Activating persistent luminescence and thermal stability of K2Ba7Si16O40: Eu2+ via traps modulation

Herein, using K₂Ba₇Si₁₆O₄₀ as a host, we achieved strong cyan persistent luminescence (PersL) through codoping Eu²⁺ and Nd³⁺ ions. In comparison with Eu²⁺ ions single doped sample, the initial PersL intensity and duration of Nd³⁺ ions co-doped sample (in which Eu²⁺ and Nd³⁺ concentration was optimized to be 0.015 mol) were discovered to be 4.8 times stronger and 6.5 times longer, respectively. The PersL duration of which above 0.32 mcd m-2 sustained more than 10 h. Moreover, Nd³⁺ ions co-doping not only substantially enhances photoluminescence (PL) emission of Eu²⁺ ions but also the thermal stability, attributed to the energy transfer from the newly acquired traps to the 5d energy levels of Eu²⁺ ions, leading to the radiative recombination. This significant discovery greatly expands the filed of PersL phosphors and provides a theoretical basis and a new approach by introducing appropriate traps to minimize the thermal quenching and improve the efficient of luminescent materials.