Combinations of Superior Inorganic Phosphors for Level‐Tunable Information Hiding and Encoding

Abstract

Inorganic photoluminescence (PL) phosphors (including upconversion (UC), down‐shifting (DS), and persistent (PersL) materials) with tunable outputs, high quantum yields (QYs), and excellent photostability have attracted tremendous attention in advanced information hiding and encoding (IHE). The three kinds of phosphors endow security patterns in different IHE levels owing to their unique optical features. For security applications, it is very necessary to review how to boost optical performance and achieve multi‐level anti‐counterfeiting. Herein, diversely pivotal approaches on the achievement of multicolor emissions, high QYs, and excellent photostability are summarized. Full learning of these methods is promising to design superior inorganic phosphors. Based on the appealing optical properties of inorganic PL materials, a progressively improved IHE level is revealed by using unitary inorganic PL material, the couples of UCL, DS, and PersL, and further combinations together with external stimuli. This review not only deepens an understanding of designing high‐performance inorganic PL phosphors, but also gets inside into the construction of high‐performance IHE.

Highly Luminescent Copper(I) Halide Phosphors Encapsulated in Fumed Silica for Anti‐Counterfeiting and Color‐Converting Applications

“…The screen printing technique is particularly attractive due to its low cost, large area for preparation, and wide range of choice for substrates. [60,61] We then optimized and prepared the aqueous anti-counterfeit inks with suitable viscosity and surface tension for screen printing using PVP as the main polymer. The blue, green, and orange emission inks were successfully prepared using CNCCl@FS, CNCI@FS, and CNCBr@FS as the phosphor additive, respectively.…”

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

“…The development of anti-counterfeiting materials has attracted particular attention in order to prevent the increasing counterfeits on the current market, including brands, luxury items, banknotes, tickets, and certificates. [1][2][3][4][5][6][7][8][9] In the past few decades, a DOI: 10.1002/advs.202201565 wide variety of security and anticounterfeiting technologies have been developed, including thermal, [10][11][12][13] magnetic, [14] light, [15][16][17] and mechanical responses. [18,19] Therein, the single-mode (photoluminescence or reflective color) with single-state (only one reflective color or fluorescence) is the most widely used, possessing the advantages of a broad range of materials sources, easy operation, and observation.…”

High-level information encryption based on optical nanomaterials with multi-mode luminescence and dual-mode reading

“…Luminescence, an optical phenomenon, is commonly considered to be the most promising technology in the field of information security because of the facile design, low cost, and colorful features of luminescent materials. [1][2][3] Along with the development of optical materials, diverse luminescent materials, such as those that exhibit down-conversion luminescence (DCL), 4 up-conversion luminescence (UCL), 5 and per-sistent luminescence (PersL), [6][7][8][9] have been developed and have found application in the field of information security. [10][11][12][13][14][15][16][17][18] However, a single luminescence mode is usually insufficient to meet the demands of high-level information security and is easily imitated.…”