Carbon dots as emerging luminophores in security inks for anti-counterfeit applications - An up-to-date review

Amongst the various techniques that have been developed to combat counterfeits, security printing using advanced luminescent materials has been extensively used for a wide range of applications not only due to facile design, high-throughput production and simple operation, but also due to superior-level security features. Fluorescent carbon-based nanodots are a widely accepted emerging class of luminophores, which own exceptional optical properties. The initial section of the article presents the various synthetic and sustainable techniques that are adopted for the synthesis of luminescent carbon dots. Further, the recent advancements reported on the security inks formulated from various carbon-based nanomaterials such as carbon nanodots, carbon quantum dots, graphene quantum dots and carbonized polymer dots for realizing advanced anti-counterfeiting are highlighted. Moreover, based on the present critical challenges in using these carbon dots in fluorescent security ink formulations, the scope for future research developments to improve the existing security features are also discussed.