Structural, characterization and linear/nonlinear optical properties of oxygen beam irradiated PEO/NiO composite films

In this work, PEO/NiO films composed of polyethylene oxide (PEO) and nickel oxide (NiO) were fabricated using solution cast method to be used in optoelectronics applications. The PEO/NiO films are irradiated by oxygen fluence of 0.8 × 10¹⁸, 1.6 × 10¹⁸, and 2.4 × 10¹⁸ ions/cm². The XRD as well as FTIR techniques were used to assess the effect of ion bombardment on the crystalline structures and functional group of PEO/NiO films. The absorption (A) and reflection (R) of the untreated and irradiated films was determined using UV–vis spectrophotometer in wavelength range of 200 to 1000 nm at room temperature. The data of A and R were used to calculate the parameters including band gap (E_g), absorption coefficient (α) and refractive index (n). The band gap as well as Urbach energies of un-bombarded as well as bombarded PEO/NiO films was calculated by Tauc's relationship. The band gap is reduced from 3.37 eV for PEO/NiO, to 2.66 eV, 2.57 eV and 2.50 eV after exposed to 0.8 × 10¹⁸, 1.6 × 10¹⁸, and 2.4 × 10¹⁸ ions/cm² correspondingly, Moreover, the ubrach band tail is increased from 1.25 eV for PEO/NiO to 1.36 eV,1.41 eV and 1.45 eV after oxygen irradiation respectively. Additionally, linear optical characteristics have been calculated, including the refractive index and dielectric constant. The dispersing factors of the investigated films have also been computed using the Wemple-Di-Domenico model. The non-linear optic susceptibilities and refractive indices are calculated for un-bombarded as well as bombarded films. This work concluded that the optical behaviour of the bombarded PEO/NiO composite films were modified, indicating that these composites films can used in optoelectronics devices.