Weak electron-phonon coupling contributing to high thermoelectric performance in n-type PbSe

Area of Science:

• Materials Science
• Solid-State Physics
• Thermoelectrics

Background:

• Lead selenide (PbSe) is a promising thermoelectric material.
• Previous measurements may have overestimated its thermal conductivity.
• Thermoelectric figure of merit (zT) exceeding 1 is achievable in PbSe.

Purpose of the Study:

• Investigate the thermoelectric properties of PbSe.
• Understand the factors contributing to high zT in both p-type and n-type PbSe.
• Highlight the role of band structure engineering in optimizing thermoelectric materials.

Main Methods:

• Analysis of thermal conductivity measurements.
• Evaluation of valence and conduction band structures.
• Comparison of valley degeneracy and electron-phonon coupling in PbSe and PbTe.

Main Results:

• PbSe demonstrates a zT > 1 at high temperatures for both p-type and n-type materials.
• N-type PbSe achieves high zT despite lower valley degeneracy (4) compared to p-type (≥12).
• Weaker electron-phonon coupling in the conduction band enhances electron mobility in n-type PbSe.

Conclusions:

• The deformation potential coefficient is crucial for band structure engineering in thermoelectrics.
• PbSe's performance rivals PbTe, emphasizing the importance of considering band structure details.
• Optimizing thermoelectric materials requires a comprehensive understanding of charge carrier properties and band structure.