Growth of porous light scattering sub-micrometer particle films by occlusion electrolysis for dye-sensitized solar cells

The development of new low-temperature synthetic routes for the growth of light scattering layers is an important issue notably due to their use for light confinement in active films and devices. We present the preparation of porous ZnO made of sub-micrometer sized particles by occlusion electrolysis using the zinc oxide electrodeposition route in a chloride medium. The films show strong light scattering properties. Following this preparation step, the open framework has been conformaly covered by a nanoporous nanocrystalline ZnO material electrodeposited at room temperature and an original hierarchical architecture has been developed. A consequence was a marked increase in the film surface area and a better contact between the deposited layer and the substrate. These films have been used for the preparation of dye sensitized solar cell (DSSC) photoelectrodes after their sensitization by the D149 metal-free organic indoline dye. The cell performances were dramatically increased in the presence of the secondary phase compared to the initial occluded sub-micrometer particle framework layer.