The electrochemical doping of heterocyclic polymers

Once deposited as conductive films, the heterocyclic polymers can be repeatedly cycled from the undoped to the doped forms (and vice versa) in electrochemical cells substantially similar to those used for the electropolymerisation reactions. 

For example, the p-doping process of a typical heterocyclic polymer, say polypyrrole, can be reversibly driven in an electrochemical cell by polarising the polymer electrode vs a counterelectrode (say Li) in a suitable electrolyte (say LiC104-PC). Under these circumstances the p-doping redox reaction (9.15) can be described by the scheme  

It is worth noting that the doping level y acquired by the electrochemical processes may be expressed as the percentage of moles of the doping anion (X ) over the moles of the monomeric repeating unit (e.g. 

Accordingly, the moles of the monomeric unit are given by the ratio of the dilference between the number of Faradays used for the entire process, and the number of cyclable Faradays, F yc, over the number of electrons for the entire process (ne, , = 2 in the case of (9.16))  

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