Strategies for optimizing the thermoelectricity of PbTe alloys

The thermoelectric materials have been considered as a potential candidate for the new power generation technology based on their reversible heat and electricity conversion. Lead telluride (PbTe) is regarded as an excellent mid-temperature thermoelectric material due to its suitable intrinsic thermoelectric properties. So tremendous efforts have been done to improve the thermoelectric performance of PbTe, and figures of merit, zT > 2.0, have been reported. Main strategies for optimizing the thermoelectric performance have been focused as the main line of this review. The band engineering and phonon scattering engineering as two main effective strategies are systemically summarized here. The band engineering, like band convergence, resonant levels, and band flatting have been addressed in improving the power factor. Additionally, phonon scattering engineerings, such as atomic-scale, nano-scale, meso-scale, and multi-scale phonon scatterings have been applied to reduce the thermal conductivity. Besides, some successful synergistic effects based on band engineerings and phonon scatterings are illustrated as a simultaneous way to optimize both the power factor and thermal conductivity. Summarizing the above three main parts, we point out that the synergistic effects should be effectively exploited, and these may further boost the thermoelectric performance of PbTe alloys and can be extended to other thermoelectric materials.