Comprehensive design analysis of ZnO anti-reflection nanostructures for Si solar cells

Six different shapes of zinc oxide (ZnO) nanostructured antireflective coatings on Si substrate, namely hemispheres, pyramids, motheye-like, cubes, rods and hexagonal prisms, were modeled numerically using finite element simulation, by solving Maxwell wave equation for periodic nanostructure arrays. COMSOL Multiphysics commercial package was used to perform the simulation by adopting the wave optics module. Geometrical parameters including structure size and period were studied in order to obtain better insight on how light and matter interaction is affected by structure geometry. However, among the studied structure geometries, hemispherical ones have the worst optical performance with a maximum reflectance of 45% for a 20 nm hemisphere radius. Pyramidal, motheye and cubic shapes yielded an intermediate optical performance while rod and hexagonal shapes revealed a minimum reflectance (less than 5%) values over a wide range of wavelengths and also showing interesting interference patterns.This research was fully supported by the Jordanian Royal Hashemite Court under the Royal Initiative for Innovative Projects in Nanotechnology

Preparation and Characterization of Blank and Nerolidol-Loaded Chitosan–Alginate Nanoparticles

Recently, there has been a growing interest in using natural products as treatment alternatives in several diseases. Nerolidol is a natural product which has been shown to have protective effects in several conditions. The low water solubility of nerolidol and many other natural products limits their delivery to the body. In this research, a drug delivery system composed of alginate and chitosan was fabricated and loaded with nerolidol to enhance its water solubility. The chitosan–alginate nanoparticles were fabricated using a new method including the tween 80 pre-gelation, followed by poly-ionic crosslinking between chitosan negative and alginate positive groups. Several characterization techniques were used to validate the fabricated nanoparticles. The molecular interactions between the chitosan, alginate, and nerolidol molecules were confirmed using the Fourier transform infrared spectroscopy. The ultraviolet spectroscopy showed an absorbance peak of the blank nanoparticles at 200 nm and for the pure nerolidol at 280 nm. Using both scanning and transmission electron microscopy, the nanoparticles were found to be spherical in shape with an average size of 12 nm and 35 nm for the blank chitosan–alginate nanoparticles and the nerolidol-loaded chitosan–alginate nanoparticles, respectively. The nanoparticles were also shown to have a loading capacity of 51.7% and an encapsulation efficiency of 87%. A controlled release profile of the loaded drug for up to 28 h using an in vitro model was also observed, which is more efficient than the free form of nerolidol. In conclusion, chitosan–alginate nanoparticles and nerolidol loaded chitosan–alginate nanoparticles were successfully fabricated and characterized to show potential encapsulation and delivery using an in vitro model