Dye-sensitized solar cells containing plasma jet deposited hierarchically nanostructured TiO2 thin photoanodes

Abstract

The investigation of dye-sensitized solar cells (DSCs) using a very thin (0.8 to 4.7 μm) transparent photoanode based on a hierarchically nanostructured TiO₂ film prepared via Plasma Assisted Supersonic Jet Deposition (PA-SJD), in combination with the DSC benchmark photosensitizer N719, is presented. The cell photovoltages (nearly 0.8 V) and the amount of adsorbed dye and photocurrent densities, normalized over the film thickness, are higher than those of DSCs prepared with thicker (9 μm) conventional screen-printed TiO₂ films. A record efficiency value of 5.7% (standard AM 1.5G solar irradiation) for very thin nanostructured titania photoanodes is obtained with a 2 μm PA-SJD TiO₂ film. Electrochemical impedance spectroscopy shows that PA-SJD devices are endowed with higher charge recombination resistance (lower recombination losses) and electron lifetimes compared to conventional nanocrystalline films.