Highly efficient bismuth telluride–based thermoelectric microconverters

The flash evaporation method was used to fabricate high-performance p- and n-type Bi₂Te₃-based thermoelectric (TE) thin films. Optimized technological conditions of film preparation, as well as subsequent annealing, give the possibility to achieve a significant improvement in the TE properties of the designed TE films, which are state-of-the-art compared with bulk materials. Furthermore, a brand-new sandwich-layered design of the flexible film thermoelectric microconverter (FTEM) is offered here through the use of perforation cuts between p- and n-legs and a flexible polyimide substrate. Such a unique design makes it possible to avoid a rise in electrical resistance due to an increase in the number of elements in the microconverter. The dimensionless effective figure of merit ZT ≈0.6 (including losses due to parasite heat flux along with the substrate, radiation, and conversion) and TE efficiency η_max ≈3.4% were achieved for the FTEM prototype at the temperature difference ΔT of 100 K (T_c = 300 K). Therefore, the use of flash evaporation technology offers the possibility to produce large-scale film TE devices with high efficiency. Moreover, the applicability of the developed FTEM is demonstrated for a thermal detector with a high output voltage, which is used to determine a weak heat flux up to ~10⁻⁷ W.