Tristate Photonic Crystal Film with Structural, Fluorescent, and Up-Conversion Luminescent Color for Multilevel...

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Growing global counterfeit market impacts economy and health.
• Conventional anticounterfeiting tags are easily imitated.
• Need for advanced, robust anti-counterfeiting solutions.

Purpose of the Study:

• To develop a novel, scalable anticounterfeiting technology.
• To overcome limitations of conventional, imitable anticounterfeiting tags.
• To create multilevel anticounterfeiting films with unique optical properties.

Main Methods:

• Assembled colloidal nanospheres and luminescent micromaterials into composite photonic crystals (PhC).
• Utilized a rapid, massive scale-up fabrication process via thermal rolling (minutes).
• Incorporated masking templates for multilevel anticounterfeiting images.

Main Results:

• Fabricated PhC films exhibit three distinct optical states: angle-dependent structural color, green luminescence (980 nm light), and red luminescence (UV light).
• Achieved multilevel anticounterfeiting images by integrating physical and chemical security features.
• Demonstrated high-quality PhC film fabrication via thermal rolling for diverse microunit sizes.

Conclusions:

• Developed a scalable and efficient method for producing advanced anticounterfeiting photonic crystal films.
• The novel PhC films offer multiple, integrated security features surpassing conventional tags.
• The thermal rolling process is a viable technique for mass-producing complex, functional photonic crystal materials.