Multifunctional core-shell nanoparticles for temperature sensing and anti-counterfeiting

In this paper, the multi-functional multi-layer core-shell structure NaYF4: Ce3+/Eu3+@NaYF4 @NaYF4: Ho3+/Yb3+ nanoparticles (NPs) were prepared. These multi-layer NPs can be applied in temperature sensing with high relative sensitivity. Moreover, these NPs can be used in multimode optical anti-counterfeiting. Based on structure design and doped earth ions optimized, the maximum relative sensitivity is further promoted from 0.9 %·K−1 at 234 K (Eu/Ho) to 5.1 %·K−1 at 113 K (Ce/Eu@Y@Ho/Yb) by the blocking effect of the inter layer and by cross-relaxation of introducing Ce3+ and Yb3+ ions. Meanwhile, by introducing Ce3+ and Yb3+ ions, the NPs provide multimode emissions under multiple excitations, which are beneficial for the application of optical anti-counterfeiting. The NPs present increased sensitivity of temperature sensing and improved security of optical anti-counterfeiting, which has promising applications in biological cell calibration, micro-integrated circuits, etc.