Effects of titanium oxide nanotube arrays with different lengths on the characteristics of dye-sensitized solar cells

The self-aligned highly ordered TiO₂ nanotube (TNT) arrays were fabricated by potentiostatic anodization of Ti foil, and we found that the TNT-array length and diameter were dependent on the electrolyte (NH ₄F) concentration in ethylene glycol and anodization time. The characteristics of the fabricated TNT arrays were characterized by XRD pattern, FESEM, and absorption spectrum. As the electrolyte NH₄F concentration in the presence of H₂O (2 vol%) with anodization was changed from 0.25 to 0.75 wt% and the anodization period was increased from 1 to 5 h, the TNT-array length was changed from 9.55 to 30.2 m and the TNT-array diameter also increased. As NH₄F concentration was 0.5 wt%, the prepared TNT arrays were also used to fabricate the dye-sensitized solar cells (DSSCs). We would show that the measured photovoltaic performance of the DSSCs was dependent on the TNT-array length.