Influence of Ag+ and Mn2+ ions on structural, optical and photoluminescence features of ZnS quantum dots

Abstract

The current study deals with the structural, morphological, elemental, optical and photoluminescence behaviors of Ag+, Mn2+ dual doped ZnS quantum dots (QDs). The X-ray diffraction (XRD) and Transmission Electron Microscope (TEM) studies confirmed the cubic structure and size of the crystallites (~2 nm). The Scanning Electron Microscope (SEM) photographs portrayed the surface and morphological structure of prepared samples. Energy dispersive X-ray (EDX) and Fourier Transform Infrared Spectra (FTIR) ensured the presence of Zn, Ag, Mn and, S in the samples as per the anticipated stoichiometry ratio. The UV–visible spectra showed a red shift in optical absorption and band gap gets narrowed due to the incorporation of Ag+ ions. The size effect has overcome the quantum confinement effect in this case. Through photoluminescence (PL) studies, a weak UV emission and strong red wavelength emissions were received and discussed on the basis of sulfur vacancies. This red emission was dealt in terms of d-electrons transition between host and dopant ions.