Room-Temperature Micron-Scale Exciton Migration in a Stabilized Emissive Molecular Aggregate.

Area of Science:

• Supramolecular chemistry
• Materials science
• Physical chemistry

Background:

• Light-harvesting nanotubes (LHNs) are crucial for efficient energy transfer.
• Understanding exciton transport dynamics is key to developing advanced organic electronic devices.
• Previous studies faced challenges with stability and damage, limiting observations.

Purpose of the Study:

• To investigate exciton transport in self-assembled supramolecular LHNs.
• To enhance the stability of LHNs for detailed photophysical studies.
• To correlate energetic disorder with exciton diffusion length.

Main Methods:

• Assembly of amphiphilic cyanine dyes into LHNs.
• Stabilization of LHNs within a sucrose glass matrix.
• Cryogenic measurements of static and dynamic energetic disorder.
• One-dimensional diffusion modeling of exciton transport.

Main Results:

• Observed exciton transport with a diffusion length of 1.6 ± 1 μm.
• Achieved high exciton diffusion constant of 55 ± 20 cm²/s.
• Demonstrated reduced light and oxidative damage in the sucrose matrix.
• Model predicted a diffusion constant of 32 cm²/s, consistent with experiments.

Conclusions:

• Matrix-stabilized LHNs exhibit exceptionally long exciton diffusion lengths.
• Low static and dynamic energetic disorder contribute to efficient exciton transport.
• Matrix-stabilized LHNs serve as an excellent model for studying coherent excitonic transport.