Photoanodes for aqueous dye-sensitized solar cells: effect of different TiO2 pastes

In the photovoltaics field, dye-sensitized solar cells (DSSCs) have aroused much interest due to their low cost and unique possibility of diffuse light conversion. A key aspect to be considered is the stability under real outdoor conditions, as well as the sustainability of materials and components. To this purpose, water-based electrolytes are considered as one of the possible breakthroughs toward large-scale diffusion DSSCs. Moreover, the possibility of gellyfing the electrolyte into a solid matrix reduces its leakage outside the device, thus increasing long-term stability. Consequently, the dye-sensitized TiO2 photoanode should be wettable, allowing electrolyte penetration in its bulk, and at the same time must prevent the water-induced desorption of dye molecule. Herein, we report morphologic modifications of TiO2 photoanodes, introduced by adding various kinds of additives to the commercial Dyesol TiO2 paste, typically used for screen printing DSSC electrodes onto conductive glass. It was found out that the addition of polyethylene glycol (PEG) modified both the morphology and thickness of photoanodes. As a result, PEG-based cells showed an increased short-circuit current density (+18%) and power conversion efficiency (48%) with respect to the pristine counterpart.