Highly Stretchable and Highly Conductive Organic Transparent Conductors Based on Aqueous‐Processable Conducting Polymer/Ionic Liquid Composites

Abstract

Deformable (semi)conducting polymers have attracted great attention for realizing next‐generation wearable and stretchable electronics. A conductive π‐conjugated polymer, poly(3,4‐ethylenedioxythiophene) : poly(styrenesulfonate) (PEDOT : PSS) is considered as a key component based on the promising electrical characteristics and aqueous processability. However, the general trade‐off relationship between electrical and mechanical performance in PEDOT : PSS is a crucial issue for its practical application as a stretchable conductor. Herein, a simultaneous improvement in electrical conductivity and mechanical stretchability was achieved from PEDOT : PSS by introducing a water‐soluble ionic liquid, 1‐ethyl‐3‐methylimidazolium dicyanoimidazolate (EMIM : DCIM). The electromechanical improvement is closely related with the EMIM : DCIM contents, in which EMIM : DCIM not only causes a morphological transition but also acts as a plasticizing agent. As a result, highly stretchable and highly conductive PEDOT : PSS/EMIM : DCIM composites were obtained with an initial electrical conductivity of ≈550 S cm⁻¹ and maximum strain of 70 % while maintaining the initial electrical properties. Finally, a potential application of PEDOT : PSS/EMIM : DCIM as a stretchable transparent conductor was successfully demonstrated with given high visible transparency and eco‐friendly processability.