Preparation of PbS Quantum Dots Using Inorganic Sulfide as Precursor and Their Characterization

PbS semiconductor quantum dots with different particle sizes were successfully prepared by the colloidal chemistry method according to the theory of fast nucleation at high temperature and slow growth at low temperature. Sodium sulfide was used as a sulfur precursor because it is odorless and is less noxious, which allows it to be classified as a green precursor. Oleic acid was used as a stabilizing agent to control the particle growth and it thus assisted in the formation of monodisperse PbS quantum dots. The crystalline structures, morphology, and particle size of the quantum dots were characterized by powder X-ray diffraction and high-resolution transmission electron microscopy. The quantum size effect of the PbS nanoparticles was analyzed by visible near-infrared (Vis-NIR) absorption spectroscopy. The mean size of the PbS quantum dots increased with a decrease in the concentration of oleic acid. A possible growth mechanism for the PbS nanoparticles was also discussed.