Conductance Switching in an Asymmetric Single-Molecule Junction

Area of Science:

• Molecular electronics
• Nanotechnology
• Materials science

Background:

• Single-molecule electronics offers precise control over electronic properties.
• Developing stable and reproducible molecular junctions is crucial for device applications.
• Fullerene derivatives are promising candidates for molecular electronic components.

Purpose of the Study:

• To demonstrate electric switching in a single-molecule junction using the C60 pyrrolidine tris-acid (CPTA) molecule.
• To investigate the transport mechanisms and structural modulations in molecular junctions.
• To explore the potential of CPTA for room-temperature bistable switching.

Main Methods:

• Fabrication of nanogap electrodes spin-coated with a CPTA thin film.
• Two-terminal conductance measurements at room temperature.
• Analysis using single-level tunneling transport model and transition voltage spectroscopy.

Main Results:

• Reproducible bistable switching between low- and high-conductance states observed at room temperature.
• Identified two distinct transport regimes: metal-fullerene conduction and through-space tunneling.
• Confirmed single-molecule charge transport in the high-conductance state.
• Demonstrated strong dependence of junction asymmetry on molecule-electrode distance in the low-conductance state.

Conclusions:

• CPTA molecules can form functional single-molecule junctions exhibiting electric switching.
• The switching mechanism involves modulation of molecule-electrode distance and distinct transport regimes.
• This study provides insights into structural modulation and charge transport in molecular junctions for future electronic devices.