Nanostructured NiOx-coated TiO2 electrodes for dye-sensitized solar cells.

NiO x nanostructures are employed to modify the nanoporous TiO 2 photoanode for dye-sensitized solar cells with the surface sol-gel process by multiple spin coating. X-ray photoelectron spectroscopy confirms that the chemical states for the as-prepared NiO x nanostructures are more diverse than those derived by magnetron sputtering. Combined with SEM-EDX results, the structure of NiO x layer cannot be interpreted a uniform “thin film”, but as incomplete coating with a few particulate nickel oxides. The results of dark current measurement and electrochemical impedance spectroscopy analysis suggest that an energy barrier is formed at the interface of electrode and electrolyte by the coated NiO x layers. The basic NiO x -coated surface favors dye attachment, leading to a dramatic enhancement in the amount of adsorbed dye onto the TiO 2 surface. It also demonstrates that an energy conversion efficiency of 6.64% could be achieved for the NiO x -coated TiO 2 electrode with three spin-coated layers of NiO x which accounts for a 27% increment in energy conversion efficiency over that for the unmodified TiO 2 electrode. [ABSTRACT FROM AUTHOR]