Thermoelectric energy conversion is of great potential in low-grade heat recovery, and the key to enhance the efficiency of a thermoelectric device is to develop thermoelectric materials with high figure of merit (ZT). Recently, nanostructures such as superlattices and nanocomposites have been developed, in which the thermal conductivity is suppressed due to interfacial phonon scattering whereas the electrical transport is nearly unaffected, which leads to enhanced ZT. However, the fabrication techniques of such nanostructures, such as molecular beam epitaxy, chemical vapor deposition, melt growth, and ball milling, are usually tedious and/or energy intensive. Here, we present a facile solution phase synthesis of dumbbell-like PbTe-Ag2Te heterostructures, which can be directly used as building blocks to fabricate nanocomposites by hot press. The thermoelectric properties of these nanocomposites have been studied and compared with the bulk counterparts. The Seebeck coefficient of our nanocomposites increases from 125 mV/K to 236 mV/K when temperature rises from 300 K to 400 K, whereas the Seebeck coefficient of the bulk counterparts is in the range of -90 mV/K to -105 mV/K. The high Seebeck coefficient could be explained by energy filtering effect due to the discontinuity of the band structure of PbTe and Ag2Te. Our nanocomposites also exhibit a thermal conductivity as low as ~0.3 W/(m�K). However, the low relative density might have impaired the electrical conduction and limited the ZT, which could be improved by optimizing the fabrication process. Moreover, our synthesis approach can be readily modified to produce a serial of telluride cation heterostructures such as PbTe-Bi2Te3, Bi2Te3-Ag2Te, etc., which enables us to design a family of nanocomposites with more favorable band alignments and thus higher ZT is possible.

Solution phase synthesized dumbbell-like PbTe-Ag<sub>2</sub>Te heterostructures with enhanced Seebeck coefficient for thermoelectric applications

246th National Meeting (2013)

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Solution phase synthesized dumbbell-like PbTe-Ag2Te heterostructures with enhanced Seebeck coefficient for thermoelectric applications

Solution phase synthesized dumbbell-like PbTe-Ag₂Te heterostructures with enhanced Seebeck coefficient for thermoelectric applications