Abstract
A conventional casting method was used to produce promoted polyvinyl alcohol (PVA) films via rubrene additive. The 1.2 g of PVA dissolved in 120 ml of distilled water and doped with various concentrations (0, 0.1, 0.3 and 0.4 wt%) of rubrene dye. The influence of rubrene dopants on the structural properties of PVA was studied using FTIR and XRD techniques. The semicrystalline nature of the PVA polymer was established by the XRD pattern. FT-IR analysis shows changes in peaks intensities of PVA and their widths are expanded in the presence of rubrene dopants which indicates the interactions between the functional groups of PVA and the rubrene dopants. XRD patterns exhibit the existence of rubrene inside the PVA structure leads to form cross-linking which enhances the amorphous nature within the doped PVA samples. The optical characteristics were investigated using spectrophotometric measurements of transmittance T(λ), reflectance R(λ), and absorbance A(λ) in the spectral range of 200–2500 nm. The indirect and direct optical band-gap values of PVA films decreased from 5.15 eV and 5.69 eV to 3.63 eV and 4.50 eV as rubrene doping ratio was increased from 0 to 0.4 wt%, respectively. The refractive index dispersion region was explained using the single oscillator (Wemple–DiDomenico) model. The extracted values of dispersion energy (Ed), dielectric constant at infinite frequency (ε∞) and lattice dielectric constant (εL) of PVA/rubrene composite films increased from 0.74 eV, 1.31 and 1.35 to 5.35 eV, 3.47 and 4.35; respectively, whereas oscillator energy (Eo) decreased from 2.41eV to 2.17 eV as rubrene contents increased from 0 to 0.4 wt%, respectively. Indeed, these changes in values of dispersion parameters is evidence to the cross-linking bonds between the host polymer and the rubrene dopants. The improvement of optical properties of PVA/rubrene films demonstrates their applicability as eco-friendly packaging materials, particularly in flexible optoelectronic and microelectronic devices.
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•PVA/rubrene composite films were synthesized using a casting method.•The addition of rubrene dopants in the PVA polymer leads to a decrease in the diffraction peak intensities in XRD spectra.•The estimated values of the band gap decrease with the increase of rubrene content.•The refractive index dispersion was explained using the single oscillator (Wemple– Didomenico) model.•The prepared films can be used as eco-friendly transparent packaging materials for a variety of microelectronic devices.