Molecular Dynamics Study of Morphology of Doped PEDOT: From Solution to Dry Phase.

Morphology of the conducting polymer PEDOT:TOS (poly(3,4-ethylenedioxythiophene) doped with molecular tosylate) and its crystallization in aqueous solution were studied using atomistic molecular dynamics simulations. It was found that (a) PEDOT comprises crystallite aggregates consisting of 3-6 π-π stacked chains. The crystallites are linked by interpenetrating π-π stacked chains such that percolative paths in the structure are formed. (b) The size of the crystallites depends on the water content, but the π-π stacking distance is practically independent of the chain length, charge concentration and water content. (c) TOS counterions are located either on the top of the chains or on the side of the crystallites and their distribution depends on the charge concentration but is practically independent of the water content; (d) PEDOT chains and crystallites exhibit bending that depends on their length and water content.