Highly stretchable fiber transistors with all-stretchable electronic components and graphene hybrid electrodes

Textile-based electronic devices should be not only bendable but also highly stretchable for human-friendly wearable electronic applications. Herein, a highly stretchable and mechanically durable fiber transistor was designed and prepared by combining all-stretchable electronic components. First, electrically conductive and stretchable electrodes were fabricated by simple prestraining-then-buckling of graphene/silver hybrid fibers on a highly elastic thermoplastic polyurethane (TPU) monofilament, which maintained a low resistivity (∼30 Ω cm) at a high stretching strain (∼70%) and under many stretch/release cycles (∼1,000). A highly stretchable active channel was prepared by directly blending semiconducting poly(3-hexylthiophene) (P3HT) and viscoelastic TPU without using pre-grown P3HT nanofibrils. The P3HT/TPU blend (5/5 w/w blend ratio) active layer possessed reasonably high mobility (1.46 × 10−3 cm2 V−1 s−1) and adequate mechanical strength (21 MPa) with a high elongation strain (∼120%). In addition, a stretchable dielectric layer and gate electrode were prepared using an elastic ion-gel film and a liquid metal composite, respectively. The assembled fiber transistor exhibited excellent stretchability (∼50%) while maintaining good electrical properties (average charge carrier mobility of 1.74 cm2 V−1 s−1, on/off current ratio of 104) and showed outstanding electrical stability up to 1,000 cycles of stretch/release testing. To the best of our knowledge, these superior stretchability and stability have not been reported elsewhere in the area of fiber-type transistors. We believe that our work can serve as an important step toward the development of core components in wearable devices, such as wearable displays, computers, and biomedical sensors.