A groundbreaking system combines programmable structural coloration and switchable circularly polarized luminescence for advanced anti-counterfeiting measures. Published on March 6, 2025, this research unveils innovative materials capable of enhancing information security beyond traditional methods.
Information security and anti-counterfeiting have become focal points of research over the past decades, driven by the increasing sophistication of counterfeit products and the necessity to protect sensitive information. The pursuit of systems capable of displaying diverse information across distinct optical channels has led scientists to explore materials known for their ability to manipulate light, including structural coloration materials. These materials generate colors from periodic microstructures rather than from chemical pigments, making them invaluable for applications ranging from displays to secure labeling.
Despite their advantages, existing structural coloration approaches often suffer from limitations, typically performing poorly under weak ambient light and offering limited viewing angles. On the other hand, traditional fluorescence materials, which generate images upon excitation, are inactive under standard lighting conditions and can be easily mimicked, leading to potential lapses in security. Recent enhancements through circularly polarized luminescence (CPL) have addressed some of these challenges, yet the effective application of CPL remains constrained by substantial interference between different optical signals.
To address these issues, the research team employed polydiacetylene (PDA) gel films and integrated two-dimensional programmable patterns with chiral fluorescence layers containing perovskite nanocrystals and twisted-stacking silver nanowires (NWs). This combination enables the production of vibrant structural colors and highly responsive fluorescent emissions, achieving peak dissymmetry factors (glum) of up to 1.3 — significant advancements for depth and security.
Using photomasks aligned with grates and multi-stage photo-patterning processes, the researchers crafted truly programmable patterns on the PDA gels, allowing for dynamic display and information encryption. Notably, the structural coloration and fluorescent patterns can be modified independently, allowing users to conceal or reveal specific information simply by altering environmental factors or through targeted treatments with substances like acetonitrile.
Another key aspect is the capacity of these patterns to adapt based on viewing angles — as one approaches or tilts the object, dynamic images emerge or alter, showcasing patterns such as playful depictions of pandas and elephants, which only reveal themselves from specific distances or angles.
Through this strategy, anti-counterfeiting materials exhibit remarkable self-contained flexibility and resilience; the fluorescent intensity of labels sustained under cooler temperatures demonstrated stability over weeks, whereas those subjected to higher temperatures showed diminished responses significantly within minutes. This indicates potential for practical usages, such as labels on consumer goods, clothing, or secure documents where visual cues are tied to specific environmental changes.
Key findings suggest not only the enhanced capacity for information storage but also greater levels of anti-counterfeiting security, all thanks to this smart-material technology. "The structural coloration information and FL patterns (including CPL pattern) can be independently modulated without mutual interference," explain the researchers. This degree of separation mitigates typical crosstalk found in conventional systems, securing information integrity.
To conclude, the integration of programmable structural coloration with dynamic CPL could redefine standards for visual information systems, paving the way for their implementation across various fields ranging from commercial packaging to high-end security applications, signaling readiness for modern challenges related to information integrity and counterfeiting. Such advancements encapsulate not just scientific innovation, but also the practical and artistic possibilities of responsive materials.