Synthesis and characterization of carboxystyryl end-functionalized poly(3-hexylthiophene)/TiO2 hybrids in view of photovoltaic applications

Regioregular head-to-tail α-bromo-ω-carboxystyryl poly(3-hexylthiophene) (P3HT-COOH) has been prepared by a Wittig reaction of α-bromo-ω-formyl poly(3-hexylthiophene) (P3HT-CHO) with [(4-carboxyphenyl)methyl]triphenylphosphonium bromide. This carboxylic end-group functionalized polymer was used to functionalize TiO2 nanoparticles in view of improving the miscibility between poly(3-hexylthiophene) and the nanoparticles, for future photovoltaic applications. The anchoring of the polymer on the surface of the TiO2 nanoparticles was demonstrated by sedimentation tests in THF, and by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), 1H MAS solid-state NMR, UV–vis and X-ray photoelectron spectroscopies. Films were produced by solvent casting and the dispersion of the TiO2 nanoparticles was evaluated by atomic force microscopy (AFM). Fluorescence quenching studies in CHCl3 were performed on these hybrids materials.