Low-Cost Synthesis And Characterization Of Lead Sulfide Colloidal Quantum Dots

In the last 20 years, quantum dots(QDs) have become one of the hottest research areas. ?-?colloidal QDs(e.g. PbS, PbSe, PbTe, etc.) attracted lots of attentions as its small bandgap(0.28~0.41eV), strong quantum confinement effect and wide absorption spectra which covered the near infrared region(NIR).This work demonstrates a low-cost synthesis of lead sulfide colloidal QDs which utilized the low-cost H2 S gas produced from reaction between iron sulfide(FeS) and diluted sulphuric acid(H2SO4) as the sulfur source. Monodispersive lead sulfide(PbS) colloidal QDs were prepared by introducing the H2 S gas into a mixture of lead oxide(PbO), oleic acid(OA) and 1- octadecene(ODE) at a relatively low reaction temperature(60?). The synthesis was optimized by changing some reaction parameters such as reaction time, reaction temperature, amount of ligand, rate of injecting H2 S gas and ratio of Pb to S(Pb:S), and obtained QDs with small particle diameter and narrow size distribution.The PbS QDs were characterized by absorption spectrum and X-ray diffraction. We found that the size of QDs increased with the reaction time, reaction temperature and amount of ligand, However, oppositely, it decreased rapidly with the increase of rate of injecting H2 S gas and Pb:S.Then we studied the growth kinetics and synthetic mechanism of PbS colloidal QDs and provided a controlled synthesis strategy for monodispersive PbS colloidal QDs with a continuous and tunable 1st exciton peak in NIR.