Structure and Applications of Lead Telluride(PbTe)-Based Material
Thermoelectric material is a kind of functional material that uses the movement of carriers inside a solid to realize the direct mutual conversion of heat and electric energy. It provides a safe, reliable, pollution-free, noise-free, all-solid-state power generation and cooling method and has a wide range of application prospects. Among them, the characteristics of low valence band degeneracy, low effective quality of conduction band, strong phonon non-harmonicity, simple crystal structure and adjustable microstructure have made Lead Telluride(PbTe)-based materials the focus of research in the thermoelectric field.
In a recent review[1], authors discussed the strategy of improving the thermoelectric performance of PbTe by introducing foreign atom doping to increase the carrier concentration and introducing nanostructures to reduce the thermal conductivity to optimize the TE figure of merit. The challenges of Lead Telluride(PbTe)-based TE materials and their perspectives are summarized.
Structure
Figure 1 Crystal structure of PbTe[1].
Lead telluride has a highly symmetric face-centered cubic crystal structure, so it has excellent electrical conductivity. Its electronic energy band structure shows that the maximum value of the valence band is 7.00389 ev, the minimum value of the conduction band is 7.80069 ev and the Fermi level is located at 7.49630 ev. Because the maximum value of the valence band and the minimum value of the conduction band are located in k-space at the same position, this means that the material is a direct bandgap semiconductor, and it is also a narrow bandgap semiconductor, because its ideal forbidden band width is 0.32 ev. This band structure is conducive to electron transmission and gives lead telluride a highly complex Seebeck coefficient. In addition, due to the strong non-harmonics caused by the local eccentricity of Pb, lead telluride has a lower lattice thermal conductivity (2.2 W/mk). Therefore, PbTe is a promising medium temperature power generation material and it is one of the most advanced traditional TE materials that have been used in the medium temperature range for the past 50 years.
Application
Lead telluride is a semiconductor TE material with excellent performance in the mid-temperature region. It is widely used in deep space exploration and waste heat recovery systems, such as radioisotope thermoelectric generators and waste heat recovery in automotive thermoelectric generators. In addition, researchers have also found it can be used to manufacture flexible TE conversion equipment for wearable applications and many other fields. These devices have many advantages, such as excellent reliability, no noise and no pollution.
Reference
[1] Performance Optimization for PbTe-Based Thermoelectric Materials. doi: 10.3389/fenrg.2021.754532
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