# Fileset [R_SI_JF_Marked.pdf](https://mdr.nims.go.jp/filesets/149ffe34-3573-477c-908a-03d06cf7feec/download) ## Creator Feng Jiang, Zhengtao Wanga, Wen Zhonga, Yifan Zhoua, Zhengyang Zhou, Longzhi Wu, Jiang Chen, Yao Xua, Xiaodong Wang, Feng Cao, Qian Zhang, Jun Mao ## Rights [Creative Commons BY Attribution 4.0 International](https://creativecommons.org/licenses/by/4.0/) ## Other metadata [Towards the practical realization of high-performance Ag2Se-based thermoelectric coolers](https://mdr.nims.go.jp/datasets/604a2dab-8f1c-4db9-aa43-42508ebee93d) ## Fulltext 1 Supplementary information Towards the practical realization of high-performance Ag2Se-based thermoelectric coolers Feng Jianga†, Zhengtao Wanga†, Wen Zhonga, Yifan Zhoua, Zhengyang Zhoua, Longzhi Wua, Jiang Chena, Yao Xua, Xiaodong Wanga,d, Feng Caoc, Qian Zhanga, b, e*, and Jun Maoa, b, e* a School of Materials Science and Engineering, and Institute of Materials Genome & Big Data, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, P.R. China. b State Key Laboratory of Precision Welding & Joining of Materials and Structures, Harbin Institute of Technology, Harbin 150001, P.R. China. c School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, P.R. China. d Institute of Special Environments Physical Sciences, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, P.R. China. e School of Materials Science and Engineering, Shenzhen Key Laboratory of New Materials Technology, Shenzhen 518055, P.R. China. †These authors contributed equally to this work. *Corresponding authors, email: zhangqf@hit.edu.cn; maojun@hit.edu.cn; mailto:maojun@hit.edu.cn 2 Contents 1. Setting parameters for the finite element simulation of Ag2Se-based cooler 2. Sample density of Ag2Se materials with different sizes 3. Specific heat capacity of the Ag2Se sample 4. Energy dispersive spectroscopy mapping of the Ag2Se sample 5. Hall carrier concentration and mobility of the Ag2Se sample 6. The lattice thermal conductivity of the Ag2Se sample 7. Thermoelectric properties of five Ag2Se samples 8. Contact resistivity of the soldered Ag/Ag2Se joint 9. Energy dispersive spectroscopy and linear scanning of the Ag/Ag2Se interface 10. Linear energy dispersive spectroscopy scanning of the Ag/SnBi interface 11. Comparison of thermoelectric cooling performance for Ag2Se, Bi2Te3, and Mg3(Sb, Bi)2-based devices at the hot-side temperature of 300 K 12. The simulated cooling performance of the 7 pairs Ag2Se/(Bi, Sb)2Te3 thermoelectric cooler 13. Thermoelectric cooling performance of the Ag2Se-based cooler at the hot-side temperature of 325 K 14. Coefficient of performance as a function of the electrical current of the Ag2Se-based thermoelectric cooler 15. Interfacial properties of the Ag2Se-based thermoelectric cooler after cycling 3 1. Setting parameters for the finite element simulation of Ag2Se-based cooler Table S1. Finite element simulation setting parameters. Parameter Value Cross-sectional area of the Ag2Se legs 1.8 × 1.8 mm2 Height of the Ag2Se legs 2.5 mm Cross-sectional area of the (Bi, Sb)2Te3 legs 2.0 × 2.0 mm2 Height of the (Bi, Sb)2Te3 legs 2.5 mm Thickness of copper electrode 0.065 mm Thickness of Al2O3 substrate 0.38 mm The area of the Al2O3 substrate of the cold side 13.0 × 13.0 mm2 The area of the Al2O3 substrate of the hot side 13.0 × 16.0 mm2 Thermal conductivity of the substrate 20 W m-1 K-1 Thermal conductivity of the thermal grease 4.8 W m-1 K-1 Heat load 0.0-2.5 W Hot-side temperature 300 K Contact resistivity of Ag2Se legs 5.0 μ cm2 Contact resistivity of (Bi, Sb)2Te3 legs 5.0 μ cm2 4 2. Sample density of Ag2Se materials with different sizes Table S2. Sample density of Ag2Se materials with different sizes Sample diameter (mm) Measured density (g cm-3) Relative density (%) 10.0 8.05 98.17 12.7 8.07 98.41 20.0 8.03 97.93 25.4 8.06 98.29 5 3. Specific heat capacity of the Ag2Se sample Figure S1. Specific heat capacity of the Ag2Se sample. 6 4. Energy dispersive spectroscopy mapping of the Ag2Se sample Figure S2. (a) Surface morphology, and (b-d) energy dispersive spectroscopy mapping of the Ag2Se sample. 7 5. Hall carrier concentration and mobility of the Ag2Se sample Figure S3. Hall carrier concentration and mobility of the Ag2Se sample. (a) Carrier concentration. (b) Carrier mobility. 8 6. The lattice thermal conductivity of the Ag2Se sample Figure S4. The lattice thermal conductivity of the Ag2Se sample. 