A metal-molecule-GNP assembly has been fabricated using an acetylene-terminated phenylene-ethynylene molecular monolayer, namely 4-((4-((4-ethynylphenyl)ethynyl)phenyl)ethynyl)benzoic acid (HOPEA), sandwiched between a gold substrate bottom electrode and gold nanoparticle (GNP) top contact electrode. In the first stage of the fabrication process, a monolayer of directionally oriented (carboxylate-to-gold) HOPEA was formed onto the bottom electrode using the Langmuir-Blodgett (LB) technique. In the second stage, the gold-substrate supported monolayer was incubated in a solution of gold nanoparticles (GNPs), which resulted in covalent attachment of the GNPs on top of the film via an alkynyl carbon-Au σ-bond thereby creating the metallic top electrode. Adsorption of the GNPs to the organic LB film was confirmed by both UV-vis absorption spectroscopy and X-ray photoemission spectroscopy (XPS), whilst the contact angle showed changes in the physical properties of the film surface as a result of top-coating of the LB film with the GNPs. Importantly, surface-enhanced Raman scattering (SERS) confirmed the covalent attachment of the metal particles to the LB film by formation of Au-C σ-bonds via a heterolytic cleavage of the alkyne C-H bond. Electrical properties of these nascent metal-molecule-GNP assemblies were determined from I-V curves recorded with a conductive-AFM in the Peak Force Tunneling AFM (PF-TUNA™) mode. The I-V curves obtained from these structures rule out the formation of any significant number of short-circuits due to GNP penetration through the monolayer, suggesting that this strategy of self-assembly of GNPs to alkyne-terminated monolayers is an effective 'soft' procedure for the fabrication of molecular junctions without damaging the organic layer. This journal is © the Partner Organisations 2014.
CITATION STYLE
Osorio, H. M., Cea, P., Ballesteros, L. M., Gascón, I., Marqués-González, S., Nichols, R. J., … Martín, S. (2014). Preparation of nascent molecular electronic devices from gold nanoparticles and terminal alkyne functionalised monolayer films. Journal of Materials Chemistry C, 2(35), 7348–7355. https://doi.org/10.1039/c4tc01080a
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