A stable and narrowly distributed dispersion of Mn-doped ZnS nanoparticles with an average diameter of 3 nm, has been synthesized via chemical precipitation without using any surfactant. The surface of the particles has been functionalized with acrylic acid for compatibilization with PMMA. Transparent luminescent nanocomposite powder was obtained using solvent polymerization of ZnS:Mn nanoparticles in a mixture of methyl methacrylate and acrylic acid. Nanocomposites produced by effectively processing this powder into pure PMMA demonstrated "down shifting" performance. The nanocomposite plaques produced were shown to improve the efficiency of a silicon solar cell. (C) 2013 Elsevier B.V. All rights reserved.