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Glass, with its unique amorphous properties, offers low thermal conductivity, high catalytic activity, insensitivity to interfacial lattice mismatch, and the absence of grain boundaries. Melt‐quenched organic–inorganic hybrid glass has recently gained significant attention as an emerging material because of its excellent processability and formability. Here, an SbCl3(C25H46ClN)x halide with a low melting point (90 °C) and significant formability is reported. Both the crystalline and glass states of SbCl3(C25H46ClN)x have double broadband emission, and the glass state exhibits negative thermal quenching, which is rare in metal halides. Interestingly, the luminescence properties of SbCl3(C25H46ClN)x glass with different x values differ. This feature is utilized to design multimodal anti‐counterfeiting and information encryption applications. Additionally, The inherent melt processing capability of SbCl3(C25H46ClN)x allows it to be shaped into various forms suitable for practical applications. SbCl3(C25H46ClN)x scintillator screens (diameter 2.2 cm) are successfully prepared by low‐temperature melting, achieving an X‐ray imaging resolution of 18 line pairs per millimeter (18 lp mm−1). This study demonstrates the potential of melt‐processed organic–inorganic hybrid glass SbCl3(C25H46ClN)x in anti‐counterfeiting, information encryption, and X‐ray detection. [ABSTRACT FROM AUTHOR]

Perovskites have gained widespread attention across various fields such as photovoltaics, displays, and imaging. Despite their promising applications, achieving precise and high‐quality patterning of perovskite films remains a challenge. In this study, femtosecond laser direct writing technology is utilized to achieve rapid and highly precise micro/nanofabrication on perovskites. The study successfully fabricates multiple structured and emission‐tunable perovskite patterns composed of A2(FA)n−1PbnX3n+1 (A represents a series of long‐chain amine cations, and X = Cl, Br, I), encompassing 2D, quasi‐2D, and 3D structures. The study delves into the intricate interplay between fabrication technology and the growth of multi‐dimensional perovskites: higher repetition rates, coupled with appropriate laser power, prove more conducive to perovskite growth. By employing precise halogen element design, the simultaneous generation of two distinct color quick‐response (QR) code patterns is achieved through one‐step laser processing. These mirrored QR codes offer a novel approach to anti‐counterfeiting. To further enhance anti‐counterfeiting capabilities, artificial intelligence (AI)‐based methods are introduced for recognizing patterned perovskite anti‐counterfeiting labels. The combination of deep learning algorithms and a non‐deterministic manufacturing process provides a convenient means of identification and creates unclonable features. This integration of materials science, laser fabrication, and AI offers innovative solutions for the future of security features. [ABSTRACT FROM AUTHOR]

Low‐dimensional hybrid organic‐inorganic metal halides (OIMHs) have attracted considerable attention in anti‐counterfeiting due to their non‐toxicity and high photoluminescence quantum yield (PLQY). However, many reported OIMHs are either not reversible or have a poor PLQY. In this study, two antimony‐based halides, (C21H21P)2SbCl5 and (C22H24P)2SbCl5, are synthesized using different organic cations. Both compounds exhibit bright orange–yellow emissions with a PLQY of 82.6% and 83.5%, respectively. The orange–yellow emission of (C21H21P)2SbCl5 and (C22H24P)2SbCl5 are attributed to the radiative recombination of self‐trapping excitons. While (C21H21P)2SbCl5 maintains stable orange–yellow luminescence when exposed to ethanol, (C22H24P)2SbCl5 undergoes a structural transformation to non‐luminescent (C22H24P)2Sb2Cl8 upon ethanol treatment, which can be reverted to its luminescent state by heating. Even after multiple cycles, the PLQY of (C22H24P)2SbCl5 is still over 80%, demonstrating excellent cycling stability. (C21H21P)2SbCl5 and (C22H24P)2SbCl5 are also explored as fluorescent materials for Morse code anti‐counterfeiting and optical logic gate applications. This work offers a completely new option for fluorescent material used for security information. [ABSTRACT FROM AUTHOR]

Herein, a new concept is proposed for the humidity‐induced disappearance of the photonic stop band (PSB) in multilayer films of 1D photonic crystals (PCs). These films are fabricated via alternating spin‐coating of photo‐cross‐linkable high and low‐refractive‐index polymers onto a black polyethylene terephthalate (PET) substrate, followed by surface immobilization using UV light irradiation. The sensitivity to humidity is adjusted by varying the degree of quaternization (DQ) of the P(4VP‐co‐BPA) layers. The resulting films initially display vivid colors; however, as the humidity gradually increases, the PSB undergoes a red shift accompanied by a decrease in reflectivity, thus leading to the disappearance of the color. The reduction in reflectivity of the PSB can be attributed to the infiltration of water molecules (n = 1.33) into the quaternized high‐refractive‐index layers, thus resulting in a decrease in the refractive index and an increase in layer thickness. This leads to a diminished contrast between the refractive indices of the high‐ and low‐refractive‐index layers, ultimately causing the simultaneous disappearance of the PSB and the reflection color. Additionally, two patterned films are fabricated with high humidity responsiveness for application as anti‐counterfeiting labels. These findings advance photonic crystal research and offer innovative solutions for security and authentication. [ABSTRACT FROM AUTHOR]

