Multimode Emission from Lanthanide-Based Metal-Organic Frameworks for Advanced Information Encryption

Although remarkable progress on luminescent materials is made in advanced optical information storage and anti-counterfeiting applications, many challenges still remain in these fields. Currently, most luminescent materials are based on a single photoluminescent model that can be easily imitated by substitutes. In this work, a series of multimodal emission lanthanide-based metal-organic frameworks (MOFs) are developed, where they emit red and green light originating from Eu3+ and Tb3+ under ultraviolet light irradiation. Meanwhile, under 980 nm near-infrared laser irradiation, these MOFs show cyan upconversion cooperative luminescence derived from Yb3+ and characteristic upconversion luminescence from lanthanide activators (Eu3+, Tb3+, or Ho3+), respectively. Based on the integrated optical functionality, the functional information storage applications are successfully designed, which indicates that multimodal emission features can be easily detected under ultraviolet lamps (254 or 393 nm) or 980 nm near-infrared laser. And, the unique optical features show a high level of security in the advanced information storage application, which would be sufficiently complex to be forged.