Organic Light‐Emitting Physically Unclonable Functions

Abstract

The development of novel physically unclonable functions (PUFs) is of growing interest and fluorescent organic semiconductors (f‐OSCs) offer unique advantages of structural versatility, solution‐processability, ease of processing, and great tuning ability of their physicochemical/optoelectronic/spectroscopic properties. The design and ambient atmosphere facile fabrication of a unique organic light‐emitting physically unclonable function (OLE‐PUF) based on a green‐emissive fluorescent oligo(p‐phenyleneethynylene) molecule is reported. The OLE‐PUFs have been prepared by one‐step, brief (5 min) thermal annealing of spin‐coated nanoscopic films (≈40 nm) at a modest temperature (170 °C), which results in efficient surface dewetting to form randomly positioned/sized hemispherical features with bright fluorescence. The random positioning of molecular domains generated the unclonable surface with excellent uniformity (0.50), uniqueness (0.49), and randomness (p > 0.01); whereas the distinctive photophysical and structural properties of the molecule created the additional security layers (fluorescence profile, excited‐state decay dynamics, Raman mapping/spectrum, and infrared spectrum) for multiplex encoding. The OLE‐PUFs on substrates of varying chemical structures, surface energies and flexibility, and direct deposition on goods via drop‐casting are demonstrated. The OLE‐PUFs immersed in water, exposed to mechanical abrasion, and read‐out repeatedly via fluorescence imaging showed great stability. These findings clearly demonstrate that rationally engineered solution‐processable f‐OSCs have a great potential to become a key player in the development of new‐generation PUFs.

Unclonable Anti‐Counterfeiting Labels Based on Microlens Arrays and Luminescent Microparticles

“…Ultimately, the ability to label a variety of goods, including those with curved surfaces, is of key importance for unclonable labels. [ 20 ] Given the use of a glass substrate for the microlens array, the prototype labels used to demonstrate the general concept herein are not yet well suited to such an application. The further development of this concept to use a single flexible polymer layer in which the microparticles are doped and onto which the microlens array is imprinted is a direct (and feasible) target that would allow the transfer of the complete label onto a product.…”

“…[ 19 ] This latter work is especially relevant to the present study in that it shares the goal of enabling a wider‐spread uptake of unclonable labels by allowing simpler hardware—based around ubiquitous smartphones—to authenticate the labels. The work on creating and characterizing unique optical point patterns continues to rapidly progress, with Kayaci and coworkers converting a thin layer of emissive polymers into unclonable patterns of micron‐scale islands through a brief anneal, [ 20 ] and continued development of plasmonic scattering patterns and their analysis. [ 21 ] Our current work expands on these contributions to establish the potential for microlens arrays integrated into the label design to simplify the detection hardware while maintaining security.…”

Random fractal-enabled physical unclonable functions with dynamic AI authentication

“…The intrinsic randomness ensures sufficient complexity and huge encoding capacity of the PUFs, making them nearly impossible to be duplicated in anti-counterfeiting. Up to now, various types of PUFs have been developed, for example, (i) directly visualized graphical PUFs composed of randomly distributed micro/nanostructures (e.g., wrinkling [7][8][9][10] /buckling 11 /folding 12 -based artificial fingerprints, randomly formed evaporative patterns 13,14 , and randomly arranged micro/nanoparticles [15][16][17][18][19] ); (ii) spectral PUFs with the aid of an analytical tool for readout (e.g., stimulated luminescence 20,21 , surface-enhanced Raman scattering (SERS) 22,23 ); and (iii) complex electronic systems with diverse disorders 24 . Among these PUFs, the graphically encoded tags mainly focused on the surface information are more convenient and robust in identification due to the direct imaging by the simple optical microscopy.…”

“…Among these PUFs, the graphically encoded tags mainly focused on the surface information are more convenient and robust in identification due to the direct imaging by the simple optical microscopy. Particularly, the levels of the PUF tags in complexity can be actively regulated only by recording different pattern areas or changing the physical feature size [7][8][9]18 . For example, a random wrinkle system has flexible controllability in code complexity by modulating wrinkle instability 7,9,25 , and thus, it owns a configurable encoding capacity that can be sufficiently adaptable to an on-demand encryption strategy.…”

Transferrable SERS Barcodes

“…[4][5][6][7][8] A conventional approach to solving this problem has been the use of security labels. [9,10] Different forms of barcodes have been developed to encode information. The unique and sizedependent properties of nanomaterials offer unprecedented routes to increase the complexity of such barcodes.…”