Multi-purpose metal-free dyes for energy and hydrogen production

Sunlight is, by far, the most abundant, economic and well distributed energy source over the world. For this reason, many different photovoltaic technologies exploit solar energy in order to produce electric current or eco-friendly fuels as hydrogen. Organic chemistry can play a pivotal role in the field of renewable energies because totally organic molecules are often the most suitable candidates as photoactive materials, thanks to their unique optical and electrochemical properties which can be finely tuned through a balanced modification of the structure of the compounds. Our first interest in this field was the design and the synthesis of organic dyes as photoactive materials for Dye-Sensitized Solar Cells (DSSCs), a very promising photovoltaic technology which is currently finding its market niche where the traditional silicon solar cells cannot be used. Recently we decided to broaden our horizons exploring new applications of our molecules toward other research fields which involve the exploitation of sunlight, such as in the photo-catalyzed production of hydrogen, or the employment of solid-state hole-transport materials (ss-HTMs) for DSSCs and PSCs (Perovskite Solar Cells). Our main interest was that of studying the influence of small structural modifications, such as the substitution of some functional groups or the insertion of alkyl chains in different regions of the molecules, on the physical and electrochemical properties of the dye, and on the efficiency of the final photovoltaic devices.