Universal ultrafast signatures of photoexcitations in conjugated polymers: Excitons and charge-transfer polarons

D. W. McBranch, B. Kraabel, S. Xu, H. L. Wang, Victor I Klimov

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Using subpicosecond transient absorption spectroscopy, we have investigated the primary photoexcitations in thin films and solutions of several phenylene-based conjugated polymers and an oligomer. We identify two features in the transient absorption spectra and dynamics that are common to all of the materials which we have studied from this family. The first spectral feature is a photoinduced absorption (PA) band peaking near 1 eV which has intensity-dependent dynamics which match the stimulated emission dynamics exactly over two orders of magnitude in excitation density. This band is associated with singlet intrachain excitons. The second spectral feature (observed only in thin films and aggregated solutions) is a PA band peaking near 1.8 eV, which is longer-lived than the 1 eV exciton PA band, and which has dynamics that are independent (or weakly-dependent) on excitation density. This feature is attributed to charge separated (interchain) excitations. These excitations are generated through a bimolecular process. By comparing to samples in which charged excitations are created deliberately by doping with C6O, we assign these secondary species as bound polarons.

Original languageEnglish
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
PublisherSociety of Photo-Optical Instrumentation Engineers
Pages17-25
Number of pages9
Volume3797
Publication statusPublished - 1999
EventProceedings of the 1999 Organic Light-Emitting Materials and Devices III - Denver, CO, USA
Duration: Jul 19 1999Jul 21 1999

Other

OtherProceedings of the 1999 Organic Light-Emitting Materials and Devices III
CityDenver, CO, USA
Period7/19/997/21/99

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

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  • Cite this

    McBranch, D. W., Kraabel, B., Xu, S., Wang, H. L., & Klimov, V. I. (1999). Universal ultrafast signatures of photoexcitations in conjugated polymers: Excitons and charge-transfer polarons. In Proceedings of SPIE - The International Society for Optical Engineering (Vol. 3797, pp. 17-25). Society of Photo-Optical Instrumentation Engineers.