An Assessment of the Effect of Synthetic and Doping Conditions on the Processability and Conductivity of Poly(3,4-ethylenedioxythiophene)/Poly(styrene sulfonic acid)

Poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonic acid) (PEDOT/PSS) dispersions are synthesized via conventional oxidative polymerization under various synthetic (reaction times and formulations) and doping conditions (in situ and postpolymerization) with the introduction of dialysis as an additional purification step. Conductivities of films produced from these synthesized dispersions are one to three orders of magnitude higher than the equivalent commercial PEDOT/PSS reference film. In situ doped PEDOT/PSS dispersions give films that are more conductive than those doped postpolymerization. Optimum conductivity of 5.2 ± 0.7 S cm-1 is obtained from PEDOT/PSS dispersions (1:2.5 EDOT:PSS mass ratio) synthesized for 12 h with doping efficiency of 73%. Under these synthetic conditions, the film most likely has the optimal microstructure, i.e., optimal PEDOT chain length and ideal distribution and balance of PEDOT/PSS segments and free PSS chains, favoring charge transport and processability. Capillary electrophoresis is presented here as a novel method for measuring free and doped PSS in PEDOT/PSS dispersions.