title: Charge transport and electrochemical response of poly(3,4-ethylenedioxypyrrole) films improved by noble-metal nanoparticles.
abstract: 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. Valence-band spectra and optical studies revealed that nanoparticles narrowed the band gap and increased the absorption coefficient of PEDOP, which enhanced the electrochromic switching ability of PEDOP. A coloration efficiency enhancement by an order of magnitude, higher electrochemical charge intercalation capacity, and higher diffusion rates reflect the role of noble-metal nanoparticles in improving the conduction and electrochemical activity of PEDOP.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Hyderabad, Ordnance Factory Estate, Yeddumailaram, Andhra Pradesh, India. mdeepa@iith.ac.in
authors.forename: Melepurath
authors.initials: M
authors.lastname: Deepa
authors.forename: Aneeta
authors.initials: A
authors.lastname: Kharkwal
authors.forename: Amish G
authors.initials: AG
authors.lastname: Joshi
authors.forename: Avanish Kumar
authors.initials: AK
authors.lastname: Srivastava