Fine-Tuning Bi₂Te₃-Copper Selenide Alloys Enables an Efficient n-Type Thermoelectric Conversion

Area of Science:

• Materials Science
• Solid State Physics
• Energy Conversion

Background:

• Bismuth tellurides (Bi2Te3) are key thermoelectric materials for low-temperature applications.
• Improving n-type Bi2Te3 thermoelectric performance is crucial for practical device efficiency.
• Current n-type Bi2Te3 materials exhibit lower performance compared to their p-type counterparts.

Purpose of the Study:

• To enhance the thermoelectric properties of n-type Bi2Te3 by alloying with copper selenides.
• To investigate the effect of different copper selenides (CuSe, Cu3Se2, Cu2-xSe) on Bi2Te3 performance.
• To identify optimal compositions for high thermoelectric figure of merit (ZT).

Main Methods:

• Alloying of Bi2Te3 with various copper selenides (CuSe, Cu3Se2, Cu2-xSe) via grinding and sintering.
• Characterization of thermoelectric properties, including Seebeck coefficient and thermal conductivity.
• Evaluation of the dimensionless thermoelectric figure of merit (ZT).

Main Results:

• All fabricated alloys exhibited n-type thermoelectric characteristics.
• The Bi2Te3-CuSe alloy demonstrated superior Seebeck coefficient and power factor.
• The Bi2Te3-CuSe alloy achieved a maximum ZT of 1.64 at 573 K, a top result for n-type Bi2Te3.
• Low thermal conductivity was observed in the alloys.

Conclusions:

• Incorporating copper selenides, particularly CuSe, effectively enhances n-type Bi2Te3 thermoelectric performance.
• Co-doping with Selenium and Copper is identified as the mechanism for improved thermoelectric properties.
• This study presents a viable strategy for developing high-performance n-type thermoelectric materials through alloying.