Strained endotaxial nanostructures with high thermoelectric figure of merit

• Published in: Nature chemistry 2011-02, Vol.3 (2), p.160-166
• Main Authors: Biswas, Kanishka, He, Jiaqing, Zhang, Qichun, Wang, Guoyu, Uher, Ctirad, Dravid, Vinayak P., Kanatzidis, Mercouri G.
• Format: Article
• Language: English
• Subjects: 30 DIRECT ENERGY CONVERSION; Analytical Chemistry; Biochemistry; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Conductivity; Electric Conductivity; Electric power; Electrons; Heat conductivity; Heat flow; Inorganic Chemistry; Lead - chemistry; Manufactured Materials; MATERIALS SCIENCE; Mobility; Nanocrystals; Nanoparticles - chemistry; NANOSCIENCE AND NANOTECHNOLOGY; Nanostructures - chemistry; Organic Chemistry; Physical Chemistry; Sodium - chemistry; solar (thermal), phonons, thermal conductivity, thermoelectric, mechanical behavior, charge transport, materials and chemistry by design, synthesis (novel materials), synthesis (self-assembly), synthesis (scalable processing); Strontium - chemistry; Tellurium - chemistry; Thermal Conductivity; Transmission electron microscopy; Waste heat
• ISSN: 1755-4330; 1755-4349
• DOI: 10.1038/nchem.955

Thermoelectric materials can directly generate electrical power from waste heat but the challenge is in designing efficient, stable and inexpensive systems. Nanostructuring in bulk materials dramatically reduces the thermal conductivity but simultaneously increases the charge carrier scattering, which has a detrimental effect on the carrier mobility. We have experimentally achieved concurrent phonon blocking and charge transmitting via the endotaxial placement of nanocrystals in a thermoelectric material host. Endotaxially arranged SrTe nanocrystals at concentrations as low as 2% were incorporated in a PbTe matrix doped with Na 2 Te. This effectively inhibits the heat flow in the system but does not affect the hole mobility, allowing a large power factor to be achieved. The crystallographic alignment of SrTe and PbTe lattices decouples phonon and electron transport and this allows the system to reach a thermoelectric figure of merit of 1.7 at ~800 K. Developing efficient thermoelectric materials that can directly generate electrical power from heat is a challenge, but now a nanostructured system of SrTe nanocrystals in a Na 2 Te-doped PbTe matrix achieves high efficiency by blocking heat flow without impeding carrier flow.