Optical and morphological properties of poly(vinyl chloride)-nano-chitosan composites doped with TiO2 and Cr2O3 nanoparticles and their potential for solar energy applications

In the present work, the poly(vinyl chloride) (PVC)-nano-chitosan thin films were prepared, and the influence of filling Cr2O3 and TiO2 nanoparticles on the lattice was investigated. PVC and nano-chitosan (15 wt.%) were dissolved in tetrahydrofuran (THF) to ultimately form thin films by the casting method. The thin films' optical properties were characterized via a diffusive reflectance device within an approximate wavelength range of 250 to 1300 nm. Furthermore, the transmittance, reflectance, refractive index, absorption, optical conductivity, skin depth, dielectric constant, and Urbach energy were computed. The absorbance values of plain and NPs-filled thin films ranged between 92 and 99%. Also, the energy gap of films filled with NPs was reduced in the direct transmission from 3.9 to 2.9 eV and in the indirect transition from 3.0 to 2.55 eV. However, similar behavior for the Urbach energy was observed. The Fourier-transform infrared (FTIR) spectroscopy was used to study the interaction between the PVC and nano-chitosan as a new polymer composite. The X-ray powder diffraction (XRD) test showed a crystalline structure of the thin films, while the microscopic and atomic force microscopy (AFM) images demonstrated a good dispersion of nano-chitosan and NPs within the PVC lattice. The synthesized films could be good candidates for optoelectronics, glass processing, and ceramic production applications.