Luminescent metal halides, as a type of luminescent semiconductor material, offer advantages that fulfill the requirements of emerging light source devices, such as high luminescence efficiency, good thermal stability, and tunable colorful emission. Blue light being one of the three primary colors plays a crucial role in the field of lighting and colorful displays. However, the progress in device performance of blue‐light materials lags behind that of green and red‐light materials. Currently, there have been numerous reports on metal halide perovskite blue‐light materials, but a comprehensive review on the development and performance control of blue‐light metal halides is yet to be found. This paper provides a comprehensive summary of the design strategies and luminescence mechanisms of blue‐light perovskites with various luminescence centers, as well as their application progress in the fields of light‐emitting diodes (LEDs), X‐ray scintillators, information anti‐counterfeiting and encryption. It also explores possible directions for subsequent performance improvement. This work aims to offer valuable insights and recommendations for the future development of blue‐light metal halides, with significant implications for the fabrication of novel blue light devices and advancements in detection technology. [ABSTRACT FROM AUTHOR]

Materials with structural coloration capable of multimode color manipulation are gaining growing significance for advanced encryption and high‐security anti‐counterfeiting applications. Among the most promising candidates are naturally derived biomaterials, owing to their renewable, biocompatible, and biodegradable features for developing sustainable, bio‐interfaced photonic platforms. Nevertheless, structural color encryption strategies developed from biological materials usually exhibit limited optical operation modes, lowering their encryption capability and security level. Here, an all‐biomass‐based photonic crystal platform is reported that hierarchically integrates chiral nematic and inverse opal structures through a combination of colloidal assembly, silk protein self‐assembly, and chiral self‐assembly of cellulose nanocrystals, enabling multiplex structural color manipulation in 2D and 3D spaces. The platform's Janus‐style integration brings specular and diffuse reflection, direction‐dependent reflection, circular dichroism, and birefringence into a single form, thereby facilitating multimode structural color tuning in a 2D plane by altering the illumination‐viewing modes. The inherent shape plasticity of silk proteins allows the subsequent creation of 3D photonic platforms with diverse configurations, offering additional spatial flexibility for color encoding. It is demonstrated that this all‐biomass‐based photonic framework exhibits versatile, multilevel, and high‐capacity encryption capability in 2D and 3D spaces, representing an innovative solution to bolster security measures against counterfeiting for future technologies. [ABSTRACT FROM AUTHOR]

Lanthanide-doped inorganic perovskite luminescent materials have always been regarded as a good platform for multi-functional applications such as anti-counterfeiting and information encryption, owing to their good visibility, diverse colors and simple design. In this study, we design the Cs 2 NaTbCl 6 : Ce/Yb double perovskite single crystals, achieving visible green luminescence under various excitation sources such as ultraviolet, near-infrared (980 nm) and X-ray. The possible emission and energy transfer mechanisms between Tb3+ ions and Ce3+, Ce4+, Yb3+ ions under different excitations are discussed in detail. Our work skillfully takes advantage of the Tb3+ ions acquiring the transferred energy from non-luminescent Ce4+ ions and luminescent Ce3+ ions, broadening the ultraviolet response and improving its stability. The luminescence intensity of Cs 2 NaTbCl 6 double perovskite single crystal was increased about 40 times under 343 nm excitation by doping Ce4+ and Ce3+ ions, which shows that Ce4+ and Ce3+ ions doping effectively introduces a new excitation band. Furthermore, diversified anti-counterfeiting modes are fabricated to highlight the promising applications of Cs 2 NaTbCl 6 double perovskite systems with tunable luminescence in advanced anti-counterfeiting, paving the way for future research on the multi-light sources luminescent materials. [ABSTRACT FROM AUTHOR]

Luminescent materials with multi-emission features are difficult to be replicated, which are highly desirable for advanced anti-counterfeiting. Here, we report the pioneering synthesis of Mn2+/Yb3+/Er3+ tri-doped Cs2Ag0.8Na0.2InCl6 double perovskites (MYE-DP), which exhibit photoluminescence (PL) covering from visible to near-infrared (NIR). The PL colors under excitations of 254 and 365 nm are notably different due to the changed relative emission intensities of self-trapped excitons (STEs) and Mn2+ d–d transition. Moreover, under the excitation of a NIR laser, the MYE-DP exhibits upconversion (UC) emissions of Mn2+ and Er3+. After ceasing the excitation, the long-lived trapped electrons can be thermally released to Mn2+ and Er3+ ions, resulting in both visible and NIR afterglow. Based on multi-modal emissions of the MYE-DP, we demonstrate a five-level anti-counterfeiting strategy, which significantly increases the anti-counterfeiting security. In addition, this work provides valuable insights into the energy transfer between STEs, Mn2+, Ln3+, and traps, laying a solid foundation for future development of new lead-free perovskites. [ABSTRACT FROM AUTHOR]

