Electrostatic control of thermoelectricity in molecular junctions

Area of Science:

• Nanotechnology
• Materials Science
• Condensed Matter Physics

Background:

• Molecular junctions offer potential for efficient thermoelectric energy conversion.
• Previous research faced challenges in electrostatic control of thermoelectric properties in these devices due to technical limitations.

Purpose of the Study:

• To develop a platform for electrostatic control of thermoelectric properties in molecular junctions.
• To investigate the relationship between electronic structure and thermoelectric performance.
• To enable systematic exploration of computational predictions for efficient molecular thermoelectric devices.

Main Methods:

• Establishing large temperature gradients (exceeding 1 × 10(9) K m(-1)) in nanoscale gaps bridged by molecules.
• Simultaneously controlling the electronic structure of molecular junctions using a gate electrode.
• Studying prototypical Au-biphenyl-4,4'-dithiol-Au and Au-fullerene-Au junctions.

Main Results:

• Demonstrated simultaneous increase in Seebeck coefficient and electrical conductance via electrostatic control.
• Showed significant enhancement of thermoelectric properties in fullerene junctions when the dominant transport orbital is near the electrode's Fermi level.
• Established an intimate link between thermoelectric properties and charge transmission characteristics.

Conclusions:

• The developed platform enables electrostatic control over molecular junction thermoelectric properties.
• Optimizing orbital alignment with the Fermi level is crucial for enhancing thermoelectric performance.
• This work facilitates further research into high-efficiency molecular thermoelectric energy conversion.