Thermoelectric properties of p-type Bi-=SUB=-0.5-=/SUB=-Sb-=SUB=-1.5-=/SUB=-Te-=SUB=-3-=/SUB=- films on flexible substrate

Abstract

Bi2Te3-based compounds are excellent candidates for the low-temperature thermoelectric application. In the present work, a technology for fabrication of p-Bi0.5Sb1.5Te3 films with high thermoelectric efficiency on a thin flexible polyimide substrate has been developed. The preparation of films was carried out by a flash evaporation method. A systematic study of the transport properties (Hall coefficient, Seebeck coefficient, electrical conductivity, transverse Nernst coefficient) over the entire temperature range of 80-400 K for p-Bi0.5Sb1.5Te3 films has been performed. The power factor (PF) for the Bi0.5Sb1.5Te3 (doped with 0.5 wt% Te) film reached the value of ~ 30 μW/cm · K2, which is among the highest values of the PF reported in the literature to date for a film on a flexible polyimide (amorphous) substrate. The measured thermal diffusivity along the film allowed us to accurately estimate the figure of merit Z for p-Bi0.5Sb1.5Te3 films considering the anisotropic effect of Bi2Te3-based materials. A significant enhancement of Z up to ~ 3.0·10-3 K has been obtained for these films, which is state-of-the-art even compared to bulk materials. This research can provide insight into the fabrication of p-type branch of the film thermoelectric modules (FTEM), which could be a candidate for application in micro-scale thermoelectric generators. Keywords: p-Bi0.5Sb1.5Te3 film, thin flexible substrate, thermoelectric properties.