UV-Vis-NIR spectroelectrochemical and in situ conductance studies of unusual stability of n- and p-doped poly(dimethyldioctylquaterthiophene-alt- oxadiazole) under high cathodic and anodic polarizations

Combined CV studies and UV-Vis-NIR spectroelectrochemical investigations revealed an unusual stability of the p- and n-doped PMOThOD in the wide potential window of 4 V. The n-doping process occurs in this polymer down to -2.7 V (vs. Ag/Ag⁺) in a non-destructive way with the characteristic development of the ω₃ transition as a function of the doping level. In situ electronic transport studies revealed a high conductivity of the n-doped polymer which implies high mobility of the negatively charged carriers in the freshly doped PMOThOD film electrodes. An increase in the cathodic polarization, long-term cycling of the film electrodes, especially of higher thickness, results in a growing contribution of the negatively charged carriers trapping to the redox properties of the PMOThOD. The trapping of the charged carriers reduces gradually the electronic conductance of the PMOThOD film, but its effect on the redox-capacity of the film (in a typical scan rates range up to 50 mV s^-1) is only minor.