100% aqueous Dye-sensitized Solar Cells: a starting point for the choice of dyes and iodine salts

A key aspect still to be addressed in the DSSC community is the presence of water in the cell, either in the electrolyte or at the electrode/electrolyte interface. While it has been considered strongly harmful for a long time, in the last few years the scientific community suddenly turned the efforts in the direction of using water as a solvent, as demonstrated by the increasing number of research articles being published in the literature. Indeed, by means of DSSCs fabricated with water-based electrolytes, reduced costs, non-flammability, reduced volatility and improved environmental compatibility could be easily achieved. As a result, an increasing number of novel electrodes, dyes and electrolytes components are continuously proposed, being highly challenging from the materials science viewpoint and with the golden tread of producing truly water-based DSSCs. If the initial purpose of DSSCs was the construction of an artificial photosynthetic system able to convert solar light into electricity, the use of water as key component may represent a great step forward towards their widespread diffusion in the market. A starting point in this direction is given in this work, and a few curious and anomalous behaviours observed in the literature and in our laboratories are presented for this class of electrolytes. After a brief discussion of the current state of the art, this contribution proposes the investigation of both the stability of different classes of dyes (Ru complexes, squaraines, indolenines, carbazoles) in fully a aqueous environment, and the effect of the concentration of different iodine salts on the cell parameters and their stability