Structural and optical analysis of eosin Y-doped polymeric blend (PVA/PVP) films for solar energy: towards multi-bandgap solar absorbing materials

Abstract

The progression of the optical field employing dye materials has created remarkable attention in optoelectronics technology. The polymeric blend of Polyvinyl alcohol (PVA)/Polyvinyl pyrrolidone (PVP) was doped with various weight concentrations of eosin Y (EY) dye ((0, 0.06, 0.3, 0.6, 2.96, 5.925, and 17.77 wt%), using a simple, low-cost, effective, and friendly solution casting method. The synthesised EY-PVA/PVP polymeric films’ semi-crystallinity and the impact of the various doped concentrations on the degree of crystallinity size, dislocation, and lattice strain were both validated by the X-ray diffraction (XRD) results. The functional chemical groups and significant intermolecular interaction between the host PVA/PVP polymeric matrix and the filler eosin Y dye were validated by the FT-IR approach. The significant impacts of different EY dye weight percentages on the optical characteristics, absorbance, transmittance, absorption coefficient, and optical energy direct/indirect bandgaps of the suggested EY: PVA/PVP composite polymeric films were examined using UV–Vis-NIR spectrophotometry. The transmission was recorded to be 87% for the 17.77 wt% EY-doped composite at 1300 nm. The absorption spectra depicted three intense peaks at 517, 313, and 199 nm wavelengths, which were dropped with the increase in wt% concentration for the EY-doped PVA/PVP films. Another standout characteristic is the attenuation of total absorption, visible as a cut-off absorbance in approximately 600 nm wavelength. The optical energy bandgap for the host PVA/PVP blend polymer was about 5.19 eV, while the indirect value was 4.96 eV. Directly bandgaps for the EY-doped PVA/PVP composites lowered from 5.35 eV to 1.94 eV, where the second region of the direct energy gap is in the range of 3.71–2.69 eV, and the third is in the 2.24–1.94 eV range. The optical limiting effects of two laser sources (532 nm green diode) and (635 nm He–Ne) using a (fixed sample holder) Z-scan system were studied for the planned EY-doped PVA/PVP polymeric films. The remarkable structural and amazing optical results of the novel EY-doped PVA/PVP composite polymeric films have approved the ability for optoelectronics, cut-off filters, solar cells, LEDs, communication devices, optical switches, and optical laser limiters.