Thermoelectric Properties of Strained β-Cu₂Se

Area of Science:

• Materials Science
• Condensed Matter Physics
• Thermoelectrics

Background:

• The high-temperature phase of copper selenide (β-Cu₂Se) exhibits excellent thermoelectric properties.
• Existing experimental synthesis yields p-type β-Cu₂Se, necessitating n-type materials for complete thermoelectric devices.
• The unique ion-liquid behavior of copper ions in β-Cu₂Se influences its structural and electronic properties.

Purpose of the Study:

• To investigate the thermoelectric performance of strained β-Cu₂Se using computational methods.
• To explore the potential for achieving n-type β-Cu₂Se with high thermoelectric efficiency.
• To propose experimental strategies for optimizing β-Cu₂Se for thermoelectric applications.

Main Methods:

• First-principles calculations were employed to study electronic structures and properties.
• Molecular dynamics simulations were utilized to analyze lattice thermal conductivity.
• The effects of compressive and tensile strain on thermoelectric performance were systematically evaluated.

Main Results:

• Both n-type and p-type β-Cu₂Se demonstrate superior thermoelectric figure of merit (zT) values.
• Compressive strain enhances the power factor, while tensile strain reduces lattice thermal conductivity.
• Predicted maximum zT values reach 1.65 for n-type and 1.71 for p-type β-Cu₂Se at 800 K.

Conclusions:

• Strain engineering is a viable approach to optimize the thermoelectric performance of β-Cu₂Se.
• Halogen doping presents a practical experimental strategy to tune the carrier type and lattice structure.
• This research provides critical insights for the development of high-performance Cu₂Se-based thermoelectric devices.