Interfacial Stability in Bi₂Te₃ Thermoelectric Joints.

Area of Science:

• Materials Science
• Thermoelectric Materials
• Surface Engineering

Background:

• Bismuth telluride (Bi2Te3)-based materials exhibit high thermoelectric figure-of-merit (zT) at low temperatures.
• Reliable, long-term thermoelectric devices require stable joints resistant to interfacial reactions.
• Traditional solders can form brittle intermetallic compounds with Bi2Te3, compromising device integrity.

Purpose of the Study:

• To investigate the use of electroless cobalt-phosphorus (Co-P) as an interfacial coating.
• To prevent severe interfacial reactions between solder joints and Bi2Te3 in thermoelectric modules.
• To enhance the mechanical strength and long-term stability of Bi2Te3 thermoelectric modules.

Main Methods:

• Application of electroless Co-P coating on Bi2Te3 interfaces.
• Analysis of interfacial reactions and intermetallic compound formation (e.g., SnTe).
• Mechanical testing of joints to evaluate strength and fracture mode.
• Long-term aging tests to assess thermoelectric property degradation.

Main Results:

• Electroless Co-P successfully inhibited the formation of thick, brittle SnTe intermetallic layers.
• Joint strength was improved, and the fracture mode shifted towards ductile behavior.
• No significant degradation of thermoelectric properties was observed after Co-P deposition and long-term aging.

Conclusions:

• Electroless Co-P acts as an effective diffusion barrier at the solder-Bi2Te3 interface.
• Co-P coatings enhance interfacial stability and mechanical reliability of Bi2Te3 thermoelectric modules.
• This approach offers a promising solution for durable thermoelectric device fabrication.