TiO2 nanocrystals – MEH-PPV composite thin films as photoactive material

The optoelectronic processes occurring in colloidal anatase TiO2 nanocrystalsyMEH-PPV conjugated polymer blends are reported. Composite films were prepared by spin-coating an homogeneous solution of low molecular weight MEH-PPV and surfactant-capped TiO2 nanocrystals onto low resistivity ITO substrates. Both nearly spherical and rod-like titania nanoparticles were used in the hybrid structures and the resulting blends comparatively examined, as a function of TiO2 nanoparticle morphology. The photoinduced charge transfer and recombination processes at the interface between the two components were studied by steady-state optical spectroscopy and photoelectrochemical experiments. A significant fluorescence quenching of the polymer occurred in MEH-PPVyTiO2 nanorods hetero-junctions and higher photoactivity of as prepared blends compared to the single components was observed and explained.