Copper electrocrystallization in PEDOT in presence and absence of copper-polymer-stabilized species

Electrochemical reduction of copper ions in poly(3,4-ethylenedioxythiophene) (PEDOT), performed at low overpotential or low current density, allows for stabilization of Cu(I) species in the polymer layer. The electrocrystallization of copper at high overpotential is explored in absence and presence of pre-stabilized Cu(I) species in PEDOT. It is found that the copper-pre-stabilized material allows for a five-fold increase of the number of deposited copper crystals. Statistical analysis of the distances between neighbouring crystals shows for both (as-synthesized and copper-pre-stabilized) materials a significant deviation from random Poisson probability distribution. For the first time, the experimental distributions are fitted by a theoretical probability model, accounting for the finite size of the crystals. The statistical analysis allows excluding the role of zones of reduced overpotential in the nucleation stage of electrocrystallization and concluding that new sites for nucleation become active in the presence of Cu(I)-stabilized species in PEDOT.