A full‐color colorimetric humidity sensor with high brightness is proposed by using a hetero‐structured dielectric film in a metal‐insulator‐metal (MIM) resonator. A humidity‐responsive polymer is designed to graft on top of a metal‐organic frameworks (MOFs) thin film (MOFs‐Polymer) as insulator layer in the resonator. Programmable tuning of reflected color is achieved by controlling the polymer thicknesses, and finite difference time domain simulation of light‐matter interactions at subwavelength scales proves the dependence of the reflected wavelength on dielectric layer thickness of the resonator. Vivid full‐color changing is realized during tracking humidity process due to swelling of the stimuli‐responsive polymer. Ultrafast response (≈0.75 s) is achieved for tracking trace H2O from H2O/methanol mixture, which is ≈104 faster than that of the pure polymer‐based MIM resonator. Meanwhile, the study observes significant spectral redshift because the porous MOFs film facilitates the preconcentration of external stimulus and improves the detection sensitivity of the resonator. Further, double‐channel anti‐counterfeiting multiplexing imaging is devised on the MIM resonator by photomask technology. Patterned encoding for security label is achieved on the MIM resonator by engineering humidity‐tunable pixels of Au/MOFs‐Polymer/Au and humidity‐invalid pixels of Au/MOFs/Au. [ABSTRACT FROM AUTHOR]

A new type of material, organic salts in the crystal and crystalline powder state, with both excitation wavelength dependent (Ex‐De) fluorescence and Ex‐De phosphorescence under ambient conditions have been reported. The single component triphenylsulfonium chloride displays tunable fluorescent colors ranging from light purple to sky blue and tunable afterglow colors varying from green to yellowish green, to yellow (lifetimes: 57, 141, 66 ms, afterglow lasting for 2.1, 2.0, 2.3 s). The relationship between the structure and luminescence performance of 17 sulfonium salt derivatives confirms the pivotal roles of both the anions and the electronic and steric effect of substituent factors for luminescence. Single‐crystal analysis reveals that unique ionic bonding and intermolecular interaction can promote an ordered arrangement of organic salts in a crystal state, which then can facilitate molecular aggregation for phosphorescence generation. Theoretical calculations have also confirmed this viewpoint. More importantly, these sulfonium salt derivatives can be used for advanced multimodal anti‐counterfeiting and mitochondrial imaging, respectively. This study has not only expanded the scope of Ex‐De materials but also extended their applications. [ABSTRACT FROM AUTHOR]

Cholesteric liquid crystals (CLCs) with chiral nanostructures take on great significance in light modulation for optical devices, especially involving the features of circularly polarized and dynamic structural colors. However, on‐demand self‐assembly by photoprogramming still remains a challenge that is ascribed to the unpredictable variation of the helical superstructures in the existing CLCs induced by light‐driven chiral switches. Here, novel binary chiral systems are designed to construct visible‐light‐actuated CLCs with multi‐degrees of freedom, including adjustable circular polarization, bidirectional photochromism, and manipulable photonic bands. Such systems consist of an o‐fluoroazobenzene‐containing chiral switch and an inert chiral dopant, whose interaction dominates the strategies of chiral cooperation or conflict to determine the CLC handedness as well as shift direction of the selective reflection. Particularly, the precise tuning range of the structural color is tailored by programmable helical twisting power to enable diverse paradigms of light‐actuated patterning. The unprecedented quantitative manipulation of circularly polarized structural colors offers unique photonic attributes for applications in information encoding and multiplexed communication. [ABSTRACT FROM AUTHOR]

