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Updated: Sep 11, 2025
08:04
Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
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Tuning Exciton Diffusion in Organic Semiconductors through Hybridization with Charge-Transfer Excitations
Jesús Cerdá1, Samuele Giannini2, Lai Xu3
1Laboratory for Chemistry of Novel Materials, University of Mons, Mons 7000, Belgium.
The Journal of Physical Chemistry Letters
|August 17, 2025
Summary
Understanding Frenkel (FE) excitons and charge-transfer (CT) states is key for exciton transport. Hybridization strategies can significantly boost exciton diffusion in organic materials.
Area of Science:
- Materials Science
- Physical Chemistry
- Organic Electronics
Background:
- Exciton transport in organic molecular aggregates is governed by the interplay between Frenkel (FE) excitons and charge-transfer (CT) states.
- Understanding this interplay is crucial for designing efficient organic electronic devices.
Purpose of the Study:
- To investigate how the energy offset between FE and CT states and coupling patterns influence exciton diffusion.
- To identify design principles for enhancing exciton mobility in organic materials.
Main Methods:
- Large-scale nonadiabatic surface hopping dynamics simulations.
- Utilized Holstein-type Hamiltonians parameterized for realistic molecular systems.
Main Results:
- Exciton diffusion strongly depends on the FE-CT energy offset and the sign patterns of excitonic and electronic couplings.
- Hybridization at the bottom of the exciton band (H- and J+) enhances diffusion by promoting delocalized states with moderate CT character (30-50%).
- Hybridization at the top of the band (H+ and J-) leads to localization and reduced transport, even under strong vibronic coupling.
Conclusions:
- Robust design principles for enhancing exciton mobility were identified.
- Delocalized states with moderate CT character are key for efficient exciton diffusion.
- Band-based descriptions may fail under strong vibronic coupling, necessitating advanced simulation methods.
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