Mechanically Induced Switching Between Orbital- and Fano-Resonance Rectification in a Dual-Anchored Molecular...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Single-molecule electronics require precise control over charge transport.
• Rectification in molecular junctions can arise from various mechanisms, often obscured by contact geometry.
• Understanding these mechanisms is key to developing novel electronic devices.

Purpose of the Study:

• To demonstrate dual-mode rectification in a mechanically controlled single-molecule junction.
• To investigate and compare different rectification mechanisms based on interface engineering.
• To establish a strategy for controlling charge transport in molecular electronics.

Main Methods:

• Utilizing scanning tunneling microscopy break-junction (STM-BJ) measurements.
• Employing mechanically controlled modulation of metal-molecule-metal junctions.
• Chemically programming interfaces with heterofunctional scaffolds (thiol and carboxyl anchors).

Main Results:

• Observed two reproducible conductance states corresponding to distinct contact configurations (thiolate-carboxylate and carboxylate-carboxylate).
• Thiolate-carboxylate configuration rectified via asymmetric molecular-orbital alignment and electrode coupling.
• Carboxylate-carboxylate configuration rectified via an interference-driven Fano-resonance pathway.

Conclusions:

• Anchored chemical synthons and mechanical control enable engineering of rectification mechanisms.
• Direct comparison of rectification mechanisms in short single-molecule junctions is feasible.
• This approach offers a practical strategy for advancing single-molecule electronics.