Charge- and Ion-Transport Properties of Polypyrrole/Poly(styrenesulfonate):Poly(3-octylthiophene) Bilayers

The electrochemical, electronic, charge-transport, and ion-transport properties of a conducting polymer bilayer, prepared using polypyrrole/poly(styrenesulfonate) (PP/PSS) and poly(3-octylthiophene) (POT) have been investigated by cyclic voltammetry, optoelectro-chemistry, and a combination of electrochemical and gravimetric techniques using the electrochemical quartz crystal microbalance (EQCM). This PP/PSS:POT bilayer presents separate redox switching potentials demonstrating that charge is efficiently transferred through the inner PP/PSS layer to the POT outer layer. While the bilayer exhibits reversible redox processes for both components during rapidly repeated cyclic voltammetric scans, poising the potential at a highly reducing value (-1.2 V vs Ag/Ag+) for a sufficient time prior to starting a potential scan severely limited the redox processes of the PP/PSS inner layer. This is most likely due to inhibited counterion transport through the neutral POT outer layer.