Titania Nanotubes Decorated with Zn‐Doped Titania Nanoparticles as the Photoanode Electrode of Dye‐Sensitized Solar Cells

We decorate Zn-doped TiO2 ¬nanoparticle-based photoanodes with carbon nanotube (CNT)-derived TiO2 nanotubes (i.e., TNs) in order to enhance the power conversion efficiency of dye-sensitized solar cells (DSCs). X-Ray photoelectron spectroscopy (XPS) analysis verifies that Zn ions, in the range of 0-1 at.%, are successfully doped into TiO2 lattice. Field emission scanning electron microscopy (FE-SSEM) and transmission electron microscopy (TEM) images of sol-gel template-assisted derived TNs reveal that a uniform TiO2 coating with the thickness of 60-120 nm is deposited on the surface of the template through the non-covalent route. We observed that the cell efficiency improves from 6.80% for pure TiO2 to 7.52% for 0.75 at.% Zn-doped TiO2 nanoparticles due to reduction of charge recombination and enhancement of electron injection, as confirmed by photoluminescence spectroscopy (PL). Further improvement of the efficiency up to 8.47% is achieved by incorporation of 5 wt.% TNs into Zn-doped TiO2 photoanodes as a result of electron transport and light scattering enhancements, as verified by diffuse reflectance spectroscopy (DRS).