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Conformation-controlled electron transport in single-molecule junctions containing oligo(phenylene ethynylene)
Le-Jia Wang1, Ai Yong, Kai-Ge Zhou
1State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China.
Chemistry, an Asian Journal
|June 5, 2013
Summary
This study explores how molecular structure impacts electronic transport in oligo(phenylene ethynylene) (OPE) wires. Molecular conductance depends on dihedral angles, revealing a cos(2)θ relationship for coherent tunneling.
Area of Science:
- Molecular Electronics
- Condensed Matter Physics
- Materials Science
Background:
- Understanding molecular structure-electronic transport relationships is crucial for molecular electronics.
- Oligo(phenylene ethynylene) (OPE) molecular wires are promising candidates for electronic applications.
- The influence of intramolecular conformation on conductance needs further investigation.
Purpose of the Study:
- To investigate the single-molecule conductance of OPE molecular wires.
- To determine the relationship between molecular structure (dihedral angles) and electronic transport.
- To elucidate the mechanism governing conductance in OPE molecular junctions.
Main Methods:
- Experimental study using scanning tunneling microscopy (STM)-based break-junction techniques.
- Variable temperature and bias potential measurements were performed.
- Theoretical investigations using density functional theory (DFT) and nonequilibrium Green's functions (NEGF).
Main Results:
- Coherent tunneling mechanism identified in 2.5 nm OPE molecular wires.
- Molecular conductance is strongly influenced by coupling strength between π systems, tunable via conformation.
- A cos(2)θ dependence was observed between molecular conductance and dihedral angles.
Conclusions:
- Intramolecular conformation significantly dictates molecular conductance in OPE wires.
- Experimental and theoretical findings are consistent, validating the cos(2)θ relationship.
- This work provides fundamental insights for designing molecular electronic devices.
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