Energy Migration Layer Modulated Lanthanide Luminescent Nanoparticles Toward Multimode Ratio Fluorescence Thermometers

Abstract Fluorescent temperature sensing is considered as a research hotspot in the fields of life sciences and medicine. Despite the existence of numerous materials, the low sensitivity still limits their broader application. Herein, a core‐shell‐shell structure of lanthanide‐doped nanoparticles is designed, which can adjust the energy transfer process by controlling the Yb 3+ concentration in the energy migration layer, so as to generate different but regular visible upconversion and near‐infrared downshifting emission modes depending on 808 or 980 nm excitation wavelengths. And the energy migration, cross relaxation, and energy cycling processes involved in energy migration ions are analyzed and summarized. Subsequently, unlike traditional thermal coupled fluorescence thermometers, the visible and near‐infrared emission under different excitations is selected as the fluorescence intensity ratio by combining both thermal quenching and enhancement. Thus, a new type of fluorescence thermometer with deep penetration capability and high sensitivity within the biological temperature range is obtained, which can inspire a new design strategy for the future biosensing field.