Decoding Excimer Formation in Covalent-Organic Frameworks Induced by Morphology and Ring Torsion
Jeet Chakraborty1, Amrita Chatterjee1, Korneel Molkens2,3,4
1Centre for Ordered Materials, Organometallics and Catalysis (COMOC), Department of Chemistry, Ghent University, Krijgslaan 281-S3, Ghent, 9000, Belgium.
Advanced Materials (Deerfield Beach, Fla.)
|April 15, 2024
Summary
Understanding exciton behavior in covalent-organic frameworks (COFs) is key for optoelectronics. Morphology and topography influence exciton dynamics, impacting photocatalysis applications.
Area of Science:
- Materials Science
- Photophysics
- Organic Chemistry
Background:
- Covalent-organic frameworks (COFs) show promise for optoelectronic and photocatalytic applications.
- Precise structure tuning is crucial for optimizing COF photophysical properties.
Purpose of the Study:
- To investigate the impact of morphology and surface topography on the photophysics of COFs.
- To understand the fate of excitons in COFs after photoexcitation.
Main Methods:
- Synthesis of a COF library with identical backbones but varied physical properties.
- Transient absorption spectroscopy.
- Luminescence decay time measurements.
Main Results:
- Crystallite size and surface topography variations led to different aggregation patterns and altered photophysical properties.
- An inverse correlation was observed between luminescence decay time and exciton binding energy.
- Localized, immobile Frenkel excitons were identified, with relaxation favoring long-lived excimer formation over direct emission.
Conclusions:
- Structural and topological design significantly influences exciton dynamics in COFs.
- These findings are vital for targeted applications of COFs in photocatalysis and optoelectronics.
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