One stone, two birds: Luminescence properties of Ca8ZnY(PO4)7:Eu2+, Mn2+ and multifunctional applications in WLEDs & optical anti-counterfeiting

The construction of high luminous quality (quantum efficiency, color purity, etc.) cyan emission phosphor has a milestone significance for improving lighting quality and expanding the application fields of phosphor. Here, a kind of cyan emission phosphor Ca8ZnY(PO4)7:Eu2+ is prepared by using β-Ca3(PO4)2 as prototype according to structural engineering strategy. Through the activation of Eu2+ and the energy transfer from Eu2+ to Mn2+ in Ca8ZnY(PO4)7, the applications of WLEDs and optical anti-counterfeiting are realized. Excited at 320 nm, the central peak of Ca8ZnY(PO4)7:Eu2+ spectra is at around 490 nm, the full width at half maximum is ~80 nm, and the internal quantum efficiency is up to 51.52%. Based on Rietveld refinement of XRD data and Gaussian fitting, three luminescence centers are identified. The maximum energy transfer efficiency from Eu2+ to Mn2+ is 51.05%, and the energy transfer type is also determined by calculation. With the regulation of Mn2+ concentration, the luminous color of the series phosphor transitions from cyan to white and finally to red. The prepared phosphors possess certain thermal stability, which can not only compensate the cyan gap in the commercial phosphor combination LEDs, but also be used as phosphor raw material for single-phase WLEDs. In addition, the optical anti-counterfeiting films prepared by mixing the prepared phosphors with polyvinyl alcohol have the advantages of transparency, flexibility and rapid response, exhibiting great potential applications in the fields of optical anti-counterfeiting, information encryption and even criminal investigation. In summary, the prepared phosphors have the potential of multi-functional application in the field of high-quality lighting and anti-counterfeiting.