Novel persistent phosphors of lanthanide–chromium co-doped yttrium aluminum gallium garnet: design concept with vacuum referred binding energy diagram

Abstract

We have developed Pr³⁺–Cr³⁺ and Tb³⁺–Cr³⁺ co-doped Y₃Al₂Ga₃O₁₂ (YAGG) persistent phosphors with orange (Pr³⁺) and light green (Tb³⁺) persistent luminescence. The duration of their persistent luminance (of 0.32 mcd m⁻²) can last up to about 8 h and 12 h, respectively. On the other hand, the persistent luminescence intensities of Nd³⁺–Cr³⁺ and Dy³⁺–Cr³⁺ co-doped YAGG samples are much weaker than those of the Pr³⁺–Cr³⁺ and Tb³⁺–Cr³⁺ co-doped ones, and the dominant persistent luminescence is mainly due to the deep-red transition of Cr³⁺. The mechanisms of different persistent luminescence behaviors of these four samples can be explained by the vacuum referred binding energy (VRBE) diagram of lanthanide ions in the YAGG host. The stability of hole traps at the ground states of Pr³⁺, Nd³⁺, Tb³⁺ and Dy³⁺ ions and the possibility to collaborate with Cr³⁺ electron traps to induce persistent luminescence are discussed in detail.