Defect engineering boosted ultrahigh thermoelectric power conversion efficiency in polycrystalline SnSe

Karthikeyan, V. , Oo, S. L., Surjadi, J. U., Li, X., Theja, V. C.S., Kannan, V., Lau, S. C., Lu, Y., Lam, K.-H. and Roy, V. A.L. (2021) Defect engineering boosted ultrahigh thermoelectric power conversion efficiency in polycrystalline SnSe. ACS Applied Materials and Interfaces, 13(49), pp. 58701-58711. (doi: 10.1021/acsami.1c18194) (PMID:34851624)

Abstract

Two-dimensional (2D)-layered atomic arrangement with ultralow lattice thermal conductivity and ultrahigh figure of merit in single-crystalline SnSe drew significant attention among all thermoelectric materials. However, the processing of polycrystalline SnSe with equivalent thermoelectric performance as single-crystal SnSe will have great technological significance. Herein, we demonstrate a high zT of 2.4 at 800 K through the optimization of intrinsic defects in polycrystalline SnSe via controlled alpha irradiation. Through a detailed theoretical calculation of defect formation energies and lattice dynamic phonon dispersion studies, we demonstrate that the presence of intrinsically charged Sn vacancies can enhance the power factor and distort the lattice thermal conductivity by phonon-defect scattering. Supporting our theoretical calculations, the experimental enhancement in the electrical conductivity leads to a massive power factor of 0.9 mW/mK2 and an ultralow lattice thermal conductivity of 0.22 W/mK through the vacancy-phonon scattering effect on polycrystalline SnSe. The strategy of intrinsic defect engineering of polycrystalline thermoelectric materials can increase the practical implementation of low-cost and high-performance thermoelectric generators.

• Item Type: Articles
• Additional Information: We acknowledge grants from the Research Grants Council of Hong Kong Special Administrative Region Project no: T42-103/16N and Environmental and Conservation Fund (ECF) project number 44/2014.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Vellaisamy, Professor Roy and Lau, Mr Siu Chuen and Karthikeyan, Dr Vaithinathan and Lam, Dr Koko
• Authors: Karthikeyan, V., Oo, S. L., Surjadi, J. U., Li, X., Theja, V. C.S., Kannan, V., Lau, S. C., Lu, Y., Lam, K.-H., and Roy, V. A.L.
• College/School: College of Science and Engineering > School of Engineering; College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering; College of Science and Engineering > School of Engineering > Systems Power and Energy
• Journal Name: ACS Applied Materials and Interfaces
• Publisher: American Chemical Society
• ISSN: 1944-8244
• ISSN (Online): 1944-8252
• Published Online: 01 December 2021
• Copyright Holders: Copyright © 2021 American Chemical Society
• First Published: First published in ACS Applied Materials and Interfaces 13(49): 58701-58711
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher