High Thermoelectric Performance Achieved by Manipulating the Band Structure and Lattice Dislocations in n-Type Ge/Pb/Br Codoped Polycrystalline SnSe

Abstract

Polycrystalline SnSe has attracted significant attention due to its facile processing, machinability, and scale-up application. However, n-type polycrystalline SnSe consistently exhibits inferior thermoelectric performance compared to p-type polycrystalline, because SnSe is an intrinsic p-type semiconductor. Here, we promoted the thermoelectric performance of n-type polycrystalline SnSe through manipulating the band structure and dislocations. The band convergence and enhanced density of states in the electronic structure of SnSe promoted by Pb/Ge/Br codoping, lead to significant enhanced Seebeck coefficient. The carrier concentration was simultaneously enhanced through Ge/Pb/Br codoping. The combination of a large Seebeck coefficient and the enhanced electrical conductivity gives rise to a high power factor as high as 7.47 μW cm⁻¹ K⁻² at 873 K. Furthermore, we found that dopants induce strong atomic strain disturbance in the SnSe matrix because of large differences in atom radius with host elements, leading to the formation of high-density dislocations. The presence of dislocations and nanoprecipitates forms strong phonon scattering centers, effectively scattering phonons and suppressing lattice thermal conductivity. As a result, a high peak ZT of 1.6 has been obtained in n-type Sn_1.04Ge_0.02Pb_0.02Se_0.97Br_0.03.

Keywords

density of states / n-type / nanoprecipitates / polycrystalline SnSe / thermoelectric performance

References

[1] G. Tang, Y. Liu, X. Yang, et al., “Interplay Between Metavalent Bonds and Dopant Orbitals Enables the Design of SnTe Thermoelectrics,” Nature Communications 15, no. 1 (2024): 9133.

[2] Y. Pei, A. D. LaLonde, N. A. Heinz, et al., “Stabilizing the Optimal Carrier Concentration for High Thermoelectric Efficiency,” Advanced Materials 23, no. 47 (2011): 5674–5678.

[3] G. J. Snyder and E. S. Toberer, “Complex Thermoelectric Materials,” Nature Materials 7, no. 2 (2008): 105–114.

[4] X. L. Shi, X. Tao, J. Zou, and Z. G. Chen, “High-Performance Thermoelectric SnSe: Aqueous Synthesis, Innovations, and Challenges,” Advanced Science 7, no. 7 (2020): 1902923.

[5] G. Tan, L.-D. Zhao, and M. G. Kanatzidis, “Rationally Designing High-Performance Bulk Thermoelectric Materials,” Chemical Reviews 116, no. 19 (2016): 12123–12149.

[6] L.-D. Zhao, V. P. Dravid, and M. G. Kanatzidis, “The Panoscopic Approach to High Performance Thermoelectrics,” Energy & Environmental Science 7, no. 1 (2014): 251–268.

[7] Z.-G. Chen, X. Shi, L.-D. Zhao, and J. Zou, “High-Performance SnSe Thermoelectric Materials: Progress and Future Challenge,” Progress in Materials Science 97, no. (2018): 283–346.

[8] Y. Xiao and L.-D. Zhao, “Seeking New, Highly Effective Thermoelectrics,” Science 367, no. 6483 (2020): 1196–1197.

[9] K. Zhao, H. Duan, N. Raghavendra, et al., “Solid-State Explosive Reaction for Nanoporous Bulk Thermoelectric Materials,” Advanced Materials 29, no. 42 (2017): 1701148.

[10] S. Singh, S. Lee, H. Kang, J. Lee, and S. Baik, “Thermoelectric Power Waves From Stored Chemical Energy,” Energy Storage Materials 3, no. (2016): 55–65.

[11] Z.-G. Chen, G. Han, L. Yang, L. Cheng, and J. Zou, “Nanostructured Thermoelectric Materials: Current Research and Future Challenge,” Progress in Natural Science: Materials International 22, no. 6 (2012): 535–549.

[12] K. Nielsch, J. Bachmann, J. Kimling, and H. Böttner, “Thermoelectric Nanostructures: From Physical Model Systems Towards Nanograined Composites,” Advanced Energy Materials 1, no. 5 (2011): 713–731.

[13] L. Hu, T. Zhu, X. Liu, and X. Zhao, “Point Defect Engineering of High-Performance Bismuth-Telluride-Based Thermoelectric Materials,” Advanced Functional Materials 24, no. 33 (2014): 5211–5218.

[14] Y. Zheng, T. J. Slade, L. Hu, et al., “Defect Engineering in Thermoelectric Materials: What Have We Learned?,” Chemical Society Reviews 50, no. 16 (2021): 9022–9054.

