SEAWATER AS AN ELECTROLYTE SOLVENT FOR SUSTAINABLE DYE-SENSITIZED SOLAR CELLS

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 ICPOES 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 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. The reported results indicate that seawater can be consider as a highly sustainable electrolyte for DSSCs, and future developments will include an optimization of both dye and counter-electrode to achieve more efficient and stable devices.