Tuning the band gap, optical, mechanical, and electrical features of a bio-blend by Cr₂O₃/V₂O₅ nanofillers for optoelectronics and energy applications

This work presents a facile approach for controlling the optical and electrical parameters of a biopolymeric matrix for optoelectronics. Vanadium oxide (V₂O₅) and chromium oxide (Cr₂O₃) nanoparticles (NPs) were prepared and incorporated into the carboxymethylcellulose/polyethylene glycol (CMC/PEG) blend by simple chemical techniques. Transmission electron microscopy (HR-TEM), and X-ray diffraction (XRD) data showed that V₂O₅ and Cr₂O₃ exhibited spherical shapes with sizes in the range of 40–50 nm and 10–20 nm, respectively. In addition, the blend's degree of crystallinity was sensitive to the V₂O₅ and Cr₂O₃ doping ratios. The scanning electron microscopy (FE-SEM) and the elemental chemical analysis (EDAX) used to study the filler distribution inside the blend, and confirmed the existence of both V and Cr in the matrix. Fourier transform infrared (FTIR) spectroscopy showed that the dopants significantly affected the blend reactive (C–O–C, OH, and C=O) groups. The stress–strain curves illustrated the reinforcing effect of the dopants up to 1.0 \(\text{wt\%}\) $\text{wt\%}$ Cr₂O₃/V. The transmittance and absorption index spectra in the visible-IR wavelengths decreased with increasing filler content. Utilizing Tauc's relation and (optical) dielectric loss, the direct (indirect) band gap narrowed from 5.6 (4.5) eV to 4.7 (3.05) eV at 1.0   \(\text{wt\%}\) $\text{wt\%}$ Cr₂O₃/V. All films have an index of refraction in the range of 1.93–2.17. AC conductivity was improved with increasing filler content and temperature. The energy density at 50 °C is in the range of 1–3 J/m³. The influence of V₂O₅ and Cr₂O₃ content on the optical conductivity, dielectric constant, loss, and dielectric modulus of CMC/PEG was reported. These enhancements in electrical and optical properties, along with the potential for band gap engineering, offer promising prospects for advanced applications in optoelectronics and energy-related fields.