Optical properties of synthesized PVA/Cellulose phosphate composite films doped with Zn2+ ions for optical device applications

In this work, composite films of polyvinyl alcohol/cellulose phosphate doped with Zn2+ (PVA/CP/Zn2+) were prepared through a film casting procedure. The prepared films were analyzed using XRD, FTIR, TGA, and SEM. The XRD revealed a decrease in the semi-crystalline nature as Zn2+ concentrations increased. The TGA showed enhanced thermal stability for the composite films, where the SEM images illustrated the formation of a non-homogeneous surface morphology. The transmittance-absorption spectroscopic measurements showed a noticeable decrease in both the indirect energy gap (Eig) and the direct energy gap (Eg). Eig was decreased from 5.05 to 4.77 eV and Eg decreased from 5.51 eV to 5.12 eV with increasing Zn2+ concentration from zero to 14 wt%. Moreover, the transition strength (Ed), oscillator wavelength (λo), and the excitation energy (Es) were found to increase as Zn2+ content increased. These findings not only shed light on the physicochemical attributes of the prepared films but also emphasize their promising potential utilization in optical components.