NOVELTY - Composition-1 comprises: a polymer matrix, rare earth metal nanoclusters dispersed in the polymer, and antenna ligands disposed on the exterior of the rare earth metal nanoclusters, where the rare earth metal nanoclusters are present in the size of 1-100 nm and comprise lanthanide atoms bonded to at least one semimetal or transition metal via an oxygen or sulfur atom.    USE - The compositions are useful: for making composite material; and in an optical device and solar cell (all claimed).    ADVANTAGE - The compositions: exhibit superior absorption/luminescence properties; provide flexibility in materials processing, and excellent durability; and has good adhesion to glass and plastic substrates.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a composition-2 comprising: rare earth metal nanoclusters and antenna ligands interacting with the rare earth metal nanoclusters, where the composition-2 possess a broad absorption peak of 375-450 nm photoluminescence spectrum and the peak is at least 25 nm wide at half height;    (2) a composition-3 comprising a rare earth metal nanocluster and a cyclic olefin bonded to the rare earth metal nanocluster, where the rare earth metal nanocluster is present in the size of 0.5-1000 nm and comprises lanthanide atoms bonded to at least one semimetal or transition metal via an oxygen atom;    (3) an optical device comprising the compositions;    (4) a method of making the compositions, comprising: forming a layer of the compositions; and, after the layer is formed, and adding an antenna ligand that binds to the rare earth metal nanoclusters to result in a material with enhanced luminosity;    (5) a method of making a composite material comprising: providing the compositions, and reacting the compositions with an olefin to form a composite comprising the rare earth metal nanocluster dispersed in a cyclic olefin copolymer; and    (6) a solar cell having a luminescent coating, comprising a coating on a solar cell, where the coating comprises an organic host material, and a luminescent rare earth metal nanocluster in which one or more other kinds of metals are coordinated to at least one kind of rare earth metal via oxygen or sulfur, that is disposed in the host material, and further comprising a sensitizer that is complexed with the luminescent rare earth metal nanocluster.