Characterization of a tantalum capacitor fabricated with a conducting polypyrrole as a counter electrode

A tantalum solid electrolytic capacitor, using a conducting polypyrrole composite as a counter electrode, has been investigated concerning the temperature dependence of the series resistance and leakage current. The resistance of the capacitor changes along the curve expected from the variable-range-hopping (VRH) process. The conductivity of polypyrrole in the capacitor, estimated from the known VRH parameter of the polymer, coincides with that for polypyrrole synthesized alone. The current-voltage curves for the capacitor follow the Schouky or Pool-Frenkel emission. The capacitor demonstrates the features of an ideal capacitor, indicating a constant capacitance and proportional decrease of impedance with frequency up to the resonance point.