Performance of poly-3-methylthiophene in aqueous solutions of differen
t salts and acids is studied by means of cyclic voltammetry. Doping of
the polymer can be associated with the generation of charge carriers
in the polymer, namely, the complexes of two positive charges on the p
olymer chain bound with a dopant anion. The formation of this associat
e is possible only if the size of the anion is optimal in providing a
bridge between the charges.