Redox Properties of Conjugated Polymers

Chance, R. R.; Boudreaux, D. S.; Brédas, Jean‐Luc; Silbey, R.

doi:10.1021/bk-1984-0242.ch034

Cited by 14 publications

(18 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In other words, the IR spectral pattern of doped P(NDI2OD-T2) does not indicate the occurrence of peculiar long-range polarization phenomena coupled with the vibrational modes of the polaron such as those active in polyacetylene, polythiophene, and related materials. ,,, Thus, the observed behavior of the IR intensities of doped P(NDI2OD-T2) parallels the conclusions of previous studies, ,, suggesting that charge defects in P(NDI2OD-T2) are confined. Quantum chemical molecular modeling, presented in Section , corroborates this conclusion.…”

Section: Experimental Results and Discussionsupporting

confidence: 87%

“…The prototypical case of polyacetylene was widely investigated through experiments and theoretical models. Worth noting, Brèdas et al discussed in a pioneering work the charge distribution and geometry relaxation in charged polyene chains. These studies provided a clear picture of the defect, which involves several polymer units with a relevant modulation of the bond length alternation (BLA) parameter and delocalization of the transferred charge in a large domain.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Polaron Confinement in n-Doped P(NDI2OD-T2) Unveiled by Vibrational Spectroscopy

et al. 2019

View full text Add to dashboard Cite

Through specific marker bands, IR and Raman spectra of chemically doped polyconjugated polymers allow investigation of doping and monitoring of its effectiveness. The vibrational modes associated with the doping-induced features provide information about the polymer units affected by the transferred charge and the structure relaxation associated with the formation of the polaron. Here, we doped the P(NDI2OD-T2) copolymer with three differently substituted 1H-benzimidazoles, which allow for doping in solution, leading to an increase of conductivity values up to four orders of magnitude. Careful inspection of the IR and Raman spectra of P(NDI2OD-T2) while varying the dopant concentration and the kind of dopant proves that the polaron markers are almost independent from the dopant species. The IR intensity of the polaron markers is a very sensitive probe of charge delocalization upon doping: for n-doped P(NDI2OD-T2), these bands show absorption intensities of the same strength as those of the pristine species. In other words, they are very weak in comparison to the so-called IRAV bands of doped polyacetylene, polythiophenes, and related materials. This experimental observation provides evidence of the strong confinement of the polaron on the NDI2OD unit. Multiwavelength Raman spectra of n-doped P(NDIOD-T2) further corroborate this point, showing that the T2 moiety is almost unaffected by doping. The analysis of the experimental data is complemented by DFT calculations which fully support the diagnosis of the formation of localized polarons. Hence, vibrational spectroscopy is an effective tool to characterize charge carriers induced by doping P(NDIOD-T2): it indicates that the observed conductivity enhancement is ascribed to an efficient interchain hopping involving charged NDI2OD units, whereas polaron diffusion along the chain is unlikely.

show abstract

Section: Experimental Results and Discussionsupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Polaron Confinement in n-Doped P(NDI2OD-T2) Unveiled by Vibrational Spectroscopy

et al. 2019

View full text Add to dashboard Cite

show abstract

“…(The above formula is used for analysis, not for actual calculations.) In Peierls systems E g topol = 0 and E g relax becomes the Peierls gap. − , In the ladder polymers studied in this paper, E g relax is usually substantial, typically amounting to about 1 / 2 eV, which is a reflection of the strong coupling of the electrons to in-plane CC skeletal vibrations in these materials. This necessitates full geometry optimization whenever reasonable agreement with experiment is to be obtained.…”

Section: Techniques Of Calculationmentioning

confidence: 84%

“…(2) What type of localized defect structures are generated if additional charges are transferred to the ladder polymer? It has been well established that on single chain conjugated polymers charges tend to localize and generate a deformation of the geometry, producing charged solitons, polarons, and bipolarons . We will attempt to answer the following question: which types of localized charged defects does the ladder topology harbor?…”

Section: π-Conjugation In Ladder Polymersmentioning

confidence: 99%

Electronic Structure of Polyfluoranthene Ladder Polymers

Kertész

Ashertehrani

1996

Macromolecules

View full text Add to dashboard Cite

Fully unsaturated fluoranthene-type ladder polymers (PFA: polyfluoranthene) recently synthesized by Schlüter et al. show a high degree of π-electron localization. Variation of the size of the two oligoacenic components separated by the characteristic five-membered ring, however, can lead to more delocalized structures with small (few tenths of an electronvolt) band gaps and can be used for engineering the electronic properties. Charge transfer produces bipolaronic defect states in these polymers; sp3 defects produce polaronic defects. Interpretation of the differences between the published absorption spectra for two members of the PFA family is also given.

show abstract

“…Here, δ is the bond alternation parameter and t is the transfer integral. There has also been a correlation of doped trans -PA conduction properties with BLA, since there is a reversal in the BLA pattern when moving past a defect in doped trans -PA and the efficient transport of the defect across the chain is assumed to be responsible for the conducting properties of such doped conjugated polymers …”

Section: Introductionmentioning

confidence: 99%

Rational Design of Molecules with Large Hyperpolarizabilities. Electric Field, Solvent Polarity, and Bond Length Alternation Effects on Merocyanine Dye Linear and Nonlinear Optical Properties

1996

View full text Add to dashboard Cite

The effects of applied electric fields and solvent polarity on the linear and nonlinear optical (NLO) properties of three prototypical merocyanine (donor−conjugated pathway−acceptor) chromophores of differing architectural types are analyzed using semiempirical INDO/1 calculations in the presence of imposed static electric fields, using finite-field self-consistent field (FFSCF), and in the presence of solvent dielectrics, self-consistent reaction field (SCRF), models. The NLO properties are computed using the computationally efficient correction vector approach. Both applied electric fields and solvent are found to affect the extent of charge separation induced in the ground states of these molecules. This charge separation leads to a geometric distortion, measured by the bond-length alternation (BLA) parameter, which indexes the geometrical evolution of the molecular architecture from a neutral polyenic structure to a partially ionic cyanine-like structure to an ionic polymethine-like structure. These geometric variations lead to large changes in the linear as well as NLO response properties, which are different, both qualitatively and quantitatively, at the three different structural limits. The applied electric field is found to produce large variations in the structural, electronic, linear, and NLO properties. However, an analysis based on the Onsager reaction field model shows that in general the electric field produced by even the most polar solvents is inadequate to produce large geometric distortions. This trend is also observed experimentally in solvent-dependent electronic and optical properties, where even the most polar solvents produce effects equivalent only to those produced by a very small electric field. However, variations in structural and optical properties are also found to be highly architecture specific and large variations are possible in chromophore structures stabilized on charge separation. The field at which the chromophore geometry attains the cyanine-like structure is not coincident with the field at which the SHG coefficient goes to zero; an asymmetry in the BLA pattern is required to attain the zero-β limit. Optimal NLO response occurs when the geometry of the conjugation pathway lies between the polyenic and cyanine-like structures.

show abstract

Redox Properties of Conjugated Polymers

Cited by 14 publications

References 0 publications

Polaron Confinement in n-Doped P(NDI2OD-T2) Unveiled by Vibrational Spectroscopy

Polaron Confinement in n-Doped P(NDI2OD-T2) Unveiled by Vibrational Spectroscopy

Electronic Structure of Polyfluoranthene Ladder Polymers

Rational Design of Molecules with Large Hyperpolarizabilities. Electric Field, Solvent Polarity, and Bond Length Alternation Effects on Merocyanine Dye Linear and Nonlinear Optical Properties

Contact Info

Product

Resources

About