Doping‐Induced Viscoelasticity in PbTe Thermoelectric Inks for 3D Printing of Power‐Generating Tubes

Abstract

Thermoelectric (TE) technologies offer promising means to enhance fossil energy efficiencies by generating electricity from waste heat from industrial or automobile exhaust gases. For these applications, thermoelectric modules should be designed from the perspective of system integration for efficient heat transfer, system simplification, and low processing cost. However, typical thermoelectric modules manufactured by traditional processes do not fulfil such requirements, especially for exhaust pipes. Hence, a 3D‐printing method for PbTe thermoelectric materials is reported to design high‐performance power‐generating TE tubes. The electronic doping‐induced surface charges in PbTe particles are shown to significantly improve the viscoelasticities of inks without additives, thereby enabling precise shape and dimension engineering of 3D bulk PbTe with figures of merit of 1.4 for p‐type and 1.2 for n‐type materials. The performance of the power‐generating TE tube fabricated from 3D‐printed PbTe tubes is demonstrated experimentally and computationally as an effective strategy to design system‐adaptive high‐performance thermoelectric generators.

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

“…23 Moreover, the colloidal stabilities can also be assessed using stress sweep curves. 20 In the linear viscoelastic region, the storage modulus is approximately constant. When the shear stress is beyond the critical value, there is a sudden decrease in the modulus which indicates the deformation of colloidal structures.…”

“…Direct ink writing (DIW), a type of extrusion 3D printing technology, has recently emerged as a convenient and low-cost method of constructing custom-built shapes. [14][15][16] To date, many TE materials and devices including conducting polymers, 17,18 Bi 2 Te 3 -based, 13,19 PbTe-based, 20 and Cu 2 Se-based 21 compounds can be printed. Nevertheless, the ZT values of 3D-printed materials are lower than those of bulk counterparts.…”

“…[24][25][26] Furthermore, the pores created from the pressureless sintering process also hinder the transportation of electrons. 13,20,21,27 Therefore, organic residuals and porosities are the longstanding challenges in ZT enhancement, which so far has not been achieved in DIWed TE materials.…”

Additive Manufacturing of Thermoelectrics: Emerging Trends and Outlook

“…Lee and colleagues found that undoped PbTe has an almost neutral surface charge as shown in Figure 6a. 116 Through the introduction of doping-induced surface charges on the TE particles, they managed to obtain viscoelastic inks suitable for DIW. Sodium dopants produce negatively charged PbTe particles, while doping with antimony produces positively charged PbTe particles.…”

Generalised optical printing of photocurable metal chalcogenides

“…This is in stark contrast to the direct ink writing (DIW) techniques, which is an extrusion-based 3D printing method to create meso- and micro-scales architectures. By developing the viscoelastic inks containing inorganic particles, the DIW has been extensively utilized for fabricating various types of functional inorganic materials 18 – 20 . For example, the DLP-printed thermoelectric BiSbTe materials was reported to exhibit the ZT value of 0.12, which is one order of magnitude lower than that of inorganic bulk reference materials or that of even DIW-printed BiSbTe because the printed objects contain organic residues 21 .…”