Linear and non-linear optics of nano-scale 2′,7′dichloro-fluorescein/FTO optical system: Bandgap and dielectric analysis.

2′,7′ dichloro-Fluorescein (DCF) is a promising organic semiconductor material in different technological aspects such as solar cell, photodiode, Schottky diode. DCF thin film/conductive glass (FTO glass) was prepared by a low-cost spin coating technique. The spectrophotometric data such as the absorbance, reflectance and transmittance were cogitated in the 350–2500 nm wavelength range, at the normal incidence. The absorption ( n ) and linear refractive indices ( k ) were computed using the Fresnel's equations. The optical band gap was evaluated and it was found that there is two band gap described as follows: (1) It is related to the band gap of FTO/glass which is equal 3.4 eV and (2) the second one is related to the absorption edge of DCF equals 2.25 eV. The non-linear parameters such as the refractive index ( n 2 ) and optical susceptibility χ (3) were evaluated by the spectroscopic method based on the refractive index. Both ( n 2 ) and χ (3) increased rapidly on increasing the wavelength with redshift absorption. Our work represents a new idea about using FTO glass for a new generation of the optical device and technology. [ABSTRACT FROM AUTHOR]