Modifying the optical properties of hydrogen-beam-irradiated flexible PVA polymeric films

In this study, poly(vinyl alcohol) (PVA) films were irradiated with hydrogen beams with fluences of 8 × 10¹⁷, 16 × 10¹⁷ and 24 × 10¹⁷ ions/cm² using a handmade cold beam ion source. The resulting changes in the structural characteristics and functional groups of irradiated PVA films were studied using the X-ray diffraction and Fourier transform infrared spectroscopy methods, respectively. Besides, the optical bandgaps and Urbach energies of untreated and irradiated PVA were calculated using Tauc’s equation. The tail is 1.29 eV for PVA, which improved to 1.59 and 4.17 eV when PVA was exposed to 8 × 10¹⁷ and 24 × 10¹⁷ ions/cm² beams, respectively. Furthermore, the parameters of untreated and treated samples, including refractive index, extinction coefficient, conductivities and permittivity, were calculated. Furthermore, the dispersion characteristics of unirradiated and treated films were evaluated. With an increase in hydrogen fluence from 8 × 10¹⁷ to 24 × 10¹⁷ ions/cm², the relaxation time was reduced from 2.75 × 10⁻¹⁴ to 0.045 × 10⁻¹⁴ s. Moreover, the optical susceptibility of pure and treated PVA was calculated. The modification induced in the optical characteristics of the irradiated films suggests that these films can be applied in different uses such as in optoelectronic devices.