Electrosynthesis and characterization of poly(3-methylthiophene) on different substrates

We report on the study of the electropolymerization of 3-methylthiophene on to Pt, p-Si and indium-tin oxide deposited on polyester using quartz crysta l microgravimetry, electrochemical and spectroelectrochemical measurements. We observe that potential variation during the galvanostatic electrodeposi tion is correlated with the nucleation process. The mass variation of poly( 3-methylthiophene) is linear with the amount of the electrochemical charge whereas the absorbance variation curve shows two distinct slopes. The latte r result has been explained in terms of conjugation length variation during polymer growth. Scanning electron microscopy analysis allowed the detectio n of morphological changes from a dense and compact structure to an open mo rphology when the poly(3-methylthiophene) film thickness increases. The rou ghness of the films did not change considerably with the substrate, as obse rved by atomic force microscopy, Absorption and photocurrent spectra at dif ferent film thicknesses show a shift of the peaks to lower wave lengths whe n the thickness increased, thus confirming the decrease of mean conjugation length in thicker films.