Dual-mode luminescence from lanthanide tri-doped NaYF₄ nanocrystals

Silica-coated NaYF₄:Yb/Er(Tm)/Eu nanocrystals (NCs) with a mean size of 35nm were prepared and characterized. Each of the core/shell NCs can be dispersed in ethanol and water to form stable colloidal solutions and emit bright visible light of two colors (blue and red, green and red) by up- and down-converting excitation modes. As we know, this is the first time to obtain the distinct dual-color photos of NaYF₄:Yb/Er(Tm)/Eu NCs which were dispersed in deionized water. In particular, the ability to optically manipulate luminescence color of NCs doped with RE ions opens the door to multiplexed detection for high precision in more complex biotic environment.