Low temperature sintering of aqueous TiO2 colloids for flexible, co-sensitized dye-sensitized solar cells

Colloidal TiO 2 films have been prepared using a binder-free aqueous paste with Degussa P25 and hexafluorotitanic acid (H 2 TiF 6 ), which was optimised for different substrates. Dye-sensitized solar cells (DSSC) fabricated using this paste were sintered at ( ca. 393 K) and efficiencies ( η ) of 3.0, 4.2 and 6.1% were measured for devices using titanium foil ( ca. 1 mm thickness), indium-doped tin oxide on polyethylene terephthalate (ITO-PET), and for co-sensitized devices on fluorine-doped tin oxide (FTO) glass substrates, respectively. Electrochemical impedance measurements show that the charge transport resistance is less consistent for devices fabricated at low sintering temperature ( ca. 393 K) by comparison to devices sintered at 773 K. These measurements correlate with the increased variation in device efficiency (η) for low temperature sintered DSSC devices.