Enabling Persistent Luminescence of Eu³⁺ in Nanoparticles through Interfacial Energy Transfer for Advanced X-ray Imaging

Persistent luminescence (PersL) emerged recently in nanoparticles which greatly promotes and expands their frontier applications. However, achieving X-ray-activated PersL of Eu³⁺ in fluoride nanoparticles has remained a huge challenge. Here, we propose a conceptual model to realize this aim by constructing the interfacial energy transfer in a core-shell nanostructure. We show that the terbium sublattice is a good sensitizer to absorb X-ray energy and activate Eu³⁺ in the shell with its resultant intense PersL. A gradual color change from red to yellow and green is achieved by a fine manipulation of interfacial interactions between Tb³⁺ and Eu³⁺. Moreover, the presence of Eu³⁺ in the Tb lattice annihilates the PersL of Tb³⁺ with only its radioluminescence, being helpful to avoid ghost imaging. Our findings gain a deep insight into the PersL mechanism in nanoparticles, which help design new classes of PersL materials and provide new possibilities for advanced flexible imaging applications.