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Singlet fission in linear chains of molecules
Francesco Ambrosio1, Alessandro Troisi1
1Department of Chemistry and Centre for Scientific Computing, University of Warwick, Coventry CV4 7AL, United Kingdom.
The Journal of Chemical Physics
|November 29, 2014
Summary
We developed a model to study singlet fission in molecular chains. Multi-exciton states are stabilized by proximity and localized by electron-phonon coupling, differing from isolated dimers.
Area of Science:
- Physical Chemistry
- Theoretical Chemistry
- Materials Science
Background:
- Singlet fission is a crucial process for enhancing solar cell efficiency.
- Understanding exciton dynamics in molecular aggregates is key to optimizing this process.
Purpose of the Study:
- To develop a theoretical model for studying singlet fission in linear molecular aggregates.
- To investigate the electronic structure and stabilization of multi-exciton states.
Main Methods:
- Configuration interaction Hamiltonian modeling.
- Matrix partitioning technique for arbitrary aggregate sizes.
- Methodology for non-radiative transitions applied to singlet fission dynamics.
Main Results:
- Multi-exciton (ME) states are stabilized at short inter-monomer distances, dependent on orbital coupling.
- Coupling between ME states is minimal (~10 meV bandwidth), indicating strong localization.
- Electron-phonon coupling localizes ME states, contrasting with delocalized Frenkel excitons.
Conclusions:
- Singlet fission dynamics in molecular crystals differ significantly from isolated dimers.
- The transition involves delocalized excitons to localized multi-exciton states.
- The developed model provides insights into exciton behavior in aggregates for singlet fission applications.
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