Theoretical Study on Thermal Structural Fluctuation Effects of Intermolecular Configurations on Singlet Fission in
Takayoshi Tonami1, Hajime Miyamoto1, Masayoshi Nakano1
1Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
The Journal of Physical Chemistry. A
|February 17, 2023
Summary
Static disorder in molecular aggregates accelerates singlet fission (SF) by disrupting excited-state coherence. This finding aids in designing materials for efficient SF processes.
Area of Science:
- Materials Science
- Quantum Chemistry
- Condensed Matter Physics
Background:
- Singlet fission (SF) converts one singlet exciton into two triplet excitons.
- SF dynamics involve complex excited-state relaxation and interactions with nuclear motions.
- Understanding static disorder is crucial for optimizing SF efficiency.
Purpose of the Study:
- To investigate the impact of thermal structural fluctuations (static disorder) on SF in pentacene crystal models.
- To elucidate the role of intermolecular configuration disorder on excited-state dynamics.
- To provide insights for designing materials with enhanced SF.
Main Methods:
- Combined quantum dynamics simulations using the quantum master equation approach.
- All-atom classical molecular mechanics/molecular dynamics for modeling static disorder.
- Analysis of excited states, charge transfer states, and nuclear motion interactions.
Main Results:
- Static disorder accelerates the decay of coherence between singlet exciton (FE) and charge transfer (CT) states.
- This accelerated coherence decay leads to faster FE → TT relaxation pathways.
- Fluctuations in CT state energies and electronic couplings are key drivers of SF acceleration.
Conclusions:
- Static disorder significantly influences SF dynamics by affecting excited-state coherence and relaxation pathways.
- The study highlights the importance of intermolecular interactions and nuclear motions in SF.
- Findings contribute to the rational design of materials for efficient singlet fission in condensed phases.
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