Investigations on optical properties of synthesized covellite CuS hollow nano cubic structures

Abstract

In this work, hollow nanocubes of CuS were synthesized by employing a chemical route via Kirkendall effect. The influence of sulphur concentration on the optical and structural properties of CuS by varying the amount of sulphur during synthesis was investigated. The synthesized hollow cubes were characterized by using Scanning Electron microscope (SEM), X-Ray Diffraction (XRD) Analysis, Ultra Violet -Visible (UV-Vis.) Spectroscopy, Photoluminescence (PL) Spectroscopy, Raman Spectroscopy and X-ray photoelectron Spectroscopy (XPS). The formation of cubic morphology was affirmed by SEM analysis in all three samples. The length of the sidesthe of the cube lies in the range of 500-600 nm. XRD studies confirmed the formation of the pure phase of covellite CuS. Also, XPS analysis validated the presence of excess sulphur in the sample with Cu:S as 1:150 along with variation in the stoichiometric ratio of 1: 0.5. Since, this was not the case for Cu:S as 1:100, as it showed the desired stoichiometry of 1.1: 0.9 that supports the pure phase of CuS. Raman spectra further confirmed the purity of the sample. Absorption analysis revealed a well-defined bandgap with the absence of an intermediate defect state with a bandgap of 1.4 eV in the optimized sample. PL spectra displayed a decent recombination rate and minimum non-radiative losses in the 1:100 sample. These outcomes assurances the sample with Cu:S as 1:100 could be used as a potential material for solar cell applications.