Structural, optical, and electronic characteristics of non-stoichiometric nanocadmium sulfide

Samples of non-stoichiometric nano-CdS_1−x were synthesized by a simple thermolysis method by lowering the ratio of thiourea relative to cadmium acetate as starting precursors: Cd(Ac):(1 − x) thiourea (x = 0.0, 0.03, 0.05, and 0.1). X’pert HighScore Plus program manifested biphasic CdS (cubic and hexagonal), and the Rietveld analysis was utilized to match the structural and microstructure parameters of the formed samples. The possibility of formed CdS_1−xO_x alloy due to the sulfur deficiency is also examined using the Rietveld method. A high-resolution transmission electron microscope imaging exhibited nanosize particles with homogeneous morphology. Fourier transform infrared spectrometer was utilized to confirm the existence of O₂ in CdS_1−x matrix. The band-gap energies for CdS_1−x are reduced below the values of energy gaps of CdS and CdO upon increasing the parameter (x) forming a band-gap “bowing.” The photoluminescence (PL) emitted visible colors depending on the amount of sulfur deficiency and excitation wavelength used. The maximum PL intensity observed in CdS_0.9 sample confirmed the presents of oxygen inside the matrix. The influence of oxygen substitution or vacancies of sulfur on the electronic structure and optical features of CdS was also investigated applying density function calculations.