9 7. Thermoelectric properties of the Ag2Se samples Figure S5. Thermoelectric properties of the Ag2Se samples. Temperature-dependent (a) electrical resistivity, (b) Seebeck coefficient, (c) thermal conductivity, and (d) zT values. 10 8. Contact resistivity of the soldered Ag/Ag2Se joint Figure S6. Contact resistivity of the soldered Ag/Ag2Se joint. 11 9. Energy dispersive spectroscopy and linear scanning of the Ag/Ag2Se interface Figure S7. (a) The Ag/Ag2Se interface and (b-d) corresponding EDS mapping for the interface. (e) Linear EDS scanning across the Ag/Ag2Se interface. 12 10. Linear energy dispersive spectroscopy scanning of the Ag/SnBi interface Figure S8. Linear EDS scanning across the Ag/SnBi solder interface. 13 11. Comparison of thermoelectric cooling performance for Ag2Se, Bi2Te3, and Mg3(Sb, Bi)2-based devices at the hot-side temperature of 300 K Table S3. Comparison of thermoelectric cooling performance for Ag2Se, Bi2Te3, and Mg3(Sb, Bi)2-based devices at the hot-side temperature of 300 K n-type leg p-type leg Cooling temperature difference (K) Cooling power density (W cm-2) Reference Ag2Se Bi2Te3 alloys 55.4 1.5 This work Ag2Se Bi2Te3 alloys 57.7 1.5 Jiang et al.[1] Ag2Se Bi2Te3 alloys 56.0 1.4 Liu et al.[2] Ag2Se MgAgSb 52.0 0.8 Zhao et al.[3] Bi2Te3 Bi2Te3 alloys 70.1 1.6 Sun et al.[4] Bi2Te3 Bi2Te3 alloys 73.9 2.2 Zhao et al.[5] Mg3(Sb, Bi)2 Bi2Te3 alloys 69.0 1.3 Ma et al.[6] Mg3(Sb, Bi)2 MgAgSb 52.0 0.8 Xie et al.[7] Mg3(Sb, Bi)2 MgAgSb 61.0 - Zhang et al.[8] 14 12. The simulated cooling performance of the 7 pairs Ag2Se/(Bi, Sb)2Te3 thermoelectric cooler Figure S9. The simulated cooling performance of the 7 pairs Ag2Se/(Bi, Sb)2Te3 thermoelectric cooler. Cooling power as a function of (a) the temperature difference at different electrical currents and (b) electrical current at different temperature differences. (c) The coefficient of performance as a function of the temperature difference at different electrical currents. (d) The maximum cooling temperature difference at different electrical currents. 15 13. Thermoelectric cooling performance of the Ag2Se-based cooler at the hot-side temperature of 325 K Figure S10. Cooling power as a function of (a) cooling temperature difference at different electrical currents, and (b) electrical current at different cooling temperature differences. Figure S11. The relationship between cooling temperature difference and electrical current at the hot-side temperature of 300 and 325 K. 16 14. Coefficient of performance as a function of the electrical current of the Ag2Se-based thermoelectric cooler Figure S12. Coefficient of performance as a function of the electrical current of the Ag2Se-based thermoelectric cooler at the hot-side temperature of 300 K. 17 15. Interfacial properties of the Ag2Se-based thermoelectric cooler after cycling Figure S13. (a) Interfacial morphology, and (b-h) energy dispersive spectroscopy mapping of the interface of the Ag2Se-based thermoelectric cooler. 18 References: [1] Jiang F, Lin CH, Cheng JX, et al. Prefer-oriented Ag2Se crystal for high-performance thermoelectric cooling. Adv Funct Mater. (2024);35(6):2415000. doi: 10.1002/adfm.202415000 [2] Liu M, Zhang XY, Zhang SX, et al. Ag2Se as a tougher alternative to n-type Bi2Te3 thermoelectrics. Nat Commun. (2024);15(1):6580. doi: 10.1038/s41467-024-50898-6 [3] Zhao SY, Shi XL, Zhou Q, et al. Substitution energy-guided screening of diffusion barrier materials for Ag2Se-based thermoelectric coolers. Nano Res. (2025);18(10):94907903. doi: 10.26599/NR.2025.94907903 [4] Sun YX, Wu H, Dong XY, et al. High performance BiSbTe alloy for superior thermoelectric cooling. Adv Funct Mater. (2023);33(28):2301423. doi: 10.1002/adfm.202301423 [5] Zhang Y, Xu G, Nozariasbmarz A, et al. Thermoelectric cooling performance enhancement in BiSeTe alloy by microstructure modulation via hot extrusion. Small Sci. (2023);4(2):2300245. doi: 10.1002/smsc.202300245 [6] Ma XJ, Lin CH, Yang HY, et al. Elevating thermoelectric performance in the sub-ambient temperature range for electronic refrigeration. Innovation. (2025);6(5):100864. doi: 10.1016/j.xinn.2025.100864 [7] Xie LJ, Yang JW, Liu ZY, et al. Highly efficient thermoelectric cooling performance of ultrafine-grained and nanoporous materials. Mater Today. (2023);65(4):5-13. doi: 10.1016/j.mattod.2023.03.021 [8] Zhang XF, Zhu HT, Dong XJ, et al. High-performance MgAgSb/Mg3(Sb,Bi)2-based thermoelectrics with η = 12% at T ≤ 583K. Joule. (2024);8(12):3324-3335. doi: 10.1016/j.joule.2024.08.013