Warm-toned, color-tunable, and highly emissive long lasting phosphorescent composite: PMMA/RECC@SrAl2O4:Eu2+, Dy3+

Color-tuned long lasting phosphorescent composite PMMA/RECC@SrAl2O4:Eu2+,Dy3+ (SAOED) with warm-toned phosphorescent color and excellent afterglow properties were prepared by coating PMMA and a red light-emitting coumarin fluorescent dye color converter (RECC) and PMMA on the surface of the green emitting long lasting phosphor SAOED. X-ray diffraction (XRD) patterns show that the crystal lattice of the PMMA/RECC@SAOED samples are identical to the uncoated SAOED. The photoluminescence (PL) emission spectra of the PMMA/RECC@SAOED consist of two broad band ranging from 450 to 575 nm and 576-700 nm, and the spectra intensity in the range of 576-700 nm increased gradually with the increment of RECC. The CIE chromaticity coordinates and the luminescence images of the PMMA/RECC@SAOED samples indicate that the emitting color of PMMA/RECC@SAOED is composed of the phosphorescent color of SAOED and the fluorescent color of RECC, and it exhibits a reddish emitting color with color purity of 0.8726 when the concentration of the RECC was added to 0.9%. Even though the coating layer of RECC has a negative influence on the quantum yield (QY) and afterglow brightness of PMMA/RECC@SAOED, the afterglow curves of PMMA/RECC@SAOED are similar in shape with the uncoated SAOED, both of them are fitted well with a third-order exponential equation.