Security Elements and Nanomaterials as Anti-Counterfeiting Features in Paper Documents: A Review

In order to reduce forgery and counterfeiting, a big range of variable security methods are used to render a high level of security to paper documents. Stimuli-chromic (photochromic, hydrochromic, and thermochromic) and photoluminescent (fluorescent and phosphorescent) compounds are the most significant and applicable materials for development of complex anticounterfeiting technology with a high-security level and fast authentication that this highly efficient authentication technologies have been developed to reach high security and efficiency. A wide range of materials, such as organic and inorganic metal complexes, polymer nanoparticles, quantum dots, polymer dots, carbon dots, upconverting nanoparticles, and supramolecular structures, could display all of these phenomena depending on their physical and chemical characteristics. Colour patterns based on micro-nano structure have attracted enormous research interests due to unique optical switches and smart surface applications in photonic crystal, controlled adhesion, biological detection, supramolecular self-assembly and anti-counterfeiting. The interaction of the micro/nano structure with incident light can produce a structural colour which is mainly consequent on multi-layer thin film interference, diffraction of surface or periodic structure, and wavelength selective scattering by sub-wavelength particles.This article covers the main features of anti-counterfeiting technology including nanotechnology currently on the market, gives a clear definition of it, describes their main characteristics and sets out practical implementation requirements at a glance.

کلیدواژه ها:

Security paper ، anti-counterfeiting ، nanomaterials ، fluorescent ، cellulose fiber ، organnic photonic