Studies on Electrochemical Synthesis of Polythiophene in an Ionic Liquid

Polythiophene（PTh）films were prepared by the direct electropolymerization of thiophene in the ionic liquid，1-butyl-3-methylimidazolium hexafluorophosphate（BMIM）PF6 . The structure and morphology of PTh films were characterized by means of the FT-IR spectrum and the scanning electron microscopy（ SEM）. The electrical and electrochemical properties of PTh films were examined with the UV-Vis spectrum，cyclic voltammetry（CV） and four-probe method. The results showed that when the potential for electropolymerization was controlled between +1.7 and +1.9 V（vs. Ag/AgCl），very homogeneous PTh films could be prepared in the ionic liquid （BMIM）PF6 used as solvent and electrolyte. The de-doping（reduction）and re-doping（re-oxidation）of the PTh film prepared in ionic liquid are reversible and stable，and the conductivity of PTh films is 0.01-0.1 S/cm.