Enhanced Thermoelectric Performance of Cu₂Se via Nanostructure and Compositional Gradient

Area of Science:

• Materials Science
• Solid-State Physics
• Nanotechnology

Background:

• Co-alloying solid solutions are a proven method for enhancing thermoelectric materials.
• Copper selenide (Cu2Se) is a promising thermoelectric material, but its performance can be further optimized.
• Controlling nanostructure and compositional gradients is key to tailoring material properties.

Purpose of the Study:

• To investigate the effect of co-alloying with Mn, Fe, and Ni on the thermoelectric properties of Cu2Se.
• To explore the role of nanostructure and compositional gradients in optimizing thermoelectric performance.
• To prepare dense Cu2-(MnFeNi)xSe samples using a scalable fabrication process.

Main Methods:

• Synthesis of dense Cu2-(MnFeNi)xSe (x = 0-0.09) via melting-ball milling-hot pressing.
• Microstructural characterization to analyze nanostructure and compositional gradients.
• Measurement of thermal conductivity and thermoelectric figure of merit (zT) as a function of temperature.

Main Results:

• Reduced thermal conductivity from 1.54 Wm-1K-1 to 0.64 Wm-1K-1 at 300 K due to phonon scattering from atomic disorder and nano defects.
• Achieved a maximum thermoelectric figure of merit (zT) of 1.08 at 750 K for the Cu1.91(MnFeNi)0.09Se sample.
• Demonstrated a 27% improvement in zT compared to the pristine Cu2Se sample.

Conclusions:

• Co-alloying Cu2Se with Mn, Fe, and Ni effectively reduces thermal conductivity by introducing phonon scattering mechanisms.
• The optimized nanostructure and compositional gradients contribute to enhanced thermoelectric performance.
• This study presents a viable strategy for developing high-performance thermoelectric materials based on Cu2Se.