Dyes amount and light scattering influence on the photocurrent enhancement of titanium dioxide hierarchically structured photoanodes for dye-sensitized solar cells

Abstract

In this study, we prepared and analyzed the properties of hill-like hierarchically structured titanium dioxide (TiO2) photoanodes for dye-sensitized solar cells (DSSCs). We expected that the presence of appropriately aggregated TiO2 clusters in the photoanode layer would translate to relatively strong light scattering and dye loading, increasing the photovoltaic efficiency. A detailed light-harvesting study was performed by employing polyvinyl alcohol (PVA) polymers of different molecular weights as binders for the aggregation of the TiO2 nanoparticles (P-25 Degussa). Hence, we obtained a series of TiO2 films, presenting a variety of morphologies. Their reflection, as well as absorbance of light by the attached dye, the amount of dye loading, and the performance of the fabricated DSSC devices were investigated. Our optimized device, with a relatively high dye loading and good light harvesting ability, was able to enhance the short-circuit current (Jsc) in the DSSCs by 23%.