Sustainable bio-dye doped PVA films with boosting charge carrier density and optical mobility for flexible optoelectronic applications

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In this study, PVA films doped with natural Malta peel dye (MPD) were prepared and their structural and optical properties were investigated. FTIR analysis confirmed interactions between MPD molecules and the PVA polymer matrix through variations in characteristic vibrational bands. X-ray diffraction (XRD) results indicated a reduction in the intensity and sharpness of the main crystalline peak of PVA at approximately 20°, suggesting a decrease in crystallinity upon dye incorporation. UV–Vis absorption spectra showed a shift of the absorption edge from the ultraviolet region (≈ 270 nm) for pure PVA to the visible region (420–450 nm) for MPD-doped films. Optical parameters, including absorption coefficient, Urbach energy, and steepness parameter, were evaluated for all samples. The direct and indirect optical band gaps decreased from 4.79 eV (pure PVA) to 2.60 eV (MPD-doped PVA). Additional optical dispersion parameters ( \(\:{E}_{d}\) , \(\:{E}_{o}\) , \(\:{n}_{0}\) , \(\:f\) , \(\:{M}_{-1}\) , \(\:{M}_{-3}\) , \(\:{S}_{o}\) , and \(\:{\lambda\:}_{o}\) ) were determined using the Wemple–DiDomenico model. Furthermore, Drude–Lorentz analysis was used to extract parameters including \(\:N/{m}^{*}\) , \(\:{\omega\:}_{p}\) , \(\:\tau\:\) , and \(\:{\mu\:}_{opt}\) . The reported results describe the structural and optical modifications in PVA films induced by MPD doping.