Theory of photoexcitations in phenylene-based polymers

Sumitendra Mazumdar, M. Chandross

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

8 Citations (Scopus)

Abstract

We show that optical absorption spectra of polyphenylenes can be explained only within theoretical models that explicitly include the Coulomb interaction among the π-electrons. We also show that the dominant effect of substitution on the electronic structure of polyphenylenes within Coulomb correlated models is broken spatial symmetry, while broken charge conjugation symmetry plays a rather weak role. The broken spatial symmetry has a subtle, and weak, effect on the optical absorption spectrum. Consequently, optical absorption spectra of unsubstituted polyphenylenes and the substituted derivatives are nearly identical. Comparison of theoretical and experimental absorption spectra leads to the conclusion that the exciton binding energy in a long chain of poly(para-phenylenevinylene) is about 0.9 eV. Such a large binding energy would be in agreement with nonlinear spectroscopic measurements and pump-probe experiments. However, the present work also indicates that the experimental polymers actually consist of short chains with the chain length distribution peaking at about 10 phenylene units. The gaps between the energy levels above the calculated continuum threshold are much too large for transport to be an intrachain process. Photoconductivity may be predominantly an interchain process, and probably measures the dissociation energy of the exciton which is different from the exciton binding energy.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
Pages62-73
Number of pages12
Volume2528
StatePublished - 1995
EventOptical and Photonic Applications of Electroactive and Conducting Polymers - San Diego, CA, USA
Duration: Jul 12 1995Jul 13 1995

Other

OtherOptical and Photonic Applications of Electroactive and Conducting Polymers
CitySan Diego, CA, USA
Period7/12/957/13/95

Fingerprint

Photoexcitation
photoexcitation
Absorption spectra
Binding energy
Excitons
Light absorption
absorption spectra
optical spectrum
optical absorption
binding energy
excitons
polymers
Polymers
Photoconductivity
symmetry
Coulomb interactions
conjugation
Chain length
photoconductivity
Electron energy levels

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

Cite this

Mazumdar, S., & Chandross, M. (1995). Theory of photoexcitations in phenylene-based polymers. In Proceedings of SPIE - The International Society for Optical Engineering (Vol. 2528, pp. 62-73)

Theory of photoexcitations in phenylene-based polymers. / Mazumdar, Sumitendra; Chandross, M.

Proceedings of SPIE - The International Society for Optical Engineering. Vol. 2528 1995. p. 62-73.

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

Mazumdar, S & Chandross, M 1995, Theory of photoexcitations in phenylene-based polymers. in Proceedings of SPIE - The International Society for Optical Engineering. vol. 2528, pp. 62-73, Optical and Photonic Applications of Electroactive and Conducting Polymers, San Diego, CA, USA, 7/12/95.
Mazumdar S, Chandross M. Theory of photoexcitations in phenylene-based polymers. In Proceedings of SPIE - The International Society for Optical Engineering. Vol. 2528. 1995. p. 62-73
Mazumdar, Sumitendra ; Chandross, M. / Theory of photoexcitations in phenylene-based polymers. Proceedings of SPIE - The International Society for Optical Engineering. Vol. 2528 1995. pp. 62-73
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