A new type of chiral photonic anti-counterfeiting film prepared by DICP

Recently, Qing Guangyan, a researcher at the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, designed and fabricated an environmentally friendly, multimodal, switchable chiral photonic thin film
.
This research provides new ideas for the design of advanced anti-counterfeiting materials
.

As early as ancient China, anti-counterfeiting labels (such as watermarks, fingerprints and handwriting) have been widely used in cultural, economic and other fields
.
Innovative anti-counterfeiting technology is of great significance to market stability, medical health and sustainable social development
.
At present, anti-counterfeiting labels mainly use luminescent or structural color materials, such as fluorescent dyes, quantum dots, perovskites, room temperature phosphorescence, nano-imprinted photonic arrays, etc.
, to achieve coding security through physical and chemical stimulation, multi-color combination, and the use of complex patterns
.
However, due to their own spatial structure limitations, these anti-counterfeiting codes only stay in one-dimensional or two-dimensional information transmission
.

In contrast, using polarization-derived chiral luminescent materials to integrate a large amount of information about visual features and spatial structure into one composite material enables the encoding or integration of each type of information, resulting in improved anti-counterfeiting levels
.

Cellulose nanocrystals (CNCs) are abundant, green and sustainable natural polysaccharide polymers that can self-assemble to form chiral nematic structures
.
In this work, the research team combined a strong chirality CNC system with a strong luminescent rare earth complex to prepare a chiral photonic composite film carrying four kinds of optical information
.
The obtained films simultaneously carry structural color, fluorescence, chiral light, and right circularly polarized luminescence (CPL) information, which can be switched among each other
.
Based on the combined properties of these multimodal optical states, humidity-responsive fluorescence or tunable structural colors, flexibility, and durability, the optical system exhibits advanced application potential in banknote anti-counterfeiting
.
At the same time, the material also has strong CPL emission (asymmetry factor up to –0.
36), high absolute quantum yield (66.
7%) and polarization-sensitive chiral optical properties, which will promote the application of CNC photonic materials in chiral optical devices, optical Applications in detectors, vision protection, and chiral sensing
.

The related research results were recently published in Advanced Functional Materials under the title of Multimodal, Convertible, and Chiral Optical Films for Anti-Counterfeiting Labels
.
The research work has been supported by the National Natural Science Foundation of China, the Innovation Fund of the Dalian Institute of Chemistry, and the Xingliao Talents Program
.

A new type of chiral photonic anti-counterfeiting film prepared by DICP