(413c) Long TiO2 Nanotube Arrays Synthesized Directly On Transparent Conducting Oxide for Efficient Dye-Sensitized Solar Cells

Vertically aligned TiO2 1-D nanostructures synthesized directly on transparent conducting oxide (TCO) have shown great promise to overcome the limitation of the random network of TiO2 nanoparticles currently used in dye-sensitized solar cells (DSCs). Synthesis of such structures with a sufficient length for fabrication of high-efficiency DSCs, however, remains challenging. Here we show that by using a wet chemical process, arrays of TiO2 nanotubes up to 20 µm long can be directly synthesized on TCO through conversion of ZnO nanowire arrays. DSCs fabricated using the synthesized TiO2 nanotube arrays yield a power conversion efficiency of 6.1%, which is comparable to TiO2 nanoparticle-based DSCs fabricated using the same dye and electrolyte. In addition, the anode film as thick as 21 µm based on such TiO2 nanotube arrays possess a high electron collecting efficiency and an appreciable enhancement in the red light quantum yield is observed on the DSCs with such anodes. This result suggests numerous opportunities for further improvement of DSCs, for example, by employing solid-state electrolytes and redox mediators with faster kinetics.