title: Semi-metallic polymers.
abstract: Polymers are lightweight, flexible, solution-processable materials that are promising for low-cost printed electronics as well as for mass-produced and large-area applications. Previous studies demonstrated that they can possess insulating, semiconducting or metallic properties; here we report that polymers can also be semi-metallic. Semi-metals, exemplified by bismuth, graphite and telluride alloys, have no energy bandgap and a very low density of states at the Fermi level. Furthermore, they typically have a higher Seebeck coefficient and lower thermal conductivities compared with metals, thus being suitable for thermoelectric applications. We measure the thermoelectric properties of various poly(3,4-ethylenedioxythiophene) samples, and observe a marked increase in the Seebeck coefficient when the electrical conductivity is enhanced through molecular organization. This initiates the transition from a Fermi glass to a semi-metal. The high Seebeck value, the metallic conductivity at room temperature and the absence of unpaired electron spins makes polymer semi-metals attractive for thermoelectrics and spintronics.
authors: Linkoping University, Department of Science and Technology, Organic Electronics, SE-601 74 Norrkoping, Sweden.
authors: Olga
authors: O
authors: Bubnova
authors: Linkoping University, Department of Science and Technology, Organic Electronics, SE-601 74 Norrkoping, Sweden.
authors: Zia Ullah
authors: ZU
authors: Khan
authors: Linkoping University, Department of Science and Technology, Organic Electronics, SE-601 74 Norrkoping, Sweden.
authors: Hui
authors: H
authors: Wang
authors: Linköping University, Department of Physics, Chemistry and Biology, S-581 83 Linköping, Sweden.
authors: Slawomir
authors: S
authors: Braun
authors: University of South Australia, Mawson Institute, Mawson Lakes 5095, Australia.
authors: Drew R
authors: DR
authors: Evans
authors: University of South Australia, Mawson Institute, Mawson Lakes 5095, Australia.
authors: Manrico
authors: M
authors: Fabretto
authors: University of South Australia, Mawson Institute, Mawson Lakes 5095, Australia.
authors: Pejman
authors: P
authors: Hojati-Talemi
authors: Linköping University, Department of Physics, Chemistry and Biology, S-581 83 Linköping, Sweden.
authors: Daniel
authors: D
authors: Dagnelund
authors: Free University of Brussels, Laboratoire de Chimie des Polymères, CP 206/1, Boulevard du Triomphe, 1050 Bruxelles, Belgium.
authors: Jean-Baptiste
authors: JB
authors: Arlin
authors: Free University of Brussels, Laboratoire de Chimie des Polymères, CP 206/1, Boulevard du Triomphe, 1050 Bruxelles, Belgium.
authors: Yves H
authors: YH
authors: Geerts
authors: University of Mons, Laboratoire de chimie des materiaux nouveaux, Place du Parc 20, 7000 Mons, Belgium.
authors: Simon
authors: S
authors: Desbief
authors: Norwegian University of Science and Technology (NTNU), Department of Physics, Høgskoleringen 5, 7491 Trondheim, Norway.
authors: Dag W
authors: DW
authors: Breiby
authors: Technical University of Denmark, Department of Energy Conversion and Storage, Frederiksborgvej 399, 4000 Roskilde, Denmark.
authors: Jens W
authors: JW
authors: Andreasen
authors: University of Mons, Laboratoire de chimie des materiaux nouveaux, Place du Parc 20, 7000 Mons, Belgium.
authors: Roberto
authors: R
authors: Lazzaroni
authors: Linköping University, Department of Physics, Chemistry and Biology, S-581 83 Linköping, Sweden.
authors: Weimin M
authors: WM
authors: Chen
authors: Linkoping University, Department of Science and Technology, Organic Electronics, SE-601 74 Norrkoping, Sweden.
authors: Igor
authors: I
authors: Zozoulenko
authors: Linköping University, Department of Physics, Chemistry and Biology, S-581 83 Linköping, Sweden.
authors: Mats
authors: M
authors: Fahlman
authors: University of South Australia, Mawson Institute, Mawson Lakes 5095, Australia.
authors: Peter J
authors: PJ
authors: Murphy
authors: Linkoping University, Department of Science and Technology, Organic Electronics, SE-601 74 Norrkoping, Sweden.
authors: Magnus
authors: M
authors: Berggren
authors: Linkoping University, Department of Science and Technology, Organic Electronics, SE-601 74 Norrkoping, Sweden.
authors: Xavier
authors: X
authors: Crispin