Molecular Structure-(Thermo)electric Property Relationships in Single-Molecule Junctions and Comparisons with Single-...

Area of Science:

• Molecular electronics
• Condensed matter physics
• Organic chemistry

Background:

• Understanding charge transport in molecular wires is crucial for molecular electronics.
• Conjugated molecular wires with metal centers offer tunable electronic properties.

Purpose of the Study:

• To determine the single-molecule conductance of 12 conjugated molecular wires, including those with ruthenium or platinum centers.
• To investigate the charge transport mechanism and identify factors governing conductance trends.

Main Methods:

• Single-molecule conductance measurements.
• Determination of Seebeck coefficient to probe transport mechanisms.
• Density Functional Theory (DFT) calculations and Landauer-Büttiker model for transport analysis.

Main Results:

• Single-molecule conductance was measured for a series of conjugated molecular wires.
• Charge transport was identified as tunneling through the HOMO resonance tail near the HOMO-LUMO gap.
• Observed conductance trends were not explained by single-parameter models but were well-described by considering the complete molecular junction using DFT.

Conclusions:

• The complete molecular junction, not single parameters, governs charge transport in these molecular wires.
• DFT calculations within the Landauer-Büttiker framework accurately predict experimental conductance trends.
• This work advances the understanding of charge transport mechanisms in complex molecular systems.