Probing the molecular orientation of a single conjugated polymer via nano-gap SERS

Abstract

Determining the molecular orientation at the single molecule level is of key importance for a wide range of applications ranging from molecular electronic devices to biomedical applications. In this work Surface-Enhanced Raman Scattering (SERS) was used to probe the light emitting conjugated polymer F8-PFB at the single molecule level using nanoparticle on an extended metallic film nano-gap. The directional field enhancement of the nano-gap combined with Density Functional Theory (DFT) calculations was used to determine the orientation of the molecule. This analysis revealed that the spin-coated conjugated polymer preferentially aligns its molecular chains parallel to the metallic substrate. The integration of this approach in nanofabrication and synthesis will have a profound impact on different fields ranging from molecular electronic devices to biomedical applications.