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Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
Subdiffusive exciton motion in systems with heavy-tailed disorder
S M Vlaming1, V A Malyshev, A Eisfeld
1Centre for Theoretical Physics and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands. vlaming@pks.mpg.de
The Journal of Chemical Physics
|June 14, 2013
Summary
Collective excitations, or Frenkel excitons, exhibit subdiffusive transport in disordered systems with heavy-tailed energy distributions. This deviation from diffusive behavior is linked to energy landscape fluctuations and scattering rates.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Physical Chemistry
Background:
- Understanding exciton transport is crucial for optoelectronic devices.
- Disorder in transition energies significantly impacts exciton dynamics.
- Previous models often assumed Gaussian disorder, limiting applicability.
Purpose of the Study:
- To investigate exciton transport in systems with non-Gaussian, heavy-tailed disorder distributions.
- To analyze the impact of Lévy stable distributions on exciton dynamics.
- To elucidate the relationship between disorder characteristics and transport regimes.
Main Methods:
- Modeling Frenkel exciton transport with static disorder in transition energies.
- Generalizing disorder models to Lévy stable distributions.
- Analyzing the time evolution of the exciton distribution's second moment.
- Investigating phonon-assisted scattering mechanisms.
Main Results:
- Exciton dynamics exhibit subdiffusive behavior, deviating from standard diffusion.
- Heavier tails in transition energy distributions lead to greater deviations from diffusion.
- Subdiffusion is linked to large fluctuations in site energies (outliers).
- Scattering rate distributions show a peak at zero, explaining subdiffusive transport.
Conclusions:
- Lévy stable disorder distributions provide a more comprehensive model for exciton transport.
- Subdiffusive transport is a key characteristic of systems with heavy-tailed disorder.
- Understanding these dynamics is vital for designing efficient energy transfer systems.
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