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

TL;DR

This paper demonstrates that self-assembled monolayers can significantly enhance the surface conductivity of organic semiconductors, enabling potential sensing applications through reversible vapor interactions.

Contribution

It introduces a novel method of growing organosilane SAMs on organic semiconductors, dramatically increasing their surface conductivity and environmental accessibility.

Findings

Surface conductivity approaches 10^-5 S per square with SAMs

Conductivity change is fast and reversible with polar vapors

Potential for sensing applications due to environmental accessibility

Abstract

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