Linear and nonlinear optical properties of FeCl3/PVA composite flexible films for optoelectronic applications

The effect of FeCl3 loading in the poly (vinyl alcohol) (PVA) matrix can design composite films with improvement in the structural and optical properties. PVA/FeCl3 composite films with different contents of FeCl3 (0, 2.5, 5, 10, and 15 wt.%) were prepared by casting method. FTIR spectrophotometer and XRD pattern were utilized to examine the variation in the PCs' structural characteristics and the structural composition, respectively. FTIR spectra of PVA/FeCl3 exhibited peaks at similar wave numbers to pure PVA, indicating that FeCl3 has no impact on the PVA structural properties, while XRD showed the semi-crystalline nature of PVA. The UV-visible-NIR spectra measurements were used to analyze the optical performance. The absorbance, transmittance, direct energy gap, Urbach energy, extinction coefficient, and refractive index were studied. The direct band gap reduced with increasing FeCl3 in PVA matrix. Wemple and DiDomenico's model was used to determine the fundamental parameters, including single-oscillator energy (E-o), dispersion energy (Ed()), and static refractive index (n(o)). The third-order nonlinear optical susceptibility chi((3)), nonlinear refractive index (n(2)), electrical susceptibility, and relative permittivity were increased with increasing FeCl3 in PVA matrix. So, PVA/FeCl3 composite polymer films show promise for flexible optoelectronic applications.