Enhancement of microstructure and electrical conductivity of N, N′-dimethyl-3,4,9,10-perylenedicarboximide nanostructured films by thermal annealing for photoelectronic applications

Thin films of N, N′-Dimethyl-3,4,9,10-perylenedicarboximide (DMPDC) were prepared using thermal vacuum evaporating method. Fourier-transform infrared investigated the molecular structure of DMPDC in the form of powder, as well as the as-deposited, and the annealed DMPDC thin films, which reveals that the DMPDC thin films are realized by their thermal stability. The analysis of X-ray diffraction (XRD) of DMPDC in its powder form was observed to be polycrystalline with orthorhombic structure, whereas the XRD analysis of DMPDC films confirms that these films have nanostructure feature which is accompanied by increasing of crystallite size and decreasing of dislocation density as the annealing temperature increases. These results affirm that the annealing treatment enhanced the crystallite of DMPDC thin films. The electrical conductivity versus temperature was measured by applying the Arrhenius law. Also, it was found that the activation energy decreased with the increase of the annealed temperature. The current-density-voltage characteristics of as-deposited DMPDC films in the dark and at various temperatures were investigated. These results pointed out that the conduction mechanism of DMPDC films was ohmic in low voltage range. While in the high-voltage range the space charge limited conductivity was dominant and can be explained by a single dominating trap level.