The effect of electrolyte‐controlled growth morphology on the charge transport properties of poly(3‐methylthiophene)

Poly(3‐methylthiophene) films were potentiostatically and galvanostatically synthesized on platinum electrodes in acetonitrile using lithium perchlorate, lithium tetrafluoroborate, tetra‐n‐butylammonium perchlorate, and tetra‐n‐butylammonium tetrafluoroborate as supporting electrolytes. Cyclic voltammetric analyses of the polymer films indicate the synthesis is polymerization process dependent. Constant potential syntheses, which resulted in a higher current density and were carried out at higher potentials, yielded polymer films with a higher charge capacity. Chronocoulometric results show that the charge transport rates of the films were electrolyte dependent and that tetra‐n‐butylammonium tetrafluoroborate yielded poly(3‐methyl‐thiophene) with the highest charge transport rate. The charge transport rate was found to be electric field dependent for all cases, suggesting that the films resemble a porous electrode. Scanning electron microscope analyses of the films, prepared under various conditions, indicate that the synthesis method used, and the nature of the electrolyte, strongly influence morphology and charge transport.