Alumina Coatings on Fluorine-Doped Tin Oxide@Titanium Dioxide as Photoanode for Dye-Sensitized Solar Cells

Titanium dioxide coated fluorine doped tin oxide film (F-T film) is synthesized and applied as photoanode in dye-sensitized solar cells (DSCs). Efforts to improve the photovoltaic performance are made by coating an Al2O3 barrier layer to serve as the charge recombination barrier. Due to the less electron recombination with oxidized dye or I3− after two times of Al2O3 coating combined with an efficient electron extraction of F-T film, F-T-2A DSCs exhibits a maximal efficiency of 5.24% improved by 12.4% for F-T DSCs without surface modification. However the cell performance fades due to decreased photoelectron injection from dye molecules into TiO2 conduction band when the barrier became thicker. The thickness of Al2O3 by deposition cycle is well controlled and studied. Electrochemical impedance spectra are applied to disclose the low electron transfer resistance of F-T-2A DSCs for the better cell performance.