SEM study of the growth of electrochemically obtained polythiophene thin films: Effect of electrolyte and monomer concentration in acetonitrile

The initiation of the electrochemical growth of polythiophene thin films was studied by X‐ray photoelectron spectroscopy (XPS), electron probe micro analysis (EPMA), and mainly by scanning electron microscopy (SEM). The films were deposited on SnO2‐coated glass in a classical three‐electrode cell. Depositions were done under pure argon atmosphere. Two electrolytes were tested, tetrabutyl ammonium hexafluorophosphate (Bu4NPF6) and tetramethylammonium hexafluorophosphate (Me4NPF6) in anhydrous acetonitrile. The effect of the electrolyte, and monomer and electrolyte concentration, on the film properties were visualized. These results are discussed with the help of the other characterization techniques. It is shown that for optimum concentration (0.05M monomer and 0.05M electrolyte), two processes are active, one three‐dimensional (3D) and one two‐dimensional (2D). When the monomer concentration is increased, a third 3D contribution is presently active. When the electrolyte concentration increases, there is some electrolyte crystal precipitation on the synthesized polymer films.