Radiation-induced photoluminescence enhancement of zinc oxide and zinc oxide- polyvinyl alcohol nanocomposite: A green and controllable approach for tailor-made optoelectronics

Abstract

The structural and optical properties of gamma-ray-irradiated ZnO and ZnO-PVA nanocomposites, synthesized via a one-pot method, were investigated. The samples were analyzed before and after irradiation at doses up to 26 kGy using UV–Vis spectroscopy, photoluminescence spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and surface frequency generation spectroscopy. X-ray diffraction confirmed the hexagonal wurtzite structure of ZnO, while electron microscopy revealed the embedment of 40 nm ZnO nanoparticles into the PVA matrix. Shifts and decreased ratio of the CH₂–CH₂ FT-IR vibrations at 1420 cm⁻¹ and combined CH₂–CH₂/CH₂–O–CH₂ stretching at 1143 cm⁻¹ indicated not only polymer matrix dislocation resulting from incorporation of ZnO nanoparticles in the PVA matrix but also cross-linking of the polymer chains upon irradiation. Surface frequency generation spectroscopy further confirmed PVA adherence and bonding to ZnO surfaces. Photoluminescence studies revealed significant changes in the energy and intensity of the near-band-edge emission of irradiated ZnO nanoparticles attributed to the annealing of surface defects. UV–Vis spectroscopy of ZnO-PVA showed a dose-dependent absorption increase at 280 nm, suggesting polymer cross-linking. Additionally, the intensity of the blue photoluminescent peak located around 445 nm increased with irradiation dose indicating dose-dependent enhancement of ZnO-PVA bonding. These findings demonstrate that gamma-ray irradiation effectively modifies the optical and surface properties of ZnO-based materials, enhancing their performance for applications in flexible optoelectronics, light-emitting devices, and environmental sensors. The ability to precisely control material properties through irradiation offers new opportunities for developing advanced functional materials with improved performance and sustainability.