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Advances in Condensed Matter Physics
Volume 2012, Article ID 698934, 7 pages
http://dx.doi.org/10.1155/2012/698934
Research Article

Structural and Optical Properties of Nanocrystalline 3,4,9,10-Perylene-Tetracarboxylic-Diimide Thin Film

1Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo 11757, Egypt
2Physics Department, Faculty of Science, Suez Canal University, Ismailia 41522, Egypt

Received 8 March 2012; Accepted 24 April 2012

Academic Editor: Victor V. Moshchalkov

Copyright © 2012 M. M. El-Nahhas et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Thin films of nanocrystalline 3,4,9,10-perylene-tetracarboxylic-diimide (PTCDI) were prepared on quartz substrates by thermal evaporation technique. The structural properties were identified by transmission electron microscopy (TEM) and the X-ray diffraction (XRD). The optical properties for the films were investigated using spectrophotometric measurements of the transmittance and reflectance at normal incidence of light in the wavelength range from 200 to 2500 nm. The optical constants (refractive index 𝑛 and absorption index π‘˜ ) were calculated and found to be independent on the film thickness in the measured film thickness range 117–163 nm. The dispersion energy ( 𝐸 𝑑 ), the oscillator energy ( 𝐸 π‘œ ), and the high-frequency dielectric constant πœ€ ∞ were obtained. The energy band model was applied, and the types of the optical transitions responsible for optical absorption were found to be indirect allowed transition. The onset and optical energy gaps were calculated, and the obtained results were also discussed.