Doping-induced emission of infrared light from Co2+-doped ZnSe quantum dots

ZnSe quantum dots doped with Co2+ have been prepared in aqueous solution by a one-pot method using thioglycolic acid as stabilizer. The quantum dots were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), UV-visible spectrophotometry, and spectrofluorimetry. The results confirmed the quantum dots formed a single cubic phase with zinc blende structure. The average particle size of the quantum dots was approximately 5 nm. Co2+ ions were doped into ZnSe lattice sites by substitution. As a result, infrared (IR) emission of Co2+ T-4(2)(F) -> (4)A(2)(F) at approximately 3.5 mu m was detected on excitation with 755 nm radiation.