Thermoelectric Ratchet Effect for Charge Carriers with Hopping Dynamics

Area of Science:

• Condensed Matter Physics
• Materials Science
• Physical Chemistry

Background:

• Recent observations show unexpectedly large Seebeck coefficients in ionic conductors.
• Understanding the underlying transport mechanisms is crucial for thermoelectric applications.

Purpose of the Study:

• To elucidate the physical mechanisms responsible for high Seebeck coefficients in ionic conductors.
• To develop a theoretical model that explains experimental observations without free parameters.

Main Methods:

• Theoretical modeling based on activated ion jumps and diffusiophoresis.
• Analysis of temperature gradient effects on ion and molecular transport.

Main Results:

• A ratchet effect explains ion transport driven by temperature gradients in simple ionic conductors.
• Diffusiophoresis, driven by thermally induced concentration gradients, enhances transport in complex systems.
• The model successfully describes experimental data for ionic liquids (EMIM-TFSI) and hydrated polymers (NaPSS).

Conclusions:

• The proposed model provides a unified explanation for high Seebeck coefficients in diverse ionic conductor systems.
• The findings offer insights into optimizing thermoelectric materials and understanding ion transport phenomena.