IN-SITU STM TIP-INDUCED ELECTROPOLYMERIZATION OF POLY(3-OCTYLTHIOPHENE)

Poly(3-octylthiophene) has been grown on an indium-tin-oxide (ITO)-coa ted glass substrate by an STM tip-induced polymerization technique in which a high anodic bias is applied on the substrate. Molecular images of resultant polymer structures are obtained by a subsequent in situ STM study. We find that a three-dimensional nucleation and growth mech anism operates to deposit both nodular and helical polymer structures. Consideration of the helix diameters (range 25-70 Angstrom) obtained points to the existence of both simple helices and superhelices. Initi al nucleation occurs preferentially at the ITO grain boundaries, proba bly because of an altered electronic state from the segregation of dop ants there.