Highly Stretchable, High‐Mobility, Free‐Standing All‐Organic Transistors Modulated by Solid‐State Elastomer Electrolytes

Abstract Highly stretchable, high‐mobility, and free‐standing coplanar‐type all‐organic transistors based on deformable solid‐state elastomer electrolytes are demonstrated using ionic thermoplastic polyurethane (i‐TPU), thereby showing high reliability under mechanical stimuli as well as low‐voltage operation. Unlike conventional ionic dielectrics, the i‐TPU electrolyte prepared herein has remarkable characteristics, i.e., a large specific capacitance of 5.5 µF cm −2 , despite the low weight ratio (20 wt%) of the ionic liquid, high transparency, and even stretchability. These i‐TPU‐based organic transistors exhibit a mobility as high as 7.9 cm 2 V −1 s −1 , high bendability ( R c , radius of curvature: 7.2 mm), and good stretchability (60% tensile strain). Moreover, they are suitable for low‐voltage operation ( V DS = −1.0 V, V GS = −2.5 V). In addition, the electrical characteristics such as mobility, on‐current, and threshold voltage are maintained even in the concave and convex bending state (bending tensile strain of ≈3.4%), respectively. Finally, free‐standing, fully stretchable, and semi‐transparent coplanar‐type all‐organic transistors can be fabricated by introducing a poly(3,4‐ethylenedioxythiophene):polystyrene sulfonic acid layer as source/drain and gate electrodes, thus achieving low‐voltage operation ( V DS = −1.5 V, V GS = −2.5 V) and an even higher mobility of up to 17.8 cm 2 V −1 s −1 . Moreover, these devices withstand stretching up to 80% tensile strain.