Structural, surface morphological and optical properties and their correlation with the thickness of spin coated superior quality CdS thin film synthesized using a novel chemical route

Abstract

Cadmium sulfide (CdS) is considered as a superior buffer/window layer in thin-film solar cells apart from its various applications. The thickness of the buffer/window layer that defines the interface between the absorber layer is very important and needs to be thoroughly investigated for optimized device performance, particularly when a novel synthesis route and deposition technique is used. This manuscript presents the investigation on the various structural, morphological, and optical parameters and their correlation with the thickness of CdS thin film synthesized using a novel thiol-amine cosolvent with the help of Triton-X 100 surfactant. Spin coating technique is used to deposit CdS thin-films having thicknesses ranging from 100 to 300 nm on a glass substrate. X-ray diffraction (XRD) exposed the polycrystalline nature of the CdS films. All the diffraction peak intensities were found to increase with the thickness. Structural parameters like dislocation density, lattice strain, and crystallites per unit area calculated from the XRD data were found superior to those parameters for CdS films synthesized through various chemical routes, and the parameters indicated a positive correlation of the degree of crystallinity on the thickness. Similarly,surface morphology and optical properties of CdS films that were investigated by the scanning electron microscope (SEM) and UV–VIS spectrophotometer, were also dependent on film thickness. These results show that CdS thin film with superior crystallinity can be synthesized using thiol-amine cosolvent along with the Triton-X 100 surfactant and deposited by low-cost spin-coating on glass substrate. Moreover, the thickness variation appeared to be a single tool for obtaining application-specific various properties of CdS thin-film.