Synthesis and characterization of PbS nanocrystallites organized into different morphological assemblies

We present a new, simple procedure for the synthesis of PbS nanocrystallites (NCs) via a solvothermal reaction based on decomposition of lead thiocyanate in a boiling solvent, in the presence of the surfactant cetyltrimethylammoniumbromide (CTAB). Fractional precipitation was used to obtain a narrow size distribution of NCs. The formation of different morphological assemblies depends on the reaction time. The sizes of PbS NCs in ranges of 3-7nm and 8-14nm were determined by transmission electron microscopy (TEM) and by the blue shift of the absorption edge. The statistical TEM analysis enables characterization of size distribution of the particles. Dependence of the size and the shape of PbS NCs on the kinds of solvents, surfactants, and the thermal treatments has been demonstrated. The selected area electron diffraction (SAED) confirmed the existence of the rock salt cubic structure of the PbS NCs.