Reconfigurable and tunable holograms hold significant practical value in the fields of anti‐counterfeiting, optical security, and information display due to their ability to reprogram holographic patterns and create variable visual effects. However, current encryption techniques face challenges in achieving rapid encryption/decryption and ensuring consistent methods. In this study, a method for producing a reconfigurable encryption hologram utilizing the deformation and recovery properties of micropillars in response to liquid is demonstrated. Micron‐scale micropillars are fabricated using femtosecond laser two‐photon polymerization. By exploiting the rapid deformation and recovery capabilities of micropillars with specific pitches and aspect ratios in response to liquids, micropillar structures and holograms are combined to construct reconfigurable holograms. The encrypted pattern information in the reconfigurable holograms is only readable following immersion in alcohol and laser irradiation. The proposed method offers a facile, reversible, reusable, and practical solution for information encryption, with significant potential in anti‐counterfeiting and optical security. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals (CNCs) can self‐assemble to form cholesteric liquid crystal, which make it one of the most promising optical materials at present. CNCs can be produced by sulfuric acid hydrolysis. It is found that hydrolysis conditions influence the existing form of reaction components and their reaction activities, which leads to different reaction routes and mechanisms under varied reaction conditions, with CNCs of varied quality produced. High‐quality CNC with more uniform particle size could be prepared at a critical acid concentration of 64 wt%, which was used to study the formation process of CNC liquid crystal and the structure regulation of cholesteric liquid crystal. By adjusting the drying temperature and adding a small molecule of water‐soluble chitosan (WSC) can well regulate cholesteric liquid crystal and change the pitch of a film, and the reflection wavelength can be redshifted, thus enriching texture patterns and creating distinctive color. Suitable addition of WSC can enhance the multi‐domain effect during liquid crystal formation process and finally creates more colorful film with fine texture. The rich and tunable liquid crystal characteristics endowed by WSC addition is irreplicable and artistic, which helps to realize the great potential application of the composite film in advanced anti‐counterfeiting. [ABSTRACT FROM AUTHOR]

Doping in semiconductor quantum dots (QDs) using optically active dopants tailors their optical, electronic, and magnetic properties beyond what is achieved by controlling size, shape, and composition. Herein, we synergistically modulated the optical properties of eco‐friendly ZnInSe2/ZnSe core/shell QDs by incorporating Cu‐doping and Mn‐alloying into their core and shell to investigate their use in anti‐counterfeiting and information encryption. The engineered "Cu:ZnInSe2/Mn:ZnSe" core/shell QDs exhibit an intense bright orange photoluminescence (PL) emission centered at 606 nm, with better color purity than the undoped and individually doped core/shell QDs. The average PL lifetime is significantly extended to 201 ns, making it relevant for complex encryption and anti‐counterfeiting. PL studies reveal that in Cu:ZnInSe2/Mn:ZnSe, the photophysical emission arises from the Cu state via radiative transition from the Mn 4T1 state. Integration of Cu:ZnInSe2/Mn:ZnSe core/shell QDs into poly(methyl methacrylate) (PMMA) serves as versatile smart concealed luminescent inks for both writing and printing patterns. The features of these printed patterns using Cu:ZnInSe2/Mn:ZnSe core/shell QDs persisted after 10 weeks of water‐soaking and retained 70 % of PL emission intensity at 170 °C, demonstrating excellent thermal stability. This work provides an efficient approach to enhance both the emission and the stability of eco‐friendly QDs via dopant engineering for fluorescence anti‐counterfeiting applications. [ABSTRACT FROM AUTHOR]

Circularly polarized luminescence (CPL) of chiral luminescent materials has gained increasing attention because of their significant applications in 3D displays, chiral optoelectronics, anti‐counterfeiting, and encryption. A strongly emissive chiral dye BAcT is synthesized using (R)‐BINOL as the chiral source and a tetraphenylethene group as the fluorophore. Upon the addition of BAcT to the nematic liquid crystal, a left‐handed cholesteric structure is induced. Different concentrations of R/S5011 as chiral co‐dopants are added to prepare a series of structurally colored cholesteric liquid crystal polymer network (CLCN) films. CPL bands are detected for these green emissive CLCN films, and relatively high |glum| values (up to 0.48) are obtained. Furthermore, a fluorescent PMMA‐BAcT layer is prepared by embedding the dye in the PMMA matrix and stacked with a CLCN layer to construct a composite film. Because of the chiral filtering effect of the CLCN film, a high |glum| value up to 1.41 is successfully achieved. Colorful CLCN patterns are prepared, and clear pictures are observed in both reflective and fluorescent modes, contributing to optical anti‐counterfeiting with enhanced security. This work not only provides a deeper understanding of CPL, but also establishes a practical strategy to prepare colorful CLCN patterns for anti‐counterfeiting using inkjet printing technology. [ABSTRACT FROM AUTHOR]

The issue of counterfeiting has always been a major challenge in today's society, putting forward high requirements for anti‐counterfeiting technology. Here, a promising 2D/3D anti‐counterfeiting security system is developed based on anthracene‐functionalized poly(styrene‐butadiene‐styrene) (SBS‐CAN), which possessed the physical unclonable self‐wrinkling patterns, fluorescence, and shape memory behavior. By controlling the dimerization of anthracene groups with ultraviolet light and external pre‐stretched operation, 2D information with surface wrinkle and fluorescence is achieved, allowing for the design of security systems based on actual needs. Furthermore, 3D structures constructed based on the shape memory behavior can further be utilized to encrypt these 2D information, enhancing the security level and weakening the cloneable risk of surface wrinkle and fluorescence for further. This programmable 2D/3D anti‐counterfeiting system has multiple advantages over the commonly used fluorescent wrinkled tag or fluorescent shape memory label, providing an intelligent choice for high‐security information carriers. [ABSTRACT FROM AUTHOR]

