Promoting Room-Temperature n-type Bismuth Telluride Thermoelectrics via High-Potential Barrier Heterointerfaces.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Polycrystalline n-type bismuth telluride (Bi2Te3) typically shows peak thermoelectric figure of merit (ZT) above 400 K, limiting room-temperature (RT) applications.
• Conventional methods for regulating point defects have limited effectiveness for improving RT thermoelectric performance.

Purpose of the Study:

• To develop innovative strategies for enhancing RT thermoelectric performance in bismuth telluride-based materials.
• To investigate the effect of high-potential barrier heterointerfaces on thermoelectric properties.

Main Methods:

• Fabrication of Bi2Te2.7Se0.3 (BTS) with La2O3 nanoparticles (NPs) to create high-potential barrier heterointerfaces.
• Analysis of carrier scattering and localization mechanisms at grain boundaries due to O-Bi ionic bonding and O-Te hybridization.
• Investigation of phonon scattering by nano-oxide inclusions to improve thermal performance.

Main Results:

• Achieved an RT figure of merit (ZT) of 1.2, with a maximum ZT of 1.3 at 325 K.
• Significantly increased the RT Seebeck coefficient from 148.67 μV K⁻¹ to 222.84 μV K⁻¹ at 300 K.
• Demonstrated a maximum output voltage (Vmax) of 239.73 mV and power (Pmax) of 10.50 mW at ΔT = 10 K.

Conclusions:

• High-energy barrier interface engineering using La2O3 NPs is a promising strategy for enhancing thermoelectric materials in lower temperature regions.
• The engineered interfaces effectively scatter carriers and phonons, leading to improved thermoelectric performance.
• This approach offers a pathway to overcome limitations of conventional methods for RT thermoelectric applications.