Conduction Band Convergence and Modular Nanostructures: Driving High Thermoelectric Performance in n-Type PbSe.

Area of Science:

• Materials Science
• Solid State Physics
• Thermoelectrics

Background:

• N-type lead chalcogenides are rare for high thermoelectric performance due to electronic band structure limitations.
• Modulating electronic structure and suppressing phonon transport are key strategies for improving thermoelectric materials.

Purpose of the Study:

• To enhance the thermoelectric figure of merit (zT) in n-type PbSe.
• To investigate the effects of MoCl5 doping on the electronic structure and thermal conductivity of PbSe.
• To explore the formation of nano-heterostructures for improved thermoelectric properties.

Main Methods:

• Doping n-type PbSe with MoCl5.
• Analyzing the electronic band structure and density of states.
• Investigating phonon transport and lattice thermal conductivity.
• Characterizing nano-heterostructure formation.

Main Results:

• Achieved a thermoelectric figure of merit (zT) of ~1.8 at 873 K in n-type PbSe doped with MoCl5.
• MoCl5 doping induced conduction band convergence and increased density of states, boosting the Seebeck coefficient.
• Obtained an excellent power factor (σS²) of ~21 µW cm⁻¹ K⁻² at 873 K.
• Exceeding solid solution limit formed PbSe-MoSe2 nano-heterostructures, significantly reducing lattice thermal conductivity (κlat) to 0.20 W m⁻¹ K⁻¹ at ~725 K.

Conclusions:

• MoCl5 doping effectively modulates the electronic structure of PbSe, enhancing its thermoelectric performance.
• The formation of PbSe-MoSe2 nano-heterostructures is crucial for suppressing lattice thermal conductivity.
• This work presents a promising strategy for developing high-performance n-type thermoelectric materials.