Doping-dependent studies of the Anderson-Mott localization in polyaniline at the metal-insulator boundary

Abstract

Publisher's copyright statement:Reprinted with permission from the American Physical Society: Physical Review B 66, 085202 c 2002 by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modied, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society.Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Temperature-dependent dc conductivity measurements and infrared reflectivity measurements ͑20-9000 cm Ϫ1͒ were performed on a series of polyaniline samples with two different dopant acids at various doping levels. The typical fingerprints of a disordered metal such as a positive temperature coefficient of resistivity at high temperatures, a very high reflectivity in the far infrared, and a plasma resonance have been observed. The results were analyzed in the framework of the Anderson-Mott localization model and considerable consistency between transport studies and optical measurements was obtained. Various parameters enabling a comparative classification of the materials are also reported.

Tunable Plasmon Resonance of Gold Nanoparticles Functionalized by Electroactive Bisthienylbenzene Oligomers or Polythiophene

“…25,27,29 As for these other conducting polymers, this blue-shift can be qualitatively explained by the Drude free-electron model. 46− 48 We can assume that the dielectric function (ε) of polythiophene in its reduced state is real, whereas in its oxidized state it is complex (ε = ε Re + iε Im ). Moreover, the oxidized state of polythiophene is conducting and, consequently, follows a Drude-like behavior with a plasma frequency ω P leading to a simplified expression of the real part of the dielectric function, given by ε Re = ε ∞ [1 − (ω P /ω) 2 ], where ε ∞ corresponds to the high-frequency dielectric constant.…”

On the energy scale involved in the metal to insulator transition of quadruple perovskite EuCu3Fe4O12: infrared spectroscopy and ab-initio calculations

“…It clearly deviates from usual Drude model since it exhibits a broad bump at 200 cm −1 . This could be due to either localization by disorder293031, electronic correlations3233 or strong electron-lattice coupling (polarons)293435. With decreasing temperature, the optical conductivity dramatically drops three order of magnitude at low frequency, and exhibits an insulating behavior, with an optical gap energy Δ ≈ 125 meV and a broad mid infrared band.…”

Applicability of the localization-interaction model to magnetoconductivity studies of polyaniline films at the metal-insulator boundary

“…34 The values of k F were obtained within the framework of the localizationinteraction model, but were derived from the optical properties of the samples, suggesting, thus, a considerable consistency in the sample's behavior.…”

“…According to a recent study, 34 PANI-CSA 60% and PANI-CSA 30% are, respectively, the most metallic and least metallic of all the PANI-CSA films studied thereby. Figure 1 shows the conductivity values as a function of temperature for those two samples.…”

“…Several issues regarding the applicability of the model will be clarified and more corroborating evidence regarding the intrinsic metallic character of PANI will be presented throughout comparative investigation of the differences between the distinct polyaniline systems. A comparison with the conclusions derived from the optical properties 34,35 will also be performed.…”