Crystalline α‐Gd2(MoO4)3 is synthesized by sintering at 800 °C using a coprecipitation method to prepare the precursor. The resulting α‐Gd2(MoO4)3 displayed a monocrystalline structure with a strong main peak (‐221) in the X‐ray diffraction signal. To develop a light‐emitting material, rare earth ions are added during synthesis. By doping with Tb3+ and Eu3+, the Gd2(MoO4)3 down‐conversion phosphor shows potential for use in UV–LED chips, counterfeit money prevention, and fingerprint identification. Additionally, co‐doping with [Er3+]/[Yb3+] and [Ho3+]/[Yb3+] ions produce green and red emissions when applied to a 980 nm LED chip, useful for anti‐counterfeit ink. The magnetic properties of gadolinium are leveraged to confirm magnetic resonance imaging luminescence. A flexible composite for heat detection and explored various applications for its use is also developed. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Many industries are plagued by economic losses and product failures caused by counterfeit goods. Therefore, advanced anti‐counterfeiting techniques are continuously needed. In this study, we constructed a series of acid‐base sensitive cyclic chalcone dyes A—F by modifying different electron‐donating groups. Differences in acid sensitivity of different structures are well rationalised by NMR and theoretical calculations. Aniline is difficult to protonate than fatty amines, so there is a difference in fluorescence. Hiding and anti‐counterfeiting of information is achieved by this phenomenon. Powder X and Y are the anti‐counterfeit fluorescent powder containing montmorillonite and cyclic chalcone, which have orange fluorescence and the very similar appearance. However, under the influence of acid the Powder X containing triphenylamine modified cyclic chalcone shows red shifted fluorescence and Powder Y containing morpholino and diethylamino groups modified cyclic chalcone shows blue shifted fluorescence. Therefore, the anti‐counterfeiting strategy based on cyclic chalcone is not only limited to UV‐irradiated fluorescence development, but also has more colorization and pattern variations with the aid of acid developer. Data encryption and decryption of numbers, English alphabets and Chinese characters have been realized using A—F, which have great potential for practical applications. [ABSTRACT FROM AUTHOR]

Developing dynamic color‐tunable ultra‐long room temperature phosphorescence (URTP) polymers with afterglow of over 1 s, photo‐chromism, and multi‐stimuli response for practical anti‐counterfeiting and information security applications is attractive but very challenging. Herein, by doping multicolor phosphorescence pyridinium bromide L block or viologen‐based photo‐chromic V block into polyvinyl alcohol matrixes, the water‐stimuli‐responsive color‐tunable URTP polymer films with afterglow of up to 8 s and the reversible viologen‐based photochromic polymer films have been developed. More significantly, a series of dynamic color‐tunable URTP polymer films with ultra‐long afterglow of over 6 s, photo‐chromism, and water‐stimuli response have been successfully exploited by integrating L and V blocks into one polymer system. Mechanistic investigations have revealed that their photo‐chromism mainly comes from the photo‐generated viologen free radicals. Furthermore, their dynamic multilevel anti‐counterfeiting applications have been demonstrated. These results pave the way to develop smarter multifunctional URTP materials for anti‐counterfeiting and optical sensing. [ABSTRACT FROM AUTHOR]

Plasmonic structural color originates from the scattering and absorption of visible light by metallic nanostructures. Stacks consisting of thin, disordered semicontinuous metal films are attractive plasmonic color media, as they can be mass-produced using industry-proven physical vapor deposition techniques. These films are comprised of random nano-island structures of various sizes and shapes resonating at different wavelengths. When irradiated with short-pulse lasers, the nanostructures are locally restructured, and their optical response is altered in a spectrally selective manner. Therefore, various colors are obtained. We demonstrate the generation of structural plasmonic colors through femtosecond laser modification of a thin aluminum film–isolator–metal mirror (TAFIM) structure. Laser-induced structuring of TAFIM's top aluminum film significantly alters the sample's specular and diffuse reflectance depending on the fluence value and the number of times a region is scanned. A "negative image" effect is possible, where a dark field observation mode image is a negative of a bright field mode image. This effect is visible using an optical microscope, the naked eye, and a digital camera. The use of self-passivating aluminum results in a long-lasting, non-fading coloration effect. The reported technique could be used in anti-counterfeiting and security applications, as well as in plasmonic color printing and macroscopic and microscopic marking for personalized fine arts and aesthetic products such as jewelry. [ABSTRACT FROM AUTHOR]

