TiO(2) micro-flowers composed of nanotubes and their application to dye-sensitized solar cells

TiO(2) micro-flowers were made to bloom on Ti foil by the anodic oxidation of Ti-protruding dots with a cylindrical shape. Arrays of the Ti-protruding dots were prepared by photolithography, which consisted of coating the photoresists, attaching a patterned mask, illuminating with UV light, etching the Ti surface by reactive ion etching (RIE), and stripping the photoresist on the Ti foil. The procedure for the blooming of the TiO(2) micro-flowers was analyzed by field emission scanning electron microscopy (FESEM) as the anodizing time was increased. Photoelectrodes of dye-sensitized solar cells (DSCs) were fabricated using TiO(2) micro-flowers. Bare TiO(2) nanotube arrays were used for reference samples. The short-circuit current (J(sc)) and the power conversion efficiency of the DSCs based on the TiO(2) micro-flowers were 4.340 mA/cm(2) and 1.517%, respectively. These values of DSCs based on TiO(2) micro-flowers were higher than those of bare samples. The TiO(2) micro-flowers had a larger surface area for dye adsorption compared to bare TiO(2) nanotube arrays, resulting in improved J(sc) characteristics. The structure of the TiO(2) micro-flowers allowed it to adsorb dyes very effectively, also demonstrating the potential to achieve higher power conversion efficiency levels for DSCs compared to a bare TiO(2) nanotube array structure and the conventional TiO(2) nanoparticle structure.