Electrodeposition and characterisation of copolymers based on pyrrole and 3,4-ethylenedioxythiophene in BMIM BF4 using a microcell configuration

Electrochemical copolymerization of pyrrole (Py) and 3,4-ethylenedioxythiophene (EDOT) was performed in an ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, (BMIM BF4) employing a 'micro-cell' in order to use the materials efficiently. Characterization of the copolymers formed on an ITO substrate was performed for different Py: EDOT ratios (1:2, 1:1, 2:1) in both aqueous and ionic liquid electrolytes. The three copolymers displayed different absorbance spectra with lambda max of the polaron species at 507,540 and 580 nm for PPy-co-PEDOT ratios of 1:2, 1:1, 2:1, respectively. Electrochemical and spectroelectrochemical analysis revealed that the properties of the copolymer depend upon the Py/EDOT monomer ratio used. The copolymer PPy-co-PEDOT (2:1) displayed good stability, a switching time of 20 s and a colouration efficiency of 101.3 C-1cm2. The presence of Py in the copolymer stabilised the polaron state of the copolymer and allowed greater ion mobility compared to the PEDOT alone. (C) 2013 Elsevier Ltd. All rights reserved.