Optical absorption in the substituted phenylene-based conjugated polymers: Theory and experiment

M. Chandross, Sumitendra Mazumdar, M. Liess, P. A. Lane, Z. V. Vardeny, M. Hamaguchi, K. Yoshino

Research output: Contribution to journalArticle

137 Citations (Scopus)

Abstract

We investigate theoretically and experimentally the effects of (2,5) chemical substitution on the optical absorption in the phenylene-based conjugated polymers. Theoretically, substitution destroys both the charge-conjugation symmetry and spatial symmetry that characterize the unsubstituted materials. Within Coulomb-correlated theoretical models, the effect of broken charge-conjugation symmetry alone on the underlying electronic structure and on the absorption spectrum is rather weak. When both broken spatial symmetry and broken charge-conjugation symmetry are taken into account, a strong effect on the electronic structure of polyphenylene derivatives is found. In spite of the strong effect of the broken symmetries on the electronic structure, the effect on the optical-absorption spectrum is weak. This surprising result is a consequence of the subtle nature of the configuration interaction in the substituted polyphenylenes within Coulomb-correlated models. We demonstrate numerically an approximate sum rule that governs the strength of an absorption band at 3.7 eV in the absorption spectra of poly(para-phenylene vinylene) (PPV) derivatives. Although substitution can make a previously forbidden transition weakly allowed, the latter acquires strength from a "finite-size band" at about the same energy, and not from a higher-energy band at 4.7 eV, as has been previously claimed. It is further predicted that the 3.7-eV band is polarized predominantly along the polymer-chain axis. We have measured the polarization dependence of the optical absorption in an oriented-substituted PPV film. We found that the two lowest-energy absorption bands are polarized predominantly parallel to the chain axis, while the band at 4.7 eV is polarized predominantly perpendicular to the chain axis. These results are in excellent agreement with the theory.

Original languageEnglish (US)
Pages (from-to)1486-1496
Number of pages11
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume55
Issue number3
StatePublished - Jan 15 1997

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Conjugated polymers
Light absorption
Absorption spectra
optical absorption
absorption spectra
conjugation
polymers
Electronic structure
symmetry
Substitution reactions
substitutes
electronic structure
Experiments
Derivatives
forbidden transitions
energy absorption
Energy absorption
Band structure
configuration interaction
sum rules

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Chandross, M., Mazumdar, S., Liess, M., Lane, P. A., Vardeny, Z. V., Hamaguchi, M., & Yoshino, K. (1997). Optical absorption in the substituted phenylene-based conjugated polymers: Theory and experiment. Physical Review B - Condensed Matter and Materials Physics, 55(3), 1486-1496.

Optical absorption in the substituted phenylene-based conjugated polymers : Theory and experiment. / Chandross, M.; Mazumdar, Sumitendra; Liess, M.; Lane, P. A.; Vardeny, Z. V.; Hamaguchi, M.; Yoshino, K.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 55, No. 3, 15.01.1997, p. 1486-1496.

Research output: Contribution to journalArticle

Chandross, M, Mazumdar, S, Liess, M, Lane, PA, Vardeny, ZV, Hamaguchi, M & Yoshino, K 1997, 'Optical absorption in the substituted phenylene-based conjugated polymers: Theory and experiment', Physical Review B - Condensed Matter and Materials Physics, vol. 55, no. 3, pp. 1486-1496.
Chandross, M. ; Mazumdar, Sumitendra ; Liess, M. ; Lane, P. A. ; Vardeny, Z. V. ; Hamaguchi, M. ; Yoshino, K. / Optical absorption in the substituted phenylene-based conjugated polymers : Theory and experiment. In: Physical Review B - Condensed Matter and Materials Physics. 1997 ; Vol. 55, No. 3. pp. 1486-1496.
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