A prototype thermoelectric module based on p-type colusite together with n-type nanostructured PbTe for power generation

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Thermoelectric power generation from the prototype π-shaped module composed of p-type colusite (Cu26Cr2Ge6S32) and n-type nanostructured PbTe (Pb0.98Ga0.02Te-3% GeTe) was demonstrated in this study. The thermoelectric figure of merit zT of Cu26Cr2Ge6S32 and Pb0.98Ga0.02Te-3% GeTe was ∼0.8 and ∼1.2 at 665 K, respectively. In PbTe, transmission electron microscopic images and energy-dispersive x-ray elemental maps reveal the insertion of nanoscale precipitates induced by the GeTe alloying. Contact layers based on Au and Co-Fe were used for p- and n-type thermoelectric legs, respectively, which allow the low electrical specific contact resistances of ≤10 × 10−10 Ω m2 at room temperature. Maximum thermoelectric conversion efficiency ηmax of ∼5.5% was obtained for the Cu26Cr2Ge6S32 and Pb0.98Ga0.02Te-3% GeTe-based two-pair module when the hot-side Th and cold-side Tc temperatures were maintained at 673 and 283 K, respectively. A three-dimensional finite-element simulation predicts the ηmax of ∼7.1% for the module at Th and Tc of 673 and 283 K, respectively.