Optical Properties of Mg- and Ni- Doped Ag2S Colloidal Nanoparticles

In this work, we report the optical properties of Mg- and Ni-doped Ag2S colloidal nanoparticles. The Mg- and Ni-doped Ag2S nanoparticles were prepared using a wet chemical method. The influence of doping on the optical properties of the Mg- and Ni-doped Ag2S nanoparticles was investigated. The transmission electron microscopy (TEM) images showed the shapes of particles to be spherical with an average particle size of about 5-18 nm for all pure and doped Ag2S nanoparticles. The absorption spectra of the Mg-doped samples were red shifted from 2.42 to 2.20 eV, however, the UV-vis spectra of the Ni-doped Ag2S showed a blue shift from 2.42 to 2.60 eV. The observed blue shift in the band gap of Ni-doped Ag2S may be due to the substitution of Ni in to the Ag2S lattice. The photoluminescence intensity of the Mg-doped Ag2S nanoparticles increased as the Mg concentration was increased. However, the photoluminescence (PL) intensity of the Ni-doped Ag2S decreased as the concentration of Ni was increased.