Amount and Scattering of Dyes and their Influence on the Photocurrent Enhancement of TiO2 Hierarchically Structured Photoanodes for Dye-Sensitized Solar Cells

In this study, we prepared and analyzed the properties of hills-like hierarchically structured TiO2 photoanodes for dye-sensitized solar cells (DSSCs). We expected that the presence of appropriately aggregated TiO2 clusters in the photoanode layer would translate in a 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 the absorbance of the attached dye, the amount of dye loading, and the performance of the fabricated DSSC devices were investigated. Our optimized device presenting a relatively high dye loading and well light harvesting ability, and able to enhance the short-circuit current (J(sc)) in the DSSCs by 23%.