Nd3+-sensitized NIR downshifting emission in NaYbF4: Nd@NaYF4: Nd nanoparticles for deep tissue temperature sensing

Temperature sensing technology is of great siginificance in scientific research, agricultral production and industrial manufacture. In this work, the sub-10 nm NaYbF4: Nd@NaYF4: Nd active-core/active-shell NPs are employed for near-infrared (NIR) temperature sensing. Compared with the core-only and core/inert-shell NPs, the downshifting emission intensity of the NaYbF4: Nd@NaYF4: Nd active-core/active-shell NPs is greatly enhanced. Upon 808 nm excitation, the Yb3+ emission intensity at ∼975 nm decreases evidently while that of Nd3+ ions at ∼1055 nm only slightly decreases with the rising of temperature from 293 K to 493 K. The maximum Sa of 1.27*10−3 K−1 at 470 K and Sr of 0.7%/K at 293 K are achieved. The NIR emission studied in this work show deep penetration depth more than 4 mm.