Résumé
Nowadays, increasing the sustainability of solar cells represents one of the most important scientific challenges. The working mechanism of Dye-Sensitized Solar Cells (DSSCs) requires an electrolyte that is typically based on a mixture of organic solvents and salts to achieve highly efficient devices. In this context, seawater-based electrolytes represent an interesting alternative due to their low cost, abundance and suitable chemical composition linked to the naturally occurring ions. [1] For the same reasons, seawater has been recently studied also for water splitting reaction or storage applications. [2,3] Then, in this wok different kinds of seawater electrolytes were prepared and tested considering traditional iodide/triiodide redox mediator. Seawater samples were collected from Italian national seas (i.e., Adriatic, Ligurian and Tyrrhenian) and characterized from the chemical point of view by ICP-OES and conductivity. The optical properties and diffusion of the so-obtained electrolytes were determined by UV-Visible method and cyclic voltammetry in a three-electrode cell. In addition, symmetrical cells were prepared and used to determine their electro-catalytic properties. For this purpose, different counter-electrodes were tested, covering them with the standard platinum layer or with more sustainable materials like carbon-based ones and conducting polymers. Then, the influence of seawater on the electrochemical properties of counter-electrodes was observed and discussed. Finally, DSSCs with reference N719 dye were prepared and tested to demonstrate the real application of seawater electrolytes in a complete device thus highlighting its influence on the photovoltaic performance and interface properties (evaluated by EIS). The reported results indicate that seawater can be consider as a highly sustainable electrolyte for DSSCs; future developments will include an optimization of both dye and counter-electrode to achieve more efficient and stable devices.