Researchers optimized thermoelectric properties of lead telluride material systems

In a recent study, a team from the Institute of Solid State Physics, Hefei Institutes of Physical Science of Chinese Academy of Sciences achieved higher thermoelectric performance of n-type PbTe by adjusting band structure and enhanced phonons scattering.

The results were published in Nanoscale.

"We successfully increased the material power factor and decreased thermal conductivity," said Prf. QIN Xiaoying, who led the team.

PbTe is one of the most promising medium-temperature thermoelectric materials. However, n-type PbTe materials have a lower thermoelectric figure of merit compared to p-type PbTe materials. The main reason for this is the large energy shift between the light (L) and heavy (∑) bands in the PbTe conduction band, which makes it difficult to achieve energy band simplification in n-type PbTe, resulting in a lower power factor. Therefore, a more in-depth and systematic study is needed to effectively and significantly improve the thermoelectric performance of n-type PbTe.

Now, the group constructed the Pb_0.97Sb_0.03Te + y wt. % Cu₁₂Sb₄S₁₃(y=0,1.25,1.5,1.75) composite system. This was achieved by doping the PbTe matrix with Sb elements and introducing a small amount of Cu₁₂Sb₄S₁₃ nanoparticles. Thy also used the in-situ reaction to construct a semi-coherent nanophase.

The study focused on optimizing the carrier concentration in n-type PbTe using host element doping, while combining energy band engineering/energy filtering effects to improve its electrical properties.

On the basis of this, in situ reactions were used to construct semi-coherent nanophases and introduce multi-scale defects to scatter phonons. This allowed them to improve the power factor, reduce thermal conductivity, and thus increase ZT.

They found that the composite sample Pb_0.97Sb_0.03Te + 1.5 wt. % Cu₁₂Sb₄S₁₃ had excellent thermoelectric properties with a ZT of 1.58 (773 K), an improvement of about 75% compared to Pb_0.97Sb_0.03Te.
This work proved the incorporation of Cu₁₂Sb₄S₁₃ nanoparticles was an effective way to improve the thermoelectric properties of Pb_0.97Sb_0.03Te, which was of great importance for the study of the regulation of the thermoelectric properties of n-type Pb telluride.