Flash Nanoprecipitation Offers Large‐Format Full‐Color and Dual‐Mode Fluorescence Patterns for Codes‐in‐Code Encryption and Anti‐Counterfeiting

Fluorescent materials are used broadly for anti‐counterfeiting, including currency, passports, identity cards, and other secure documents. However, a universal procedure to print fluorescent materials is still missing due to the wide variety of properties found in fluorescent materials. Here, flash nanoprecipitation (FNP) is reported as a universal procedure for fast‐fabricating large‐scale fluorescent nanoparticles to construct cutting‐edge‐level encryption in anti‐counterfeiting, such as full‐color and dual‐mode “codes‐in‐code” large‐format fluorescent patterns. The large‐format fluorescent patterns are printed with a commercial inkjet printer. They exhibitd high concealment and environmental durability for daily use. The security labels of the 2021 Chinese Racing Pigeon Association (CRPA) certificate are then industrially fabricated based on this universal procedure. The monochrome fluorescent pattern is also upgraded into a full‐color fluorescent pattern for evolutionary encryption and anti‐counterfeiting. Finally, a “codes‐in‐code” dual‐mode encryption is realized in the UV bands. The results lead to cutting‐edge and high‐security anti‐counterfeiting technology, which will broaden the use of fluorescent materials in anti‐counterfeiting due to its universality.