Nan et al- Nanocrystal-based thermoelectric SnTe-NaSbSe2 alloys with strengthened band convergence and reduced thermal conductivity – Chemical Engineering Journal 492 (2024): 152367

Bingfei Nan^a b, Cheng Chang^c, Zhihao Li^d, Nilotpal Kapuria^e f, Xu Han^g, Mengyao Li^h, Hongchao Wang^d, Kevin M. Ryan^e, Jordi Arbiol^g i, Andreu Cabot<sup>a i

a</sup>Catalonia Institute for Energy Research – IREC, Sant Adrià de Besòs, Barcelona 08930, Spain
^bUniversitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain
^cSchool of Materials Science and Engineering, Beihang University, Beijing 100191, China
^dSchool of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
^eDepartment of Chemical Sciences and Bernal Institute, University of Limerick, V94T9PX Limerick, Ireland
^fIndiana University, Department of Chemistry, 800 E. Kirkwood, CHEM Bloomington, IN 47405-7102, United States
^gCatalan Institute of Nanoscience and Nanotechnology (ICN2), Campus UAB, Bellaterra, Barcelona 08193, Catalonia, Spain
^hKey Laboratory of Material Physics of Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
ⁱICREA, Pg. Lluís Companys 23, 08010 Barcelona, Catalonia, Spain

Link to paper: https://www.sciencedirect.com/science/article/pii/S1385894724038543

Abstract

Ternary I-V-VI₂ colloidal NaSbSe₂ nanocrystals are herein used to improve the performance of lead-free SnTe thermoelectric materials. We showcase a versatile bottom-up engineering approach to produce nanocrystal-based SnTe-NaSbSe₂ alloys from the rapid hot press of colloidal nanocrystal building blocks. The incorporation of NaSbSe₂ nanocrystals significantly enhances the Seebeck coefficient of SnTe. The band convergence and simultaneous increasing band gap of SnTe-NaSbSe₂ alloys are certified by the first-principles density functional theory calculations. Besides, defect engineering generated by the incorporation of NaSbSe₂ nanocrystals such as Sn vacancies, substitution point defects, dense dislocations, and strains generated by the NaSbSe₂ nanoparticles incorporation result in a dramatic reduction of the lattice thermal conductivity below the amorphous limit of pure SnTe, down to 0.38 W m⁻¹ K⁻¹. As a consequence, power factors enhance up to 1.77 mW m⁻¹ K⁻², which is ∼193 % higher than that of the pristine SnTe, and thermoelectric figures of merit up to 1.15 at 823 K for (SnTe)_0.85(NaSbSe₂)_0.15 are achieved.