Artificial Light-Harvesting Nanotubes: Intermolecular Charge Transfer beyond the Exciton Model

Self-assembled nanotubes of C8S3 cyanine dyes have been widely investigated as model systems for light-harvesting complexes. Recently published data point to a brick-layer molecular arrangement in the nanotubes, in contrast to the herringbone structure previously adopted to explain the absorption and linear dichroism data within the exciton model. Here we solve this conundrum by showing that, relying on the brick-layer structure as extracted from cryo-EM, the exciton model can properly account for the observed spectral features, provided it is extended to account for intermolecular charge-transfer interactions.