Luminescence properties of Eu2+/3+ co-activated La6Sr4(SiO4)6F2 polychromatic phosphors towards white light-emitting diodes and anti-counterfeiting

To obtain emitting color regulation, series of Eu2+/3+-coactivated La6Sr4(SiO4)6F2 phosphors were synthesized. The crystal structure, morphology, elemental compositions and luminescence performances of the final products were discussed. Excited by 365 nm, all of the studied samples can emit the characteristic emissions of Eu2+ and Eu3+, in which their fluorescence intensities have various responses to doping content. Specially, as the dopant content increases, the emitting color is changed from green to yellow. Moreover, via changing the excitation wavelength, tunable emissions are also realized in the studied samples. On the basis of the temperature dependent emission spectra, it is found that Eu2+/3+-coactivated La6Sr4(SiO4)6F2 phosphors possess good thermal stability. Through selecting the designed phosphors as yellow emitting components, a warm white light-emitting diode (white-LED) was packaged, in which its electroluminescence properties are hardly altered at high injection current. When the working current is 100 mA, the color coordinate, correlated color temperature and color rendering index of the fabricated white-LED are (0.358,0.358), 4580 K and 87.39, respectively. In addition, using the resultant compounds as luminescent labels, different patterns were prepared for the application in information encryption. The results demonstrated that Eu2+/3+-coactivated La6Sr4(SiO4)6F2 phosphors with multicolor emissions and outstanding thermal stability are suitable for white-LED and optical anti-counterfeiting as emitting components.