A series of functionalized ferrocene derivatives carrying electron-donor and electron-withdrawing (hetero)aromatic substituents has been designed as potential alternative electrolyte redox couples for dye-sensitized solar cells (DSSC). The compounds have been synthesized and fully characterized in their optical and electrochemical properties. A general synthetic approach that implies the use of a microwave assisted Suzuki coupling has been developed to access a significative number of compounds. The presence of different electron-rich and electron-poor substituents provided fine tuning of optical properties and energy levels. HOMO and LUMO energy values showed that the substitution of one or two cyclopentadienyl rings of ferrocene can be successfully exploited to increase the maximum attainable voltage from a standard DSSC device using TiO₂ as a semiconductor, opening the way to highly efficient, non-toxic, and cheap redox shuttles to be employed in solar energy technologies.

The photogeneration of electricity and solar fuels by solar irradiation in photoelectrochemical cells is one of the sectors with the highest growth potential in the decarbonised society. However, the use of different components, in particular photosensitizers and catalysts, can present problems of charge transfer efficiency at the interface, leading to lower final efficiencies. In this work we present novel integrated photosensitizer‐catalyst dyads based on robust and, at the same time, flexible host‐guest non‐covalent interactions through the use of calix[4]arene cavities. Current photogeneration in photoelectrochemical cells showed twice greater efficiency in the integrated calixarene‐based host‐guest dyads compared to the traditional architecture based on the separate photosensitizer‐catalyst pair. Molecular dynamics studies have shown that the enhanced performance originates from an optimization of the distances between the centres of the photosensitizer, catalyst and semiconductor involved in the charge transfer processes, thus allowing a higher final efficiency of the charge photogeneration process.

Dye–catalyst dyads based on metal-free dyes were prepared for dye-sensitized photoanodes in photoelectrochemical water splitting, showing a top ranked faradaic efficiency for O ₂ generation up to 95%.