[15] X. Hu, P. Jood, M. Ohta, et al., “Power Generation From Nanostructured PbTe-Based Thermoelectrics: Comprehensive Development From Materials to Modules,” Energy & Environmental Science 9, no. 2 (2016): 517–529.

[16] M. G. Kanatzidis, “Nanostructured Thermoelectrics: The New Paradigm?,” Chemistry of Materials 22, no. 3 (2010): 648–659.

[17] J. P. Heremans, V. Jovovic, E. S. Toberer, et al., “Enhancement of Thermoelectric Efficiency in PbTe by Distortion of the Electronic Density of States,” Science 321, no. 5888 (2008): 554–557.

[18] A. Banik, T. Ghosh, R. Arora, et al., “Engineering Ferroelectric Instability to Achieve Ultralow Thermal Conductivity and High Thermoelectric Performance in Sn_1−xGe_xTe,” Energy & Environmental Science 12, no. 2 (2019): 589–595.

[19] D. Xiang, Y. Gong, C. Chen, et al., “Orbital Splitting and Interstitial Doping Lead to High Thermoelectric Performance in n-Type PbSe,” Small 21, no. 27 (2025): 2412833.

[20] X. H. Yang, X. Y. Qin, J. Zhang, D. Li, H. X. Xin, and M. Liu, “Enhanced Thermopower and Energy Filtering Effect From Synergetic Scattering at Heterojunction Potentials in the Thermoelectric Composites With Semiconducting Nanoinclusions,” Journal of Alloys and Compounds 558, no. (2013): 203–211.

[21] T. Hong, C. Guo, D. Wang, et al., “Enhanced Thermoelectric Performance in SnTe Due to the Energy Filtering Effect Introduced by Bi₂O₃,” Materials Today Energy 25, no. (2022): 100985.

[22] P. Ying, Q. Jian, Y. Gong, et al., “Matrix Plainification Leads to High Thermoelectric Performance in Plastic Cu₂Se/SnSe Composites,” Nature Communications 16, no. 1 (2025): 3305.

[23] T. Chattopadhyay, J. Pannetier, and H. G. Von Schnering, “Neutron Diffraction Study of the Structural Phase Transition in SnS and SnSe,” Journal of Physics and Chemistry of Solids 47, no. 9 (1986): 879–885.

[24] H. Wiedemeier, H. Georg, and G. Schnering, “Refinement of the Structures of GeS, GeSe, SnS and SnSe,” Zeitschrift für Kristallographie-Crystalline Materials 148, no. 3–4 (1978): 295–304.

[25] Y. Xiao, C. Chang, Y. Pei, et al., “Origin of Low Thermal Conductivity in SnSe,” Physical Review B 94, no. 12 (2016): 125203.

[26] L.-D. Zhao, G. Tan, S. Hao, et al., “Ultrahigh Power Factor and Thermoelectric Performance in Hole-Doped Single-Crystal SnSe,” Science 351, no. 6269 (2016): 141–144.

[27] C. Chang, M. Wu, D. He, et al., “3D Charge and 2D Phonon Transports Leading to High Out-of-Plane ZT in N-Type SnSe Crystals,” Science 360, no. 6390 (2018): 778–783.

[28] L.-D. Zhao, C. Chang, G. Tan, and M. G. Kanatzidis, “SnSe: A Remarkable New Thermoelectric Material,” Energy & Environmental Science 9, no. 10 (2016): 3044–3060.

[29] X.-L. Shi, W.-Y. Chen, X. Tao, J. Zou, and Z.-G. Chen, “Rational Structural Design and Manipulation Advance SnSe Thermoelectrics,” Materials Horizons 7, no. 12 (2020): 3065–3096.

[30] L. Xie, D. He, and J. He, “SnSe, the Rising Star Thermoelectric Material: A New Paradigm in Atomic Blocks, Building Intriguing Physical Properties,” Materials Horizons 8, no. 7 (2021): 1847–1865.

[31] W.-Y. Chen, X.-L. Shi, J. Zou, and Z.-G. Chen, “Thermoelectric Coolers: Progress, Challenges, and Opportunities,” Small Methods 6, no. 2 (2022): 2101235.

[32] W. Dou, Y. Gong, X. Huang, et al., “CdSe Quantum Dots Enable High Thermoelectric Performance in Solution-Processed Polycrystalline SnSe,” Small 20, no. 28 (2024): 2311153.

[33] W. Wei, C. Chang, T. Yang, et al., “Achieving High Thermoelectric Figure of Merit in Polycrystalline SnSe via Introducing Sn Vacancies,” Journal of the American Chemical Society 140, no. 1 (2017): 499–505.

