Polaron interfacial entropy as a route to high thermoelectric performance in DAE-doped PEDOT:PSS films

Jiajia Zhang; Caichao Ye; Genwang Wei; Liang Guo; Yuhang Cai; Zhi Li; Xinzhi Wu; Fangyi Sun; Qikai Li; Yupeng Wang; Huan Li; Yuchen Li; Shuaihua Wang; Wei Xu; Xuefeng Guo; Wenqing Zhang; Weishu Liu

doi:10.1093/nsr/nwae009

Polaron interfacial entropy as a route to high thermoelectric performance in DAE-doped PEDOT:PSS films

Natl Sci Rev. 2024 Jan 9;11(3):nwae009. doi: 10.1093/nsr/nwae009. eCollection 2024 Mar.

Authors

Jiajia Zhang¹, Caichao Ye^{1

2}, Genwang Wei^{1

2}, Liang Guo³, Yuhang Cai³, Zhi Li³, Xinzhi Wu¹, Fangyi Sun¹, Qikai Li¹, Yupeng Wang¹, Huan Li¹, Yuchen Li¹, Shuaihua Wang¹, Wei Xu⁴, Xuefeng Guo⁵, Wenqing Zhang^{1

2}, Weishu Liu^{1

6}

Affiliations

¹ Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
² Academy for Advanced Interdisciplinary Studies and Guangdong Provincial Key Laboratory of Computational Science and Material Design, Southern University of Science and Technology, Shenzhen 518055, China.
³ Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
⁴ Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190,China.
⁵ College of Chemistry and Molecular Engineering, National Biomedical Imaging Centre, Peking University, Beijing 100091, China.
⁶ Guangdong Provincial Key Laboratory of Functional Oxide Materials and Devices, Southern University of Science and Technology, Shenzhen 518055, China.

Abstract

Enhancing the thermoelectric transport properties of conductive polymer materials has been a long-term challenge, in spite of the success seen with molecular doping strategies. However, the strong coupling between the thermopower and the electrical conductivity limits thermoelectric performance. Here, we use polaron interfacial occupied entropy engineering to break through this intercoupling for a PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(4-styrenesulfonate)) thin film by using photochromic diarylethene (DAE) dopants coupled with UV-light modulation. With a 10-fold enhancement of the thermopower from 13.5 μV K^-1 to 135.4 μV K^-1 and almost unchanged electrical conductivity, the DAE-doped PEDOT:PSS thin film achieved an extremely high power factor of 521.28 μW m^-1 K^-2 from an original value of 6.78 μW m^-1 K^-2. The thermopower was positively correlated with the UV-light intensity but decreased with increasing temperature, indicating resonant coupling between the planar closed DAE molecule and PEDOT. Both the experiments and theoretical calculations consistently confirmed the formation of an interface state due to this resonant coupling. Interfacial entropy engineering of polarons could play a critical role in enhancing the thermoelectric performance of the organic film.

Keywords: PEDOT:PSS; UV-light modulation; interfacial occupied entropy; resonant coupling; thermoelectric.