One-step preparation and dual mode luminescence anti-counterfeiting application of LiYF4: Yb3+, Ho3+, Ce3+@ carbon quantum dot composite materials

In the field of fluorescent anti-counterfeiting, materials with single luminous mode are easy to be forged, which cannot meet the current anti-counterfeiting requirements. Currently reported bimodal light-emitting materials usually require multi-step and tedious synthesis steps. In this paper, LiYF₄: Yb³⁺, Ho³⁺, Ce³⁺ upconversion micron particles (UCMPs)/carbon quantum dots (CDs) composite materials were prepared by one-step hydrothermal method, which greatly simplified the composite process of CDs and UCMPs. The upconversion wavelength (from green light to red light excited by 980 nm) can be achieved by changing the doping concentration of Ce³⁺ ions. Through the combination of CDs and UCMPs, an obvious dual mode luminescence phenomenon was achieved. Finally, screen printing was used to produce a clover pattern, which realized multi-color luminescence under 365 nm and 980 nm excitations respectively. The new fluorescence anti-counterfeiting composites, which uses simple and environmentally friendly one-step synthesis process, is expected to promote the development of fluorescence anti-counterfeiting field.