Nanostructured organic semiconductor films for molecular detection with surface-enhanced Raman spectroscopy

Abstract

π-Conjugated organic semiconductors have been explored in several optoelectronic devices, yet their use in molecular detection as surface-enhanced Raman spectroscopy (SERS)-active platforms is unknown. Herein, we demonstrate that SERS-active, superhydrophobic and ivy-like nanostructured films of a molecular semiconductor, α,ω-diperfluorohexylquaterthiophene (DFH-4T), can be easily fabricated by vapour deposition. DFH-4T films without any additional plasmonic layer exhibit unprecedented Raman signal enhancements up to 3.4 × 10 for the probe molecule methylene blue. The combination of quantum mechanical computations, comparative experiments with a fluorocarbon-free α,ω-dihexylquaterthiophene (DH-4T), and thin-film microstructural analysis demonstrates the fundamental roles of the π-conjugated core fluorocarbon substitution and the unique DFH-4T film morphology governing the SERS response. Furthermore, Raman signal enhancements up to ∼10 and sub-zeptomole (<10 mole) analyte detection were accomplished by coating the DFH-4T films with a thin gold layer. Our results offer important guidance for the molecular design of SERS-active organic semiconductors and easily fabricable SERS platforms for ultrasensitive trace analysis.

Quantum scale organic semiconductors for SERS detection of DNA methylation and gene expression

“…Currently, the enhancement factor obtained using bare organic semiconductor thin films is 10 3 and an enhancement factor of 10 10 with the addition of a plasmonic (gold) layer 4 . The use of thin film organic semiconductor material relies solely on charge transfer and molecular aggregation mechanism for SERS enhancement.…”

“…SERS with organic semiconductors presents distinctive advantages, including structural adaptability, tunable charge mobility, low effective carrier mass 2 . Recently reported organic semiconductor sensors are thin films 3,4 . However, organic semiconductors rely primarily on charge transfer mechanism for SERS enhancement which hinders the sensitivity to a great extent.…”

SERS Activity of Semiconductors: Crystalline and Amorphous Nanomaterials

“…Furthermore, by combining the strong EM enhancement of noble metals with the high selectivity and spectral stability of semiconductors in the fabrication of semiconductor–metal hybrid nanostructures, promising SERS platforms for the quantitative trace detection of target molecules could be obtained . One related study demonstrated that an EF up to 10 10 was accomplished by coating α‐ω‐diperfluorohexylquaterthiophene (DFH‐4T) films with a thin gold layer, as shown in Figure . Yilmaz et al.…”

Detecting the Origin of Cancer‐Mobile Quantum Probe for Single Cancer Stem Cell Detection

“…Among the different SERS‐active materials researched, organic semiconductors have recently attained increasing attention due to their exceptional properties, including tunable bandgap, high electron mobility, infinite Bohr radius . Current research on organic semiconductors for SERS application is limited to molecular sensing since most of these probes are 1D nanoprobe (thin films) fabricated through deposition. The large area of these organic semiconductor probe prevents them from being applied for cellular detection.…”