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Photoannealing of Merocyanine Aggregates
Felix Herrmann-Westendorf1,2, Torsten Sachse1,2, Martin Schulz1,2
1Institute of Physical Chemistry , Friedrich Schiller University Jena , Helmholtzweg 4 , 07743 Jena , Germany.
The Journal of Physical Chemistry. A
|December 1, 2018
Summary
Donor-π-acceptor merocyanine dyes form different aggregates in their ground and excited states. Light exposure rearranges these dye aggregates, impacting optoelectronic device performance.
Area of Science:
- Supramolecular Chemistry
- Photophysics
- Materials Science
Background:
- Donor-π-acceptor merocyanine dyes are crucial components in optoelectronic devices.
- Understanding their aggregate formation is key to optimizing device functionality.
- The electronic ground and excited states exhibit distinct aggregation behaviors.
Purpose of the Study:
- To elucidate the fundamental differences in aggregate formation between the electronic ground and excited states of merocyanine dyes.
- To investigate the impact of π-bridge size on aggregate structure.
- To analyze the effects of light irradiation on dye aggregate morphology and spectroscopic properties.
Main Methods:
- UV-vis spectroscopy to monitor changes in spectroscopic properties.
- Analysis of supramolecular structure and aggregate formation.
- Investigating intermolecular interactions like ππ-London dispersion and hydrogen bonds.
Main Results:
- Increasing π-bridge size favors π-stacked aggregates in the dark.
- Visible light irradiation induces reorientation into H-aggregates with compensating dipole moments.
- Photoannealing dramatically alters supramolecular structure and UV-vis spectra, disrupting large polymeric aggregates.
Conclusions:
- Electronic excitation significantly increases dipole moments, driving reorientation into H-aggregates.
- Photoinduced supramolecular rearrangements influence optoelectronic device performance.
- Controlling these structural changes is vital to prevent morphological decomposition of active layers.
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