Crown ether‐assisted supramolecular assembly is a robust strategy for manipulating low‐dimensional metal halides. In this study, the supramolecular assembly of 0D‐Cs3Cu2I5 is presented. Upon the addition of 15‐crown‐5 (15C5) to Cs3Cu2I5, 15C5 immediately coordinates with Cs+ to form the cone‐shaped [(15C5)Cs]+. Simultaneously, one of the iodine atoms is removed from the [Cu2I5]3‐ cluster, resulting in the formation of a sub‐planar rhombic [Cu2I4]2− unit. This process leads to white emission, specifically [(15C5)Cs]2[Cu2I4], which exhibits a photoluminescence quantum yield (PLQY) close to unity. The [(15C5)Cs]+ further reacts with 15C5 to form the sandwich‐type cationic structure [(15C5)2Cs]+, accompanied by the generation of red emission [(15C5)2Cs]2[Cu2I4]. By carefully controlling the amount of 15C5, various emission composites can be achieved, particularly tunable white emission. The assembly process is reversible. The pristine Cs3Cu2I5 can be recovered after thermal curing because of the volatility of crown ether and the weak Cs‐crown ether bond. Theoretical calculations have demonstrated that the coordination of the crown ether primarily affects the energy level, leading to changes in the excited state and photophysical properties. The applications in anticounterfeiting and LED phosphors have been demonstrated. This work provides a new approach for the development of low‐dimensional copper halides with promising applications in optoelectronics. [ABSTRACT FROM AUTHOR]

A tetraphenylethylene (TPE) derivative, TPEPhDAT, modified by diaminotriazine (DAT), was prepared by successive Suzuki–Miyaura coupling and ring-closing reactions. This compound exhibits aggregation-induced emission enhancement (AIEE) properties in the DMSO/MeOH system, with a fluorescence emission intensity in the aggregated state that is 5-fold higher than that of its counterpart in a dilute solution. Moreover, the DAT structure of the molecule is a good acceptor of protons; thus, the TPEPhDAT molecule exhibits acid-responsive fluorescence. TPEPhDAT was protonated by trifluoroacetic acid (TFA), leading to fluorescence quenching, which was reversibly restored by treatment with ammonia (on–off switch). Time-dependent density functional theory (TDDFT) computational studies have shown that protonation enhances the electron-withdrawing capacity of the triazine nucleus and reduces the bandgap. The protonated TPEPhDAT conformation became more distorted, and the fluorescence lifetime was attenuated, which may have produced a twisted intramolecular charge transfer (TICT) effect, leading to fluorescence redshift and quenching. MeOH can easily remove the protonated TPEPhDAT, and this acid-induced discoloration and erasable property can be applied in anti-counterfeiting. [ABSTRACT FROM AUTHOR]

Exploring structural phase transitions and luminescence mechanisms in zero‐dimensional (0D) metal halides poses significant challenges, that are crucial for unlocking the full potential of tunable optical properties and diversifying their functional capabilities. Herein, we have designed two inter‐transformable 0D Cu(I)‐based metal halides, namely (C19H18P)2CuI3 and (C19H18P)2Cu4I6, through distinct synthesis conditions utilizing identical reactants. Their optical properties and luminescence mechanisms were systematically elucidated by experiments combined with density functional theory calculations. The bright cyan‐fluorescent (C19H18P)2CuI3 with high photoluminescence quantum yield (PLQY) of 77 % is attributed to the self‐trapped exciton emission. Differently, the broad yellow‐orange fluorescence of (C19H18P)2Cu4I6 displays a remarkable PLQY of 83 %. Its luminescence mechanism is mainly attributed to the combined effects of metal/halide‐to‐ligand charge transfer and cluster‐centered charge transfer, which effects stem from the strong Cu−Cu bonding interactions in the (Cu4I6)2− clusters. Moreover, (C19H18P)2CuI3 and (C19H18P)2Cu4I6 exhibit reversible structural phase transitions. The elucidation of the phase transitions mechanism has paved the way for an unforgeable anti‐counterfeiting system. This system dynamically shifts between cyan and yellow‐orange fluorescence, triggered by the phase transitions, bolstering security and authenticity. This work enriches the luminescence theory of 0D metal halides, offering novel strategies for optical property modulation and fostering optical applications. [ABSTRACT FROM AUTHOR]

Stimuli‐responsive materials exhibiting exceptional room temperature phosphorescence (RTP) hold promise for emerging technologies. However, constructing such systems in a sustainable, scalable, and processable manner remains challenging. This work reports a bio‐inspired strategy to develop RTP nanofiber materials using bacterial cellulose (BC) via bio‐fermentation. The green fabrication process, high biocompatibility, non‐toxicity, and abundant hydroxyl groups make BC an ideal biopolymer for constructing durable and stimuli‐responsive RTP materials. Remarkable RTP performance is observed with long lifetimes of up to 1636.79 ms at room temperature. Moreover, moisture can repeatedly quench and activate phosphorescence in a dynamic and tunable fashion by disrupting cellulose rigidity and permeability. With capabilities for repeatable moisture‐sensitive phosphorescence, these materials are highly suitable for applications such as anti‐counterfeiting and information encryption. This pioneering bio‐derived approach provides a reliable and sustainable blueprint for constructing dynamic, scalable, and processable RTP materials beyond synthetic polymers. [ABSTRACT FROM AUTHOR]

