Improvement of the thermoelectric power factor through anisotropic growth of nanostructured PbSe thin films

Abstract

Nanostructured PbSe films with different (200)/(111) grain size ratios were prepared by anisotropic growth on glass substrates. Although face centered cubic bulk PbSe is an isotropic material, the thermopower (S), electrical conductivity (σ) and hole mobility of the prepared nanostructured PbSe films show an obvious dependence on the anisotropic parameter, (200)/(111) grain size ratio. The thermoelectric power factor (S²σ) of the nanostructured films is improved with higher (200)/(111) grain size ratio. Temperature-dependent transport measurements suggest that grain boundary scattering dominates in these nanostructured films. Subtle changes in the microstructure are discussed in the light of the effect on grain boundary activation energy (barrier height). A 20% enhancement of the room temperature thermopower (S) at given carrier concentrations is demonstrated for the CBD-grown nanostructured PbSe films compared to single crystal bulk PbSe.