Electromechanical Properties of Self-Assembled Monolayers of Tetrathiafulvalene Derivatives Studied by Conducting Probe Atomic Force Microscopy

The electrical conduction of metal-molecule-metal junctions formed between Au-supported self-assembled monolayers (SAMs) of symmetric tetrathiafulvalene (TTF) derivatives and a Pt-coated atomic force microscope (AFM) tip has been measured Under different compression forces using conducting probe AFM. The TTFs are linked to the metal through double metal-thiol linkers oil both sides of the molecule. The TTF junctions exhibit remarkably high electrical conduction with estimated single molecule resistance of 14.7 +/- 3.4 G Omega, corresponding to the Molecular resistivity of 390 Q-cm. A single molecule resistance of I comparable length 1-decanethiol molecule is estimated to be several orders of magnitude higher with the value of 950 +/- 22 G Omega. The TTF junction resistance displayed a Unique nonlinear dependence with the compression force. The dependence is attributed to the change in the intermolecular electronic coupling between the TTF molecules.