Fluorescent lead halide perovskite quantum dots (LH PQDs) micropatterns hold great potential for photonic applications. However, current photolithography for LH PQDs micropatterning is hindered by their incompatibility with traditional photolithography methods, which involve development processes using numerous solvents and exhibit poor stability due to the ionic characteristics of LH PQDs. Herein, a direct in situ photolithography to fabricate CsPbBr3 PQDs micropatterns based on ultraviolet‐C light‐driven debromination is developed. Using this approach, fluorescent CsPbBr3 PQDs micropatterns with high theoretical information storage capacity (up to 10750205) can be achieved in a single step, without the need for tedious development processes. Furthermore, the fabricated CsPbBr3 PQDs micropatterns show high stability, remaining undamaged even after immersion in water for 6 months. The combination of excellent optical properties, development‐free process, high stability, and low cost makes the in situ photolithography strategy very promising for patterning LH PQDs toward photonic integrations. [ABSTRACT FROM AUTHOR]

Fluorescent hydrogel as an advanced material has been used for anti‐counterfeiting, probe detection, and optical devices. A facile strategy to prepare fluorescent hydrogel is developed by carboxymethyl cellulose (CMC) with Europium(III) and polyvinyl alcohol (PVA). The hydrogel forms a physical cross‐linking network under mild reaction conditions without using volatile organic chemicals. The addition of CMC‐Eu(III) improves the mechanical properties of the hydrogel. At 15% CMC‐Eu(III), the hydrogel reaches its maximum tensile and compressive stress, which are 47.25 ± 10.35 and 10.14 ± 1.90 kPa, respectively. Meanwhile, the hydrogels exhibit a 5D0→7F2 characteristic emission peak assigned to Eu3+, which emits stable red fluorescence under 254 nm ultraviolet (UV) light. When this hydrogel is applied to paper, the paper showed hidden fluorescent dots under UV light. This additive also enhances the mechanical properties of the paper, which reveals the multifunctionality of this fluorescent hydrogel for anti‐counterfeiting and reinforcement. [ABSTRACT FROM AUTHOR]

In this popular science experiment, the non-toxic ZnGa2O4:Bi3+ fluorescent material was prepared which has three mode luminescence properties including tunable multicolor emission, dynamic photochromic and thermochromic fluorescence properties. By utilizing the "chameleon-like" fluorescence characteristics of the material, we designed three kinds of display schemes for information security application. The experiment is not only interactive and interesting, but also has a good effect on popular science practice, which is helpful to stimulate students' enthusiasm for learning chemistry, and help adolescents experience the rich connotation of "beautiful chemistry". [ABSTRACT FROM AUTHOR]

Six biomass carbon dots (BCDs) with adjustable emission from 450 to 680 nm under a single wavelength excitation were successfully synthesized from spinach via solvent control strategy. The obtained BCDs show blue, green, yellow, violet, pink, and red emission with high photoluminescence quantum yield (PLQY = 12.68 ~ 30.77%). Detailed characterizations disclose that the tunable-emission mechanism is caused by the synergistic effect of carbon conjugate and surface oxidation degree. Meanwhile, full-color photoluminescence BCDs/PVP powder and BCDs/PVP/PVA films were fabricated by utilizing the prepared BCDs combined with polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA), respectively, which presented excellent high-level information encryption application. Importantly, multi-color and white light-emitting diode (LED) with Commission Internationale de L' Eclairage (CIE) of blue (0.25, 0.29); green (0.25, 0.31); yellow (0.42, 0.45); red (0.52, 0.31); and white (0.32, 0.31) were achieved by only using our prepared BCDs. This work provides a valuable strategy of preparing multi-color BCDs using readily available biomass materials and paves a way for high-level information encryption and LED applications. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) have garnered extensive interest in basic physical chemistry as well as in biomedical applications due to their low cost, good biocompatibility, and great aqueous solubility. However, the synthesis of multi-functional carbon dots has always been a challenge for researchers. Here, we synthesized novel CDs with a high quantum yield of 28.2% through the straightforward hydrothermal method using Diaminomaleonitrile and Boc-D-2, 3-diaminopropionic acid. The size, chemical functional group, and photophysical properties of the CDs were characterized by TEM, FTIR, XPS, UV, and fluorescence. It was demonstrated in this study that the prepared CDs have a high quantum yield, excellent photostability, and low cytotoxicity. Regarding the highly water-soluble property of CDs, they were proven to possess selective and sensitive behavior against Cu2+ ions (linear range = 0–9 μM and limit of detection = 1.34 μM). Moreover, the CDs were utilized in fluorescent ink in anti-counterfeiting measures. Because of their low cytotoxicity and good biocompatibility, the CDs were also successfully utilized in cell imaging. Therefore, the as-prepared CDs have great potential in fluorescence sensing, anti-counterfeiting, and bioimaging. [ABSTRACT FROM AUTHOR]

