Surface Structure and Electrochemical Polymerization of Mixed, Thiophene-Capped Monolayers

Abstract

We have investigated the growth of polythiophene from self-assembled monolayers (SAMs) that contain pendant thiophene groups using electrochemistry and atomic force microscopy. The SAMs are formed on indium tin-oxide (ITO) by coadsorption of 11-(3-thienyl)undecyltrichlorosilane (3TUTS) and undecyltrichlorosilane (UTS). By altering the composition of the underlying monolayers we can manipulate the onset of electrochemical polymerization and affect the surface topography of the resultant polythiophene layer. Films made on SAMs that have high loadings of 3TUTS have small, distinct grains, but as the monolayers become enriched in UTS, the grain size increases; however, these films are neither as rough nor as diffuse as films formed on ITO without an underlying SAM. These experiments suggest that the electrochemical growth and structure of the polythiophene layer can be manipulated by tuning the underlying SAM.