Structural and optical properties of core–shell Ag2S/HgS nanostructures

Here we report on a two-step synthesis route for fabrication of core–shell Ag2S/HgS nanostructures. Nanoscale Ag2S semiconductors are prepared by a standard redox reaction using AgNO3 and CS2 as the reactants in PVP. HgS layers are developed on Ag2S cores through SS bonding at the interface separating the two systems. The properties of these core–shell nanostructures are studied via various spectroscopic and microscopic tools like UV–Vis absorption spectra, photoluminescence spectra, X-ray diffraction pattern and transmission electron microscopic images. Change in optical properties is observed while varying the shell thickness in the sample. A detailed study on the luminescence properties reveal transition from TYPE 1 to TYPE 2 core–shell nanostructures is observed with increasing shell thickness.