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 years, dye-sensitized solar cells (DSSCs) with water-based electrolytes have been considered as one of the possible breakthroughs towards DSSCs large-scale diffusion. If opportunely developed and optimized, aqueous solar cells can be truly considered as zero-impact photovoltaic devices fabricated with non-toxic components [1,2,3,4,5].

We show here the possibility of jellying the electrolyte into a solid matrix to boost stability and the possible use of different redox mediators solvated by water. Both biosourced polymers and UV-curable reactive mixtures are studied and will be discussed, along with a structure-property correlation coupled with the assessment of lab-scale solar cells performance.

Overall, we will show how much water-based photovoltaics represents a challenging topic in the current energy scenario, and how it will be able to provide safe, sustainable and easily processable solar cells for building-integrated photovoltaics and portable electronics.

References:

1. F. Bella, C. Gerbaldi, C. Barolo, M Grätzel, Aqueous dye-sensitized solar cells, Chem. Soc. Rev. 44 (2015) 3431-3473 [10.1039/C4CS00456F].

2. L. Fagiolari, M. Bonomo, A. Cognetti, G. Meligrana, C. Gerbaldi, C. Barolo, F. Bella, Photoanodes for aqueous solar cells: exploring additives and formulations starting from a commercial TiO2 paste, ChemSusChem 13 (2020) 6562-6573 [10.1002/cssc.202001898].

3. S. Galliano, F. Bella, M. Bonomo, G. Viscardi, C. Gerbaldi, G. Boschloo, C. Barolo, Hydrogel electrolytes based on xanthan gum: green route towards stable dye-sensitized solar cells, Nanomaterials 10 (2020) art. no. 1585 [10.3390/nano10081585].

4. F. Bella, L. Porcarelli, D. Mantione, C. Gerbaldi, C. Barolo, M. Grätzel, D. Mecerreyes, A water-based and metal-free dye solar cell exceeding 7% efficiency using a cationic poly(3,4-ethylenedioxythiophene) derivative, Chem. Sci. 11 (2020) 1485-1493 [10.1039/C9SC05596G].

5. S. Galliano, F. Bella, M. Bonomo, F. Giordano, M. Grätzel, G. Viscardi, A. Hagfeldt, C. Gerbaldi, C. Barolo, Xanthan-based hydrogel for stable and efficient quasi-solid truly aqueous dye-sensitized solar cell with cobalt mediator, Solar RRL [10.1002/solr.202000823].

Acknowledgements: This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 948769, project title: SuN₂rise).