Modulation of the doping level of PEDOT:PSS film by treatment with hydrazine to improve the Seebeck coefficient

Temesgen Atnafu Yemata; Yun Zheng; Aung Ko Ko Kyaw; Xizu Wang; Jing Song; Wee Shong Chin; Jianwei Xu

doi:10.1039/c9ra07648d

Modulation of the doping level of PEDOT:PSS film by treatment with hydrazine to improve the Seebeck coefficient

RSC Adv. 2020 Jan 9;10(3):1786-1792. doi: 10.1039/c9ra07648d. eCollection 2020 Jan 7.

Authors

Temesgen Atnafu Yemata^{1

2

3}, Yun Zheng¹, Aung Ko Ko Kyaw^{1

4}, Xizu Wang¹, Jing Song¹, Wee Shong Chin², Jianwei Xu^{1

2}

Affiliations

¹ Institute of Materials Research and Engineering, Agency for Science, Technology and Research (ASTAR) 2 Fusionopolis Way Singapore 138634 Republic of Singapore jw-xu@imre.a-star.edu.sg.
² Department of Chemistry, National University of Singapore 3 Science Drive 3 Singapore 117543 Republic of Singapore chmcws@nus.edu.sg.
³ Chemical Engineering Department, Bahirdar University P.O. Box 26 Bahirdar Ethiopia.
⁴ Department of Electrical and Electronic Engineering, Southern University of Science and Technology Shenzhen 518055 P. R. China.

Abstract

As the most popular conducting polymer, poly(3,4 ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is widely used for a variety of applications, including thermoelectrics. This paper reports the modulation of the doping level by treatment with hydrazine to improve the Seebeck coefficient of PEDOT:PSS films. PEDOT:PSS films were first treated with formic acid followed by hydrazine, leading to a significant increase in the Seebeck coefficient from 17.5 to 42.7 μV K^-1, about 2.5 times higher than that of the pristine film partially at the expense of electrical conductivity. An optimum power factor of 93.5 μW K^-2 m^-1, being 2.4 times that of the one treated with only formic acid, was achieved. The substantial improvement in the Seebeck coefficient and the power factor is collectively attributed to the removal of the PSS, and more importantly, the reduction of the doping level of PEDOT by the hydrazine treatment, which is evidenced clearly by UV-vis-NIR spectroscopy, XPS and Raman spectroscopy.