Near-perfect conduction through a ferrocene-based molecular wire

Abstract

Here we describe the design, single-molecule transport measurements, and theoretical modeling of a ferrocene-based organometallic molecular wire, whose bias-dependent conductance shows a clear Lorentzian form with magnitude exceeding 70% of the conductance quantum G_0. We attribute this unprecedented level of single-molecule conductance to a manifestation of the low-lying molecular resonance and extended orbital network long-predicted for a conjugated organic system. A similar-in-length, all-organic conjugated phenylethynyl oligomer molecular framework shows much lower conductance.Comment: 11 pages text, 4 figures, 4 pages supplementary material; re-submitted to Physical Review Letter

Switchable nanometer contacts: Ultrathin Ag nanostructures on Si(100)

“…These curves resemble those obtained recently as enhanced transmission for ferrocene-oligophenylethynyldithiol placed in between Au contacts. 16 In addition, their measured conductance values are very similiar to ours and seem to be characteristic of ferrocene and its derivatives. We note that the noise level for voltages above ±200 mV was quite high, indicating configurational fluctuations, which may be partly field ͑or current͒ induced.…”

Single-molecule transistors: Electron transfer in the solid state

“…This demonstrates conclusively that conjugated ligands of the type used in this complex can couple strongly to conduction electrons in a metal. Similar strong coupling has been reported recently in another conjugated system [47]. Detailed electronic structure calculations of the ligand/metal binding, with a realistic treatment of the Au surface, should help determine what makes these ligands particularly effective.…”

Electron transport through single conjugated organic molecules: Basis set effects in ab initio calculations

“…Additionally, the scissor mode made by the ferrocene moiety (i.e., rotation of the two fivemember rings with respect to each other) might also allow a higher conductance state to be realized, although this might not account for the big qualitative discrepancy. 11 Another possibility is the chemical absorption on the lead surface in the experiment 11 which was partially done in solution first. The chemical absorption may change the work function of the surface of the electrode or form a dipole layer on the surface, both of which can change the lineup between the Fermi energy and the HOMO or LUMO state and therefore cause a large increase in the conductance.…”

“…Electron transport through single conjugated organic molecules has attracted considerable experimental attention 1,2,3,4,5,6,7,8,9,10,11,12 because of the convenience of the chemical assembly and their delocalized electronic states and the resulting small HOMO-LUMO gap which is very useful in molecular electronics especially for the operation under low bias voltages. Theoretically, to understand the transport properties of junctions bridged by these molecules and to be able to calculate their conductance are important in view of both applications and fundamental physics.…”