Breakthrough in polymer research: an ordered form of polyaniline exhibits extraordinary electrical conductivity and metallic charge transport behavior.
Schematic representation of the process for synthesizing 2DPANI on the water surface.
Peng Zhang
An international research team with German participation has synthesized and characterized a layered two-dimensional polyaniline crystal (2DPANI). Thomas Heine, Professor of Theoretical Chemistry at the Technical University of Dresden (TUD), explains what is so special about it: “This material exhibits extraordinary conductivity – not only within its layers, but also perpendicular to the layers. We call this metallic out-of-plane charge transport or 3D conduction. This is a fundamental breakthrough in polymer research.”
Together with his team at the TUD and the Center for Advanced Systems Understanding CASUS in Görlitz, he first simulated the structure of the polymer and calculated its metallic character. Xinliang Feng and his team at the Center for Advancing Electronics at TUD and the Max Planck Institute for Microstructure Physics in Halle synthesized the new polymer and carried out direct current transport studies. The measurements showed an anisotropic conductivity with 16 S/cm in-plane and 7 S/cm out-of-plane, about three orders of magnitude higher than conventional linear conducting polymers.
DC Conductivity of About 200 S/cm
In addition, measurements at low temperatures show that the out-of-plane conductivity increases with decreasing temperature – a characteristic behavior of metals. According to the TUD, this confirms the “extraordinarily metallic electrical out-of-plane transport properties of the material”. Further measurements were carried out at the CIC nanoGUNE in San Sebastián, Spain, using infrared and terahertz near-field microscopy. These revealed a DC conductivity of around 200 S/cm.
According to the TUD, the breakthrough opens up the possibility of “achieving three-dimensional metallic conductivity in metal-free organic and polymeric materials”. This would offer “perspectives for applications in electronics, electromagnetic shielding or sensor technology”. The metallic polymer could serve as a functional electrode in electro- and photoelectrochemistry, for example for the production of hydrogen.
25 Years Ago: Nobel Prize for the Development of Conductive Polymers
Conductive polymers such as polyaniline, polythiophene and polypyrrole are known for their excellent electrical conductivity and have proven to be promising low-cost, lightweight and flexible alternatives to conventional semiconductors and metals. The importance of these materials was recognized in 2000 when Alan J. Heeger, Alan G. MacDiarmid and Hideki Shirakawa were awarded the Nobel Prize in Chemistry for their discovery and development of conductive polymers.
Despite significant advances, these materials primarily conduct electrons along their polymer chains. However, the conductivity between the polymer strands or layers remains limited because the molecules are not well connected and the electronic interactions are weak.
This is a partly automated translation of this german article.
