Synthesis and characterization of La3+ ions incorporated (PVA/PVP) polymer composite films for optoelectronics devices

Abstract

Polymer rare-earth composite films PVA/PVP–xLa3+ (xwt%; x = 0, 3, 5, 10, and 15) were fabricated by the solution casting method. The structural parameters of these films were determined from X-ray diffraction (XRD) pattern analysis, and the complexation of La3+ ions with the polymer composite films was studied by Fourier transform infrared (FT-IR) spectroscopy. The optical energy gap (Eopt.) and the high-frequency refractive index (n) were determined from UV–Vis transmission spectra analysis. AC electrical conductivity and dielectric characterization of the polymer composite films have been investigated. The structural parameters of the inter-planar (d) spacing, crystallite length (D), and the average crystallite separation (R) and the FT-IR spectra indicate strong bonding of La3+ ions with the carbonyl groups of the polymer composite chains. The optical gaps of the films determined by Tauc’s relation and optical absorption fitting (ASF) exhibit a slight decrease by increasing La3+ ions content, whereas the refractive indices show a slight increase. High values of the dielectric parameter e′ and dielectric loss e″ were produced in pure PVA/PVP composite polymer films, and they tend to decrease by increasing La3+ ions content in the PVA/PVP composite films due to decreasing directional polarization and ionic polarization in the films with increasing La3+ ions content. The minimum energy loss occurred at 70 kHz and these materials may be selected to be used in energy applications. I–V characteristics show a linear-like ohmic behavior because La ions are bonded well in the structure of polymers and became part of it.