Fluorinated molecules for organic SERS sensing

The detection and quantitative assessment of ultra-low concentrations of chemical and biological molecules is relevant in several fields including medical diagnostic, environmental science, and homeland security. Traditional approaches to molecular detection rely on optical, electrochemical, electronic, and gravimetric methodologies. Among these platforms, Surface-enhanced Raman Spectroscopy (SERS) using SERS-active inorganic materials is an ideal surface-sensitive technique allowing non-destructive molecular analysis with high sensitivity and selectivity approaching single-to-few molecules detection. However, the impact that organic (semi)conductors have made in this field is negligible. We recently discovered that an intrinsic (undoped) fluorinated molecular semiconductor (called DFH-4T) film is a SERS-active platform and exhibits enhancement factors (EFs) close to the limit predicted by theory for the chemical enhancement mechanism. Furthermore, DFH-4T/Au films enabled zeptomolar detection of several analytes without the need of micro/nanolithographic techniques for film nanostructure fabrication. The research goals of this proposal are: 1. Enhance DFH-4T carrier (electron) density by chemical doping or by film implementation in different device architectures to realize conditions to enhance the chemical enhancement mechanism as well as for the involvement of the electromagnetic mechanism. 2. Explore if other organic fluorinated molecular semiconductors can be SERS-active. 3. Implement (undoped/doped) organic semiconductor films into new SERS sensing platforms and devices. This study will bring organic SERS EFs to unprecedented levels, provides knowledge for the materials engineering and processing of bSERS-active organic films, and a path for the realization of new type of sensor devices potentially fabricable with inexpensive processing methodologies