In this work, we demonstrate the use of high performance nanostructured PbTe-based materials in high conversion efficiency thermoelectric modules.

X-ray structural analysis and high-temperature thermoelectric properties measurements are performed on polycrystalline samples of artificial mineral Cu12−xNixSb4S13 tetrahedrite. Analysis of the atomic displacement parameter manifests low-energy vibration of Cu(2) out of CuS3 triangle plane. The vibration results in low lattice thermal conductivity of less than 0.5 W K−1 m−1. By tuning of the Ni composition x and decrease of electronic thermal conductivity, dimensionless thermoelectric figure of merit for x = 1.5 achieves 0.7 at 665 K, which is a considerably high value among p-type Pb-free sulfides. Because the tetrahedrite is an environmentally friendly material, it constitutes a good thermoelectric material for use in support of a sustainable society.

We demonstrate a notable power factor and an extremely low lattice thermal conductivity in Pb5Bi6Se14 (cannizzarite homolog), Pb3Bi2S6 (lillianite homolog), and PbBi2S4 (galenobismuthite homolog).

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We investigated the high-temperature thermoelectric properties of misfit layered n-type (LaS) 1.20 CrS 2 and p-type (LaS) 1.14 NbS 2 . The samples were prepared by CS 2 sulfurization of 6 or 12 h duration and then consolidated using pressure-assisted sintering to produce randomly and highly oriented samples whose microstructures were tunable. Transmission electron microscopy analysis showed that perfectly layered structures containing some stacking faults had formed. The randomly and highly oriented natural superlattices provided ultralow lattice thermal conductivities (as low as ∼0.9 and ∼0.5 W K −1 m −1 , respectively, at 950 K) perpendicular to the pressing axis. The improved electrical conductivities of the oriented CrS 2 and NbS 2 samples resulted in high power factors of 170 and 410 μW K −2 m −1 , respectively. The highly oriented texture produced the highest thermoelectric figure of merit ZT of 0.14 at 950 K among the (LaS) 1.20 CrS 2 system, whereas the weakly/randomly oriented texture produced the highest ZT of 0.15 at 950 K among the (LaS) 1.14 NbS 2 system. These misfit layered sulfides exhibit phonon glass−electron crystal behavior and provide tremendous opportunities for further enhancing ZT by optimizing the thermoelectric properties.

The average thermoelectric figure of meritZTof n-type PbTe1−xIx–MgTe is successfully enhanced through nano and meso structuring.

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As a means of improving the generating efficiency of the compact SOFC system with a rated AC power of 700 W, we introduced the heat exchanger which is integrated with CoSb3, SiGe thermoelectric materials, namely TEG-HEX, instead of the air preheater in the SOFC system simulation model. We investigated the influences of changes of materials thermoelectric properties and the thermoelectric element size in the TEG-HEX. The results of simulation indicated that using low thermal conductivity materials and high aspect ratio, in other words, long and thin, elements can withdraw larger temperature difference and larger TEG output power under realistic heat transfer conditions. To enhance the SOFC's power generation efficiency, it is important to design the TEG-HEX using low thermal conductivity materials.