Tuning the emission of CdS quantum dots with silver particles

In this study, four batches of a QD-Ag hybrid in liquid state were prepared by mixing CdS quantum dots (QDs) with dispersions of Ag nanoparticle (NP). The luminescence-related properties of the CdS–Ag hybrid were tuned by adding Ag NPs. For each QD-Ag hybrid, the influence of the Ag/Cd ratio on the evolution of emission was studied systematically. We found that the PL properties of the hybrid depended on the amount of Ag concentration rather than the plasmonic properties of Ag NPs. In the hybrid, Ag doping occurred and caused the PL properties to change. As the number of Ag NPs increased, the band-edge emission decreased monotonically while the PL intensity of the dopant increased first and then decreased. A hypothetical model is proposed to explain the PL change of the QD-Ag hybrid with varying amounts of the Ag component.