Biomimetic intelligent photonic crystal composite films with tri-mode optical states for advanced anti-counterfeiting and information encryption

Counterfeiting has emerged as a significant global concern in recent years, posing serious security risks to individuals and society as a whole. Unfortunately, existing anti-counterfeiting technologies have proven to be inadequate in addressing the growing problem of counterfeit activities. In light of this, a delicate strategy inspired by Phelsuma gecko has been developed, which involves the creation of intelligent photonic crystal composite (PCC) films that combine physical (colloidal PC) and chemical elements (thermochromic microcapsules and fluorescent materials) to exhibit three distinct optical states. These states, including structural, pigmentary, and fluorescent colors, can be easily switched using thermal stimuli and UV irradiation. Laser-etched patterned PCC films have also been successfully achieved, showcasing superior performance in terms of optical capabilities. The regioselective deposition of PCC films with different thermochromism has enabled the creation of multicolored patterned PCC films, which can be activated in response to thermal fluctuations. Leveraging these advancements, a high-level anti-counterfeiting and information encryption system has been demonstrated, offering the ability to deliver three distinct optical information on-demand. This work establishes a new platform for achieving multiple optical states within a single system, opening up vast possibilities for advancements in the fields of anti-counterfeiting and information security. By embedding thermochromic microcapsules and fluorescent materials into colloidal photonic crystals (PCs), intelligent PCs composite films that mimic the physical and chemical elements found in the gecko's skin have been obtained.