Fabrication and photoelectrochemical properties of TiO2 films on Ti substrate for flexible dye-sensitized solar cells

The dye-sensitized solar cells (DSSCs) using Ti foil supporting substrate for fabricating nanocrystalline TiO₂ flexible film electrodes were developed, intending to improve the photoelectrochemical properties of flexible substrate-based DSSCs. The obtained cells were characterized by electrochemical impedance spectra (EIS), open circuit voltage decay (OCVD) measurement and Tafel plots. The experimental results indicate that the most important advantage of a Ti foil-based TiO₂ flexible electrode over a FTO glass-based electrode lies in its reduced sheet resistance, electron traps, and the retarded back reaction of electrons with tri-iodine ions in DSSCs. All above characteristics for the Ti substrate TiO₂ films are beneficial for decreasing the charge recombination in the TiO₂ electrode and prolonging the electron lifetimes for the DSSCs, as well as improvement of the overall solar conversion efficiency. The photocurrent of the cell fabricated with the Ti foil-based flexible electrode increased significantly, leading to a much higher overall solar conversion efficiency of 5.45% at 100 mW/cm² than the cell made with FTO glass-based TiO₂ electrodes. Above results demonstrate that Ti foil is a potential alternative to the conventional FTO glass substrate for the DSSCs.