Photoluminescent behaviors of several kinds of europium ternary complexes doped in PMMA

Four kinds of europium ternary complexes; Eu(DBM)3phen, Eu(DBM)3(DB-bpy), Eu(DBM)3(DN-bpy) and Eu(DBM)3biq (DBM, phen, DB-bpy, DN-bpy and biq refer to Dibenzoylmethane, 1,10-phenanthroline, 4,4′-Di-tert-butyl-2,2′-dipyridyl, 4,4′-Dinonyl-2,2′-dipyridyl and 2,2′-Biquinoline, respectively), were doped in poly(methyl methacrylate) (PMMA) matrix. The luminescence properties of the composites were investigated by emission spectroscopy and lifetime measurements. It was found that the composites formed by the three complexes, Eu(DBM)3phen, Eu(DBM)3(DB-bpy), and Eu(DBM)3(DN-bpy), exhibit strong luminescence and similar emission spectral characteristics to Eu(III). Whereas, Eu(DBM)3biq shows large differences in its luminescence spectrum compared to those of other complexes. The luminescence was very weak and broad. The emission spectral features of Eu(III) in the Eu(DBM)3biq/PMMA systems change with the molar ratios of the complex and PMMA. The lifetime of 5D0 level of Eu(III) in Eu(DBM)3biq/PMMA systems is shorter than those in the other systems. The luminescence intensity of Eu(III) in Eu(DBM)3biq/PMMA systems decreases gradually when exposed to UV-light while the broad emission band becomes stronger.