Process Development of Flexible Thermoelectric Modules Based on Printing and Sintering Technology

Thermoelectric generators (TEGs) that can convert environmental thermal energy into electricity are regarded as a potential solution to support the intermittent energy consumption of wearable devices and remote wireless sensors. Flexible TEGs (<i>f</i>-TEGs) based on printing technology have gained growing interests due to their design flexibility, ease of fabrication, and low cost. In this report, we have demonstrated a planar <i>f</i>-TEG with 8 pairs of Bi-Te based thermoelements prepared by dispenser printing and pressured sintering processes. The <i>f</i>-TEG can deliver a power of 68 µW under a temperature difference of 33 K. A modular assembly of 7 planar <i>f</i>-TEGs is sufficient to power a light-emitting diode and charge a 1.2 V NiMH battery. In addition to planar TEG configuration, a <i>f</i>-TEG with vertical thermoelement arrangement is also under development. The major issue associated with the vertical TEG fabrication is the poor electrical and mechanical contacts between Cu electrodes and thermoelements caused by gross interfacial reaction during the pressured sintering process. We have introduced a Pd/Ni composite barrier metallization in between the Cu electrode and the printed thermoelements by a selective chemical deposition method to resolve the contact issue. The influence of pressured sintering conditions on the microstructure and contact property of the Cu/thermoelements is investigated.