Persistent luminescence from Er3+,Nd3+,Ho3+ doped β-NaYF4 under x-ray excitation

Near-infrared-II afterglow luminescence phosphors, which holds lower auto-fluorescence and up to 1,000-fold reduction in scattering losses, have achieved great attention as optimal probes for bio-imaging. Er³⁺, Nd³⁺, Ho³⁺ doped fluorides are ideal near-infrared luminescent materials as well as NIR-II persistent luminescence phosphors. Although they have been used for biological imaging, their afterglow luminescence properties are not yet ideal, and their afterglow mechanism still needs further research. Here, we have conducted a detailed study on the afterglow properties of Er³⁺, Nd³⁺, Ho³⁺ doped <i>β-</i>NaYF₄ and provided their persistent luminescence mechanism, providing direction for improving the afterglow properties.