Insights into Optical Characteristics of PVA Polymer Doped with Natural Dye Derived from Solanum lycopersicum Peel

Abstract

Environmentally friendly materials made from renewable resources, have received much attention lately in green chemistry. In this study the structural and optical characteristics of polyvinyl alcohol (PVA) thin films containing natural dye derived from Solanum lycopersicum (tomato) peel were examined. The results of XRD analysis shows that the intensity of the characteristic diffraction peaks reduces, indicating an increase in the amorphous fraction in the polymer composite films. The FTIR spectra show a strong interaction between the functional groups of the tomato peel dye (TPD) and the PVA matrix. Data from UV-Vis-NIR tests show that doping causes enhanced light absorption and redshift in the absorption edge. Using Tauc and dielectric loss techniques, the energy band gap drops from 5.15 eV for pure PVA to 4.78 eV for the dye-doped film. Additionally, a refractive index increase to the value of 2.65 for the doped compound. All samples exhibit direct forbidden electronic transitions. These findings demonstrate that tomato peel-derived dye is an effective, sustainable modifier for tailoring the optical properties of PVA for potential optoelectronic applications.