Characterization of color including temporal hue shift of a range of long-lasting phosphorescent/fluorescent (SiO2/REC@SAOED) composites

A series of luminescent composites was prepared by coating the surface of longlasting phosphorescent SrAl2O4: Eu2+, Dy3+ (SAOED) compounds that emit yellow-greenish light, with various concentrations of red emitting coumarin (REC)fluorescent dye. The color of the luminescent SiO2/REC@SAOED composites, including the temporal hue shift in darkness, was characterized using photoluminescence (PL) emission spectra and spectroradiometric measurements. The PL emission spectra of the phosphorescent/fluorescent composite contains a continuous band ranging from 450 to 700 nm with two emission peaks. The emission peak for the uncoated SAOED remained invariant, while the fluorescent emission peak exhibited a bathochromic shift from 607 to 618 nm when the concentration of REC in the composite was increased from 0.1 to 0.9 (wt%), indicating that the hue of the luminescent composite would gradually shift towards red with increasing concentrations of coumarin. Although the intensity of the fluorescent peak increased gradually with an increase in the concentration of REC, the ratio of the phosphorescent to fluorescent emission peak intensity also increased gradually over time. Spectroradiometric measurements of compounds showed that the hue of the emitted light from the composites exhibited a gradual hypsochromic (blue) shift over time in darkness, and the extent of the blue-shift decreased gradually with an increase in the concentration of REC. (C) 2017 Optical Society of America