Fourier-transform infrared and electrical properties of magnesium phthalocyanine thin films

Abstract

The Fourier-transform infrared (FT-IR) spectra of magnesium phthalocyanine (MgPc) were investigated in the spectral range 500-4000 cm-1. The spectra allow characterization of vibration modes. A comparison of absorption spectra of powder, as-deposited and annealed films is presented. The dark electrical resistivity measurements were carried out at different temperatures in the range 308 to 423 K. Two activation energies ΔE1 = 0.23 eV and ΔE2 = 0.69 eV were obtained. The thermal activation energy ΔE1 is associated with impurity conduction and ΔE2 is associated with intrinsic conduction. The current density-voltage characteristics of MgPc at room temperature showed a linear ohmic conduction mechanism at low voltages. At higher voltages the space-charge-limited conduction (SCLC) accompanied as a single dominant level. The temperature dependence of current density allows the determination of some essential parameters such as the hole mobility (μh), the trapping factor Θ and the total trap concentration (Nt). © EDP Sciences, 2011.