An Advanced Tunable Multimodal Luminescent La 4 GeO 8 : Eu 2+ , Er 3+ Phosphor for Multicolor Anticounterfeiting

Abstract The development of advanced luminescent materials is of great importance to the anticounterfeiting application and still confronts with lots of challenges. At present, most anticounterfeiting luminescent materials are based on a monotonous photoluminescence model, which is easily faked by substitutes. Therefore, in this work, a multimodal La 4 GeO 8 : Eu 2+ , Er 3+ material is reported, which can emit red, purple, baby blue, and green light under the increased excitation wavelength from 250 to 380 nm. Meanwhile, the phosphor also shows green upconversion luminescence under the NIR (980 and 808 nm) laser irradiation. Moreover, the phosphor features excellent stability and humidity resistance against harsh conditions. Based on the integrated feature, a functional anticounterfeiting application is designed. Results demonstrate that the multimodal luminescent feature can be easily detected by using a portable ultraviolet lamp or NIR (808 or 980 nm) laser. The unique characteristic will be complicated to counterfeit and show high‐level security in the field of advanced anticounterfeiting.