Preparation of Nanocrystalline CdS Thin Films by a New Chemical Bath Deposition Route for Application in Solar Cells as Antireflection Coatings

Nanocrystalline cadmium sulfide thin films as antireflection materials for solar cells have been prepared by a new chemical solution deposition route in an aqueous medium at 50 °C. as-deposited thin films were studied using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and optical absorption spectra. X-ray diffraction data indicated the formation of hexagonal nanocrystalline CdS thin films as the predominant phase. High film deposition rates, film uniformity and low percentage of reflection are achieved by proper optimization of CdS chemical bath. The as-deposited CdS films had more than 85% transmittance in the visible region. The direct band gap energy (Eg) of as-deposited films ranged from 3.85 to 3.90 eV depending on deposition time. This increase in Eg of deposited thin films can be assigned to the quantum size effect as expected from the nanocrystalline nature of the CdS thin films.