Role of the Solvent Employed for the cathodic-Electrophoretic Deposition (EPD) of ITO/TiO₂ films, over its morphology, electronic properties and photoelectrochemical behavior

The role played by solvent during cathodic EPD of TiO₂ films was investigated. The differences in film morphology are attributed to the dissimilar surface excess charge of the TiO₂ agglomerates in each solvent and to the secondary reactions occurring during the EPD. For the films obtained in aqueous medium an augmentation of donor density and a change toward less negative values of the flat band potential were measured. Furthermore, a decrease in photocurrents and photovoltages was provoked by increasing the electric field used to form the film. Meanwhile, for the films formed in organic medium, the semiconductive properties did not change with the electric field employed to grow the films, and the photoelectrochemical behavior of these films showed completely different trends. The dissimilarities found were attributed to the ability of the solvent to be reduced earlier than TiO₂, avoiding the generation of species Ti³⁺ that acts like trap states.