Ultraflexible organic field-effect transistors embedded at a neutral strain position

We fabricated ultraflexible pentacene field-effect transistors (FETs) with a mobility of 0.5cm2∕Vs and an on/off ratio of 105, which are functional at the bending radius less than 1mm. The transistors are manufactured on a 13-μm-thick polyimide film and covered by a 13-μm-thick poly-chloro-para-xylylene encapsulation layer so that transistors can be embedded at a neutral position. This sandwiched structure can drastically suppress strain-induced changes in transistor characteristics. Furthermore, the FETs show no significant change after bending cycles of 60 000 times on inward and outward bending stresses.