Effect of europium doping on structural, optical and fluorescence lifetime studies of CuS nanostructures

Abstract

The purpose of the current study was to examine the impact of varying concentrations of Europium (Eu) atoms on the physical properties of copper sulphide (CuS) nanostructures designed for optical and fluorescence studies. CuS nanostructures were grown using the hydrothermal method and subsequently evaluated their structural, optical, and morphological characteristics. Nanostructures of CuS doped with Eu at levels of 0, 1, 3, 5, and 7 at. % were synthesised. For the purpose of analysing their properties, various characterisation instruments like X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), UV–Vis, photoluminescence, and FESEM were utilised. Chemical states were analysed using XPS. The XRD analysis of CuS revealed its hexagonal structure in the covellite phase and samples doped with Eu showed an increment in crystallite size. Eu-doped CuS nanostructures exhibit bandgap increment with the introduction of doping. FESEM analysis reveals the formation of flower-like structures resembling spheres, while lower magnification identifies the presence of nanoflakes. Room-temperature photoluminescence analysis was performed utilising a fluorescence spectrophotometer, revealing orange-red emission peaks at an excitation wavelength of 350 nm. The colour-correlation temperature (CCT) and colour index of extinction (CIE) values of the synthesised samples indicate significant potential for application in display technology. The analysis of fluorescence lifetime and decay in CuS nanostructures doped with Eu was validated through fluorescence lifetime measurements, indicating that the Eu dopant serves as a fluorescence-enhancing agent. Their unique luminescent properties, particularly the strong red emission, suggest potential applications in red-emitting phosphors, white LEDs, high-energy batteries, and supercapacitors.