(a) Schematic showing the organic FET with a nanopaper substrate. Inset molecular structure shows F15-NTCDI semiconductor. (b) A picture of the real fabricated device when it is bent. (c) Measured optical transmittance of nanopaper used in this study and the fabricated device (≈ 89 % and ≈ 84 % at a wavelength of 550 nm, respectively). (d) Measured drain-source current-voltage characteristics (ISD-VSD) of the device for each applied gate voltage from 0 V to 80 V. (e) Transfer characteristic of the device when VSD = 10 V is measured. Inset shows how much gate leakage current is measured under gate voltage. (f) Transfer characteristics of the device when it is bent. Black solid line, red dashed line, and blue dashed line represent measured transfer characteristics when the device is not bent, bent in vertical to the direction of conduction channel, and bent in parallel to the direction of conduction channel, respectively. Reproduced with permission.[77] Copyright 2013, American Chemical Society.