[34] Y. K. Lee, Z. Luo, S. P. Cho, M. G. Kanatzidis, and I. Chung, “Surface Oxide Removal for Polycrystalline SnSe Reveals Near-Single-Crystal Thermoelectric Performance,” Joule 3, no. 3 (2019): 719–731.

[35] C. Zhou, Y. K. Lee, Y. Yu, et al., “Polycrystalline SnSe With a Thermoelectric Figure of Merit Greater Than the Single Crystal,” Nature Materials 20, no. 10 (2021): 1378–1384.

[36] S. Li, Y. Wang, C. Chen, et al., “Heavy Doping by Bromine to Improve the Thermoelectric Properties of n-Type Polycrystalline SnSe,” Advanced Science 5, no. 9 (2018): 1800598.

[37] P.-P. Shang, J. Dong, J. Pei, et al., “Highly Textured N-Type SnSe Polycrystals With Enhanced Thermoelectric Performance,” Research; A Journal of Science and Its Applications 2019, no. (2019): 9253132.

[38] A. Abbas, Z. Xu, M. Nisar, et al., “Achieving Weak Anisotropy in N-Type I-Doped SnSe Polycrystalline Thermoelectric Materials,” Journal of the European Ceramic Society 42, no. 15 (2022): 7027–7035.

[39] X. L. Shi, J. Zou, and Z. G. Chen, “Advanced Thermoelectric Design: From Materials and Structures to Devices,” Chemical Reviews 120, no. 15 (2020): 7399–7515.

[40] Z. H. Ge, Y. Qiu, Y. X. Chen, et al., “Multipoint Defect Synergy Realizing the Excellent Thermoelectric Performance of n-Type Polycrystalline SnSe via Re Doping,” Advanced Functional Materials 29, no. 28 (2019): 1902893.

[41] D. Li, X. Tan, J. Xu, et al., “Enhanced Thermoelectric Performance in n-Type Polycrystalline SnSe by PbBr₂ Doping,” RSC Advances 7, no. 29 (2017): 17906–17912.

[42] J. Cha, C. Zhou, Y. K. Lee, S.-P. Cho, and I. Chung, “High Thermoelectric Performance in N-Type Polycrystalline SnSe via Dual Incorporation of Cl and PbSe and Dense Nanostructures,” ACS Applied Materials & Interfaces 11, no. 24 (2019): 21645–21654.

[43] Q. Zhang, E. K. Chere, J. Sun, et al., “Studies on Thermoelectric Properties of n-Type Polycrystalline SnSe_1-xS_x by Iodine Doping,” Advanced Energy Materials 5, no. 12 (2015): 1500360.

[44] S. Byun, B. Ge, H. Song, et al., “Simultaneously Engineering Electronic and Phonon Band Structures for High-Performance N-Type Polycrystalline SnSe,” Joule 8, no. 5 (2024): 1520–1538.

[45] S. Chandra, U. Bhat, P. Dutta, A. Bhardwaj, R. Datta, and K. Biswas, “Modular Nanostructures Facilitate Low Thermal Conductivity and Ultra-High Thermoelectric Performance in n-Type SnSe,” Advanced Materials 34, no. 40 (2022): 2203725.

[46] Y.-X. Chen, X.-L. Shi, Z.-H. Zheng, et al., “Two-Dimensional WSe₂/SnSe p-n Junctions Secure Ultrahigh Thermoelectric Performance in n-Type Pb/I Co-Doped Polycrystalline SnSe,” Materials Today Physics 16 (2021): 100306.

[47] L. Su, T. Hong, D. Wang, et al., “Realizing High Doping Efficiency and Thermoelectric Performance in N-Type SnSe Polycrystals via Bandgap Engineering and Vacancy Compensation,” Materials Today Physics 20, no. (2021): 100452.

[48] X.-Y. Mao, X.-L. Shi, L.-C. Zhai, et al., “High Thermoelectric and Mechanical Performance in the n-Type Polycrystalline SnSe Incorporated With Multi-Walled Carbon Nanotubes,” Journal of Materials Science & Technology 114, no. (2022): 55–61.

[49] Y. Gong, W. Dou, B. Lu, et al., “Divacancy and Resonance Level Enables High Thermoelectric Performance in N-Type SnSe Polycrystals,” Nature Communications 15, no. 1 (2024): 4231.

