Perylene-based Self-Assembly of Chloroplast-like Lamellae for Artificial Photosynthesis

Water oxidation is a vital mechanism performed by photosynthetic organisms, converting solar energy into oxygen. So far, the majority of man-made systems undergoing water oxidation after irradiation is limited into dimers, experiencing strong charge recombination. Here we report a self-assembled structure composed of multi-perylene bisimides (PBIs) and a polyoxometalate (POM) catalyst as a guest, building highly ordered three-dimensional (3D) non-covalent assembled lamellas in water. We perform Transient Absorption (TA) spectroscopy to capture the ultrafast (100 fs) formation of symmetry-breaking charge separated (SB-CS) states between PBI units, mimicking the photosynthetic special pair. Afterwards, we observe an efficient 8 ps hole transfer to the POM catalyst, creating PBI(-) and POM(+) sites. The bi-exponential recombination leads to the presence of long-lived charges in the catalytic sites, optimal for efficient water splitting. Furthermore, ultrafast TA anisotropy is employed to track the motion of the charges in real time. Our data show that the charges are rapidly move in the 3D space preventing fast recombination.