Abstract: Thermoelectric materials can directly convert heat into electricity and thus have broad prospects for commercial application as clean energy materials. However, the low energy conversion efficiency still limits their large-scale applications. It is still a fundamental issue of thermoelectric materials to improve their thermoelectric properties. Optimizing the electrical transport properties and lowering the lattice thermal conductivity are the main ways to improve the thermoelectric performance. In contrast to the strongly correlated electrical conductivity and Seebeck coefficient, it is relatively independent to modulate the lattice thermal conductivity. Hence, it is a research hotspot to realize low lattice thermal conductivity in the field of thermoelectricity. This review summarized the methods lowering the lattice thermal conductivity by means of crystal defects, such as point defects, line defects, face defects, and interstitial atoms, and presented the related phonon scattering mechanisms. In addition, the exploration of thermoelectric materials with low dimensions, low acoustic velocities, or low specific heats, as well as the underlying mechanism for their intrinsic low lattice thermal conductivities are introduced in this review.

Key words: thermoelectric material, lattice thermal conductivity, crystal defect, phonon scattering