A Review of Strategies for Developing Promising Thermoelectric Materials by Controlling Thermal Conduction

Thermoelectric (TE) materials can play an important role in developing next-generation advanced energy conversion technologies. The underlying principle for thermoelectric power generation is the utilization of Seebeck effect in which temperature differences drive the electrical current. The performance of a TE material is evaluated by a dimensionless figure of merit, ZT, expressed as ZT = S-2 sigma T/kappa, where S, sigma, T, and kappa denote the Seebeck coefficient, electrical conductivity, temperature and thermal conductivity, respectively. As seen from this expression, controlling thermal conduction in TE materials is a key toward obtaining high TE response. The thermal conductivity (kappa) consists of two components, namely lattice thermal conductivity (kappa(L)) and electronic thermal conductivity (kappa(e)), of which the latter is linearly proportional to the electrical conductivity of the material following the Wiedemann-Franz law. Since reducing the value of kappa(e) worsens the value of sigma, which is not desired, kappa(L) has to be reduced to get an overall lower thermal conductivity. Numerous studies focusing on reducing the thermal conductivity of TE materials have been performed recently. In this paper, a comprehensive review of various strategies used for developing efficient thermoelectric systems by controlling thermal conduction in the TE materials has been provided.