Eur. Phys. J. Appl. Phys.
Volume 48, Number 2, November 2009
|Number of page(s)||6|
|Section||Physics of Organic Materials and Devices|
|Published online||17 September 2009|
Optical properties of Azo Dye (1-Phenylazo-2-Naphthol) thin films
Physics Department, Faculty of Science, Mansoura University, Damitta, Egypt
2 Department of Physics and Mathematical Engineering, Faculty of Engineering, Suez Canal University, 11571 Port-Said, Egypt
Corresponding author: firstname.lastname@example.org
Accepted: 25 May 2009
Published online: 17 September 2009
Thin Films of Azo Dye (1-Phenylazo-2-Naphthol) have been prepared by thermal evaporation technique onto quartz substrates held at about 300 K during the deposition process with different thicknesses range 625–880 nm. X-ray diffraction and the differential thermal analysis showed that the Azo Dye sample is crystalline nature and thermal stable in temperature range from room temperature to 100 C. The optical constants (the refractive index n, the absorption index k and the absorption coefficient α) were calculated for Azo Dye (1-Phenylazo-2-Naphthol) thin films by using spectrophotometer measurements of the transmittance and reflectance at normal incidence in the spectral range 400–2200 nm. The obtained values of both n and k were found to be independent of the film thicknesses. The refractive index has anomalous behavior in the wavelength range 400–1000 nm besides a high energy transition at 2.385 eV. The optical parameters (the dispersion energy Ed, the oscillation energy Eo, the room temperature optical dielectric constant , the lattice dielectric constant , the high frequency dielectric constant and the ratio of carrier concentration to the effective mass ) were calculated. The allowed optical transition responsible for optical absorption was found to be direct transition with optical energy gap of 1.5 eV for Azo Dye sample. The band tail obeys Urbach's empirical relation.
PACS: 61. – Structure of solids and liquids; crystallography / 68.55.-a – Thin film structure and morphology / 78. – Optical properties, condensed-matter spectroscopy and other interactions of radiation and particles with condensed matter
© EDP Sciences, 2009
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