Inkjet-Printed Quantum Dot Fluorescent Security Labels with Triple-Level Optical Encryption

Abstract

Optical security labels play a significant role in protecting both our wealth and health. However, simultaneously meeting the requirements including low-cost fabrication, easy detection, and high-level security is still challenging for security labels. Here, we design an unclonable anti-counterfeiting system with triple-level security by using the inkjet printing technique, which can be authenticated by naked eyes, a portable microscope, and a fluorescence microscope. These labels are achieved by printing microscale quantum dot (QD) ink droplets on premodified substrates with random-distributed glass microspheres. Due to the unique capillary action induced by the glass microspheres, QDs in the ink droplets are deposited around the microspheres, forming microscale multicircular patterns. Multiple pinning of QDs at the three-phase contact lines appears during the evaporation of the droplet, resulting in the formation of a nanoscale labyrinthine pattern around the microspheres. The nanoscale labyrinth pattern and the microscale multicircular microsphere array, together with the printed macroscopic image, constitute a triple-level progressive anti-counterfeiting system. Moreover, the system is compatible with an artificial intelligence-based identification strategy that allows rapid identification and verification of the unclonable security labels.

Size-Controlled Indium Phosphide Quantum Dots for Bright and Tunable Light Emission by Simple Hindered Diamine Addition

“…Colloidal quantum dots (QDs) are used in many high tech-fields such as LED-based displays and lighting, bioimaging, , anticounterfeit labeling, , lasers, or even quantum computing . Because of quantum confinement, the absorption and emission properties of semiconducting QDs are size-controlled.…”

Hybrid Plasmonic/Photonic Nanoscale Strategy for Multilevel Anticounterfeit Labels

“…Fluorescence has been widely used as an optical anticounterfeit function. − Photoluminescence occurring in the perovskite and inkjet-printed quantum dots has been recently used as a PUF. Biological systems consisting of colonized populations of T-cells have also been demonstrated as high-security level biological unclonable functions …”

Lanthanide Polyoxometalate Based Water-Jet Film with Reversible Luminescent Switching for Rewritable Security Printing

“…Nowadays, information leakage poses a serious threat to military, economy, and our daily lives. − Therefore, the development of effective information encryption and decryption strategies is urgently needed. One of the most effective methods to realize secure information storage is luminescent printing, where the printed information is only visible under UV light, which exhibits high concealment. − Although electronic media have been developed rapidly now, the paper still occupies an important role in information storage, communication, and dissemination.…”