High Seebeck Coefficient Achieved by Multinuclear Organometallic Molecular Junctions

Area of Science:

• Materials Science
• Nanotechnology
• Chemistry

Background:

• Molecular junctions are key components in nanoscale electronic devices.
• Thermoelectric materials convert heat energy into electrical energy, crucial for energy harvesting and thermal management.

Purpose of the Study:

• To investigate the thermoelectric properties of molecular junctions based on multinuclear ruthenium alkynyl complexes.
• To understand how metal nuclearity, oxidation state, and ligand substituents influence thermoelectric performance.

Main Methods:

• Synthesis of multinuclear ruthenium alkynyl complexes with thioether anchors.
• Measurement of Seebeck coefficient using the liquid metal technique.
• Computational analysis of molecular orbital energy levels and Fermi level alignment.

Main Results:

• Observed high Seebeck coefficients up to 73 μV/K.
• Demonstrated appreciable thermal stability with thermovoltage up to ~3.3 mV at 423 K.
• Identified a close proximity of the highest occupied molecular orbital (HOMO) to the Fermi level as the reason for high performance.

Conclusions:

• Multinuclear ruthenium alkynyl complexes exhibit remarkable thermoelectric properties.
• The HOMO-Fermi level alignment is critical for efficient molecular thermoelectric devices.
• This research provides insights for developing advanced molecular-scale thermoregulation and energy conversion devices.