Enhanced efficiency for dye-sensitized solar cells using a surface-treated photo-anode

Well-ordered TiO2 nanotube arrays with an inner average pore diameter of 85 nm and a length of 15.69 μm are fabricated by electrochemical anodization in ethylene glycol solution and used as the photo-anode in dye-sensitized solar cells (DSSCs). The photo-conversion efficiency of the DSSCs is significantly enhanced by appropriate surface treatments. The surface of the TiO2 nanotube arrays is treated with titanium (IV) n-butoxide using a hydrothermal method in combination with an oxygen-plasma treatment. The variations in the TiO2 nanotubes are investigated using field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), atomic force microscopy (AFM), contact-angle analysis, X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). Comparative studies show that the surface area and hydrophilicity are increased, while electron recombination rate is decreased. The TiO2 nanotube arrays treated by the combined methods under optimum conditions exhibits a conversion efficiency is approximately double that of the untreated TiO2 nanotube arrays under backside illumination conditions.

► We use well-ordered TiO2 nanotubes as photo-anode in DSSCs.
► We provide a new technique to treat photo-anode.
► The technique is titanium n-butoxide combination with an oxygen-plasma treatment.
► The results show that efficiency of DSSCs improves approximately double.