Sponge-like Porous ZnO Photoanodes for Highly Efficient dye-sensitized Solar Cells (original) (raw)

We propose a 3D branched ZnO nanostructure for the fabrication of highly ecient dye-sensitized solar cell photoanodes. A coral-shaped structured Zn layer was deposited by radio frequency magnetron sputtering at room temperature onto uorine-doped tin oxide/glass sheets and then thermally oxidized in ambient atmosphere, obtaining a high-density branched ZnO lm. The porous structure provides a large surface area, and, as a consequence, a high number of adsorption sites, and the size and spacing of the nanostructures (on the order of the exciton diusion length) are optimal for good electron collection eciency. The proposed synthesis technique is simple and scalable and the reproducibility of the growth results was tested. The crystalline phase of the lm was investigated, evidencing the complete oxidation and the formation of a pure wurtzite crystalline structure. ZnO-based solar harvesters were fabricated in a microuidic architecture, using conventional sensitizer and electrolyte. The dependence of the cell eciency on dye incubation time and lm thickness was studied with IV electrical characterization and electrochemical impedance spectroscopy. The obtained conversion eciency values, with a maximum value of 4.83%, conrm the highly promising properties of this material for the implementation in dye-sensitized solar cell photoanodes.