The sun, the main natural resource of our planet, has been studied in recent years optimizing materials, technologies and processes to obtain electrical energy thanks to the best renewable and clean source: the solar energy.

Photovoltaic cells are devices able to carry out this conversion and technologies based on the use of organic materials are raising interest, since they could be a viable alternative to traditional systems based on silicon. The most promising are the dye sensitized solar cells (DSSC), which mimic the chlorophyll photosynthesis process.

One of the most important cells’ elements is the dye, which absorbs sunlight and injects electrons in a semiconductor on which it is adsorbed, generally titania, a non-toxic and low-cost oxide.

The present work aims to enhance, through innovative solutions, the main waste product of the vinification processes of red and white grapes, in particular lees and marc, for the realization of DSSC cells.

Using different synthetic approaches, a nanostructured titania with high surface area and ordered porosity was prepared and low molecular weight tannins and anthocyanins extracted from by-products of winemaking were adsorbed on its surface. Tests were carried out on solar cell prototypes to evaluate power and photocurrent generated under simulated solar light irradiation. The use of polyphenolic compounds as dyes for photovoltaic cells can represent an extremely eco-friendly and low environmental impact solution for the production of electric energy, transforming an agri-food waste into a resource and improving the environmental index of wineries.

Article based on the paper presented at the SIVE OENOPPIA Awards (12th edition of Enoforum; Vicenza, Italy, May 21-23, 2019).