Effect of material anisotropy on the transverse thermoelectricity of layered composites

Abstract

Thermoelectric devices can achieve conversion between thermal and electrical energies. In contrast to longitudinal thermoelectrics, transverse thermoelectrics can decouple the directions of heat flux and electric current, which in turn offers more flexibility in device design. While many studies have focused on composite structures constructed using materials with isotropic properties, this work investigated the effect of material anisotropy on the transverse thermoelectricity of layered composite materials. A simplified analytical model was derived based on the equivalent circuit principle to correlate the effective thermoelectric properties of the composite structure and the properties of the constituting phases. The effects of the geometrical design parameters of the composite structure and the material anisotropy were investigated. The transverse thermoelectric figure of merit increases with the increase in material anisotropy. The analytical model was then compared with the finite element analysis model with respect to the cooling capacity of transverse thermoelectric devices. The good agreement achieved between the two approaches indicated the effectiveness of the simplified analytical model in predicting the transverse thermoelectric performance of layered structures with anisotropic material properties.