Tuning the Optical, Electrical and Dielectric Properties of Sodium Alginate/Polyethylene Glycol Blend by Incorporating AgNO₃ NPs for Optoelectronic Devices and Energy Storage Applications

This study investigates the properties of novel flexible polymer nanocomposite films made with polyethylene glycol (PEG), sodium alginate (NaAlg), and silver nitrate (AgNO₃) nanoparticles. The nanocomposites were fabricated using a casting method and characterized by various techniques to understand the influence of AgNO₃ content on their optical, electrical and dielectric properties. The frequency range for characterization was 10 Hz to 7 MHz. XRD analysis revealed a decrease in the intensity of the peaks in the nanocomposite films compared to the pristine blend, suggesting changes in the crystalline structure with increasing AgNO₃ concentration. FT-IR spectroscopy confirmed the successful formation of the composite material through interaction between the components. Ultraviolet-visible (UV-Vis) spectroscopy was utilized to examine the optical properties of the films. Tauc’s plot analysis was used to calculate the energy bandgap values for both direct and indirect transitions in the nanocomposites. The results showed a decrease in the bandgap (E_g) with increasing AgNO₃ content. This trend was observed for both direct transitions (E_g decreasing from 5.59 eV to 5.16 eV) and indirect transitions (E_g decreasing from 4.93 eV to 3.95 eV). Electrical and dielectric characterization revealed that the nanocomposite with 20 wt% AgNO₃ loading exhibited the most favorable electrical properties. The direct current conductivity (σ_dc) increased significantly from 2.55 × 10^− 10 S/cm to 5.65 × 10^− 9 S/cm, while the frequency exponent (S) decreased from 0.81 to 0.49. These observations suggest significant modifications in the electrical transport behavior of the films upon AgNO₃ incorporation. The improved electrical properties make these PEG/NaAlg-AgNO₃ nanocomposites promising candidates for applications in flexible solar cells and electrical energy storage devices.