The efficient monochromatic 800 nm near-infrared emission from Tm3+-doped NaYbF4 upconversion luminescence nanoparticles

The NaYbF4:Tm3+/NaYF4 core/shell upconversion luminescence nanoparticles (UCNPs) with different Tm3+-doped concentrations are synthesized via solvothermal method to obtain efficient monochromatic 800 nm emission under 970 nm excitation. The results indicate that the monochromaticity of 800 nm emission from the UCNPs exhibits exponential growth, while the intensity presents exponential attenuation with increasing Tm3+ -doped concentration. The optimal Tm3+-doped concentration in the UCNPs is given, which can be used to generate efficient upconversion emission with high intensity and monochromaticity as high as 1469. The monochromaticity of 800 nm emission calculated by theory is compared with that measured by experiment, and good agreement is found.