Defect-Tolerant Frenkel Exciton Delocalization in Supramolecular Nanotubes

Preserving exciton delocalization in the presence of structural and environmental disorder is a central challenge for nanoscale photonic and optoelectronic materials. Here we show that Frenkel excitons in two-dimensional supramolecular nanostructures retain extensive delocalization even in the presence of intentionally incorporated deep-energy traps. Fluorescent trap molecules introduced during the self-assembly of double-walled molecular nanotubes provide a controlled model system in which strong local energetic perturbations are created without significant distortion of the host structure. Increasing the trap concentration shortens the host-exciton PL lifetime from ∼190 ps to ∼15 ps, while polarization-resolved microscopy of individual nanotubes shows that the collective excitonic polarization remains essentially unchanged. Frenkel-exciton calculations based on experimentally established molecular structures reproduce this robustness and reveal that delocalization decreases only weakly because the excitonic wave functions redistribute around the trap sites while remaining extended over large molecular domains. These results demonstrate an intrinsic defect tolerance of delocalized Frenkel excitons in a two-dimensional supramolecular architecture and identify dimensionality as an important design principle for preserving collective excitonic states in structurally imperfect nanomaterials.