Singlet Exciton Diffusion in Organic Crystals Based on Marcus Transfer Rates

Area of Science:

• Materials Science
• Theoretical Chemistry
• Optoelectronics

Background:

• Exciton diffusion is crucial for energy conversion in optoelectronic devices.
• Accurate theoretical methods are needed to determine exciton transport parameters.
• Current methods for calculating exciton hopping rates can be computationally expensive.

Purpose of the Study:

• To adapt Marcus theory for calculating exciton diffusion parameters.
• To develop a computationally less expensive theoretical approach for exciton transport.
• To assess the accuracy and applicability of the adapted Marcus theory.

Main Methods:

• Adapted Marcus theory for exciton diffusion, utilizing reorganization energy instead of spectral overlap.
• Calculated exciton diffusion constants for naphthalene, anthracene, and diindenoperylene crystals.
• Compared results with established methods (coupling and spectral overlap) and experimental data.

Main Results:

• The adapted Marcus theory provides qualitatively correct exciton diffusion properties and can predict trends.
• Calculated diffusion constants using this method tend to be lower than experimental values.
• Reorganization energies require high-level quantum chemical calculations, but only need to be computed once.

Conclusions:

• The adapted Marcus theory offers a computationally efficient alternative for estimating exciton diffusion.
• While yielding smaller values, the method is useful for predicting trends in exciton transport.
• Lower-level approaches can be used for coupling constants, further reducing computational cost.