Aqueous-based route toward Fe:ZnSe semiconductor nanocrystals: Synthesis and characterization

Nearly monodisperse and luminescent Fe-doped ZnSe semiconductor nanocrystals were synthesized by an aqueous-based route. The obtained nanocrystals were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, photoluminescence and ultraviolet–visible absorption spectroscopy. The resulting nanocrystals were well retained in the zinc blende structure, and the Fe dopants were doped into the ZnSe nanocrystals, as confirmed by X-ray photoelectron spectroscopy. From combination of transmission electron microscopy result and computing methods according to ultraviolet–visible absorption spectrum and X-ray diffraction pattern, particle size of the obtained nanocrystals was found to be about 5 nm. Thioglycolic acid as ligand was successfully capped on the surface of the resulting nanocrystals, confirmed by Fourier transform infrared and energy dispersive X-ray spectroscopy. The obtained nanocrystals exhibit an emission peak at 431 nm; and the photoluminescence band is relatively narrow and symmetric, which indicates that the nanocrystals are nearly monodisperse and homogeneous. Absorption shoulder of the resulting nanocrystals is blue-shifted compared with that of corresponding bulk ZnSe, indicating the quantum confinement effect. The possible reaction mechanism of formation of Fe-doped ZnSe nanocrystals in the aqueous solution was also discussed. Our results demonstrate that the aqueous-based route could be successfully adopted for producing high-quality doped semiconductor nanocrystals.