Thermally activated charge transport in carbon atom chains

Area of Science:

• Molecular electronics
• Quantum transport phenomena
• Nanoscale science

Background:

• Single-molecule electronics leverage quantum effects in electrode-molecule-electrode systems.
• Understanding charge transport mechanisms at elevated temperatures is critical for practical applications.
• Previous research has limited experimental focus on high-temperature electron transport.

Purpose of the Study:

• To investigate the electron transport mechanism in single-molecule junctions at temperatures above ambient.
• To explore the interplay between electron tunneling and charge hopping in carbon chains.
• To provide insights for designing functional molecular junctions under practical conditions.

Main Methods:

• Fabrication of single-molecule junctions using alkanedithiols sandwiched between two gold electrodes.
• Measurement of single-molecule conductance at temperatures ranging from 300 K to 420 K in a vacuum environment.
• Analysis of temperature-dependent conductance to elucidate charge transport pathways.

Main Results:

• Observed a subtle interplay between electron tunneling and charge hopping in Au-alkanedithiol-Au junctions at elevated temperatures.
• Demonstrated that for alkane chains longer than heptane, superexchange and inter-chain charge hopping play significant roles at higher temperatures.
• The temperature dependence of conductance provided evidence for these complex transport mechanisms.

Conclusions:

• High temperatures significantly influence charge transport mechanisms in molecular junctions.
• Superexchange and inter-chain charge hopping become important for longer alkane chains at elevated temperatures.
• Findings guide the design of molecular electronic devices for operation under practical, high-temperature conditions.