New low-temperature preparation method of the TiO2 porous photoelectrode for dye-sensitized solar cells using UV irradiation

Thick porous TiO2 films have been prepared at low temperature from a mixture of a commercial TiO2 powder (Degussa P25) and an easy-to-handle water-soluble titania precursor: titanium(IV) bis(ammonium lactato)dihydroxide. Films have been obtained spreading the mixture using “doctor blade” technique. UV light treatment using a medium-pressure mercury vapor lamp leads to decomposition of the titania precursor as a result of the photocatalytic activity of nanocrystalline TiO2 present in the blend. The additional titanium oxide thus formed assures both, necking between particles and film adhesion to the substrate. Porous nano-structured TiO2 films were fabricated by this low-temperature method (always lower than 80 °C) on transparent conducting oxide-covered glass and flexible plastic substrates (indium-tin-oxide on glass and on PET, and fluorine-doped tin oxide on glass). The photoelectrodes obtained by this method have been characterized by scanning electron microscopy, attenuated total reflection Fourier transform infrared spectroscopy, photoluminiscence, monochromatic incident photon-to-current conversion efficiency (IPCE) and I-V measurements. Results obtained with dye-sensitized solar cells (DSSC) built with these films are promising.