Layer-by-Layer Fabrication of Multiple-Dye-Sensitized TiO₂ Films for Dye-Sensitized Solar Cells by Vacuum Cold Spray

Space-separate co-sensitization allows a more flexible design of dye sensitizers and promotes the development of high performance dye-sensitized solar cells, since the negative interactions between different dyes are minimized by the spatial seperation. The key point involves depositing nano-TiO₂ particles on the dye-loaded TiO₂ layer to form an efficient electron transport between the outer TiO₂ layer and the inner dye-loaded layer. Layer-by-layer fabrication of multiple-dye-sensitized TiO₂ films was realized through high velocity impact deposition by vacuum cold spray. Results show that the effective connection between the nano-TiO₂ particles in the outer layer and the inner dye-loaded layer was realized through the high compressive pressure pulses resulting from the high velocity particle impact on deposit surface. It is found that the photovoltaic performance of the inner dye-loaded photoanode was not influenced by the deposition of the outer layer. A significant enhancement of photocurrent was obtained by space-separate co-sensitization of N719 dye and Black dye due to the effective connection between the outer layer and the inner dye-loaded layer.