Influence of dopant size on the junction properties of polyaniline

Polyaniline (PANI) doped with sulfate anion (SA) or methane sulfonate anion (MSA) was used to fabricate the Schottky devices: Al/PANI(SA)/ITO and Al/PANI(MSA)/ITO. Current density (J)–voltage (V) measurements and AC impedance analysis were used to evaluate the junction parameters of the devices, ideality factor, barrier height and rectification ratios. An equivalent circuit was developed and the impedance parameters were evaluated. The differences in junction parameters between the devices were analyzed in terms of the differences in dopability of PANI with the dopants, morphology of the films and mobility of carriers in Al/conducting polymer junction.