Photochromism and Long Persistent Luminescence in Pr³⁺-Doped Garnet Transparent Ceramic via UV or Blue Light Up-Conversion Charging

Multifunctional phosphors with photochromism and persistent luminescent (PersL) properties have attracted increasing interest owing to the capability of absorbing the photon energy and trapping the generated carriers via defects. However, the opacity of materials compromises the enhancement of photochromism and PersL properties; besides, the need of high energy excitation light source limits their applicability. To bridge these obstacles, Pr3+-doped Y3Al2Ga3O12 transparent ceramic with in-line transmittance over 80% at 1,800 nm is reported, which exhibits strong red PersL after several minutes UV light or blue light up-conversion charging. The luminance duration time can reach >7 h at 0.32 mcd m(-2) threshold value after UV light charging. Interestingly, the phosphor also displays photochromic properties with robust fatigue resistance, i.e., the color changes from light green to red by UV/blue light illumination and is bleached at 300 degrees C. The nature of trap centers, trapping and detrapping processes is explored based on thermoluminescence and electron spin resonance. Finally, the mechanism of photochromism and PersL is discussed by using vacuum referred binding energy diagram. This work opens new avenues for future research on multifunctional materials and brings potential applications in optical information encryption media and optical sensors.