Morphological, optical and electrical characterization of titania-nanotubes-based dye-sensitized solar cells

Self-ordered, vertically aligned, titanium oxide (TiO2) nanotubes were grown on an electropolished titanium foil by anodic oxidation in a viscous organic electrolyte. We chose two different anodization times to obtain nanotubes of approximately 9 and 17 μm in length. Some of the TiO2 nanotubes were post-treated with TiCl4 or hydrothermally with TiO2 P25. Their structure and morphology were investigated with field-emission scanning electron microscopy (FSEM) and transmission electron microscopy (TEM). To improve the sensitizing of the high-aspect-ratio nanotubes with dye we used a new approach in which the TiO2 arrays were immersed into the dye solution at elevated temperature in an autoclave. The current-voltage characteristics of the assembled DSSCs gave an average energy-conversion efficiency of 5.7% for the untreated nanotubes.