Mesoporous\nTiO₂ Microbead Electrodes for\nCobalt-Mediator-Based Dye-Sensitized Solar Cells

Abstract

Light scattering, porosity, surface\narea, and morphology of TiO₂ working electrode can affect\nthe power conversion efficiency\nof dye -sensitized solar cells dramatically. Here mesoporous TiO₂ microbeads were tested as working electrode in dye-sensitized\nsolar cells based on cobalt tris-bipyridine electrolyte. Power conversion\nefficiencies up to 6.4% were obtained with D35 dye adsorbed onto the\nlight-scattering microbeads. Electron transport, studied using small\nlight perturbation methods, was found to be significantly faster in\nthe microbead films than in standard mesoporous TiO₂ films.\nThis was attributed to the favorable assembly of nanocrystals in the\nmicrobeads, which can increase the electron diffusion coefficient\nin the conduction band. Electron lifetimes were similar in both types\nof film. While solar cell performance of microbead films was comparable\nto that of standard mesoporous films in acetonitrile-based electrolytes,\na significant improvement was found when the more viscous 3-methoxypropionitrile\nwas used as solvent for electrolyte.