Influence of UV irradiation on the structural and optical properties of Ch-HPQ thin films

Abstract

The influence of ultraviolet (UV) irradiation on the structural, linear optical and non-linear optical properties of 2-Amino-4-(2-chlorophenyl)-6-ethyl-5-oxo-5,6-dihydro-4H-pyrano [3,2-c] quinoline-3-carbonitrile (Ch-HPQ) thin films is elaborated. The morphology of the UV irradiated, for different irradiation times, Ch-HPQ thin films is studied using both scanning electron microscopy and X-ray diffraction and compared with the UV non irradiated one. The transmittance and reflectance spectra of Ch-HPQ thin films are studied based on spectrophotometric measurements in the spectral range (200–2500) nm. Several parameters (e.g. the molar extinction coefficient, the onset and optical energy gap values) are calculated from the absorption spectra. Dispersion of the studied material is explained by Wemple and Di Domenico single-oscillator model. The influence of UV irradiation on the loss functions is discussed. The theoretical calculations of the non-linear optical parameters such as third order non-linear susceptibility and the non-linear refractive index are investigated from linear optical parameters using semi-empirical relations. The homogeneity of Ch-HPQ thin films are found to be stable under the UV irradiation which recommends using this material in optoelectronic applications.