Film thickness and electrolyte concentration effects on the EIS response of poly(o-toluidine) in the conducting state

MARÍA JOSÉ RODRÍGUEZ PRESA; HELEN L. BANDEY; RICARDO I. TUCCERI; MARÍA INÉS FLORIT; DIONISIO POSADAS; A. ROBERT HILLMAN

ELECTROCHIMICA ACTA

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 1999 vol. 44 p. 2073 - 2085

0013-4686

The impedance response of electrochemically synthesized Poly-(o-toluidine) (POT) films was measured, in the potential region corresponding to polymer oxidation (0.25 V< E30 mC cm-2) both RLF and σ remain approximately constant. In the region of small thickness, RLF and s increase as the charge decreases. This is interpreted in terms of the polymer morphology. For thin films, this type of polymer has a compact structure through which ion motion into the polymer is slow. Otherwise, thick films develop fibrilar aggregates on top of the compact layer which can explain the constancy of RLF and σ. The analysis of the potential dependence of equivalent circuit elements through impedance models allows one to conclude that ionic motion is the rate controlling step for charge transport in this polymer.