Enhanced Band-Crystal Engineering Drives Superior Power Generation in GeTe.

Area of Science:

• Materials Science
• Solid State Physics
• Energy Conversion

Background:

• Optimizing thermoelectric (TE) materials is difficult due to coupled carrier and phonon transport.
• GeTe-based materials offer potential but require performance enhancements.

Purpose of the Study:

• To decouple carrier and phonon transport in GeTe-based materials.
• To enhance the thermoelectric performance through synergistic band structure and crystal lattice engineering.

Main Methods:

• Doping GeTe with Zr, Pb, and Cu2Te to modulate band structure and crystal lattice.
• Investigating the effects of doping on carrier concentration, mobility, and thermal conductivity.
• Analyzing phonon scattering mechanisms and band structure modifications.

Main Results:

• Optimized Ge$_{0.885}$Zr$_{0.02}$Pb$_{0.08}$Te$_{0.985}$(Cu$_{2}$Te)$_{0.015}$ exhibited enhanced Seebeck coefficient and carrier-weighted mobility (µ$_{w}$ ≈210 cm$^{2}$ V$^{-1}$ S$^{-1}$).
• Significant reduction in lattice thermal conductivity (κ$_{L}$) due to enhanced phonon anharmonicity and defect scattering.
• Achieved a peak figure of merit (zT) of ≈2.2 at 650 K, a ≈238% improvement in µ$_{w}$/κ$_{L}$ at 650 K.
• Demonstrated a maximum heat-to-electricity conversion efficiency of 8.5% for a 7-pair device.

Conclusions:

• Synergistic control of band structure and crystal lattice effectively decouples carrier and phonon transport.
• The developed GeTe-based material shows great promise for advanced thermoelectric applications.
• This approach provides a pathway for designing high-performance thermoelectric materials.