In Situ Investigations of the Electrodeposition and Electrochromic Properties of Poly(3,4-ethylenedioxythiophene) Ultrathin Films by Electrochemical−Surface Plasmon Spectroscopy

The electropolymerization and optical properties of poly(3,4-ethylenedioxythiophene) (PEDOT) was investigated in detail by a combined electrochemistry and surface plasmon spectroscopy setup. The simultaneous electrochemical−surface plasmon spectroscopy (EC-SPS) technique allowed for characterization of the changing dielectric constant and thickness of an electrodeposited PEDOT film at various stages of the electrodeposition process in situ. Surface plasmon spectroscopy (SPS) was used to investigate the electrochromic properties of PEDOT upon doping and dedoping and its effect on reflectivity at two laser wavelengths. The SPS curves change dramatically when the polymer film was switched to different electrochromic states upon doping and dedoping revealing important property changes on the film dielectric constants and electrochromic behavior. The SPS characterization was found to be consistent with previously observed changes in the bulk absorption (transmission) properties of PEDOT. The importance of this work is in the use of attenuated total reflection phenomena to characterize electrochromism in ultrathin conjugated polymer films.