Photoluminescence of (Zn, Pb, Mn)S Quantum Dots in Polyacrylate Matrix

Abstract

Solutions of (Zn, Pb, Mn)S quantum dots with different molar ratios between cations are produced by colloidal synthesis in a methyl methacrylate (MMA) medium. By the thermal polymerization of MMA in a block, the colloidal solutions are converted into the vitreous state. The optical transparency of the poly(MMA)/(Zn, Pb, Mn)S composites at the wavelengths >500 nm reaches 90% at a thickness of the absorbing layer up to 5 mm. The photoluminescence of the composites in the spectral range 400–480 nm is defined by the recombination of electrons at the levels of defects of the ZnS crystal structure, and photoluminescence in the range 520–620 nm by the ⁴T₁ → ⁶A₁ electronic transition in Mn²⁺ ions. Photoluminescence excitation is a result of interband transitions in ZnS, with energy transfer from the conduction band of ZnS to the levels of Mn²⁺ ions. The luminescence spectrum depends on the molar ratio between Mn²⁺ and Pb²⁺ ions, the order of introduction of substances into the reaction mixture, and the excitation-radiation wavelength.