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Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
Observation of long-range exciton diffusion in highly ordered organic semiconductors
1Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
Nature Materials
|October 12, 2010
Summary
Triplet excitons in organic semiconductors like rubrene diffuse over micrometers, not nanometers. This long diffusion distance significantly contributes to photocurrent generation, challenging previous limitations.
Area of Science:
- Organic electronics
- Materials science
- Photophysics
Background:
- Exciton diffusion in organic semiconductors is typically limited to 10-50 nm in disordered films.
- Understanding exciton behavior is crucial for optimizing organic electronic devices.
Purpose of the Study:
- To investigate the diffusion length of triplet excitons in the highly ordered organic semiconductor rubrene.
- To determine the contribution of triplet excitons to photoconductivity.
- To explore the role of exciton fission and surface interactions in organic materials.
Main Methods:
- Polarization- and wavelength-dependent photoconductivity measurements.
- Time-resolved photoluminescence and photocurrent analysis.
- Surface functionalization with exciton splitters.
Main Results:
- Triplet excitons in rubrene exhibit macroscopic diffusion lengths (2-8 μm).
- Exciton dissociation at the crystal surface is the primary source of photoconductivity.
- Surface functionalization with exciton splitters quenched photoluminescence and enhanced photoconductivity.
Conclusions:
- Long-lived triplet excitons are generated via singlet fission in molecular crystals.
- These triplet excitons significantly contribute to surface photocurrent in organic materials.
- Exciton diffusion is not an intrinsic limitation in organic semiconductors, suggesting potential for improved device performance.
