A novel cheap, one-step and facile synthesis of hierarchical TiO2 nanotubes as fast electron transport channels for highly efficient dye-sensitized solar cells

Abstract

The well-aligned hierarchical TiO2 nanotubes (HTNTs) have been synthesized by a one-step hydrothermal method employing potassium titanium oxalate, ethanol and H2O, which are strongly adhered onto transparent conducting oxide glass. The preparation is straightforward, cheap and applicative for mass manufacture. The thickness of membranes is changed from 12 to 22 μm by adjusting the reaction time. The HTNTs consist of one-dimensional (1D) long TiO2 nanotube trunks and numerous short TiO2 nanorod branches, which can balance surface area and charge transport. By employing optimized HTNTs for dye-sensitized solar cells, a remarkable power conversion efficiency of 9.89% is obtained. The result is superior to P25 (8.34%), because 1D trunk-1D branch structure of HTNTs offers the advantages of strong light-harvesting, directed electron transport, and efficient charge collection. The HTNTs may find an underlying application in the manufacture of photovoltaic devices.