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In situ Grazing Incidence Small Angle X-ray Scattering on Roll-To-Roll Coating of Organic Solar Cells with Laboratory X-ray Instrumentation

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Theoretical Study on Singlet Fission Dynamics in Slip-Stack-like Pentacene Ring-Shaped Aggregate Models.

Hajime Miyamoto¹, Kenji Okada¹, Kazuaki Tokuyama¹

¹Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.

The Journal of Physical Chemistry. A

|June 18, 2021

Summary

Optimizing pentacene aggregate structure enhances singlet fission (SF) efficiency. Specific rotation angles unlock efficient pathways for double triplet (TT) generation, crucial for advanced materials.

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Area of Science:

Organic Photovoltaics
Materials Science
Quantum Chemistry

Background:

Singlet fission (SF) is a process that can generate two high-energy triplet excitons from one high-energy singlet exciton.
Ring-shaped organic aggregates offer tunable electronic properties for enhanced photophysical processes.

Purpose of the Study:

To investigate the singlet fission dynamics in slip-stack-like pentacene ring-shaped aggregates.
To determine the influence of aggregate size and rotational angle on SF rates and double triplet (TT) yields.

Main Methods:

Quantum master equation method to simulate SF dynamics.
Analysis of relative relaxation factors and electronic couplings.

Main Results:

Optimal rotation angles (α) exist for efficient SF and high TT yields, dependent on aggregate size (N).
For an 8-mer model, SF rates increased significantly (up to 38.6x) at specific angles (e.g., 43°), with TT yields reaching 0.988.
Efficient SF occurs at α=40° for medium N (7-10) and α=30° for large N (>10).

Conclusions:

Tuning the rotation angle opens many-to-many relaxation paths, enabling fast SF and high TT yields.
Quantum superposition of exciton states, driven by energy inequalities and coupling variations, underlies efficient SF.
Findings provide design guidelines for advanced SF materials.