Synthesis, structural, and optical properties of core/shell ZnS:Fe/ZnS nanocrystals

ZnS:Fe/ZnS core/shell nanocrystals (NCs) were synthesized by a simple liquid-solid-solution (LSS) method and the influence of ZnS shell thickness on the optical properties of ZnS:Fe/ZnS NCs was investigated. The crystalline and optical properties of ZnS:Fe/ZnS core/shell NCs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, UV-Visible spectrometer and FT-IR spectrometer, respectively. It was found that the ZnS:Fe/ZnS core/shell NCs are highly crystalline and show zincblende structure with an average particle size of about 7 nm. The lattice constants of the ZnS:Fe/ZnS NCs decrease slightly by the introduction of Fe, and the Fe dopants were well doped into the ZnS:Fe/ZnS NCs, as confirmed by XPS. Compared to the pure ZnS:Fe NCs, the ZnS:Fe/ZnS core/shell NCs exhibited significantly enhanced luminescence properties. A red-shift can be observed in the absorption and PL spectra as the ZnS shells thickened. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim