Strain‐Invariant, Highly Water Stable All‐Organic Soft Conductors Based on Ultralight Multi‐Layered Foam‐Like Framework Structures

Abstract

AbstractSoft and flexible conductors are essential for the development of soft robots, wearable electronics, electronic tissue, and implants. However, conventional soft conductors are inherently characterized by a large change in conductance upon mechanical deformation or under alternating environmental conditions, e.g., humidity, drastically limiting their application potential. This work demonstrates a novel concept for the development of strain‐invariant, highly elastic and highly water stable all‐organic soft conductors, overcoming the limitations of previous strain‐invariant soft conductors. For the first time, thin film deposition technologies are combined in a three‐dimensional fashion, resulting in micro‐ and nano‐engineered, multi‐layered (<50 nm), ultra‐lightweight (< 15 mg cm−3) foam‐like framework structures based on Poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) and Polytetrafluoroethylene (PTFE), characterized by a highly strain‐invariant conductivity (≈184 S/m) between 80% compressive and 25% tensile strain. Both the initial electrical and mechanical properties are retained during long‐term cycling, even after 2000 cycles at 50% compression. Furthermore, the PTFE thin film renders the framework structure highly hydrophobic, resulting in stable electrical properties, even when immersed in water for a month. Such innovative multi‐scaled and multi‐layered functional materials are of interest for a broad range of applications in soft electronics, energy storage and conversion, sensing, water and air purification, as well as biomedicine.