https://doi.org/10.1051/epjconf/201920506017
Exciton-Exciton Annihilation as a Mechanism for Uphill Transfer in a Molecular Excitonic System
1 Photonics Institute, Vienna University of Technology, Gusshausstrasse 27, 1040 Vienna, Austria
2 Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians-Universität, Oettingenstr. 67, 80538 München, Germany
3 Forschungszentrum für Elektronenmikroskopie, Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstrasse 36a, D-14195 Berlin, Germany
4 Professur für Dynamische Spektroskopien, Fakultät für Chemie, Technische Universität München, Lichtenbergstr. 4, D-85748, Garching b. München, Germany
* Corresponding author: juergen.hauer@tum.de
Published online: 16 April 2019
Exciton dynamics in a HJ-aggregate of cyanine dye TTBC are investigated by transient absorption with a time resolution of <60 fs and power-dependent emission spectroscopies. Both measurements are consistent with an exciton delocalization length of ~28 monomers. A model assuming diffusive exciton motion reveals that the exciton mobility is at least bimodal and restricted to one spatial dimension. J-band diffusion rates of 2.69 and 2.79e-3 cm2s-1 are found, leading to maximal diffusion lengths of 449 and 14.5 nm. The findings indicate that exciton-exciton annihilation is the origin of effective uphill transfer. This mechanism, if present under solar radiation, maybe useful for organic photovoltaic systems.
© The Authors, published by EDP Sciences, 2019
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