Zirconium Oxide Post-treatment for TiO₂ Photoelectrodes in Dye-Sensitized Solar Cells

Zirconium was newly utilized as a post-treatment material for photoelectrodes in dye-sensitized solar cells (DSSCs), and DSSCs with a high energy conversion efficiency were developed. The Zr oxide-post-treated TiO₂ photoelectrodes were prepared by dipping Degussa P25 in a Zr butoxide solution, followed by calcination for 30 min at 475 °C. In the prepared sample, the particle size decreased, and the specific surface area increased, leading to improved dye adsorption. Zr oxide-post-treatment formed ZrO₂ on TiO₂ surfaces and the electron transport increased by the formation. This post-treatment decreased the recombinant ratio of electrons by reducing resistance in the interparticle electrode/dye/electrolyte. The energy conversion efficiency of Zr oxide-post-treated TiO₂ photoelectrodes was 7.03%, which is a 61% improvement over P25 photoelectrodes and is similar to that of TiCl₄-post-treated TiO₂ photoelectrodes (7.28%). This enhanced energy conversion efficiency could be attributed to the increased surface area, which enabled higher dye loading, and to the improved interparticle connections, which enhanced charge transport and reduced charge recombination.