Fabrication of TiO2 nanotube–nanocube array composite electrode for dye-sensitized solar cells

Abstract

One dimensional TiO2 nanotube structure recently plays an important role in the application of dye sensitized solar cells (DSSCs) due to its faster electron transport. The fabrication of photoanode using the TiO2 nanotube structures mixed with the TiO2 nanoparticles was investigated to enhance the photovoltaic efficiency of DSSCs by increasing the surface area of electrode. In this work, self-organized and vertically-oriented TiO2 nanotube arrays (TNAs) covered with uniformly distributed TiO2 nanocubes (TNCs) were fabricated in a simple one-step anodization process. The X-ray diffraction patterns reveal that both TNAs and TNCs are in anatase phase. The scanning electron microscopy analysis demonstrates that the wall thickness and inner diameter of hexagonal close-packed TiO2 nanotubes from chemically polished Ti foils are 10–15 and 100–120nm, respectively, and the particle size of TNCs is 60–75nm. The DSSC fabricated by the mixed morphological TNAs with TNCs shows an enhanced photoconversion efficiency of ~63% than that of TNAs alone, due to the increase of both dye adsorption and electron transportation rate.