Synthesis,characterization and photovoltaic properties of a new thiophene-based double-cable polymer with pendent fullerene group

In this paper we report the synthesis of a new thiophenic 3-substituted monomer with a plastifying side chain bearing a C₆₀-fullerene moiety at the end. The monomer has been copolymerized with 3-hexylthiophene through the simplest chemical method, namely oxidative polymerization with iron trichloride. The final copolymer, with a high fullerene content (1:1 wt/wt), was fully soluble in common organic solvents and its solubility allowed for its complete physic-chemical characterization. The copolymer thermal behavior was investigated by TGA analysis showing that the incorporation of fullerene has beneficial effects on thermal stability. The fluorescence spectroscopy showed a strong quenching of fluorescence of the copolymer main chains in film, while the AFM analysis confirmed the homogeneous morphology of its films with only very small and uniformly distributed aggregates. The photovoltaic performances of the copolymer and of a film obtained by blending the prepared monomer with poly(3-hexylthiophene) were significantly higher than those obtained using conventional materials and architectures.