中国物理B ›› 2023, Vol. 32 ›› Issue (4): 47202-047202.doi: 10.1088/1674-1056/acb765

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Advancing thermoelectrics by suppressing deep-level defects in Pb-doped AgCrSe2 alloys

Yadong Wang(王亚东)1,†, Fujie Zhang(张富界)1,†, Xuri Rao(饶旭日)1, Haoran Feng(冯皓然)1, Liwei Lin(林黎蔚)1,‡, Ding Ren(任丁)1, Bo Liu(刘波)1, and Ran Ang(昂然)1,2,§   

  1. 1 Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, China;
    2 Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610065, China
  • 收稿日期:2022-11-28 修回日期:2023-01-17 接受日期:2023-01-31 出版日期:2023-03-10 发布日期:2023-03-14
  • 通讯作者: Liwei Lin, Ran Ang E-mail:linliwei@scu.edu.cn;rang@scu.edu.cn
  • 基金资助:
    Project supported by the National Key Research and Development Program of China (Grant Nos. 2018YFA0702100 and 2022YFB3803900), the Joint Funds of the National Natural Science Foundation of China and the Chinese Academy of Sciences (CAS)' Large-Scale Scientific Facility (Grant No. U1932106), and the Sichuan University Innovation Research Program of China (Grant No. 2020SCUNL112).

Advancing thermoelectrics by suppressing deep-level defects in Pb-doped AgCrSe2 alloys

Yadong Wang(王亚东)1,†, Fujie Zhang(张富界)1,†, Xuri Rao(饶旭日)1, Haoran Feng(冯皓然)1, Liwei Lin(林黎蔚)1,‡, Ding Ren(任丁)1, Bo Liu(刘波)1, and Ran Ang(昂然)1,2,§   

  1. 1 Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, China;
    2 Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610065, China
  • Received:2022-11-28 Revised:2023-01-17 Accepted:2023-01-31 Online:2023-03-10 Published:2023-03-14
  • Contact: Liwei Lin, Ran Ang E-mail:linliwei@scu.edu.cn;rang@scu.edu.cn
  • Supported by:
    Project supported by the National Key Research and Development Program of China (Grant Nos. 2018YFA0702100 and 2022YFB3803900), the Joint Funds of the National Natural Science Foundation of China and the Chinese Academy of Sciences (CAS)' Large-Scale Scientific Facility (Grant No. U1932106), and the Sichuan University Innovation Research Program of China (Grant No. 2020SCUNL112).

摘要: AgCrSe$_{2}$-based compounds have attracted much attention as an environmentally friendly thermoelectric material in recent years due to the intriguing liquid-like properties. However, the ultra-low carrier concentration and the high Ag$_{\rm Cr}$ deep-level defects limit the overall thermoelectric performance. Here, we successfully introduced Pb into Ag-deficient Ag$_{0.97}$CrSe$_{2}$ alloys to tune the carrier concentration across a broad temperature range. The Pb$^{2+}$ as an acceptor dopant preferentially occupies Cr sites, boosting the hole carrier concentration to 1.77$\times 10^{19}$ cm$^{-3}$ at room temperature. Furthermore, the Pb strongly inhibits the creation of intrinsic Ag$_{\rm Cr}$ defects, weakens the increased thermal excited ionization with the increasing temperature and slowed the rising trend of the carrier concentration. The designed carrier concentration matches the theoretically predicted optimized one over the entire temperature range, leading to a remarkable enhancement in power factor, especially the maximum power factor of $\sim 500 $μW$\cdot $m$^{-1}\cdot $K$^{-2}$ at 750 K is superior to most previous results. Additionally, the abundant point defects promote phonon scattering, thus reducing the lattice thermal conductivity. As a result, the maximum figure of merit $zT$ ($\sim 0.51$ at 750 K) is achieved in Ag$_{0.97}$Cr$_{0.995}$Pb$_{0.005}$Se$_{2}$. This work confirms the feasibility of manipulating deep-level defects to achieve temperature-dependent optimal carrier concentration and provides a valuable guidance for other thermoelectric materials.

关键词: AgCrSe2, deep-level defects, carrier concentration modulation, thermoelectric properties

Abstract: AgCrSe$_{2}$-based compounds have attracted much attention as an environmentally friendly thermoelectric material in recent years due to the intriguing liquid-like properties. However, the ultra-low carrier concentration and the high Ag$_{\rm Cr}$ deep-level defects limit the overall thermoelectric performance. Here, we successfully introduced Pb into Ag-deficient Ag$_{0.97}$CrSe$_{2}$ alloys to tune the carrier concentration across a broad temperature range. The Pb$^{2+}$ as an acceptor dopant preferentially occupies Cr sites, boosting the hole carrier concentration to 1.77$\times 10^{19}$ cm$^{-3}$ at room temperature. Furthermore, the Pb strongly inhibits the creation of intrinsic Ag$_{\rm Cr}$ defects, weakens the increased thermal excited ionization with the increasing temperature and slowed the rising trend of the carrier concentration. The designed carrier concentration matches the theoretically predicted optimized one over the entire temperature range, leading to a remarkable enhancement in power factor, especially the maximum power factor of $\sim 500 $μW$\cdot $m$^{-1}\cdot $K$^{-2}$ at 750 K is superior to most previous results. Additionally, the abundant point defects promote phonon scattering, thus reducing the lattice thermal conductivity. As a result, the maximum figure of merit $zT$ ($\sim 0.51$ at 750 K) is achieved in Ag$_{0.97}$Cr$_{0.995}$Pb$_{0.005}$Se$_{2}$. This work confirms the feasibility of manipulating deep-level defects to achieve temperature-dependent optimal carrier concentration and provides a valuable guidance for other thermoelectric materials.

Key words: AgCrSe2, deep-level defects, carrier concentration modulation, thermoelectric properties

中图分类号:  (Thermoelectric and thermomagnetic effects)

  • 72.15.Jf
73.50.Lw (Thermoelectric effects) 74.25.fc (Electric and thermal conductivity) 74.25.fg (Thermoelectric effects)