Towards high nonlinear optical susceptibility of Acid Fuchsin dye deposited on FTO substrate for optoelectronic applications

This work aims to investigate the effect of thickness on Acid Fuchsin properties. A spin coater developed Acid Fuchsin as thin films with thicknesses (82–312 nm) on FTO glass substrates. X-ray diffraction was used to determine the structural morphology of these thin films exposing the amorphous structure of all synthesized films. The optical properties of these thin films were studied, and it was discovered that an indirect transition is possible. The Acid Fuchsin/FTO systems have three energy band gaps: 3.61 eV is related to the FTO; and 2.44–2.64 eV and 1.42–1.5 eV are related to the Acid Fuchsin films with thicknesses of the range 82–312 nm. The values of the energy band gap increase slightly with increasing the film thickness. The dispersion and single oscillator energy, static refractive index, and dielectric constant have been determined. They have average values of 2.42 eV, 2.81 eV, 1.47, and 2.16, respectively. The wavelength and thickness dependences of the nonlinear optical parameters have been explored, showing a wide range of values. The high values of the nonlinear parameters at the short wavelengths show the rapid response required for electro-optical applications.