Electrochemical characterization of TiO2 blocking layers prepared by reactive DC magnetron sputtering

Thin TiO2 (anatase) films were prepared by reactive DC magnetron sputtering and characterized in detail. Specifically, they were tested as compact blocking underlayers in dye-sensitized solar cells. Elastic recoil detection analysis and optical measurement showed some porosity in the sputtered films, but electrochemical measurements demonstrated good blocking characteristics. This suggests the presence of small voids rather than pinholes in the deposited films. In the case of an iodide/iodine redox couple, thin underlayers (∼20 nm) improved the fill factor without affecting other properties of the cell. In case of a ferrocene/ferrocenium-based electrolyte, the presence of underlayers was necessary to obtain functional dye-sensitized solar cells.