Chiral Luminescent Liquid Crystal with Multi‐State‐Reversibility: Breakthrough in Advanced Anti‐Counterfeiting Materials

Abstract

Creating a security material that carries distinct information in reflective color, fluorescence, and chiroptical property will enhance anti‐counterfeiting levels to deter counterfeits ranging from currencies to pharmaceuticals, but is proven extremely challenging. In this work, an advanced anti‐counterfeiting material, with three‐state of each mode reversibly converted into multi‐mode materials including reflective color, fluorescence, and circularly polarized luminescence signal, is constructed by loading photofluorochromic spiropyran (SP) and zinc ion (Zn2+) into the chiral liquid crystal. Under UV irradiation, the complexes of SP and Zn2+ will be transformed into merocyanine (MC) and MC‐Zn2+, while the energy transfer occurs from MC‐Zn2+ to MC. Upon heating, MC is easy to recover to SP, while the MC‐Zn2+ remains unchanged. The MC and MC‐Zn2+ can be transformed into the SP and Zn2+ under visible light irradiation. The three states of each mode can reversibly convert. Furthermore, the reflective color or fluorescence of each state shows different intensities under left‐ and right‐handed circular polarized filters, enabling easy distinguishing by naked eyes. The advanced anti‐counterfeiting method with multi‐state of each mode for multi‐mode encryption information output will provide a new concept for designing and fabricating multi‐mode anti‐counterfeiting materials, improving the security level for practical application.

Carbon Quantum Dots doped Cholesteric Liquid Crystal Films and Microdroplets for Anti-Counterfeiting

“…Because of the easy technique, the resultant achievement can contribute to anticounterfeiting applications and is more cost-effective than traditional approaches. Many methods for altering the color of CLCs have been proposed in the past, including applying an electric field, changing the viewing angle, adjusting temperature, changing the polarization state, loading zinc ions and photofluorochromic spiropyran into CLC, and so on. − These approaches have been used in many applications because they make it simple to change the structural color of CLCs. On the other hand, these conventional methods demand intricate experimental equipment including voltage generators and heat controllers.…”

Chiral Exciplex Acceptor Enables Circularly Polarized Electroluminescence with High Dissymmetry Factor Close to 10−2

“…Circularly polarized luminescence (CPL) materials are attracting extensive attention in the field of organic lightemitting diode (OLED), [1][2][3][4] information anticounterfeiting, [5] photophysical processes such as energy transfer and charge transfer. Generally, chiral small organic molecules possess low g lum values because they have large electric dipole moments, while the magnetic dipole-moment transitions are forbidden.…”

Chiroptical Performances in Self-Assembled Hierarchical Nanosegregated Chiral Intermediate Phases Composed of Two Different Achiral Bent-Core Molecules

“…For this system fabricated using the NLC confined within the nanospace between the HNFs, the evaluated CPL performance is comparable with previously reported values for low-molecular-weight, chiral, organic compounds in solution [ 12 ]. However, developing a strategy to further amplify the CPL performance is vital for applying this system to potential applications in display [ 18 ], sensing [ 19 ], communication [ 20 ], security [ 21 ], and recording technologies [ 22 ].…”