High Thermoelectric Power Factor of Poly(3-hexylthiophene) through In-Plane Alignment and Doping with a Molybdenum Dithiolene Complex

Viktoriia Untilova; Jonna Hynynen; Anna I Hofmann; Dorothea Scheunemann; Yadong Zhang; Stephen Barlow; Martijn Kemerink; Seth R Marder; Laure Biniek; Christian Müller; Martin Brinkmann

doi:10.1021/acs.macromol.0c01223

High Thermoelectric Power Factor of Poly(3-hexylthiophene) through In-Plane Alignment and Doping with a Molybdenum Dithiolene Complex

Macromolecules. 2020 Aug 11;53(15):6314-6321. doi: 10.1021/acs.macromol.0c01223. Epub 2020 Jul 23.

Affiliations

¹ CNRS, ICS UPR 22, Université de Strasbourg, F-67000 Strasbourg, France.
² Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg, Sweden.
³ School of Chemistry & Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States.
⁴ Centre for Advanced Materials, Heidelberg University, 69120 Heidelberg, Germany.

Abstract

We report a record thermoelectric power factor of up to 160 μW m^-1 K^-2 for the conjugated polymer poly(3-hexylthiophene) (P3HT). This result is achieved through the combination of high-temperature rubbing of thin films together with the use of a large molybdenum dithiolene p-dopant with a high electron affinity. Comparison of the UV-vis-NIR spectra of the chemically doped samples to electrochemically oxidized material reveals an oxidation level of 10%, i.e., one polaron for every 10 repeat units. The high power factor arises due to an increase in the charge-carrier mobility and hence electrical conductivity along the rubbing direction. We conclude that P3HT, with its facile synthesis and outstanding processability, should not be ruled out as a potential thermoelectric material.