Li Chengjun, Wu Hong, Zhang Bin, Zhu Huaxing, Fan Yijing, Lu Xu, Sun Xiaonan, Zhang Xiao, Wang Guoyu, Zhou Xiaoyuan
Chongqing Key Laboratory of Soft Condensed Matter Physics and Smart Materials, College of Physics , Chongqing University , Chongqing 400044 , P. R. China.
Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Science , Chongqing 400714 , P. R. China.
ACS Appl Mater Interfaces. 2020 Feb 19;12(7):8446-8455. doi: 10.1021/acsami.9b20610. Epub 2020 Feb 5.
This work systematically investigated the thermoelectric properties of p-type Na and M (M = K, Li, Ag) codoped polycrystalline SnSe. It is found that the electrical properties of polycrystalline SnSe can be improved significantly for (Na, Ag) codoped samples, contributed by the enhanced carrier concentration. Specifically, a carrier concentration of 6.23 × 10 cm was obtained in SnNaAgSe sample at 335 K, an increase of 18% compared with that of the Na single-doped sample (5.22 × 10 cm). The power factor reached ∼0.73 mW m K for the SnNaAgSe sample at 785 K, enhanced by ∼26% compared with Na single-doped one. In addition, Sn-rich and Ag-rich particles/areas observed in the matrix of SnNaAgSe contribute to the reduction of lattice thermal conductivity from 0.61 W m K for SnAgSe to 0.47 W m K at 785 K. The combination of simultaneously enhanced power factor and depressed thermal conductivity leads to a maximum ≈ 1.2 at 785 K and a high average ≈ 0.74 at 335-785 K for SnNaAgSe, and generating a high theoretical conversion efficiency of ∼11%. These illuminating discoveries could provide routes to enhance the thermoelectric performance in p-type polycrystalline SnSe.
本工作系统研究了p型Na与M（M = K、Li、Ag）共掺杂多晶SnSe的热电性能。研究发现，对于（Na，Ag）共掺杂样品，多晶SnSe的电学性能可得到显著改善，这得益于载流子浓度的提高。具体而言，在335 K时，SnNaAgSe样品的载流子浓度达到6.23×10 cm，与Na单掺杂样品（5.22×10 cm）相比增加了18%。在785 K时，SnNaAgSe样品的功率因子达到约0.73 mW m K，比Na单掺杂样品提高了约26%。此外，在SnNaAgSe基体中观察到的富Sn和富Ag颗粒/区域有助于将晶格热导率从SnAgSe的0.61 W m K降低到785 K时的0.47 W m K。功率因子的同时提高和热导率的降低相结合，使得SnNaAgSe在785 K时的最大ZT≈1.2，在335 - 785 K时的平均ZT≈0.74较高，并产生了约11%的高理论转换效率。这些有启发性的发现可为提高p型多晶SnSe的热电性能提供途径。
