High thermoelectric performance of p-type Bi0.5Sb1.5Te3 films on flexible substrate

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 by 0.5 wt % Te) film reaches the value of ~30.4 μW cm−1K−2, 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. •A technology for fabrication of p-Bi0.5Sb1.5Te3 films has been developed.•The transport properties have been studied over the entire temperature range.•The density of states effective mass and carrier scattering mechanism were estimated.•The highest reported values of the ZT and PF for a flexible film was obtained.