Flexible and innovative PVA/ZrO2/g-C3N4/CNT nanocomposites film for optoelectronic applications

This study successfully prepared polyvinyl alcohol (PVA) polymer films doped with ZrO₂/(g-C₃N₄/CNT) nanofillers using the solution casting technique. The crystal structure of the nanocomposite films was characterized by X-ray diffraction (XRD), revealing the semi-crystalline nature of PVA and an average ZrO₂ crystallite size of 13.17 nm. Fourier-transform infrared (FTIR) spectroscopy confirmed the chemical composition and functional groups present in the nanocomposites. Scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis showed uniform dispersion of the nanofillers without noticeable phase separation, with EDX confirming the successful incorporation of ZrO₂, g-C₃N₄, and CNT into the PVA matrix. X-ray photoelectron spectroscopy (XPS) further validated the elemental composition and chemical states, indicating the presence of carbon, oxygen, nitrogen, and zirconium. Optical analysis demonstrated that increasing ZrO₂/(g-C₃N₄/CNT) content reduced the direct and indirect band gaps from 5.41 eV to 5.25 eV and from 5.18 eV to 4.92 eV, respectively. In addition, the single-oscillator energy (E₀) and dispersion energy (E_d) increased, while the static refractive index (n₀) decreased. Improvements were also observed in linear optical susceptibility (χ⁽¹⁾) and third-order nonlinear optical susceptibility (χ⁽³⁾), enhancing the polarizability of the polymer molecules. These results indicate that PVA films doped with ZrO₂/(g-C₃N₄/CNT) hold promise for optoelectronic applications due to their enhanced optical properties.