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Molecular order of alkyl and aryl thiols self-assembled on Au using STM

Ferreira, Q. ; Alcácer, L. ; Morgado, J.

Molecular order of alkyl and aryl thiols self-assembled on Au using STM, Proc Workshop Nanoscale Self-organizing Structures for Plastic Electronics, Faro, Portugal, Vol. 0, pp. 0 - 0, March, 2009.

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Nowadays, a great deal of attention has been devoted to organic electronics for low-cost, large-scale, and flexible electronic device applications. Thiols self-assembled monolayers (SAMs) have attracted considerable attention due to their potential applications in molecular electronics. In particular, aromatic thiol SAMs are being studied in various areas such as control of charge transfer, organic-based electronic functionality or patterning at the nanometer scale. The structural and electrical characterization of organic monolayers is therefore of importance and this is in fact an emerging area of study.
This work explores some factors that influence the thiols SAMs characteristics, such as molecular structure of the thiol and the adsorption conditions, such as time, solvent and temperature. We report the preparation conditions and characterization of monolayers formed on Au(111) with two different thiol molecules: an aromatic (thiophenol) and an alkanethiol (dodecanethiol). The key difference between aryl and alkyl thiolate SAMs is the rigid ð-conjugation of the aryl thiol. This characteristic affects the adsorption kinetic as well as the equilibrium structure of the SAMs. The STM images of thiophenol SAMs showed higher packing density and stability.