Uniform nanostructured photoelectrodes made of a zinc-stabilized TiO2 gel for dye-sensitized solar cell applications

Uniform sponge-like films are deposited by a novel TiO2 gel, in which anatase phase was stabilized using zinc chloride, for dye-sensitized solar cells (DSCs) applications. The introduction of Zn into TiO2 lattice limits the transformation from anatase to rutile phase, stabilizing anatase nanoparticles. The films are composed of uniform spherical particles with diameter around 3 µm, containing small nanoparticles with the average grain size of 40 nm, deposited by a dip coating method. X-Ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) reveal that Zn2+ is well incorporated into the titania crystal lattice without forming specific zinc phases. UV-visible spectra show that the doped-TiO2 films have lower band gap energy than that of undoped-TiO2, extending the absorption of TiO2 into visible region. The DSC stabilized with 0.4 at% Zn (i.e., Z4) had the highest power conversion efficiency of 7.15% as a result of less recombination, which is demonstrated by electrochemical impedance spectroscopy (EIS).