Fabrication and characterization of eco-friendly PVA/chitosan/TEA-TOS composites as a potential light-absorbing...

The need for efficient and reliable multifunctional optical and optoelectronic devices is driving the development of new materials. In this work, a novel eco-friendly biopolymer composite based on PVA, chitosan, and the ionic liquid [TEA-TOS] is developed as an efficient light-absorbing material for energy storage and optoelectronic applications. PVA/chitosan/[TEA-TOS] composites are successfully prepared using casting technique. The molecular structure and interaction between the PVA/Cs matrix and the [TEA-TOS] ionic liquid are evaluated using X-ray diffraction (XRD) and FTIR spectroscopy. XRD analysis showed that crystallinity is reduced from 55.65% for PVA/Cs blend to 29.82% for PVA/Cs/40 wt% TEA-TOS composite. The shifts and changes in the intensity of the FTIR bands of the PVA/Cs blend upon incorporation of [TEA-TOS] showed the formation of strong intermolecular interactions between PVA/Cs and [TEA-TOS]. The energy gap and Urbach energy values, as well as linear/nonlinear optical parameters of the composites are estimated. It is found that the bandgap reduced from 5.62/5.01 eV for pure PVA/Cs to 5.00/4.68 eV for PVA/Cs/40 wt% [TEA-TOS], indicating improved optoelectronic performance. UV-Vis spectroscopy demonstrated confirmed that the optical properties of the samples could be tailored by adjusting the [TEA-TOS] content. The Wemple model further confirmed the modification of electronic transitions, demonstrating that the incorporation of [TEA-TOS] effectively tunes the optical behavior of PVA/Cs films for potential optoelectronic applications.