Enhanced Thermoelectric Power Factor of Tensile Drawn Poly(3-hexylthiophene)

Jonna Hynynen; Emmy Järsvall; Renee Kroon; Yadong Zhang; Stephen Barlow; Seth R Marder; Martijn Kemerink; Anja Lund; Christian Müller

doi:10.1021/acsmacrolett.8b00820

Enhanced Thermoelectric Power Factor of Tensile Drawn Poly(3-hexylthiophene)

ACS Macro Lett. 2019 Jan 15;8(1):70-76. doi: 10.1021/acsmacrolett.8b00820. Epub 2018 Dec 26.

Authors

Jonna Hynynen¹, Emmy Järsvall¹, Renee Kroon¹, Yadong Zhang², Stephen Barlow², Seth R Marder², Martijn Kemerink³, Anja Lund¹, Christian Müller¹

Affiliations

¹ Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg, Sweden.
² School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States.
³ Complex Materials and Devices, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden.

Abstract

The thermoelectric power factor of a broad range of organic semiconductors scales with their electrical conductivity according to a widely obeyed power law, and therefore, strategies that permit this empirical trend to be surpassed are highly sought after. Here, tensile drawing of the conjugated polymer poly(3-hexylthiophene) (P3HT) is employed to create free-standing films with a high degree of uniaxial alignment. Along the direction of orientation, sequential doping with a molybdenum tris(dithiolene) complex leads to a 5-fold enhancement of the power factor beyond the predicted value, reaching up to 16 μW m^-1 K^-2 for a conductivity of about 13 S cm^-1. Neither stretching nor doping affect the glass transition temperature of P3HT, giving rise to robust free-standing materials that are of interest for the design of flexible thermoelectric devices.