Polycrystalline SnSe with a thermoelectric figure of merit greater than the single crystal

Thermoelectric materials generate electric energy from waste heat, with conversion efficiency governed by the dimensionless figure of merit, ZT. Single-crystal tin selenide (SnSe) was discovered to exhibit a high ZT of roughly 2.2–2.6 at 913 K, but more practical and deployable polycrystal versions...

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Published in:Nature materials Vol. 20; no. 10; pp. 1378 - 1384
Main Authors: Zhou, Chongjian, Lee, Yong Kyu, Yu, Yuan, Byun, Sejin, Luo, Zhong-Zhen, Lee, Hyungseok, Ge, Bangzhi, Lee, Yea-Lee, Chen, Xinqi, Lee, Ji Yeong, Cojocaru-Mirédin, Oana, Chang, Hyunju, Im, Jino, Cho, Sung-Pyo, Wuttig, Matthias, Dravid, Vinayak P., Kanatzidis, Mercouri G., Chung, In
Format: Journal Article
Language:English
Published: London Nature Publishing Group UK 01.10.2021
Nature Publishing Group
Subjects:
639/301/299/2736
639/638/263/915
Biomaterials
Chemistry and Materials Science
Condensed Matter Physics
Crystal lattices
Crystals
Electrical resistivity
Figure of merit
Heat conductivity
Heat transfer
Lead free
Materials Science
Nanotechnology
Optical and Electronic Materials
Oxides
Polycrystals
Reagents
Single crystals
Thermal conductivity
Thermoelectric materials
Tin
Tin oxides
Tin selenide
Waste to energy
ISSN:1476-1122, 1476-4660, 1476-4660
Online Access:Get full text
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Summary:Thermoelectric materials generate electric energy from waste heat, with conversion efficiency governed by the dimensionless figure of merit, ZT. Single-crystal tin selenide (SnSe) was discovered to exhibit a high ZT of roughly 2.2–2.6 at 913 K, but more practical and deployable polycrystal versions of the same compound suffer from much poorer overall ZT, thereby thwarting prospects for cost-effective lead-free thermoelectrics. The poor polycrystal bulk performance is attributed to traces of tin oxides covering the surface of SnSe powders, which increases thermal conductivity, reduces electrical conductivity and thereby reduces ZT. Here, we report that hole-doped SnSe polycrystalline samples with reagents carefully purified and tin oxides removed exhibit an ZT of roughly 3.1 at 783 K. Its lattice thermal conductivity is ultralow at roughly 0.07 W m –1  K –1 at 783 K, lower than the single crystals. The path to ultrahigh thermoelectric performance in polycrystalline samples is the proper removal of the deleterious thermally conductive oxides from the surface of SnSe grains. These results could open an era of high-performance practical thermoelectrics from this high-performance material. SnSe has a very high thermoelectric figure of merit ZT, but uncommonly polycrystalline samples have higher lattice thermal conductivity than single crystals. Here, by controlling Sn reagent purity and removing SnO x impurities, a lower thermal conductivity is achieved, enabling ZT of 3.1 at 783 K.
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USDOE
ISSN:1476-1122
1476-4660
1476-4660
DOI:10.1038/s41563-021-01064-6