Solution processable titanium dioxide precursor and nanoparticulated ink: application in Dye Sensitized Solar Cells

Colloidal TiO2 anatase nanoparticles of 4-8 nm diameter capped with 3,6,9-trioxadecanoic acid (TODA) were synthesized at low temperature using water and ethanol as the solvents. ATR-FTIR and (1)H NMR characterization showed the capping acid capability of stabilizing the TiO2 nanoparticles through labile hydrogen bonds. The presence of the capping ligand permitted the further preparation of homogeneous and stable colloidal dispersions of the TiO2 powder in aqueous media. Moreover, after solvent evaporation, the ligand could be easily eliminated by soft treatments, such as UV irradiation or low-temperature thermal annealing. These properties have been used in this work to fabricate mesoporous TiO2 electrodes, which can be applied as photoanodes in Dye Sensitized Solar Cells (DSSCs). For the preparation of the electrodes, the as-synthesized mesoporous TiO2 nanoparticles were mixed with commercial TiO2 (Degussa P25) and deposited on FTO substrates by using the doctor blade technique. A mixture of water and ethanol was used as the solvent. A soft thermal treatment at 140 °C for 2h eliminated the organic compound and produced a sintered mesoporous layer of 6 μm thickness. The photovoltaic performance of the DSSCs applying these electrodes sensitized with the N3 dye resulted in 5.6% power conversion efficiency.