[50] A. M. Guloy and J. D. Corbett, “La₁₅Ge₉Z. Interstitial Derivatives With an Ordered Superstructure of the Mn₅Si₃ Structure Type. Property Trends in a Series of Homologous Intermetallic Phases,” Inorganic Chemistry 35, no. 16 (1996): 4669–4675.

[51] Y. Gong, P. Ying, Q. Zhang, et al., “Realizing the High Thermoelectric Performance of Highly Preferentially Oriented SnSe Based Nanorods via Band Alignment,” Energy & Environmental Science 17, no. 4 (2024): 1612–1623.

[52] Y. Gong, S. Zhang, Y. Hou, et al., “Enhanced Density of States Facilitates High Thermoelectric Performance in Solution-Grown Ge- and In-Codoped SnSe Nanoplates,” ACS Nano 17, no. 1 (2022): 801–810.

[53] J. G. Speight, Lange's Handbook of Chemistry, Seventeenth Edition (CD&W Inc., 2005).

[54] G. Tang, W. Wei, J. Zhang, et al., “Realizing High Figure of Merit in Phase-Separated Polycrystalline Sn_1–xPb_xSe,” Journal of the American Chemical Society 138, no. 41 (2016): 13647–13654.

[55] C. Chang, D. Wang, D. He, et al., “Realizing High-Ranged Out-of-Plane ZTs in N-Type SnSe Crystals Through Promoting Continuous Phase Transition,” Advanced Energy Materials 9, no. 28 (2019): 1901334.

[56] S. Chandra, A. Banik, and K. Biswas, “n-Type Ultrathin Few-Layer Nanosheets of Bi-Doped SnSe: Synthesis and Thermoelectric Properties,” ACS Energy Letters 3, no. 5 (2018): 1153–1158.

[57] X. Wang, J. Xu, G. Liu, et al., “Optimization of Thermoelectric Properties in n-Type SnSe Doped With BiCl₃,” Applied Physics Letters 108, no. 8 (2016): 083902.

[58] H. Liu, S. Zhang, Y. Zhang, et al., “Study on the Thermoelectric Properties of n-Type Polycrystalline SnSe by CeCl₃ Doping,” ACS Applied Energy Materials 5, no. 12 (2022): 15093–15101.

[59] B. Su, Y. Jiang, H.-L. Zhuang, et al., “Ultralow Lattice Thermal Conductivity and High ZT of n-Type Polycrystalline SnSe Realized by Liquid Phase Sintering,” Research; A Journal of Science and Its Applications 8, no. (2025): 0962.

[60] V. Taneja, N. Goyal, S. Das, et al., “Nanostructured Ferecrystal Intergrowths With TaSe₂ Unveiled High Thermoelectric Performance in n-Type SnSe,” Journal of the American Chemical Society 146, no. 35 (2024): 24716–24723.

[61] M. Nisar, A. Abbas, J. Zhang, et al., “Anion/Cation Co-Doping to Improve the Thermoelectric Performance of Sn-Enriched n-Type SnSe Polycrystals With Suppressed Lattice Thermal Conductivity,” Small 20, no. 32 (2024): 2312003.

[62] G. J. Snyder, A. H. Snyder, M. Wood, R. Gurunathan, B. H. Snyder, and C. Niu, “Weighted Mobility,” Advanced Materials 32, no. 25 (2020): 2001537.

[63] G. S. Nolas and H. J. Goldsmid, “Thermal Conductivity of Semiconductors,” Thermal Conductivity Physics of Solids & Liquids 35, no. (2004): 105–121.

[64] Y. Xiao, D. Wang, Y. Zhang, et al., “Band Sharpening and Band Alignment Enable High Quality Factor to Enhance Thermoelectric Performance in n-Type PbS,” Journal of the American Chemical Society 142, no. 8 (2020): 4051–4060.

[65] X.-L. Shi, K. Zheng, W.-D. Liu, et al., “Realizing High Thermoelectric Performance in n-Type Highly Distorted Sb-Doped SnSe Microplates via Tuning High Electron Concentration and Inducing Intensive Crystal Defects,” Advanced Energy Materials 8, no. 21 (2018): 1800775.

[66] C. Chang, Q. Tan, Y. Pei, et al., “Raising Thermoelectric Performance of n-Type SnSe via Br Doping and Pb Alloying,” RSC Advances 6, no. 100 (2016): 98216–98220.

[67] L. D. Zhao, S. H. Lo, Y. Zhang, et al., “Ultralow Thermal Conductivity and High Thermoelectric Figure of Merit in SnSe Crystals,” Nature 508, no. 7496 (2014): 373–377.

Rights & permissions

2026 The Author(s). Carbon Energy published by Wenzhou University and John Wiley & Sons Australia, Ltd.