Long-Range Exciton Transport in Anthracene-Based Supramolecular Mesostructures and Its Control by Surface Plasmons

Efficient singlet exciton transport is essential for optoelectronic applications, but in organic solids exciton diffusion is limited to tens of nanometers. We study exciton transport in supramolecular nanofibers self-assembled from 9,10-bis(phenylethynyl)anthracene (BPEA) derivatives end-capped with hydrophilic dendritic structures. Hydrogen bonds determine the nanofiber structure and induce J-aggregate character of the BPEA chromophores. Position-dependent fluorescence lifetime reveals exciton diffusion lengths up to 350 nm and diffusion coefficients up to 0.7 cm²/s, among the highest reported for organic solids. Quantum-chemical calculations combined with exciton diffusion simulations qualitatively reproduce the spectral properties and diffusion behavior. Structural rigidity, exciton delocalization over 2-3 monomers, and mixing of the locally excited and charge-transfer states are proposed as factors enabling the long-range transport. Additionally, plasmonic nanohole gold substrates enhance exciton transport by more than 2-fold, with a nanofiber orientation revealing the role of local electric field in the plasmonic enhancement of the Förster-type exciton transport.