Nanoscale engineering of conducting polymers for emerging applications in soft electronics

Soft electronics featuring exceptional mechanical compliance and excellent electrical performance hold great promise for applications in soft robotics, artificial intelligence, bio-integrated electronics, and wearable electronics. Intrinsically stretchable and conductive materials are crucial for soft electronics, enabling large-area and scalable fabrication, high device density, and good mechanical compliance. Conducting polymers are inherently stretchable and conductive. They can be precisely synthesized from vastly available building blocks, and thus they provide a fruitful platform for fabricating soft electronics. However, amorphous bulk-phase conducting polymers typically exhibit poor mechanical and electrical characteristics. Consequently, it is highly desirable to develop novel engineering approaches to overcome the intrinsic limitations of conducting polymers. In recent years, numerous engineering strategies have been developed to enhance their performances in soft electronic devices via constructing various nanostructures. In this review, we first summarize several unique methodologies to fabricate conducting polymer-based nanostructures. We then discuss how nanoscale engineering approaches can improve several crucial parameters, including electrical conductivity, stretchability, sensitivity, and self-healing property of conducting polymers. Moreover, we also discuss device-level integration of conducting polymer-based nanostructures with other materials for applications in skin-inspired electronics and bio-integrated electronics. Finally, we provide perspectives on challenges and future directions in engineering nanostructured conducting polymers for soft electronics.