Fabrication and photovoltaic properties of dye-sensitized ZnO thick films by a facile doctor-blade printing method using nanocrystalline pastes

ZnO films used as photoanodes for dye-sensitized solar cells were fabricated by a facile doctor-blade printing method. Pastes containing nanocrystalline ZnO powders and polyethylene glycol (PEG) were coated on conducting glass sheets and heated at 450°C for 10 min in air. It was shown that the microstructure of the resultant films was largely dependent on the amount of PEG in the pastes. The film without PEG had large interconnected voids, which were decreased by increasing the PEG amount. The films were dyed with a ruthenium complex dye (N-719) and their photoelectrochemical performance was investigated in terms of film properties such as thickness, specific surface area, density, and roughness factor. By optimizing the film thickness and introducing the light scattering layer, a light-to-electricity conversion efficiency of a cell using our ZnO/N-719 photoanode reached 4.3% under the AM 1.5 illumination at 100 mW/cm2 (1 sun).