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arXiv · 1705.05861

Exciton-Exciton Annihilation Is Coherently Suppressed in H-Aggregates, but Not in J-Aggregates

Roel Tempelaar·Thomas L. C. Jansen·Jasper Knoester
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Abstract

We theoretically demonstrate a strong dependence of the annihilation rate between (singlet) excitons on the sign of dipole-dipole couplings between molecules. For molecular H-aggregates, where this sign is positive, the phase relation of the delocalized two-exciton wavefunctions causes a destructive interference in the annihilation probability. For J-aggregates, where this sign is negative, the interference is constructive instead, as a result of which no such coherent suppression of the annihilation rate occurs. As a consequence, room temperature annihilation rates of typical H- and J-aggregates differ by a factor of ~3, while an order of magnitude difference is found for low-temperature aggregates with a low degree of disorder. These findings, which explain experimental observations, reveal a fundamental principle underlying exciton-exciton annihilation, with major implications for technological devices and experimental studies involving high excitation densities.

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Roel Tempelaar, Thomas L. C. Jansen, Jasper Knoester. 2017-05-16. Exciton-Exciton Annihilation Is Coherently Suppressed in H-Aggregates, but Not in J-Aggregates. https://arxiv.org/abs/1705.05861

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