Compromise and Synergy in High-Efficiency Thermoelectric Materials

Area of Science:

• Materials Science
• Solid-State Physics
• Energy Conversion

Background:

• Thermoelectric (TE) research has rapidly grown over the past two decades.
• Novel concepts and paradigms are emerging to target superior TE materials and performance.
• Classical TE material performance has improved, but the figure of merit (zT) remains suboptimal.

Purpose of the Study:

• To describe novel concepts and paradigms for superior TE materials and performance.
• To discuss strategies for optimizing individual TE properties and decoupling interrelated properties.
• To present representative systems of synergistic optimization for TE materials.

Main Methods:

• Review and discussion of emerging concepts: band convergence, phonon-glass electron-crystal, multiscale phonon scattering, resonant states, and anharmonicity.
• Identification of new TE materials with features like high band degeneracy, rattling atoms, and nanostructures.
• Elaboration on four main compromises between TE properties, analyzing underlying mechanisms and decoupling strategies.

Main Results:

• Identification of new TE materials and significant performance improvements in classical materials.
• Highlighting that most TE materials have a figure of merit (zT) around 1.0, below the target of 2.0.
• Demonstration of synergistic optimization strategies in representative TE material systems.

Conclusions:

• Realizing an overall zT > 2.0 necessitates thorough decoupling of interrelated TE properties or adding new degrees of freedom.
• Synergistic optimization of electrical and thermal transport is crucial for advancing TE materials.
• The study provides insights and references for future TE material development and optimization.