Luminescent Polymeric Films with Spectral and Temporal Encoding for Advanced Anti-Counterfeiting Security

• Grant number: 25/04765-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2025
• End date: June 30, 2026
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Inorganic Chemistry
• Principal Investigator: Airton Germano Bispo Júnior
• Grantee: Tayne Paranhos Pereira
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Luminescent materials invisible to the naked eye but detectable under ultraviolet (UV) or infrared (IR) radiation have been applied as security tags to combat the counterfeiting of documents and products. EuII-based phosphors exhibiting persistent luminescence and EuIII complexes displaying conventional luminescence have stood out for such a proposal. This is due to their intense luminescence, absorption capability within the ultraviolet or infrared spectral regions, and high thermal and chemical stability. However, the dissemination of knowledge about these technologies may enable counterfeiters to develop methods to imitate or bypass these security mechanisms. To work around this issue, this project seeks to fabricate polymeric films containing two luminophores: one exhibiting persistent luminescence and the other displaying the conventional luminescence. This approach takes advantage of different temporal dynamics and absorption in distinct spectral ranges to develop orthogonal and temporal security codes presenting two different security layers: (1) emission color change as a function of the excitation wavelength (orthogonal codification) and (2) emission color change as a function of time after turning off the excitation source (temporal codification). To fabricate the films, polymethyl methacrylate (PMMA) will be used as polymer matrix, SrAl2O4:EuII,DyIII as the persistent luminescence material, and the complex [Eu(nta)¿(phen)] (nta = 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butadione; phen = phenanthroline) as the conventional luminescent emitter.