Strategies for electrodes and electrolytes design for aqueous solar cells

Photovoltaic (PV) technology 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 operational durability 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. If opportunely developed and optimized, aqueous solar cells can be truly considered a zero-impact photovoltaic device with no toxic components. Moreover, the possibility of gellyfing the electrolyte into a solid matrix and the replacement of Pt cathodes with conductive polymers could increase the long-term stability and lower fabrication costs. The electricity production of DSSCs and the change of consumption for lighting and air conditioning of offices/flats depending on the different orientations of the building can be estimated. The integration of aqueous DSSCs with windows causes an increase of about 14% of the electricity consumption for lighting due to the lower light transmittance, slightly increases the energy needs for heating (less than 10%), but greatly reduces the demand for energy for cooling, shielding part of the solar thermal contributions. When the building is oriented towards the West and South, the application of the DSSC is advantageous. Lastly, the investment cost for a solar plant was assessed. It was found that platinum DSSCs have a 12% higher cost that polymer-based DSSCs, due to the scarcity of Pt. The lowest discounted return time (12 years) was obtained for cells with PEDOT:PSS as conductive polymer, when the building is oriented towards the West.