High-Performance Industrial-Grade p-Type (Bi,Sb)₂ Te₃ Thermoelectric Enabled by a Stepwise Optimization Strategy.

Area of Science:

• Materials Science
• Solid State Physics
• Energy Conversion

Background:

• Bismuth telluride (Bi2Te3)-based alloys dominate the commercial thermoelectric market.
• These materials are crucial for Peltier cooling and waste heat recovery.
• Improving their thermoelectric efficiency (figure of merit, ZT) remains a key challenge.

Purpose of the Study:

• To enhance the thermoelectric performance of p-type (Bi,Sb)2Te3 alloys.
• To achieve higher ZT values for practical thermoelectric applications.
• To develop industrial-grade thermoelectric materials.

Main Methods:

• Incorporation of Ag8GeTe6 and Selenium (Se) into a p-type (Bi,Sb)2Te3 matrix.
• Optimization of carrier concentration and density-of-states effective mass through diffused Ag and Ge.
• Introduction of Sb-rich nanoprecipitates for coherent interfaces.
• Suppression of lattice thermal conductivity via Se-induced phonon scattering.

Main Results:

• A peak ZT of 1.53 at 350 K and an average ZT of 1.31 (300-500 K) were achieved in Bi0.4Sb1.6Te0.95Se0.05 + 0.10 wt% Ag8GeTe6.
• Optimized sample size (Ø40 mm-200 g) and a 17-couple module demonstrated 6.3% conversion efficiency at ΔT = 245 K.
• Significant reduction in lattice thermal conductivity while maintaining a decent power factor.

Conclusions:

• The combined addition of Ag8GeTe6 and Se effectively enhances the thermoelectric properties of (Bi,Sb)2Te3.
• This facile method yields high-performance, industrial-grade thermoelectric materials.
• The findings pave the way for broader practical applications in energy harvesting and cooling.