Photoelectron studies of electrochemical diffusion of conducting polymer/transparent conductive metal oxide film interfaces

X-ray photoelectron spectroscopy (XPS) investigations of conducting polymer polythiophene (PT)/indium tin oxide (ITO) and PT/SnO₂ interfaces have been conducted. Interfacial electrochemical diffusion of the metal oxide substrate species has been observed in both cases through electrochemical reduction process. XPS investigation has focused on the core-level energies and spectral profiles of the diffused substrate species into polymer matrix. A larger part of the diffused species is metal oxides in both cases determined by measuring chemical shifts of core-levels of In Sd_5/2 and Sn Sd_5/2. However, increase in lower binding energy components of In Sd_5/2 and Sn Sd_5/2 spectra of the diffused species indicates that the diffused species in polymer matrix are a mixture of metallic and oxide states of In and Sn. Furthermore, with regard to PT backbone-originated S 2p lines, a large splitting was observed indicating the large interaction between diffused metal oxides and sulfur sites of the polymer backbone.