X-ray-excited afterglow below 190 K in Cs2ZnCl4: Mn crystal

Compared to the extensive investigations of room-temperature afterglow phosphors, little attention was focused on the low-temperature afterglow phosphor of shallow traps. Here, we report a Mn2+-doped Cs2ZnCl4 crystal grown in a hydrothermal reactor. Without Mn doping, the crystal exhibited a purple emission under X-ray excitation. After doping, the crystal showed a green emission at 523 nm. Importantly, an intense green afterglow was activated at 183 K after ceasing X-ray excitation. Such low-temperature afterglow associated with a large number of shallow traps, which was further probed by a thermal-cleaning method. This work provided new insights into the shallow-trap afterglow phosphors, enabling many potential applications under low-temperature conditions, for example, cold-chain vaccine tracking system.