Fabrication and characterization of nano-structured ZnS thin films as the buffer layers in solar cells

Abstract

High quality nanocrystalline ZnS thin films were deposited on glass substrates by a chemical bath deposition (CBD) method from an aqueous solution containing triethylamine, as a nontoxic complexing agent for zinc ions, at temperatures ranging from 50 to 90 °C. The effects of the deposition time and temperature on thickness as well as structural, morphological and optical properties of the ZnS thin films were examined by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and ultraviolet-visible (UV-vis) spectroscopy. Fourier transform infrared spectroscopy (FT-IR) studies were done to investigate the presence of organic and/or other compounds in films. UV-vis spectroscopy data revealed the obtained ZnS films to have an optical band gap ranging from 4.1 to 3.9 eV. XRD results showed that the prepared films were highly crystalline with a cubic zinc blende structure consisting of very small nanocrystallites, 2.0–2.5 nm in size, showing quantum confinement effects.