中国物理B ›› 2022, Vol. 31 ›› Issue (2): 28507-028507.doi: 10.1088/1674-1056/ac3504

所属专题： SPECIAL TOPIC — Organic and hybrid thermoelectrics

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Donor-acceptor conjugated copolymer with high thermoelectric performance: A case study of the oxidation process within chemical doping

Liangjun Chen(陈凉君)†, Wei Wang(王维)†, Shengqiang Xiao(肖生强)‡, and Xinfeng Tang(唐新峰)§   

  1. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
  • 收稿日期:2021-09-22 修回日期:2021-10-25 接受日期:2021-11-01 出版日期:2022-01-13 发布日期:2022-01-13
  • 通讯作者: Shengqiang Xiao, Xinfeng Tang E-mail:shengqiang@whut.edu.cn;tangxf@whut.edu.cn
  • 基金资助:
    This work was supported by the National Key Research and Development Program of China (Grant No. Q2019YFE0107200).

Donor-acceptor conjugated copolymer with high thermoelectric performance: A case study of the oxidation process within chemical doping

Liangjun Chen(陈凉君)†, Wei Wang(王维)†, Shengqiang Xiao(肖生强)‡, and Xinfeng Tang(唐新峰)§   

  1. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
  • Received:2021-09-22 Revised:2021-10-25 Accepted:2021-11-01 Online:2022-01-13 Published:2022-01-13
  • Contact: Shengqiang Xiao, Xinfeng Tang E-mail:shengqiang@whut.edu.cn;tangxf@whut.edu.cn
  • Supported by:
    This work was supported by the National Key Research and Development Program of China (Grant No. Q2019YFE0107200).

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摘要： The doping process and thermoelectric properties of donor-acceptor (D-A) type copolymers are investigated with the representative poly([2,6'-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b] dithiophene]3-fluoro-2-[(2-ethylhexyl)-carbonyl]thieno[3,4-b]thiophenediyl)) (PTB7-Th). The PTB7-Th is doped by FeCl3 and only polarons are induced in its doped films. The results reveal that the electron-rich donor units within PTB7-Th lose electrons preferentially at the initial stage of the oxidation and then the acceptor units begin to be oxidized at a high doping concentration. The energy levels of polarons and the Fermi level of the doped PTB7-Th remain almost unchange with different doping levels. However, the morphology of the PTB7-Th films could be deteriorated as the doping levels are improved, which is one of the main reasons for the decrease of electrical conductivity at the later stage of doping. The best electrical conductivity and power factor are obtained to be 42.3 S·cm-1 and 33.9 μW·mK-2, respectively, in the doped PTB7-Th film at room temperature. The power factor is further improved to 38.3 μW·mK-2 at 75℃. This work may provide meaningful experience for development of D-A type thermoelectric copolymers and may further improve the doping efficiency.

关键词: donor-acceptor copolymer, doping, oxidization process, thermoelectric performance

Abstract: The doping process and thermoelectric properties of donor-acceptor (D-A) type copolymers are investigated with the representative poly([2,6'-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b] dithiophene]3-fluoro-2-[(2-ethylhexyl)-carbonyl]thieno[3,4-b]thiophenediyl)) (PTB7-Th). The PTB7-Th is doped by FeCl3 and only polarons are induced in its doped films. The results reveal that the electron-rich donor units within PTB7-Th lose electrons preferentially at the initial stage of the oxidation and then the acceptor units begin to be oxidized at a high doping concentration. The energy levels of polarons and the Fermi level of the doped PTB7-Th remain almost unchange with different doping levels. However, the morphology of the PTB7-Th films could be deteriorated as the doping levels are improved, which is one of the main reasons for the decrease of electrical conductivity at the later stage of doping. The best electrical conductivity and power factor are obtained to be 42.3 S·cm-1 and 33.9 μW·mK-2, respectively, in the doped PTB7-Th film at room temperature. The power factor is further improved to 38.3 μW·mK-2 at 75℃. This work may provide meaningful experience for development of D-A type thermoelectric copolymers and may further improve the doping efficiency.

Key words: donor-acceptor copolymer, doping, oxidization process, thermoelectric performance

中图分类号:  (Semiconductor-device characterization, design, and modeling)

  • 85.30.De
72.80.Le (Polymers; organic compounds (including organic semiconductors))