Submillimeter radius bendable organic field-effect transistors

We have successfully fabricated ultra-flexible pentacene field-effect transistors (FETs) with a mobility of 0.5 cm2/V s and an on/off ratio of 105, which are functional even at a bending radius (R) smaller than 1 mm. The FETs are manufactured on a 13-μm-thick plastic substrate and encapsulated by a 13-μm-thick parylene passivation layer, thus placing the FET in the neutral plane. We measured the electrical properties of FETs under varying compressive and tensile strains, by changing the bending radius of the substrate. If the bending radius is larger than 2 mm, the mobility changes less than 3%. Further decrease in bending radius causes larger change in mobility. At R = 0.5 mm, the mobility increases by 20% in compression or decreases by 30% in tension.