The nature of singlet excitons in oligoacene molecular crystals

H. Yamagata*, J. Norton, E. Hontz, Y. Olivier, D. Beljonne, J. L. Brédas, R. J. Silbey, F. C. Spano

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

230 Scopus citations


A theory for polarized absorption in crystalline oligoacenes is presented, which includes Frenkel exciton coupling, the coupling between Frenkel and charge-transfer (CT) excitons, and the coupling of all neutral and ionic excited states to the dominant ring-breathing vibrational mode. For tetracene, spectra calculated using all Frenkel couplings among the five lowest energy molecular singlet states predict a Davydov splitting (DS) of the lowest energy (0-0) vibronic band of only -32cm-1, far smaller than the measured value of 631cm-1 and of the wrong sign-a negative sign indicating that the polarizations of the lower and upper Davydov components are reversed from experiment. Inclusion of Frenkel-CT coupling dramatically improves the agreement with experiment, yielding a 0-0 DS of 601cm-1 and a nearly quantitative reproduction of the relative spectral intensities of the 0-n vibronic components. Our analysis also shows that CT mixing increases with the size of the oligoacenes. We discuss the implications of these results on exciton dissociation and transport.

Original languageEnglish (US)
Article number204703
Issue number20
StatePublished - May 28 2011
Externally publishedYes

Bibliographical note

Funding Information:
F.C.S. and H.Y. were supported by the National Science Foundation (NSF) under Award DMR-0906464. Work at Georgia Tech was partly supported by the Office of Naval Research (ONR), the STC Program of the National Science Foundation under Award DMR-0120967, and the Center for Advanced Molecular Photovoltaics, Award No KUSC1–015-21, made by King Abdullah University of Science and Technology (KAUST). Research in University of Mons was supported by the Interuniversity Attraction Pole program of the Belgian Federal Science Policy Office (PAI 6/27), Programme d’Excellence de la Région Wallonne (OPTI2MAT project), and FNRS-FRFC; D.B. is an FNRS Research Director. R.J.S. was supported as part of the Center for Excitonics, an Energy Frontier Research Center funded by U.S. Department of Energy and Office of Science, Office of Basic Energy Science (Grant No. DE-SC0001088).

ASJC Scopus subject areas

  • General Physics and Astronomy
  • Physical and Theoretical Chemistry


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