Synthesis, characterizations, optical and photoluminescence properties of polymer blend PVA/PEG films doped eosin Y (EY) dye

Abstract

A solution casting process has been used to produce PAV/PEG/EY blend polymer composite films with different PEG concentrations. The structure and morphological of PAV/PEG/EY blend composite film have been characterized by XRD, TGA, FT-IR, TEM,SEM, EDAX and the UV–vis spectra were used to investigate the optical properties. The absorption spectra show a critical change in absorbance around (λ = 580 nm, photon energy = 2.13ev), which corresponds to the energy gap of the blend. The same behavior of refractive index, n, the extinction coefficient k and dispersion parameters were noticed. Optical energy band gap using Kubelka–Munk coordinate was estimated for direct and indirect allowed transitions, which was found to be 2.58eV for direct transition and 2.47 for indirect transition. The real and imaginary parts of the dielectric constant, εr and εi are quite consistent with the absorption spectra and show a sharp change around λ = 560 with photon energy = 2.21 eV and corresponds to the average energy gap of the blend. The optical conductivity, σopt, was sharply changed at the same value of wavelength. With increasing PEG content in the of PVA/PEG/EY composite samples films, the emission peaks regarding the photoluminescence and fluorescence properties are red shifted, with the highest emission occurred at wavelengths ranges from λem=553to575nm. These values are very close to the energy gap values founded earlier in this work.