Persistence in photoconductivity and optical property of nanostructured copper (II) phthalocyanine thin films

The optical and photoconductive properties of nanostructured copper (II) phthalocyanine (CuPc) surface cells have been studied at room temperature (30 °C). The change in the conductivity of the surface type sample cells under illumination of light was studied as a function of duration and wavelength of photoexcitation. The photoconductivity spectrum of a film of CuPc surface cell does not agree with the absorption spectrum. Particularly for the photoexciting wavelengths in the region 400–500 nm, the photoconductivity shows an appreciable value (or comparatively higher value), although the absorbance in this region is minimum or very less. The change in current under illumination of light and after turning it off has indicated that photoinduced effects persist for a longer period of time even after turning off the illumination of light of various wavelengths and duration. An increase in persistence in photocurrent was noticed with the repeated exposure within a short interval of time. Such studies are important for searching new types of electrically conducting systems (semiconductors) in the form of nanostructured thin films for use as photoactive materials in optoelectronic and memory devices.