Preparation of porous nanoparticle TiO2 films for flexible dye-sensitized solar cells

A TiO₂ paste was prepared by mixing commercial TiO₂ (P25), ethanol, distilled water and a small amount of Ti (IV) tetraisopropoxide (TTIP), following by a hydrothermal treatment. Before hydrothermal treatment, a stirring for 48 h can prevent cracking TiO₂ films. TTIP significantly promote the chemical connection between TiO₂ particles and its adherence to the substrate, the TTIP amount of 6 mol% is suitable. UV irradiation can remove some impurities and water from the TiO₂ film with an optimal time of 2 h. Transmission electron microscopy, X-ray diffraction, scanning electron microscopy and photovoltaic tests are characterized and measured. Short-circuit current density, open-circuit voltage, fill factor and photoelectric conversion efficiencies for the fabricated flexible dye-sensitized solar cell are 7.20 mA cm⁻², 0.769 V, 0.686 and 3.84%, respectively, under irradiation with a simulated solar light of 100 mW cm⁻².