This suggests that a significant fraction of (S)-2PDI is not associated with (R)-1NDI nanofibers on the plasma-treated glass slide. We then examined glass slides treated with alkylsilanes, noctyltriethoxysilane and n-dodecyltriethoxysilane (Figure ), as more hydrophobic substrates. A 7-and 8-fold enhancement of the relative emission intensity (I540/I480) was observed for the substrate surface treatment with n-octyltriethoxysilane and n-dodecyltriethoxysilane, respectively (Table , supporting information). Although the chemical origin of this significant effect of surface hydrophobicity on the energy harvesting efficiency of the supramolecular nanowires is not fully understood, we focused on the fluorescence properties of the nanofibers formed on alkylsilane-coated glass slides, which showed good reproducibility. Our host-guest lightharvesting system successfully demonstrated efficient energy transfer both in solution and when deposited on treated glass substrates, although the relative fluorescence efficiency (I540/ I480) in the solvent-dispersed phase was not fully reproduced. assembly likely proceeds during the solvent drying process driven by strong - interactions. Although the compound 2 was previously reported to form nanofibers in MCH-rich solution, they