Synthesis and electronic properties of polythiophene containing thienyl S,S-dioxide units

Abstract

This research surveyed for suitable conditions to synthesis polythiophene and poly(3-hexylthiophene) containing thienyl S, S-dioxide groups by polymerization with ferric chloride, followed by oxidation. Experimental factors under investigation included types of oxidizing agents, reaction time, temperature and solvent. The products were analyzed by various spectroscopic methods and a four-point Probe method for their conductive properties. Polythiophene and poly(3-hexylthiophene) have been successfully prepared and oxidized to obtain the end products having higher UV-visible absorption in longer wavelength region. Changes in UV-visible spectra, that corresponded to partial oxidation of poly(3-hexylthiophene), was followed by a newly proposed ‘absorption-conjugation index’ (AC-index) method. The product from the oxidation of poly(3-hexylthiophene) by hydrogen peroxide/trifluoroacetic acid can be prepared into film which, after being doped by iodine-vapor showed the conductivity of 0.60 S.cm-1, higher than the non-oxidized poly(3-hexylthiophene) (0.37 S.cm-1).