Mesostructured self-assembled titania films for photovoltaic applications

Mesostructured titania thick films were tested as photovoltaic materials to be used for the fabrication of Grätzel-type dye-sensitized solar cells. The titania films, prepared by evaporation-induced self-assembly, showed a 3D orthorhombic porous mesostructure obtained using non-ionic tri-block copolymers as templating agents and controlled conditions of processing. Thick films (up to 1 μm) were synthesized via repetitive dip-coating. Grazing incidence small angle X-ray scattering and X-ray diffraction analysis showed that, after calcination at temperatures higher than 350 °C, anatase crystallites were formed in the titania pore walls without loss of organization. The block copolymers were removed after thermal calcination at 350 °C, as shown by infrared spectroscopy. Photoaction spectra of 1 μm thick films, treated at 350 °C, exhibited an incident photon-to-current efficiency above 40% at λ = 380 nm.