Electrodes and electrolyte materials for aqueous dye-sensitized solar cells

Third generation photovoltaic (PV) has evolved rapidly in the past few decades and now encompasses a large variety of materials and device structures. A key aspect to be considered in any PV technology is the stability under real outdoor conditions, as well as the sustainability of materials/components and the facile integration with energy storage systems. In the last five years, dye-sensitized solar cells (DSSCs) with water-based electrolytes have been considered as one of the possible breakthroughs towards DSSC large-scale diffusion. In fact, the replacement of the organic electrolyte ensures better stability and safety. If opportunely developed and optimized, aqueous solar cells can be truly considered a low-impact photovoltaic device with non-toxic components. Herein, we show our last results on this field, such as the possibility of gellyfing the electrolyte into a solid matrix and the replacement of Pt cathodes with conductive polymers or biomass-derived carbon substrates could increase the long-term stability and lower fabrication costs. Also, we report morphological modifications of TiO2 photoanodes, introduced by adding various kinds of additives, both molecular and polymeric, 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 the 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.