Photoluminescence of polymethylmethacrylate/(Zn, Cu, Ag)S : Eu$^{3+}$ compositions

Luminescent (Zn, Cu, Ag)S : Eu$^{3+}$ nanoparticles (quantum dots, QDs) are synthesized upon decomposition of thioacetamide metal complexes in methylmethacrylate during block polymerization upon heating. The QD formation is confirmed by a corresponding band in the optical absorption spectrum of polymer compositions. Photoluminescence of polymethylmethacrylate/(Zn, Cu, Ag)S : Eu$^{3+}$ compositions manifests itself as a complex band, related to crystal structure defects formed during doping of ZnS with copper and silver ions, and a set of narrow luminescence bands of Eu$^{3+}$ ions. The luminescence is excited due to the interband transition and electronic transitions from the valence band to ZnS defect levels and intrinsic energy absorption by Eu$^{3+}$ ions. The bond between Eu$^{3+}$ ions and ZnS particles is confirmed by the dependence of the ZnS broadband luminescence intensity on the Eu$^{3+}$ ion concentration and the increase in the intensity of the narrowband luminescence of Eu$^{3+}$ ions as a result of energy transfer from the doped ZnS crystal levels to the energy levels of Eu$^{3+}$ ions.