Integration of Photoresponsive Single-Molecule Bithermoelectric Devices

Area of Science:

• Materials Science
• Nanotechnology
• Sustainable Energy

Background:

• Organic thermoelectric materials are crucial for sustainable energy conversion.
• Single-molecule devices offer high-efficiency thermopower by controlling molecular energy levels.
• Scalable output is limited by challenges in assembling heteromolecular units with opposite polarities.

Purpose of the Study:

• To develop a photoresponsive single-molecule bithermoelectric device for dynamic control of Seebeck coefficient polarity.
• To overcome limitations in scalable thermopower output from molecular junctions.
• To demonstrate a strategy for programmable and scalable molecular thermoelectrics.

Main Methods:

• Utilized dithienylethene (DTE) derivatives in a photoresponsive single-molecule bithermoelectric device.
• Employed the scanning tunneling microscope break-junction (STM-BJ) technique with a thermoelectric module.
• Confirmed photoisomerization and Seebeck coefficient switching using UV/visible light, thermoelectric measurements, and DFT calculations.

Main Results:

• Achieved reversible switching of the Seebeck coefficient between positive (P-type) and negative (N-type) upon UV and visible light irradiation.
• Demonstrated an array of DTE monolayer with alternating P-type and N-type junctions using an optical mask.
• Realized a series-integrated molecular thermoelectric device with amplified thermopower output (>9000 μV at 30 K).

Conclusions:

• Presented a viable strategy for programmable and scalable molecular thermoelectrics.
• Successfully utilized photoswitchable dithienylethene (DTE) derivatives for dynamic polarity control.
• Enabled amplified thermopower output through series integration of photoresponsive molecular junctions.