A Facile Etching-Exfoliation Method for High-Performance Flexible Ag₂Se Based Thermoelectric Films

Area of Science:

• Materials Science
• Nanotechnology
• Energy Conversion

Background:

• Silver selenide (Ag₂Se) films show potential for flexible thermoelectric devices (F-TEDs) due to good electrical properties.
• Current Ag₂Se fabrication methods are complex and costly, limiting commercial use.
• Existing flexible thermoelectric devices often rely on expensive materials like bismuth telluride (Bi₂Te₃).

Purpose of the Study:

• To develop a facile, low-cost, and environmentally robust method for fabricating highly oriented Ag₂Se films.
• To optimize the thermoelectric performance of Ag₂Se films through post-treatment.
• To demonstrate the potential of these films for high-performance flexible thermoelectric devices.

Main Methods:

• Fabrication of Ag₂Se films using a simple and cost-effective approach.
• Post-treatment processes to tune crystalline structure and chemical composition.
• Characterization of thermoelectric properties, including power factor and mechanical flexibility.

Main Results:

• Achieved highly oriented Ag₂Se films with an optimal balance of carrier concentration and mobility.
• Obtained a competitive average power factor of approximately 27 µW cm⁻¹ K⁻² (298–393 K).
• Demonstrated an in-plane device with a normalized power density of 3.4 µW cm⁻² K⁻² at a 10 K temperature difference, surpassing most reported F-TEDs.

Conclusions:

• The developed fabrication strategy is simple, effective, and scalable for producing high-performance Ag₂Se films.
• This method provides a viable pathway for the commercialization of advanced flexible thermoelectric technologies.
• The Ag₂Se films exhibit excellent thermoelectric performance and mechanical flexibility, comparable to expensive alternatives.