Interaction between Thiophene and Solvated Lewis Acids and the Low-Potential Electrochemical Deposition of a Highly Anisotropic Conducting Polythiophene Film

Abstract

Fourier transform Raman spectroscopy of a thiophene solution shows a reduction of aromaticity of the thiophene ring by the interaction with a solvated Lewis acid, which lowers the oxidation potential of the monomer. Low-potential electrochemical deposition of polythiophene was carried out in the presence of a Lewis acid in a solvent with a suitable donor number. High quality conducting polythiophene films were prepared at low potential in BF 3 −ethyl ether. The conductivity parallel to the film surface is more than 10 4 times that across the film thickness. This anisotropy is related to the orientation of polythiophene chains. The molecular arrangement of polythiophene on a stainless steel electrode was investigated by surface-enhanced Raman scattering and infrared reflection−absorption spectroscopy.