Semiconductor/porous silica glass nanocomposites via the single-source precursor approach

The utilization of single-source molecular precursor approach to obtain II-VI and IV-VI semiconductors encapsulated in porous Vycor glass (PVG) is described. The procedure is based on the impregnation of cadmium and lead(II) diethyl-dithiocarbamate complexes, Cd(S2CNEt2)2 and Pb(S2CNEt2)2, inside the porous environment of PVG followed by a thermal treatment of the glass. The pyrolysis of the impregnated precursor gives rise to binary semiconductors CdS and PbS, respectively. The impregnation step is driven by interactions between the precursors and active sites located at glass pore surfaces. After completing the impregnation-decomposition cycle, it was found that the active glass sites were regenerated, making new cycles possible. The amount of encapsulated semiconductor increases linearly as a function of the number of cycles. Nanocomposites obtained after 1-10 cycles were prepared and characterized by optical spectroscopy, X-ray diffraction powder and transmission electron microscopy.