Impedance Response of Redox Polymer Films

Complex Impedance Response of Redox Polymer Films 

In this section we outline in some detail the salient features of the theory required to interpret quantitatively the complex impedance response of thin, surface-deposited redox polymer films. The analysis is 

In simple terms the impedance response of a redox polymer film can be modeled in terms of the general circuit illustrated in Fig. 1.72. This circuit has been proposed by Sharp and coworkers. We note from Fig. 

72 that the equivalent circuit contains two elements labeled I and II. The upper nonconducting branch of Element I consists of the interfacial or double-layer capacitance C l at the support electrode/film interface connected in series with a parallel combination of a capacitance Cb and a resistance Rb that reflect the dielectric properties of the polymer. In Fig. 

FIGURE 1.72. (a) General equivalent circuit representing an electroactive polymer film exhibiting redox conduction. Each individual circuit element corresponds to a particular kinetic/transport/structural property of the polymer, (b) Approximate equivalent circuits and associated Nyquist plots for various simplified limiting situations encountered in practice. Approximation (i) is valid when / ct is very low, / ps = = 0, the redox site 

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