Investigating the structural and optical properties of thermally evaporated 1,3,3-trimethylindolino-β-naphthopyrylospiran thin films

Abstract

1,3,3-Trimethylindolino-β-naphthopyrylospiran (SO) thin films were synthesised using thermal evaporation technique. The crystal structure of the (SO) compound as powder and thin film forms was studied using X-ray diffraction (XRD), transmission electron microscope, and Fourier transformation infrared techniques. Subsequently, Miller’s indices, hkl, values were estimated for each individual peak in the XRD chart of powder form and given a polycrystalline with monoclinic structure. The optical properties of the thin films as-deposited were inspected using spectrophotometric measurements of reflectance and transmittance in the wavelength range from 200 to 2500 nm. The refractive index, n, and the absorption index, k, were calculated. The electronic transitions of as-deposited thin film were direct transitions with energy gap of ~2.3 eV. Regarding the obtained data in normal dispersion region, the optical parameters, such as oscillator energy, E o, dispersion energy, E d, lattice dielectric constant, e L, high frequency dielectric constant, e ∞, and the ratio of the free charge carrier concentration to the effective mass, N/m*, were estimated. Finally, the extinction molar coefficient, e molar, oscillator strength, the electric dipole strength, dielectric constant, and loss tangent are calculated for the films.