In situ STM tip-induced electropolymerization of poly(3-octylthiophene)

Abstract

Poly(3-octylthiophene) has been grown on an indium-tin-oxide (ITO)-coated glass substrate by an STM tipinduced 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 mechanism operates to deposit both nodular and helical polymer structures. Consideration of the helix diameters (range 25-70 Å) obtained points to the existence of both simple helices and superhelices. Initial nucleation occurs preferentially at the ITO grain boundaries, probably because of an altered electronic state from the segregation of dopants there. © 1998 Springer-Verlag.