Luminescent nanomaterials based covert tags for anti-counterfeiting applications: A review

Counterfeiting has emerged as a new global threat that challenges companies, securities, governments, and customers. Because of the banal advancements in technology, it is extremely prevalent. Ultimately have a more concerning effect than terrorism in terms of the standard of goods, organizations, banks' financial standing, people's health, the nation's financial situation, etc. Thus, it requires an urgent high-tech solution to combat counterfeiting. The present review surveys the anti-counterfeiting technologies that have been applied to combat and discourage counterfeiting. It presents the photoluminescence properties of quantum dots, metal-organic-framework, and lanthanide-doped nanomaterials and their applications in anti-counterfeiting. Recently, lanthanide-doped nanomaterials have emerged as potential candidates that provide strong security for the products due to their excellent color tunable luminescence properties under the wide range (UV to NIR) of excitation. Therefore, the present review mainly focused on the strategies of luminescence features of lanthanide-doped downconversion/downshifting and upconversion nanomaterials and their potential uses in fighting counterfeiting. Moreover, the key barriers and opportunities to combat counterfeiting advances are discussed. In addition, the crucial factors, such as the fabrication of luminescent ink, various printing techniques employed for printing different kinds of fluorescent security labels, patterns, and codes, etc., have been highlighted. This review will provide detailed information to the readers to design the security labels based on the lanthanide-doped luminescent nanomaterials for high-tech security against counterfeiting.