Light-Harvesting Systems Based on Organic Nanocrystals To Mimic Chlorosomes

We report the first highly efficient artificial light-harvesting systems based on nanocrystals of difluoroboron chromophores to mimic the chlorosomes, one of the most efficient light-harvesting systems found in green photosynthetic bacteria. Uniform nanocrystals with controlled donor/acceptor ratios were prepared by simple coassembly of the donors and acceptors in water. The light-harvesting system funneled the excitation energy collected by a thousand donor chromophores to a single acceptor. The well-defined spatial organization of individual chromophores in the nanocrystals enabled an energy transfer efficiency of 95%, even at a donor/acceptor ratio as high as 1000: 1, and a significant fluorescence of the acceptor was observed up to donor/acceptor ratios of 200 000: 1.