Current-Voltage Hysteresis Behavior of PVA-Assisted Functionalized Single-Walled Carbon Nanotube Free-Standing Film

The formation of a free-standing film containing oriented functionalized single-walled carbon nanotube (SWCNT) grafted by poly(vinyl alcohol) (PVA) using a simple solution casting technique is demonstrated in detail. The Raman and X-ray photoelectron spectroscopy spectra engraved the formation of p-n junction at the point of contact between the PVA chain and the aligned functionalized carbon nanotubes. The formation of localized state in the forbidden gap due to the presence of a dangling bond in the composite film is confirmed through the photoluminescence study. The electrical study suggests 3 times higher dielectric constant in the aligned amine-functionalized SWCNT films grafted by PVA than that in pristine SWCNT incorporated in the polymer film. Hysteresis behavior of the current-voltage characteristic is observed in the metal/composite film/metal (Au/PVA/SWCNT/Au) capacitor system in the temperature window 373-413 K. The capacitor system shows an oscillatory behavior in current for the successive loop due to modulation in the hopping distance. This type of composite material may be used as a flexible memory device.