Relaxation dynamics of photoexcited excitons in rubrene single crystals using femtosecond absorption spectroscopy

The relaxation dynamics of an exciton in rubrene was investigated by femtosecond absorption spectroscopy. Exciton relaxation to a self-trapped state occurs via the coherent oscillation with 78 cm(-1) due to a coupled mode of molecular deformations with phenyl-side-group motions and molecular displac...

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Bibliographic Details
Published in:Physical review letters 2012-08, Vol.109 (9), p.097403-097403, Article 097403
Main Authors: Tao, S, Ohtani, N, Uchida, R, Miyamoto, T, Matsui, Y, Yada, H, Uemura, H, Matsuzaki, H, Uemura, T, Takeya, J, Okamoto, H
Format: Article
Language:English
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Summary:The relaxation dynamics of an exciton in rubrene was investigated by femtosecond absorption spectroscopy. Exciton relaxation to a self-trapped state occurs via the coherent oscillation with 78 cm(-1) due to a coupled mode of molecular deformations with phenyl-side-group motions and molecular displacements. From the temperature dependence of the decay time of excitons, the energy necessary for an exciton to escape from a self-trapped state is evaluated to be ~35 meV (~400 K). As a result, a self-trapped exciton is stable at low temperatures. At room temperature, excitons can escape from a self-trapped state and, subsequently, they are dissociated to charged species. The exciton dissociation mechanism is discussed on the basis of the results.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.109.097403