Paradigm Enhancement of White-Light Responsive NIR-II Photoluminescence via Toroidal Energy Migration

Abstract

Near-infrared II (NIR-II, 1000–1700 nm) lanthanide-doped fluorescent probes provide a powerful new tool for existing clinical biomedical sensing and imaging. However, it is impeded in practical applications by its specific high-energy laser source. Herein, a white-light responsive Ce³⁺-mediated toroidal energy migration downshifting topological core–shell structure NIR-IIb (1500–1700 nm) fluorescent probe is reported. It is found that Ce³⁺ doping enhances the NIR downshifting luminescence of the Ho³⁺ and Nd³⁺, thereby increasing the energy-transferred Yb³⁺ luminescence. The NaCeF₄ core is able to further facilitate the crossrelaxation between the intermediate-shell layer of Er³⁺ and Ce³⁺ through the outward-to-inward core–shell topology, enhancing the 1527 nm luminescence to form the toroidal energy migration paradigm. Additionally, the luminescence of Er³⁺ exhibits strong temperature dependence, enabling superior temperature sensing under multiple light sources. Under low-power white light source, the relative sensitivity (S_r) can reach up to 0.57% K⁻¹, with a minimum temperature uncertainty (δT) of 0.2 K. Moreover, portable light conversion using highly efficient white-light responsive emission in NIR-II region enables noninjectable intravenous imaging and food inspection. This toroidal energy migration strategy provides a new direction for lanthanide energy harvesting and multisource NIR applications.