Optical and Electrical Properties of New Perylene Diimide Thin Films

Perylene diimides with high photosensitivity and high electron mobility have attracted much attention for use in organic semiconductor devices. In this investigation, thin films of six new perylene tetracarboxylic diimides (PTCDI) were fabricated by spin coating, on glass as substrate, and their optical and electrical properties were studied. The absorption spectra of thin films of PTCDI furnished more informative bands than those of the compounds in solution. The morphology of the thin films was examined by scanning electron microscopy and x-ray diffraction. The absorption spectra and I-V characteristics of the compounds were affected by their molecular structures. HOMO-LUMO band gaps of the films were in the range 1.9-2.0 eV. Band gaps calculated by use of computational methods were comparable with experimental results.