Doping-induced structural and optical modifications in γ-CuI nanocrystals

Abstract

This study investigates the structural and optical properties of doped CuI nanocrystals synthesized using a facile chemical method. Cadmium (Cd) and iron (Fe) were used as dopants, resulting in CuI–Cd and CuI–Fe samples. X-ray diffraction (XRD) was employed to characterize the crystal structure and phase purity. Rietveld refinement of the XRD data provided significant refinement parameters. The Williamson-Hall and Size-strain methods were applied for further analysis, yielding consistent size and strain values. X-ray photoelectron spectroscopy (XPS) was utilized to investigate the electronic states and dopant incorporation in CuI nanocrystals. The undoped and doped CuI samples exhibited distinctive morphologies, with pure CuI displaying an irregular shape, CuI–Cd showcasing a hexagonal morphology, and CuI–Fe featuring a triangular morphology. The average crystallite sizes of the nanocrystals were determined to be 96.67 nm, 70.57 nm, and 54.10 nm for pure CuI, CuI–Cd, and CuI–Fe, respectively. Energy-dispersive X-ray (EDX) analysis confirmed the presence of Cd and Fe in the doped samples. Optical bandgap energies estimated using Tauc's plot were 4.1 eV (CuI), 4.0 eV (CuI–Cd), and 4.0 eV (CuI–Fe).