High thermoelectric performance by resonant dopant indium in nanostructured SnTe

• Published in: Proceedings of the National Academy of Sciences - PNAS 2013-08, Vol.110 (33), p.13261-13266
• Main Authors: Zhang, Qian, Liao, Bolin, Lan, Yucheng, Lukas, Kevin, Liu, Weishu, Esfarjani, Keivan, Opeil, Cyril, Broido, David, Chen, Gang, Ren, Zhifeng
• Format: Article
• Language: English
• Subjects: Alloys; Atoms; Ball milling; Charge carriers; Doping; Electric Conductivity; Electric properties; Electrical resistivity; Heat conductivity; Hot pressing; Iridium - chemistry; Materials Testing; Melting; Microscopy, Electron, Scanning; Models, Chemical; Nanostructures - chemistry; Physical Sciences; Seebeck effect; Simulation; solar (photovoltaic), solar (thermal), solid state lighting, phonons, thermal conductivity, thermoelectric, defects, mechanical behavior, charge transport, spin dynamics, materials and chemistry by design, optics, synthesis (novel materials), synthesis (self-assembly), synthesis (scalable processing); Tellurium - chemistry; Temperature; Thermal conductivity; Thermoelectric power generation; Tin Compounds - chemistry; X-Ray Diffraction
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1305735110

From an environmental perspective, lead-free SnTe would be preferable for solid-state waste heat recovery if its thermoelectric figure-of-merit could be brought close to that of the lead-containing chalcogenides. In this work, we studied the thermoelectric properties of nanostructured SnTe with different dopants, and found indium-doped SnTe showed extraordinarily large Seebeck coefficients that cannot be explained properly by the conventional two-valence band model. We attributed this enhancement of Seebeck coefficients to resonant levels created by the indium impurities inside the valence band, supported by the first-principles simulations. This, together with the lower thermal conductivity resulting from the decreased grain size by ball milling and hot pressing, improved both the peak and average nondimensional figure-of-merit (ZT) significantly. A peak ZT of ∼1.1 was obtained in 0.25 atom % In-doped SnTe at about 873 K.