Nanostructured Bi(2-x)Cu(x)S3 bulk materials with enhanced thermoelectric performance

Area of Science:

• Materials Science
• Solid State Physics
• Inorganic Chemistry

Background:

• Thermoelectric materials convert heat energy into electrical energy.
• Bismuth sulfide (Bi2S3) is a promising thermoelectric material, but its efficiency needs improvement.
• Doping can be used to tune the thermoelectric properties of materials.

Purpose of the Study:

• To investigate the effect of copper (Cu) doping on the thermoelectric properties of nanostructured bismuth sulfide (Bi2S3).
• To optimize the Cu content for enhanced thermoelectric performance.
• To understand the relationship between microstructure and thermoelectric properties.

Main Methods:

• Fabrication of nanostructured Bi(2-x)Cu(x)S3 polycrystals using mechanical alloying (MA) and spark plasma sintering (SPS).
• Systematic variation of copper content (x = 0 to 0.03).
• Characterization of microstructure and measurement of thermoelectric properties (electrical resistivity, thermal conductivity, ZT value).

Main Results:

• Subtle tailoring of Cu content reduced both electrical resistivity and thermal conductivity simultaneously.
• A low electrical resistivity of 1.34 × 10⁻⁴ Ω m⁻¹ and low thermal conductivity of 0.52 W m⁻¹ K⁻¹ were achieved for Bi1.995Cu0.005S3 at 573 K.
• The lowest thermal conductivity is attributed to nanoscopic Cu-rich regions within the Bi2S3 matrix.
• A peak figure of merit (ZT) of 0.34 at 573 K was obtained for Bi1.995Cu0.005S3, the highest reported for the Bi2S3 system.

Conclusions:

• Copper doping is an effective strategy to enhance the thermoelectric properties of Bi2S3.
• Optimized Cu doping leads to simultaneous reduction in electrical resistivity and thermal conductivity.
• The nanostructured Bi2S3 doped with 0.005 Cu exhibits superior thermoelectric performance, making it a promising material for thermoelectric applications.