Ammonium iodide salt-doped polyvinyl alcohol polymeric electrolyte for UV-shielding filters: synthesis, optical and dielectric characteristics

Polyvinyl alcohol (PVA) incorporated with various amounts of ammonium iodide salt (NH₄I) composite polymer electrolyte films were prepared via the casting process. The XRD analysis, as a tool for structural investigation, confirms the polymer electrolytes formation. The transmittances of the studied samples are decreased with increasing NH₄I fillers. The UV–Vis absorption spectra are shifted to the higher wavelengths, which indicate their importance for light shielding devices. The bandgaps decrease with the increase in NH₄I content, attributed to the increase in the crystallite size. The calculated Urbach energy was found to increase with increasing NH₄I salt fillers. The samples' optical limiting is carefully investigated using a He–Ne laser beam of wavelength = 632.8 nm. This result enhances light absorption behavior and makes the material suitable for optical UV-protection devices. The correlation between dielectric properties and conductivity is also understood and discussed. The dielectric permittivity ε' of the samples is associated with the dipole, and polarization increased with the addition of NH₄I salt content as the particle size increased according to XRD analysis. AC impedance spectroscopy was carried out to disclose the PVA doped with NH₄I polymer electrolyte films as a function of various NH₄I salt fillers. The analysis via complex electric modulus gives abnormal behavior by adding NH₄I salt content, where the minimization of the electrode polarization can be achieved. Our results indicate that the newly designed composite polymeric electrolyte films are commonly appropriate for electronic and optoelectronic devices.