Upconversion Luminescence Reversible Modulation of Photochromic Ba2YTaO6 Double Perovskite Phosphors Toward Anticounterfeiting Application

Double perovskite (DP) phosphors attract extensive attention due to their potential applications in the field of optoelectronics. Photochromism‐induced luminescence modulation can extend their application fields. However, designing and preparing DP phosphors with expected photochromic and luminescent properties is still challenging. Herein, the photochromic Ba2YTaO6: Yb3+, Er3+, Co2+ DP with upconversion luminescence properties is developed. The color of the sample turns from white to pink upon 254 nm UV light irradiation, which is fast fading upon 473 nm laser illumination. The mechanism of photochromism is related to the formation of color centers, and the doping of Co2+ ions is crucial for the improvement of photochromism, which is from the increasing of traps depth, the oxygen vacancies, and the carrier concentration of the matrix caused by Co2+ doping. The upconversion luminescence of Er3+ ions can be reversibly modulated by the photochromic effect, exhibiting excellent reproducibility and high stability. The potential application of photochromic Ba2YTaO6: Yb3+, Er3+, Co2+ phosphor is demonstrated in the field of anticounterfeiting and three‐dimensional (3D) artwork. This work not only offers insight into the photochromic mechanism of DP but also presents guidance for developing other photochromic DP phosphors. Double perovskite (DP) phosphors with expected photochromic and luminescence properties are designed. Flexible DP phosphor‐based film demonstrates simultaneous reversible photochromism and recoverable upconversion luminescence anticounterfeiting application, along with high reproducibility and read/write erasability. The result presents guidance for developing other photochromic DP phosphors.