Comparative Study of the Electrodeposition of Poly(3-octylthiophene) Films on Gold Electrodes:  Bare and Modified with Dodecanethiol Monomolecular Layer

Poly(3-octylthiophene) (p3OT) was deposited potentiostatically on bare and dodecanethiol-coated polycrystalline gold electrodes. The obtained polymer layers were investigated by cyclic voltammetry with use of hydrophobic (ferrocene) and hydrophilic (Ru(NH3)6 3+) redox probes. The study of the morphology of obtained layers was also carried out by scanning tunneling microscopy in air. It was found that while p3OT deposited on bare gold contains a number of defects (pores, holes), the polymer deposited on thiol-coated electrode is characterized by more compact properties. It was proposed that in this case a complex system is formed where we can differentiate between a “mixed” inner layer consisting of polymer and thiol molecules and an outer layer of “pure” poly(3-octylthiophene). By “mixed” we understand the possibility of both filling the existing defects in the monolayer by the polymer and, eventually, replacing, with immediate entrapment into the matrix, some thiol molecules.