1.Near-ohmic behavior for conducting polymers: extension beyond PEDOT on gold-plated platinum to other polymer-counterion/substrate combinations.
Kayinamura YP1, Roberts JH, Rubinson JF. ACS Appl Mater Interfaces. 2012 Mar;4(3):1601-7. doi: 10.1021/am2017706. Epub 2012 Mar 5.
Conducting polymers constitute a class of materials for which electrochemical and electron transport properties are a function not only of their chemical identity but also of their complex morphology. In this paper, we investigate and compare the frequency dependence behavior of the impedance of poly(3,4-ethylenedioxythiophene), or PEDOT, and that of poly(3,4-ethylenedioxypyrrole), or PEDOP, which are doped with a series of polyatomic anions during electrodeposition. We also contrast the behavior of PEDOT on Pt|Au, Pt, glassy carbon, and gold. Initial results for polycarbazole, PCz, electrodes are, in addition, included. Deposition parameters were adjusted to produce morphologically similar films for PEDOT, PEDOP, and PCz. In doing so, we have been successful in producing frequency-independent impedance behavior similar to that previously reported for PEDOT on Pt|Au. Although the impedance behavior of these polymers appears to be primarily determined by morphological features, the impact of counterion identity (beyond ionic charge transport) is also discussed.
2.A poly(3,4-ethylenedioxypyrrole)-Au@WO3 -based electrochromic pseudocapacitor.
Reddy BN1, Kumar PN, Deepa M. Chemphyschem. 2015 Feb 2;16(2):377-89. doi: 10.1002/cphc.201402625. Epub 2014 Nov 4.
A poly(3,4-ethylenedioxypyrrole)-gold nanoparticle (Au)-tungsten oxide (PEDOP-Au@WO3 ) electrochromic supercapacitor electrode capable of optically modulating solar energy while simultaneously storing/releasing energy (in the form of charge) was fabricated for the first time. WO3 fibers, 50 to 200 nm long and 20 to 60 nm wide, were synthesized by a hydrothermal route and were electrophoretically deposited on a conducting substrate. Au nanoparticles and PEDOP were coated over WO3 to yield the PEDOP-Au@WO3 hybrid electrode. The inclusion of Au in the hybrid was confirmed by X-ray diffraction, Raman spectroscopy, and energy-dispersive X-ray analyses. The nanoscale electronic conductivity, coloration efficiency, and transmission contrast of the hybrid were found to be significantly greater than those of pristine WO3 and PEDOP. The hybrid showed a high specific discharge capacitance of 130 F g(-1) during coloration, which was four and ten times greater than the capacitance achieved in WO3 or PEDOP, respectively.
3.Charge transport and electrochemical response of poly(3,4-ethylenedioxypyrrole) films improved by noble-metal nanoparticles.
Deepa M1, Kharkwal A, Joshi AG, Srivastava AK. J Phys Chem B. 2011 Jun 9;115(22):7321-31. doi: 10.1021/jp201055y. Epub 2011 May 18.
Charge-transport phenomena and redox switching of poly(3,4-ethylenedioxypyrrole) (PEDOP) films embedded with Au and Ag nanoparticles have been investigated. In the bulk, charge transport can be described by an ohmic regime at low voltages and a space-charge-limited current regime at high voltages in PEDOP-Au, which is in contrast to trap-filled domains deduced for neat PEDOP and PEDOP-Ag nanocomposites, all indicating transitions driven by an external bias. This also allowed a direct estimation of a fairly high charge-carrier mobility at room temperature in PEDOP-Au, in addition to a higher donor density, which are advantageous for device applications. X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy affirmed the prevalence of Au/Ag nanoparticles as nonleachable entities in PEDOP, thus allowing the movement of electrons through the conducting nanoaparticles during electrochemical switching, an effect that is absent in the neat PEDOP film.