorene copolymers bearing thiophene and porphyrin

To search for more wider absorption and higher charge carriers mobilities materials of polymer solar cell, a series of soluble alternating polyfluorene copolymers were synthesized by palladium-catalyzed Suzuki coupling reaction. Their structures were determined by 1H NMR, IR and UV–vis. And their UV–vis absorption spectra indicated that they had strong absorption over 600 nm spectral range and nearly cover 400–700 nm visible region. The band gaps of copolymers calculated according to cyclic voltammetry (CV) were between 1.96 and 2.03 eV. Polymer:TiO2 bulk-heterojunction films were made from mixtures of polymer and titanium isopropoxide, a precursor for TiO2, via hydrolysis in air overnight. The photoluminescence at 380–800 nm of the blend film of PT-TPP20 (5 mg/mL):Ti(OC3H7)4 (80 μL/mL) (20% volume fraction) was significantly quenched in the 50% Ti(OC3H7)4 blend film, indicating that rapid and efficient separation of photoinduced electron–hole pairs.