TiO₂ Branched Nanostructure Electrodes Synthesized by Seeding Method for Dye-Sensitized Solar Cells

We report TiO 2 branched nanostructure photoelectrodes for dye-sensitized solar cells (DSSCs). The TiO 2 branch-type nanoparticle is synthesized by means of a seeding method with TiO 2 nanowire as a seed. During the seeding process, the TiO 2 nanostructure is evolved from a nanowire (NW) to nanobranch (NB) shape. It is also found that rutile TiO 2 -NB shows such a three-dimensional structure with branches grown along backbones of rutile TiO 2 -NW as confirmed by high-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD) analysis. In photocurrent−voltage measurements, short-circuit current density, and cell efficiency of TiO 2 -NW and TiO 2 -NB increase from 6.25 to 12.18 mA/cm 2 and increase from 2.6 to 4.3%, respectively, due to both increased specific surface area and roughness factor.