Multiple Anti-Counterfeiting Composite Film Based on Cholesteric Liquid Crystal and QD Materials

Abstract

A composite film with multiple anti-counterfeiting features was demonstrated by superposing quantum dots (QDs) polymer matrix (film A) and cholesteric liquid crystal film (film B) together. The first-line and second-line anti-counterfeiting characteristics were successfully implemented by employing thermochromic, angular photochromic, and circularly polarized discoloration of film B, respectively. By initiatively utilizing the different relative positions between the fluorescence emission peak (λ em ) of film A and the central selective reflection wavelength (λ m ) of film B at different temperatures, which resulted in changes in the fluorescence spectra or the different presence of latent patterns, the most important third-line anti-counterfeiting feature was successfully achieved.

Environment‐Sensitive Carbon Dots Derived from Naphthalenediol for Solvent Polarity Indicator and Anti‐Counterfeiting

“…Due to the excellent photostability, low toxicity, good biocompatibility, and low-cost preparation, carbon dots (CDs) have received increasing attention in various fields, including biomedicine, bio-imaging, catalysis, light-emitting devices and information security. [1][2][3][4][5][6][7][8][9][10][11] Environmentally sensitive photoluminescence (PL) is an important feature of CDs, which means that their emission wavelength and intensity can be changed by altering the microenvironment around CDs. [12] When CDs are dissolved in different solvents, the solvent effect, that is, the complex interaction between surface groups and solvent molecules, made a significant impact on the optical properties of CDs.…”

“…Due to the excellent photostability, low toxicity, good biocompatibility, and low‐cost preparation, carbon dots (CDs) have received increasing attention in various fields, including biomedicine, bio‐imaging, catalysis, light‐emitting devices and information security [1–11] . Environmentally sensitive photoluminescence (PL) is an important feature of CDs, which means that their emission wavelength and intensity can be changed by altering the microenvironment around CDs [12] .…”

A hybrid hydrogel system composed of CdTe quantum dots and photonic crystals for optical anti-counterfeiting and information encoding–decoding

“…Composite materials based on QDs and PCs could afford more complex, precise and high-dimensional anti-counterfeiting patterns, solving the low anti-counterfeiting level problem of single monochrome materials, which has aroused great interest. 35–37 Chen reported CdS QD-functionalized (CNC) to prepare nanothin films through layer-by-layer self-assembly for anti-counterfeiting applications. 38 Chen and their colleagues obtained the poly(styrene-methyl methacrylate-acrylic acid)-generated 2-polyamidoamine-CdTe/ZnS (P(St-MMA-AA)-G2 PAMAM-CdTe/ZnS) hybrid microspheres by using microfluidic printing techniques.…”

Core–Shell Structured Upconversion/Lead‐Free Perovskite Nanoparticles for Anticounterfeiting Applications

“…So far, these labels, which range from fluorescent inks (lanthanide compounds, [6, 7] upconverting nanocrystals (NCs), [8, 9] carbon dots, [10] etc [11] [12] liquid crystals, [13] nucleic acids, [14] etc [15] …”