Direct ink writing of high-performance Bi2Te3-based thermoelectric materials using quasi-inorganic inks and interface engineering

Abstract

Direct ink writing offers a unique solution for constructing shape-controllable devices. In this way, thermoelectric (TE) devices can optimize power generation from industrial waste heat by the design of structural parameters. Despite recent interest in the so-called all-inorganic inks with inorganic binders to engineer viscoelasticity, organic impurities may also be triggered by high portion of organic solvents, which hamper the electron and phonon transport. Herein, we report water-based inks to reduce organic residuals. The quasi-inorganic inks were synthesized by adding Bi₂Te₃-based particles to water solvent with a few organic binders, whose total organic content is less than that of all-inorganic inks. Moreover, an interface-solder approach is employed to fill the pores among grain particles with the liquefied phase. As a result, there is a tremendous enhancement of ZT values, reaching 0.71 and 0.59 for 3D-printed p- and n-type Bi₂Te₃-based TE materials, respectively. In particular, the flexible method promotes the realization of waste heat harvesting from an alumina pipe by fabricating a TE module integrated with printed half-annular legs. Our work demonstrates not only the effectiveness of quasi-inorganic inks and interface engineering as a means of increasing ZT values, but also the great potential of 3D-printed Bi₂Te₃-based TEGs for waste heat recovery.