Infrared reflectance of polypyrrole: ‘metal’ with a gap in the spectrum of charged excitations

Lee, Kwanghee; Reghu, M.; Yuh, E.L.; Sariciftci, Niyazi Serdar; Heeger, A.J.

doi:10.1016/0379-6779(94)02334-u

Cited by 68 publications

(7 citation statements)

References 9 publications

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“…At the low frequency end, the subsequence of the reflectivity magnitude of the three samples is the same as that of their ρ DC (RoomT ). Part (b) is the real part of σ(ω) = σ 1 (ω) + ıσ 2 (ω), which is obtained through KK relations, with similar features of reported data of a series of protonic acid doped PANI and Ppy samples [4,6,7,12,13,14,15]. The peak around 19000cm −1 corresponds to π − π * interband transition.…”

Section: Resultssupporting

confidence: 71%

Optical study on doped polyaniline composite films

Li¹,

Zheng²,

Wang³

et al. 2004

J. Phys.: Condens. Matter

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Localization driven by disorder has a strong influence on the conducting property of conducting polymer. A class of authors hold the opinion that disorder in the material is homogeneous and conducting polymer is disordered metal close to Anderson-Mott Metal-Insulator transition, while others treat the disorder as inhomogeneous and have the conclusion that conducting polymer is a composite of ordered metallic regions and disordered insulating regions. The morphology of conducting polymers is an important factor that have influence on the type and extent of disorder. Different protonic acids used as dopants and moisture have affection on polymer chain arrangement and interchain interactions. A PANI-CSA film, two PANI-CSA/PANI-DBSA composite films with different dopants ratio, and one of the composite films with different moisture content are studied. Absolute reflectivity measurements are performed on the films. Optical conductivity and the real part of dielectric function are calculated by Kramers-Kronig(KK) relations. σ1(ω) and ε1(ω) derivate from simple Drude model in low frequency range and tendencies of the three sample are different and non-monotonic. The Localization Modified Drude model(LMD) in the framework of Anderson-Mott theory can not give a good fit to the experimental data. By introducing a distribution of relaxation time into LMD, reasonable fits for all three samples are obtained. This result supports the inhomogeneous picture.

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Section: Resultssupporting

confidence: 71%

Optical study on doped polyaniline composite films

Li¹,

Zheng²,

Wang³

et al. 2004

J. Phys.: Condens. Matter

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“…Nevertheless, the identical reflectance data for PBT suggest that the butyl side chain is not long enough to induce sufficient steric interaction in the doped state. In any case, reflectances observed in this work seem to be the greatest ever published for P3ATs and are comparable to highly conductive polyaniline or polypyrrole reflectances. − …”

Section: Resultssupporting

confidence: 63%

“…In any case, reflectances observed in this work seem to be the greatest ever published for P3ATs and are comparable to highly conductive polyaniline or polypyrrole reflectances. [33][34][35]…”

Section: Resultsmentioning

confidence: 99%

Enhanced Infrared Properties of Regioregular Poly(3-alkylthiophenes)

Buvat

Hourquebie

1997

Macromolecules

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Regiorandom and regioregular head to tail coupled poly(3-butylthiophenes), poly(3-octylthiophenes) and poly(3-dodecylthiophenes) have been synthesized by direct oxidation of 3-n-alkylthiophenes using FeCl3 as oxidant and by regiospecific dehalogenation of 2-bromo-3-n-alkylthiophenes. NMR characterizations indicated 70% of head to tail couplings in the polymers synthesized by FeCl3 route, and more than 99% for regioselective polymerizations. The results of both the solution and the solid state UV−vis spectroscopic studies showed that all the regioregular poly(3-alkylthiophenes) had a lower π−π* transition energy, characteristic of a longer conjugation length. A series of visible−near-IR spectra of chloroform solution of FeCl3-doped regioregular P3ATs is reported and shows an increase of the maximum absorption energy of doped P3ATs as a function of alkyl side chain; i.e., longer conjugation lengths are observed in the P3AT possessing the longer alkyl side chain. Moreover, the effect of solvent on electronic spectra is dramatic. The spectrum in a polar solvent, nitrobenzene, is significantly shifted toward low energy compared with spectra measured in relatively non polar solvent, such as dichloromethane, chloroform or toluene. Even after complete removal of the solvent, the more expended coil conformation persists in the cast film since infrared reflectance feature is more metal like. This study allows us to generalize the concept of secondary dopant to poly(3-alkylthiophene)/FeCl3/nitrobenzene systems. Finally, reflectance spectra of regiorandom and regioregular P3ATs are compared. They are the largest values ever published for P3ATs and are comparable to highly conductive polyaniline or polypyrrole reflectances.

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“…The small plasma frequency and very long τ of the metallic state in doped polymers can be explained [3,5,7] assuming that the conductivity is provided by a small fraction ∼ 0.1% of the total carriers with long scattering time > 10 −13 s. However, it is difficult to reconcile this conclusion with the behavior for high frequencies which supports that the scattering time is usual ∼ 10 −15 s and all available electrons participate in the conduction. To account for these anomalies, the possible presence of a collective mode, as in a charge density wave conductor, or superconductor, was suggested [9].…”

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confidence: 99%

Resonance quantum transport in doped conducting polymers: The improbable becomes possible

Prigodin

Epstein

2002

Europhys. Lett.

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Metallic doped polymers (polyaniline and polypyrrole) have an electromagnetic response that, when analyzed within the standard theory of metals, is provided by an extremely small fraction of the total number of available electrons ∼ 0.1% (in contrast to ∼ 100% for common metals) but with anomalous long scattering time 10 −13 s (∼ 100 times longer than for common metals). We show that a network of metallic grains (polymer's crystalline domains) connected by resonance quantum tunneling through localized states in surrounding disordered medium produces this behavior. The small fraction of electrons is assigned to the low density of resonance states and the long scattering time is related to the narrow width of energy levels in resonance.

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Infrared reflectance of polypyrrole: ‘metal’ with a gap in the spectrum of charged excitations

Cited by 68 publications

References 9 publications

Optical study on doped polyaniline composite films

Optical study on doped polyaniline composite films

Enhanced Infrared Properties of Regioregular Poly(3-alkylthiophenes)

Resonance quantum transport in doped conducting polymers: The improbable becomes possible

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