Three-Dimensional Printing of Highly Conducting PEDOT: PSS-Based Polymers

Abstract

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) is one of the most successful conducting polymers for electronic applications. Most commonly, the spin coating process is used to fabricate PEDOT:PSS thin films from an aqueous solution, yet it is unsuitable for fabricating complicated two-dimensional (2D) structures. Extrusion-based additive manufacturing (AM) processes have been investigated for 3D printing PEDOT:PSS-based polymers with free-form architecture. However, such methods imply strict requirements on the rheological properties of materials and, as a result, have limited choices of appropriate materials. In the past, additives have been added to improve the 3D printing processability of PEDOT:PSS materials, which, however, usually deteriorate the electrical conductivity. This article reports a new type of PEDOT:PSS material capable of addressing the previously listed challenges and characterized by high processability and electrical conductivity (72 S/cm). In addition, a novel extrusion-based AM technology, electrostatically-assisted direct ink writing (eDIW), is investigated for printing materials containing PEDOT:PSS. The eDIW method prints lines at micro-scale resolution at an ultra-high speed (1.72 m/s). This combination is often deemed impossible in the framework of classical extrusion-based AM techniques. This work lays the foundation for future explorations of applications of PEDOT:PSS-based conducting polymers in fields that require superb properties and custom geometry, which were conventionally impossible.