Photosynthesis is a fascinating source of inspiration to design innovative molecular devices for the conversion and storage of solar energy. Applications of interest however rely on multielectronic catalytic processes whereas light-driven processes are single-electron events in essence. Nature perfectly masters this apparent mismatch thanks to specific cofactors, able to accumulate and then to relay two electrons at a time by coupling these processes with proton transfers. PhotoAcc thus aims at developing novel charge photoaccumulation systems, by taking inspiration from such biological cofactors, flavins in particular. The project will benefit from the complementary expertise of the four internationally recognized research groups to (i) undertake their synthesis supported by a (TD)DFT-predictive approach to allow tailormade optoelectronic properties, (ii) to decipher their electronic properties by virtue of various electrochemical and spectroscopic characterizations, including advanced EPR techniques to identify the electron storage sites, and (iii) to assess their activity in light-driven multielectron/multiproton redox processes.