An excitation wavelength-dependent color-tunable La4GeO8: Bi3+, Er3+ phosphor for multicolor anticounterfeiting

Stimulation-responsive luminescent materials have attractd intense attention due to their excellent optical properties in the anticounterfeiting application. At present, most are based on single luminescence and fixed excitation patterns, resulting a poor effect. Therefore, developing multimodal that change luminous color under different wavelength stimuli has become significant challenge. In this work, we reported La4GeO8: Bi3+, Er3+ phosphor, which could emit white, blue-green, baby blue orange-yellow light at of 250–430 nm. Moreover, it also showed green upconversion (UC) when irradiated with near-infrared (NIR, 980 nm 808 nm) lasers. Notably, material exhibited good humidity resistance stability. Based these integrated features, designed an device. The results suggested device quickly realize using common source {NIR (808 or laser ultraviolet (UV) lamp}. These combined characteristics will be difficulty forge show high security applications.