Tunable multicolor emission based on dual-mode luminescence Y₂O₃: Eu@SiO₂/Y₂O₃: Er(Tm/Yb) composite nanomaterials

Rare earth doped materials with dual-mode luminescence have broad application potential. Among them, the dual-mode luminescence ink has been widely concerned in the field of anti-counterfeiting technology. In this work, the Y₂O₃: Eu@SiO₂ nanomaterials were prepared with Y₂O₃: Eu as the core nanocrystals, SiO₂ as the shell layer. Then, the Y₂O₃: Er(Tm/Yb) nanocrystals are adsorbed on the surface of the SiO₂ layer to form Y₂O₃: Eu@SiO₂/Y₂O₃: Er(Tm/Yb) composite nanomaterials. The Y₂O₃: Eu@SiO₂/Y₂O₃: Er(Tm/Yb) composite nanomaterials can simultaneously achieve the dual-mode (up-conversion and down-shifting) luminescence. The Y₂O₃: Eu@SiO₂/Y₂O₃: Er composite nanomaterials can emit different color luminescence emission under the 405 nm excitation, 980 nm excitation and 980/405 nm co-excitation, respectively. The up-conversion luminescence color under 980 nm excitation is regulated by doping different rare earth ions in the absorption layer. The dual-mode luminescence characteristics of composite nanomaterials make it possible to extract information only when two excitation sources exist at the same time, which increases the illegal forgery difficulty. Moreover, the composite nanomaterials can emit more variable color emission via adjusting the power intensity of 980 nm laser under 980/405 nm co-excitation, which improves the color resolution of multicolor emission. These results indicate that the Y₂O₃: Eu@SiO₂/Y₂O₃: Er(Tm/Yb) composite nanomaterials are expected to be applied in the fields of color displaying and fluorescence encryption anti-counterfeiting.