Nitrogen doped carbon quantum dot printable ink for document authentication and anticounterfeiting

The global threat to document security, driven by rising rates of counterfeiting and forgery in the current technological era, necessitates the development of a robust technique for advanced document authentication. The emergence of nanotechnology has presented nanomaterials as a robust tool for developing novel techniques for document authentication and anti-counterfeiting due to their unique, difficult-to-replicate, and inherently luminescent features. Currently, nitrogen-doped carbon quantum dots (N-CQDs) are used in the development of security inks due to their unique optical properties, high fluorescence, and stability across various applications. This study focuses on the development of a nitrogen-doped carbon quantum dot-based ink for secure printing to allow for advanced document authentication. N-CQDs were first synthesized using the solvothermal method and were characterized using Ultraviolet-Visible spectrophotometry, fluorescence spectroscopy, X-ray Diffractometer (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Energy Dispersive X-ray (EDX) to assess their optical, morphological and structural properties. The N-CQD-based ink, developed using the synthesized Carbon dot as the precursor and incorporating print-friendly additives, exhibited exceptional fluorescence. The stability of the developed ink was assessed at varying temperatures over a 1-month period. The results indicated the ink’s high stability and resilience as a proof of concept. The ink was used for secure printing with an inkjet printer, demonstrating its invisibility, unique fluorescence, difficulty-of-reproduction feature, and stability in information encryption across different document surfaces. This clearly confirms the ability of N-CQD-based ink for secure printing in advanced document authentication and anti-counterfeiting applications.