All-Scale Hierarchical Structuring, Optimized Carrier Concentration, and Band Manipulation Lead to Ultra-High...

Area of Science:

• Materials Science
• Solid State Physics
• Thermoelectrics

Background:

• Manganese telluride (MnTe) shows promise for medium-temperature thermoelectric devices due to its eco-friendly and abundant nature.
• Existing MnTe materials require optimization to improve their thermoelectric performance (ZT).

Purpose of the Study:

• To enhance the thermoelectric properties of MnTe for medium-temperature applications.
• To achieve high figure of merit (ZT) through band structure engineering and microstructural modification.

Main Methods:

• Incorporation of lead (Pb) and silver (Ag) to achieve valence band convergence and optimize carrier concentration.
• Alloying with Pb to introduce PbTe nanorods into the MnTe matrix, creating hierarchical microstructures.
• Characterization of microstructural evolution and thermoelectric property measurements.

Main Results:

• Achieved multiple valence band convergence and enhanced carrier concentration via Pb and Ag codoping, boosting the power factor.
• Engineered all-scale hierarchical architectures, including PbTe nanorods, point-defect scattering, dislocations, and stacking faults.
• Reduced lattice thermal conductivity to a record low of 0.376 W m⁻¹ K⁻¹.
• Attained an ultra-high thermoelectric figure of merit (ZT) of 1.5.

Conclusions:

• The combination of valence band convergence, optimized carrier concentration, and all-scale hierarchical structuring significantly enhances MnTe's thermoelectric performance.
• The achieved ZT of 1.5 surpasses most previously reported MnTe-based thermoelectric materials, highlighting its potential for practical applications.