Studies of Single Molecular Conductance: Aryl-Gold Covalent Contacts Derived from Diazonium Groups and the Effects of Anchoring Groups
Date Issued
2011
Date
2011
Author(s)
Su, Man-Nung
Abstract
We introduce a novel approach to forming high conducting molecule-electrode covalent contacts for single molecular junction. In this study, aryl-gold contacts in molecular junction are derived from diazonium salt (R-N2+). Conductance of conjugated molecules covalently bonded to gold substrate is measured by scanning tunneling microscope break junction. To compare the effect of covalent contacts on conductance, we investigate in molecules with nitro-, amine-, and methylthio- anchoring groups. The conductance of junction with covalent contact is at least 10-fold higher than those of the same molecular framework yet with anchoring groups. By analyzing conductance to stretching distance traces, C-Au contacts are remained after break junction. On the other hand, we explore how anchoring groups affect the conductance of organic conjugated molecules. By Fowler-Nordheim plots, we conclude that anchoring groups affect their conductance by their adsorption energy with metal electrodes rather than energy alignment by adjusting the molecular orbitals.
Subjects
single molecular conductance
covalent contact
Au-C bond
Type
thesis
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