Spectroelectrochemistry of electrochromic poly(o–toluidine) and poly(m-toluidine) films

Visible-range absorption spectra of poly(o-toluidine) and poly(m-toluidine) films on tin-doped indium(III) oxide-coated optically transparent electrodes as a function of applied potential are reported. Absorption maxima and redox potentials shift from values found for polyaniline due to the lower conjugation length in poly(toluidine)s. Response times, τ, for the yellow–green electrochromic transition in the films correlate with the likely differences in the conjugation length implied from the spectroelectrochemical data. The τ values for polyaniline are found to be lower than for poly(o-toluidine), which in turn has lower values than poly(m-toluidine). As for polyaniline, response times indicate that the reduction process is faster than the oxidation. Poly(o-toluidine) and poly(m-toluidine) films offer enhanced stability of polyelectrochromic response in comparison with polyaniline.