GUWAHATI, May 25: Researchers at the Indian Institute of Technology-Guwahati (IIT-G) have developed an advanced light-emitting perovskite nanomaterial that could improve protection against fake currency, forged documents and other counterfeit products.
The research team has developed nanocrystals capable of producing light-based security patterns that cannot be replicated using traditional printing and imaging methods.
The findings of this research have been published in the prestigious journal, Advanced Optical Materials, in a paper co-authored by Prof. Saikat Bhaumik, assistant professor, in collaboration with Prof. P.K. Giri, and their research scholars, Latika Juneja and Garima Choudhary, from the Department of Physics at IIT-G.
Counterfeiting has become a global concern affecting various industries, ranging from pharmaceuticals and electronics to banking and identity documentation. With the help of modern technologies, offenders have found ways to accurately copy conventional security measures such as barcodes, QR codes, holograms and watermark labels. These challenges can also have implications for national security, as they can pose risks by enabling financial fraud, illegal activities and security breaches.
To address the challenges, Prof. Bhaumik and Prof. Giri, along with their research team, developed light-emitting perovskite nanocrystals, a group of crystalline materials known for their optical and electronic properties.
These materials have sizes in the nanometre range (a hundred thousand times smaller than the width of a single human hair), and hold the capability to produce very pure and intense colours with very narrow emission ranges.
This property helps in providing accurate optical signatures and larger colour tunability than traditional fluorescent materials. These properties make it suitable for secure authentication technologies. However, one of the major challenges of these materials is their limitation when exposed to moisture, heat and environmental conditions, under which they degrade easily.
To solve this problem, the research team developed a double-layer coating around the nanocrystals, making them heat and chemical-resistant while maintaining their light-emitting properties.
With the use of a direct laser writing technique, the team created tiny patterns from these materials. The multi-layer coating enabled the developed nanocrystals to create these patterns without using conventional lithographic masks, which helped in achieving resolutions of 10 to 40 micrometres, allowing very complex patterns and encoding of information.
Speaking about the developed technology, Prof. Bhaumik, lead author of the research, said, “A unique feature of this perovskite material is that, unlike normal security labels which always show the same mark, it exhibits very narrow emission spectra and the emission intensity changes depending on the environment.”
In the case of the developed materials, to produce a fake, a counterfeiter will need to copy the visible pattern along with the way in which the nanocrystals respond to heat and chemicals. This makes the security system much harder to copy using traditional techniques. It also has the potential to embed information into company products and banknotes for secure information storage and retrieval.
The researchers have coined this approach as “4D anticounterfeiting”.
It is notable that the laser patterning technique developed by the IIT-G researchers can also be utilised in developing cutting-edge micro-LED displays for smartphones, wearables, and Augmented Reality (AR) systems, among others.
On a broader scale, the developed technology can be applied across several sectors where product authentication and security are critical.
