Structural investigations and mobility enhanced of Vanadyl 2,3-naphthalocyanine (VONc) nanostructured films under thermal effect

Powder and films of the promised Vanadyl 2,3-naphthalocyanine (VONc) materials were studied. Structural properties of these both VONc powder and films were investigated. The structural properties were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR). XRD shows that VONc powder has polycrystalline structure, while VONc films have nanostructured nature. SEM result shows agglomerated grains under annealing effect. The observed vibrational wavenumbers in FTIR spectra were analyzed and assigned to different normal modes of the molecule. The films of VONc were electrically studied before and after annealing at different annealing temperatures of 373, 473 and 523 K. The electrical conductivity and current-voltage dependence were studied for VONc films with these suggested annealing temperatures. Both charge carrier concentration and their mobility besides the different conduction processes have been illustrated. The experimental and calculated results have shown that the present films have two regions on the current-voltage relation. In the Ohmic district, the conduction has no traps of electrons in the forbidden gap of present films. In the range of higher voltage, the current is expected a limited space charge controlled by a single trap level. Our results obtained that the holes mobility mu(0) and the density of total trap at E-t were enhanced under the thermal effect.