Effect of dopant-molecule size on the electrical conductivity of polyacetylene

Sichel, E. K.; Knowles, Michael E.; Rubner, Michael F.; Georger, Jacque H.

doi:10.1103/physrevb.25.5574

Cited by 42 publications

(10 citation statements)

References 17 publications

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“…In addition, in order to corroborate earlier findings [7,20] where it was claimed that PPy-rich and -poor domains exist in the PSS matrix, we tested the interpretation of impedance spectra by the fluctuation-induced tunneling model. [22,23] Indeed we found that the experimental data was excellently described by the fluctuation-induced tunneling model. Finally, we observed an electrical percolating behavior when the PPy volume fraction was increased (with a percolation threshold at 0.65), leading to the interpretation that PPy-rich and -poor domains are present in the PSS matrix.…”

Section: Introductionmentioning

confidence: 84%

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Conductivity of Poly(pyrrole)‐Poly(styrene sulfonate) Core–Shell Nanoparticles

2010

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The dielectric properties of poly(styrene) nanoparticles decorated at their surfaces with poly(styrene sulfonate) [PSS] brushes and subsequently loaded with polypyrrole (PPy) were studied. These film-forming materials which may serve as hole-injection layers in organic light-emitting diodes, exhibit a core-shell-type morphology with a core of electrically insulating poly(styrene) and a shell consisting of a corona of PSS chains which form the matrix in which the electrically conducting complex of PPy and PSS is embedded. This conducting complex exists in form of domains of nanoscale dimensions. Thin compressed pellets of these nanoparticles were studied using mainly impedance spectroscopy. Measurements were carried out in the temperature range between 123 and 453 K and frequency range from 10(-1) to 10(6) Hz. While earlier studies were centered around the effect of polypyrrole volume fraction on the conductivity films and pellets composed of these nanoparticles, the present study reveals in which way the conductivity can be modified by exchange of the mobile inorganic counter ions of PSS. Besides the free-acid form (H(+)), the Li(+)-, Na(+)- and Cs(+)-salts of PSS were investigated. The PPy volume fraction was the same for all PPy/PSS core-shell nanoparticles. The distance for phonon-assisted hopping between next-neighbor polypyrrolium chains is influenced by the presence of these inorganic cations. For all samples containing PPy, a transition from insulating to conducting behavior in the range of 300-350 K was found. Using the fluctuation-induced tunneling model, the average tunneling distance, as well as the potential energy barrier separating neighboring conducting grains was estimated. Finally, a detailed analysis of the dielectric spectra suggests the localization length of the charge carriers to be about 0.33 nm.

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Section: Introductionmentioning

confidence: 84%

“…[22,23] This model assumes that the charge carriers are tunneling between regions of metallic conductivity (here PPy domains) separated by insulating barriers. The fluctuation-induced tunneling model results in the temperature variation of the dc conductivity given by Equation (6):…”

Section: Samplementioning

confidence: 99%

Conductivity of Poly(pyrrole)‐Poly(styrene sulfonate) Core–Shell Nanoparticles

2010

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“…6H20) could be used to render polyacetylene electrically conductive [ 81. The temperature dependence of the resistivity of polyacetylene doped with dihydrogen hexachloroiridate(1V) was observed to follow a log p a T-"* behavior [9]. This behavior has also been observed in AsF5-doped polyacetylene [4] and is attributed to charging energy-limited tunneling in which charge carriers tunnel between conducting islands as described in the model of Sheng [ 101.…”

Section: Introductionmentioning

confidence: 87%

“…A portion of the soft gel synthesized by the technique mentioned earlier was doped with H21rC1, -6Hz0 from a nitromethane solution. The samples were subsequently washed using the procedure described elsewhere [9]. The doped soft gel in the solvent was agitated in order to prepare samples for study by transmission electron microscopy (TEM), then a few drops of the resultant suspension were deposited on electron microscope grids placed on absorbent paper.…”

Section: Methodsmentioning

confidence: 99%

“…Two classes of behavior have been seen in the p( 7') behavior of doped polyacetylene, and the differences have been attributed to dopant inhomogeneity. The resistivity of CH(IrC16), [9] and CH(ASF~)~ [4] is described by log p a T-'/*, whereas the resistivity of CH(I), and CH(Br), [ 111 follows log p a T-1/4. We have attributed the difference to the tendency of the large dopant molecules AsF5 and IrC16 to cluster, as shown in our electron micrographs, Figures 7, 8, and 9.…”

Section: Mechanism Of Conductionmentioning

confidence: 99%

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Properties of polyacetylene doped with hexachloroiridate

Rubner¹,

Druy²,

Tripathy³

et al. 1983

J. polym. sci., C Polym. symp.

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Polyacetylene was doped from solution with dihydrogen hexachloroiridate (H2IrCl6·6H2O), and also doped electrochemically with tetra‐n‐butylammonium hexachloroiridate(IV) (NBu4)2IrCl6·6H2O to form electrically conductive complexes. The doped polymer was characterized by ultraviolet, visible, and infrared spectroscopy, X‐ray diffraction, EPR spectroscopy, transmission electron microscopy, and electrical transport measurements. A hydrolyzed hexachloroiridate species was incorporated in the polymer during spontaneous doping with H2IrCl6·6H2O, whereas electrochemical doping with (NBu4)2IrCl6·6H2O resulted in the introduction of the expected hexachloroiridate species. Evidence suggests that, in the case of H2IrCl6·6H2O, doping occurs by a proton acid mechanism. TEM studies indicate that the hexachloroiridate dopant is not distributed homogeneously in the polymer. The stability of hexachloroiridate‐doped polyacetylene was examined in air, in an inert atmosphere, and at high temperatures. In air, the rate of decrease of the conductivity was about one order of magnitude per 28 days, whereas in an inert atmosphere, the conductivity dropped about one order of magnitude per 250 days.

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