Leveraging carrier mobility enables high-performance Mg₃(Sb, Bi)₂ thermoelectrics

Area of Science:

• Materials Science
• Solid State Physics
• Energy Conversion

Background:

• Carrier transport is crucial for semiconductor thermoelectric performance.
• Optimizing transport is difficult due to multiple scattering mechanisms.

Purpose of the Study:

• To construct a mobility diagram for Mg3(Sb, Bi)2 to guide carrier transport optimization.
• To enhance thermoelectric performance by understanding scattering effects.

Main Methods:

• Developed a mobility diagram considering acoustic-phonon, grain-boundary, and polar-optical-phonon scattering.
• Fabricated and characterized Mg3(Sb, Bi)2 materials.

Main Results:

• Achieved a record carrier mobility of 179 cm2 V-1 s-1.
• Obtained a peak figure of merit (zT) of ~2.0 at 723 K.
• Demonstrated ~13% conversion efficiency in single-leg modules and ~8% in two-pair modules.

Conclusions:

• Mg3(Sb, Bi)2 shows significant potential for efficient thermoelectric power generation.
• Carrier transport is a key design metric for optimizing thermoelectric materials.