Thermoelectricity in vertical graphene-C₆₀-graphene architectures

Area of Science:

• Molecular electronics
• Quantum phenomena
• Energy harvesting

Background:

• Single-molecule thermoelectricity research has identified high-performance molecules.
• Translating molecular discoveries to practical thin-film devices requires understanding parallel junction behavior for scalability.

Purpose of the Study:

• Investigate the properties of two parallel C60 fullerene molecules sandwiched between graphene electrodes.
• Determine how parallel junction configurations affect electrical and thermoelectric performance compared to single junctions.

Main Methods:

• Fabrication of vertical molecular junctions using C60 fullerene molecules.
• Electrical transport measurements of single and parallel molecular junctions.
• Analysis of Seebeck coefficient variations with junction configuration.

Main Results:

• Electrical conductance increased by over a factor of 2 when moving from one to two parallel C60 junctions.
• The Seebeck coefficient showed sensitivity to the number of parallel molecules, deviating from classical conductor behavior.
• Observed non-classical behavior attributed to inter-junction quantum interference mediated by graphene electrodes.

Conclusions:

• Parallel molecular junctions can significantly enhance electrical and thermoelectric performance.
• Quantum interference effects are crucial in understanding the behavior of multi-molecule vertical junctions.
• This study provides a foundational understanding for scalable molecular energy-harvesting devices.