Dopant induced modifications in the microstructure and nonlinear optical properties of 4N4MSP chalcone doped PVA films

4M4MSP doped PVA films were prepared with dopant concentrations of 0.1, 0.25, 0.5, 0.75 and 1.0 wt% by solution casting method. From the study of FTIR spectra of the films the molecular structure was confirmed by the frequency vibrations corresponding to functional group bonding. The frequency shift in the molecular bonding establishes the possibility of formation of charge transfer complexes (CTC). UV–Visible spectra were utilized for following investigations viz: observed the shift in the absorption peaks to the higher wavelength region; decrease in the optical band gap energy from 5.02 (for pure PVA) to 2.33eV, the enhancement in the dielectric constant from 3 (for pure PVA) to 7 in the visible region; and the shift in the dielectric loss towards shorter wavelength upon increase in the dopant concentration. The studies of powder XRD spectrum explore the increase of amorphous nature of the film with the increase of dopant. From the fluorescence spectrum it is observed that fluorescence peak intensity increases up to 0.5 wt% of dopant concentration and for higher concentration it decreases. The significantly superior nonlinear absorption and refraction parameters (~10⁻¹⁰ cm/W and ~10⁻¹¹ esu, respectively) of the composite compared with pure PVA obtained from the femtosecond Z-scan technique suggests the possibility of the composite to be useful in photonics/opto-electronics applications.