Screen Printable Flexible BiTe–SbTe-Based Composite Thermoelectric Materials on Textiles for Wearable Applications

This paper presents the optimization of a bismuth tellurium (Bi
_1.8
Te
_3.2
)-antimony tellurium (Sb
₂
Te
₃
)-based thermoelectric generator (TEG) fabricated by screen-printing technology on flexible polyimide (Kapton) and textile substrates. New formulations of screen printable thermoelectric pastes are presented with optimized composition, curing conditions, and printing parameters. The modifications of the thermoelectric materials enable them to be successfully deposited on flexible textile substrates. The optimized values of resistivity of the BiTe and SbTe thick films on Kapton were 9.97 × 10
^-3
and 3.57 × 10
^-3
Ω · cm, respectively. The measured figure of merit at room temperature was 0.135 and 0.095 for BiTe and SbTe thick films on Kapton, respectively. The dimension of each printed thermoleg was 20 mm×2 mm×70.5 μm. For the TEG on Kapton, the printed assembly comprising eight thermocouples was coiled up and generated a voltage of 26.6 mV and a maximum power output of 455.4 nW at a temperature difference of 20 °C. For a printed TEG on textile, the maximum power output reached 2 μW from the same temperature difference.