*2.6. Characterization*

A semiconductor characterization system (Keithley 4200, Beaverton, OR, USA) was used to analyze the electrical properties of the conductive electrodes. Bending and stretching tests were also performed. Photo-detective tests under the irradiation of an ultraviolet (UV) lamp (8 W, Vilber Lourmat, Marne La-Vallee, France) were also carried out at various wavelengths. The tests were also done

under a tungsten–halogen lamp (FOK-100 W, Fiber Optic Korea, Cheonan, Korea). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) images were obtained using a multimode AFM (Nanoscope IIIa, Digital Instruments, Bresso, Italy) and FE-SEM (JSM-7500F, Jeol, Tokyo, Japan), respectively.
