Enhancement of electrical properties of vanadyl phthalocyanine derivative by PCBM

Purpose - The purpose of this paper is to investigate the effect of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) on improvement of physical and electrical properties of vanadyl phthalocyanine derivative. The correlation between the physical characteristics of the active layers, comprising vanadyl 2,9,16, 23-tetraphenoxy-29H, 31H-phthalocyanine (VOPcPhO) and PCBM, and the electrical properties of metal/organic/metal devices have been studied. The use of soluble vanadyl phthalocyanine derivative makes it very attractive for a variety of applications due to its tunable properties and high solubility. Design/methodology/approach - The sandwich type structures Al/VOPcPhO/Al and Al/VOPcPhO: PCBM/Al were fabricated by spin casting the active organic layers between the top and bottom (aluminum) electrodes. The stand-alone (VOPcPhO) and composite (VOPcPhO: PCBM) thin films were characterized by X-ray diffraction, atomic force microscopy, UV/Vis and Raman spectroscopy. The electronic properties of the metal/organic/metal devices were studied using current-voltage (I-V) characteristics in dark at room temperature. Findings - The values of barrier height for Al/VOPcPhO/Al and Al/VOPcPhO: PCBM/Al devices were obtained from the forward bias I-V curves and were found to be 0.7 eV and 0.62 eV, respectively. The present study indicates that the device employing VOPcPhO: PCBM composite film as the active layer, with better structural and morphological characteristics, results in reduced barrier height at the metal-organic film interface as compared to the one fabricated with the stand-alone film. Research limitations/implications - It is shown that doping VOPcPhO with PCBM improves the crystallinity, morphology and junction properties. Practical implications - The spin coating technique provides a simple, less expensive and effective approach for preparing thin films. The soluble VOPcPhO is conveniently dissolved in a number of organic solvents. Originality/value - The physical properties of the VOPcPhO: PCBM composite thin film and the electrical properties of the composite thin-film-based metal/organic/metal devices have not been reported in the literature, as far as our knowledge is concerned.