Liquid Nitrogen Temperature Multicolor Persistent Luminescence in a Single Host Material

Abstract Persistent luminescence (PersL) phosphors have garnered significant attention for their extensive applications in various fields. It is regrettable that these PersL phosphors typically possess deep traps. At low temperatures (LT), energy stored in the trap cannot be released to the luminescent centers through thermal de‐trapping, thereby causing these PersL phosphors to lose their PersL characteristics in LT. Currently, there is little research on LT PersL phosphors, and multicolor LT PersL in a single host material has not been reported. In this work, multicolor LT PersL is achieved in a single host material by modifying the emission center. Remarkably, an ultra‐shallow trap with a depth of 0.23 eV is discovered in the Cs 2 NaLuCl 6 :5%Ln 3+ phosphors, which is essential for achieving PersL at 77 K. First‐principles calculations indicate that the ultra‐shallow trap in Cs 2 NaLuCl 6 :5%Ln 3+ is caused by the distortion of [NaCl 6 ] octahedron in the phosphors. These findings provide new perspectives into X‐ray‐induced trap generation and offer valuable insights for designing multicolor PersL phosphors for LT applications.