Abstract
TiO2/conjugated polymers are promising materials in solar energy conversion where efficient photo-induced charge transfers are required. Here, a 'grafting-from' approach for the synthesis of TiO2 nanoparticles supported with conjugated polymer brushes is presented. Poly(3-hexylthiophene) (P3HT), a benchmark material for organic electronics, was selectively grown from TiO2 nanoparticles by Surface-Initiated Kumada Catalyst-Transfer Polycondensation (SI-KCTP). The grafting of the polymer onto the surface of the TiO2 nanoparticles by this method was demonstrated by 1H and 13C solid-state NMR, XPS (X-ray photoelectron spectrometry), thermogravimetric analysis (TGA), Transmission Electron Microscopy (TEM) and UV-Visible spectroscopy. Sedimentation tests in THF revealed improved dispersion stability for the TiO2@P3HT hybrid material. Films were produced by solvent casting and the quality of the dispersion of the modified TiO2 nanoparticles was evaluated by Atomic Force Microscopy (AFM). The dispersion of the P3HT-coated TiO2 NPs in the P3HT matrix was found to be homogeneous and the fibrillar structure of the P3HT matrix was maintained which is favourable for charge transport. Fluorescence quenching measurements on these hybrids materials in CHCl3 indicated improved photo-induced electron transfer efficiency. All in all, better physicochemical properties for P3HT/TiO2 hybrid material were reached via surface-initiated "grafted from" approach compared to the "grafting onto" approach