Investigating the differences in structure, morphology, optical properties, laser photoluminescence and dielectric properties for chitosan-doped commercial and Polycladia myrica mediated ZnO nanoparticles films combined with TD-DFT simulations

Abstract

A homogeneous solution of chitosan nanoparticles in acetic acid was prepared as nano-monoblend thin film [Chit]TF. The biosynthesis ZnO nanoparticles [ZnO(b)]NPs were prepared via Polycladia myrica algal extract. A mono-nanocomposite of the chitosan nano-monoblend with commercial ZnO nanoparticles and bio ZnO nanoparticles [Chit/ZnO(c)]MNC and [Chit/ZnO(b)]MNC was synthesized using the dip casting deposition technique, respectively. Geometry optimization was achieved using TD-DFTD/Mol3 and Cambridge Serial Total Energy Bundle (TD-FDT/CASTEP) modules of the Density functional theory (TD-DFT). Molecular structure was studied and confirmed by the close matching between the experimental and simulated XRD patterns. [Chit]TF, [Chit/ZnO(c)] MNC and [Chit/ZnO(b)]MNC found to have an average crystallite size of 95.03 nm, 63.33 nm and 50.44 nm according to the calculations of XRD data. Optical energy gab of the direct allowed transition for [Chit]TF, [Chit/ZnO(c)] MNC and [Chit/ZnO(b)]MNC found to be 2.95, 2.885 and 2.705 eV, respectively. While, the simulated calculations of the isolated molecules [Chit]Iso and [Chit/ZnO]MNC/Iso by TD-DFT/DMol3 measured the energy gab as 3.217 and 2.83 eV, respectively. The suggested optical properties using CASTEP in TD-DFT agree quite well with the experimental values. A small difference in the dielectric properties between [Chit/ZnO(c)] MNC and [Chit/ZnO(b)]MNC was observed since [Chit/ZnO(b)]MNC found to have lower dielectric constant and conductivity values and higher electric modulus and impedance values. The wide range optical energy gab and good optical and dielectric properties of [Chit/ZnO(c)] MNC and [Chit/ZnO(b)]MNC are advantageous for various optoelectronic applications.