Structural aspects of electrochemical doping and dedoping of poly(3,4-ethylenedioxythiophene)

Electrochemical dedoping and redoping of p-toluene sulfonate doped poly(3,4-ethylenedioxythiophene) (PEDOT) has been studied with in situ grazing incidence diffraction with water used as an electrolyte. The diffraction peak positions and integrated intensities do not change significantly during doping and dedoping, while the peak widths increase upon dedoping and decrease upon doping. This implies that the lattice parameters and the relative positions of the polymer chains and the p-toluene sulfonate ions remain unchanged, the redox processes being carried out by the motion of smaller ions between the polymer and the electrolyte, and that the structural order decreases upon dedoping and increases upon doping in a reversible manner.