Ultralow Thermal Conductivity in Halogen-Doped PbSnS2 with Optimized Thermoelectric Properties

Zixuan Chen; Hongwei Ming; Zhi Li; Steven N Girard; Collin D Morris; Weiping Guo; Ming Wu; Yan Yu; Christopher Wolverton; Zhong-Zhen Luo; Zhigang Zou; Mercouri G Kanatzidis

doi:10.1002/anie.202501667

Ultralow Thermal Conductivity in Halogen-Doped PbSnS₂ with Optimized Thermoelectric Properties

Angew Chem Int Ed Engl. 2025 May;64(21):e202501667. doi: 10.1002/anie.202501667. Epub 2025 Mar 20.

Authors

Zixuan Chen^#¹, Hongwei Ming^#², Zhi Li^#³, Steven N Girard⁴, Collin D Morris⁵, Weiping Guo¹, Ming Wu¹, Yan Yu^{1

2}, Christopher Wolverton³, Zhong-Zhen Luo^{1

2

6}, Zhigang Zou^{1

2

7

8}, Mercouri G Kanatzidis⁵

Affiliations

¹ Key Laboratory of Advanced Materials Technologies, International (HongKong Macao and Taiwan) Joint Laboratory on Advanced Materials Technologies, College of Materials Science and Engineering, Fuzhou University, Fuzhou, Fujian, 350108, China.
² Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian, 350108, China.
³ Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois, 60208, USA.
⁴ Department of Chemistry, University of Wisconsin-Whitewater, 800 W. Main Street, Whitewater, Wisconsin, 53190, USA.
⁵ Department of Chemistry, Northwestern University, Evanston, Illinois, 60208, USA.
⁶ State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou, 350116, China.
⁷ Eco-materials and Renewable Energy Research Center, College of Engineering and Applied Sciences, Nanjing University, Nanjing, 210093, China.
⁸ National Laboratory of Solid State Microstructures, Nanjing University, Nanjing, 210093, China.

^# Contributed equally.

PMID: 40052670
DOI: 10.1002/anie.202501667

Abstract

Here, we investigate PbSnS₂, a wide band gap (1.13 eV) compound, as a promising thermoelectric material for power generation. Single crystal X-ray diffraction analysis reveals its 2D-layered structure, akin to the GeSe structure type, with Pb and Sn atoms sharing the same crystallographic site. The polycrystalline PbSnS₂ exhibits an intrinsically ultralow lattice thermal conductivity (κ_lat) of 0.37 W m^-1 K^-1 at 573 K. However, the low carrier concentration (n) leads to suboptimal electrical conductivity (σ), capping the ZT value at 0.1. Accordingly, the halogen elements (Cl, Br, and I) are employed as the n-type dopants to improve the n. The DFT results indicate a significant weakening of Pb/Sn─S bonds upon halogen-doping, contributing to the observed reduction in κ_lat. Our analysis indicates the activation of multiconduction band transport driven by halogen substitution. The PbSnS_1.96Br_0.04 has a high power factor of five times that of intrinsic PbSnS₂. Halogen-doping weakens the Pb/Sn─S bonds and enhances the phonon scattering, leading to an ultralow κ_lat of 0.29 W m^-1 K^-1 at 873 K for PbSnS_1.96Br_0.04. Consequently, PbSnS_1.96Br_0.04 achieved a maximum ZT value of 0.82 at 873 K.

Keywords: Halogen‐doping; PbSnS2; Single crystal; Thermoelectricity; Ultralow thermal conductivity.

Abstract

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