Electronic functionalization of the surface of organic semiconductors with self-assembled monolayers

摘要

Molecular self-assembly has been extensively used for surface modification ofmetals and oxides for a variety of applications, including molecular andorganic electronics. One of the goals of this research is to learn how theelectronic properties of these surfaces can be modified by self-assembledmonolayers (SAM). Here, we demonstrate a new type of molecular self-assembly:the growth of organosilane SAMs at the surface of organic semiconductors, whichresults in a dramatic increase of the surface conductivity of organicmaterials. For organosilane molecules with a large dipole moment, SAM-inducedsurface conductivity of organic molecular crystals approaches 10^-5 S persquare, which is comparable to the highest conductivity realized in organicfield-effect transistors (OFETs) at ultra-high densities of charge carriers.SAM-functionalized organic surfaces are fully accessible to the environmentwhich makes them very attractive for sensing applications. We have observedthat the interaction of vapors of polar molecules with SAM-functionalizedorganic semiconductors results in a fast and reversible change of theconductivity, proportional to the pressure of an analyte vapor.