Jung Ah Lim1 Min Jung Kye1 Ho Sun Lim2 Eunji Lee3

1, Korea Institute of Science and Technology, Seoul, , Korea (the Republic of)
2, Sookmyung Women's University, Seoul, , Korea (the Republic of)
3, Gwangju Institute of Science and Technology, Gwangju, , Korea (the Republic of)

With increasing interest in textile-based wearable electronic devices, there is a considerable need to develop stretchable and elastic conductors that can be directly patterned on a fabric. One of the most promising classes of conducting materials for e-textiles is a poly (3,4-ethylenedioxythiophene)complex with a water-dispersible polyelectrolyte dopant of poly (styrene sulfonate) (PEDOT:PSS). Due to its high conductivity, good compatibility with various electronic materials, biocompatibility, and easy processability using solution coating. However, for practical e-textile applications of PEDOT:PSS, development of a highly stretchable PEDOT:PSS materials and their highly efficient, direct patterning process are still required. Moreover, for daily use of textile devices, improvement in the long-term environmental stability and wash-resistance of PEDOT:PSS is also necessary.
Here, we demonstrate a direct-write patternable water-based poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT:PSS) composite ink which is capable of providing highly stretchable and washing-resistant electrodes on a fabric substrate for electronic textile applications. An aqueous composite ink consisting of PEDOT:PSS, graphene oxide nanosheets and anionic polyurethane does readily not permeated into hygroscopic fabric, which facilitate direct drawing of fine PEDOT electrode on the fabric without undesired blur effect. The PEDOT composite film shows unique structure of the PEDOT nanofibril network embedded by the polyurethane matrix, which resulted in an enough electrical pathway for charge carriers even though only 2.9 wt% of PEDOT:PSS existed in the composite film. The PEDOT composite film exhibited electrical conductivity of 4.6 S/cm, extremely high stretchability of 375% rupture strain, and high durability for repeated washing process with strong bleaching agent. Light emitting diode incorporated on the stretchable spandex with interconnects of the PEDOT composite pattern showed that LED light intensity was almost maintained even with stretching of PEDOT interconnects to 290%.