Thermoelectric Nanocomposites and Segmented Single-Leg Device Based on GeTe and (Bi,Sb)₂Te₃

Area of Science:

• Materials Science
• Energy Conversion
• Nanotechnology

Background:

• Thermoelectric (TE) materials convert heat to electricity via the Seebeck effect.
• GeTe excels at mid-temperatures (500-800 K), while (Bi,Sb)2Te3 is optimal at low temperatures (< 450 K).
• Current TE devices face limitations in efficiency across broad temperature ranges.

Purpose of the Study:

• To enhance thermoelectric energy conversion efficiency over a wider temperature range.
• To develop segmented single-leg TE devices using GeTe and (Bi,Sb)2Te3.
• To optimize TE performance through nanocomposite technology and structural design.

Main Methods:

• Fabrication of segmented GeTe/(Bi,Sb)2Te3 single-leg TE devices.
• Introduction of B4C nanoparticles into GeTe and SiC nanoparticles into (Bi,Sb)2Te3.
• Optimization of device geometry using finite element simulations.
• Characterization of thermoelectric properties, including conversion efficiency and power density.

Main Results:

• Nanocomposite technology optimized electrical and thermal conductivity, enhancing the thermoelectric figure of merit (ZT).
• Finite element simulations predicted a maximum conversion efficiency of 16.9% at a specific GeTe/(Bi,Sb)2Te3 ratio.
• Experimentally achieved peak conversion efficiency of 7.14% and power density of 12.5 mW/mm2 at 773 K.

Conclusions:

• Strategic segmentation of TE materials significantly broadens their operating temperature range.
• Nanoscale phonon scattering engineering is crucial for improving TE material performance.
• The developed segmented TE devices show great potential for high-efficiency thermoelectric energy conversion systems.