Molecular Conformation in Charge Tunneling across Large-Area Junctions

Area of Science:

• Surface Science
• Molecular Electronics
• Physical Chemistry

Background:

• Self-assembled monolayers (SAMs) are typically formed under thermodynamic equilibrium, implying predictable relaxation pathways.
• Understanding charge transport mechanisms in SAMs is crucial for molecular electronics applications.

Purpose of the Study:

• To investigate the correlation between charge tunneling and conformational degrees of freedom in SAMs.
• To explore how head group structure and spacer parity influence electron transport.

Main Methods:

• Fabrication and characterization of SAMs with varying head group structures (open chain and cyclic).
• Analysis of charge tunneling data using statistical moments like skewness and kurtosis.
• Bias-dependent measurements to study tunneling dynamics.

Main Results:

• Charge tunneling distribution directly correlates with head group orientation and conformational freedom.
• The odd-even effect in tunneling is significantly amplified by conformational degrees of freedom.
• Applied bias influences tunneling distribution, highlighting the dynamic nature of these systems.

Conclusions:

• Conformational flexibility plays a critical role in modulating charge transport through SAMs.
• Higher-order statistical analysis is necessary for a comprehensive understanding of dynamic tunneling phenomena.
• Tailoring head group and spacer design can control and perturb electron tunneling.