Environment-friendly luminescent inks and films based on lanthanides toward advanced anti-counterfeiting

Developing environment-friendly luminescent anti-counterfeiting materials and high-level anti-counterfeiting tactics remain challenging. Herein, the coordination of l-aspartic acid (Asp) to lanthanide ions (Ln3+) was applied to fabricate environment-friendly luminescent anti-counterfeiting materials (Asp-Ln). Multiple Asp-Ln powders with varied emission colors can be obtained by adjusting the molar ratio of Tb3+ to Eu3+. Notably, the luminescent inks and hydrogels can be facilely prepared by dissolving the powders in water with different concentrations. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy revealed the formation of coordination bonds between Asp and Ln3+. Luminescent spectrum and luminescent decay curves confirmed that the luminescent inks and hydrogels possessed excellent luminescent properties, which could be directly functionalized as luminescent anti-counterfeiting materials. The luminescent inks exhibited low toxicity, good biocompatibility, high adhesion and excellent stability. Additionally, the luminescent films were easily fabricated by doping Asp-Ln powders into polyvinyl alcohol (PVA) matrix. They could be applied as luminescent anti-counterfeiting labels with excellent performance. Furthermore, scrambled letters, quick response (QR) codes and ASCII encryption strategies based on the developed luminescent materials were designed to enhance the level of anti-counterfeiting. This work proposed a facile strategy for synthesizing environment-friendly luminescent anti-counterfeiting materials based on lanthanides, which have excellent application prospects in the fields of identification, information encryption, and anti-counterfeiting.