Ordered Crystalline TiO₂ Nanotube Arrays on Transparent FTO Glass for Efficient Dye-Sensitized Solar Cells

Abstract

The fabrication of highly ordered one-dimensional TiO2 nanotube arrays on transparent conductive glass is of key interest for constructing dye-sensitized solar cells (DSSCs) from the front-side illumination mode. We report the formation of large-scale free-standing TiO2 nanotube arrays via sonication of a TiO2 nanotube on Ti foil prepared by an anodization process, which can be further transferred to the fluorine-doped tin oxide conductive glass via a drop of TiO2 sol containing Ti(OBu)4 and polyethylene glycol. The photovoltaic performance of DSSCs based on 20.8 μm length TiO2 nanotube arrays on FTO glass reached 8.07%, which is higher than that of a TiO2 nanoparticle electrode (7.58%) because of the reduced electron combination and efficient light-harvesting efficiency for the former. It is also observed that the power conversion efficiency of DSSCs measured from the front-side illumination mode (8.07%) is higher than that of the back-side illumination mode (7.29%) owing to the light absorption by the iodine electrolyte and light reflection by the Pt counter electrode for the latter.