Colorants used in security inks are special pigments that radiate in the UV region or IR region. Obtained pigments can be from valuable rare earth elements or they can be organic based. Organic-based pigments are generally insoluble in water, which limits their use. For this purpose, an organicbased UV-radiating pigment was synthesized and made water-soluble by forming its salt. With the obtained salt-formed pigment, inkjet ink that can be used in counterfeiting was applied and its printability and resistance properties were determined. In this study, 1, 3, 6, 8-pyrene sulfonic acid tetrasodium salt was synthesized and water-based inkjet inks with hydroxy ethyl cellulose binder were produced. The prepared inks were printed on the paper surface. The color and gloss of the prints obtained were measured both in the visible region and in the UV region. Its optical properties were detected by UV spectroscopy. Strength properties such as light fastness, nitro resistance, alkali resistance, acid resistance, rub resistance, drying time, adhesion and dry film weight of the prints were determined. As a result; Inkjet ink with 1, 3, 6, 8-pyrene sulfonic acid tetrasodium salt was produced and it was concluded that it has good resistance properties. [ABSTRACT FROM AUTHOR]

Colorants used in security inks are special pigments that radiate in the UV region or IR region. Obtained pigments can be from valuable rare earth elements or they can be organic based. Organic-based pigments are generally insoluble in water, which limits their use. For this purpose, an organic based UV-radiating pigment was synthesized and made water-soluble by forming its salt. With the obtained salt-formed pigment, inkjet ink that can be used in counterfeiting was applied and its printability and resistance properties were determined. In this study, 1, 3, 6, 8-pyrene sulfonic acid tetrasodium salt was synthesized and water-based inkjet inks with hydroxy ethyl cellulose binder were produced. The prepared inks were printed on the paper surface. The color and gloss of the prints obtained were measured both in the visible region and in the UV region. Its optical properties were detected by UV spectroscopy. Strength properties such as light fastness, nitro resistance, alkali resistance, acid resistance, rub resistance, drying time, adhesion and dry film weight of the prints were determined. As a result; Inkjet ink with 1, 3, 6, 8-pyrene sulfonic acid tetrasodium salt was produced and it was concluded that it has good resistance properties.

[Display omitted] • Cellulose-based photoresponsive hydrogels were synthesized by hydrothermal method. • The hydrogel exhibited fluorescence switching with ethanol selective response. • Information encryption/decryption function of the hydrogel was realized. • Photochromic/fluorescent switching was applied in anti-counterfeiting applications. The rapid development of anti-counterfeiting technology has brought new challenges to the repeatability and stability of reversible fluorescence/photochromic switching hydrogels. To address this issue, a series of chemical cross-linked cellulose-based intelligent responsive hydrogels were synthesized by free-radical graft copolymerization in a hydrothermal process. This strategy allows for the creation of a chemical cross-linked three-dimensional structure that anchors photochromic ammonium molybdate and fluorescent carbon dots together, resulting in enhanced stability and mechanical properties. Especially, the tensile and compressive strength of hydrogel reached a maximum value of 280 kPa and 560 kPa, respectively, which far exceeds that of some reported hydrogels. The resultant hydrogels exhibited desired reversible fluorescence/photochromic switching, reversible printing and erasing of patterns, and information encryption/decryption. Notably, the change of photochromism from yellow to green can be realized, and the self-fading process can be shortened to 25 min at 60 °C instead of 6 h at room temperature. More importantly, the fluorescence quenching phenomenon of the hydrogel occurs gradually after 2 min of continuous irradiation, and it can be recovered by selective treatment with ethanol. Overall, this study provides a simple strategy for the preparation of environmentally friendly reversible fluorescence/photochromic switching cellulose-based hydrogels for information encryption. [ABSTRACT FROM AUTHOR]

0D Hybrid Zn/Cd Halied for Color-Time-Dual-Resolved Security Applications: We devise a family of zero-dimensional (0D) hybrid metal halides based RTP materials with dual phosphorescence performance and adjustable lifetime scale, which realize color-lifetime-dual-resolved encoding ability, showcasing potential applications in multilevel anti-counterfeiting and information security. [Display omitted] • A new optical multiplexing concept of simultaneously utilizing the varied emission color and lifetime as dual temporary codes was proposed. • A new family of zero-dimensional (0D) organic metal halides was directly synthesized accompanied by tailorable lifetime at the same molecular platform. • High-security anti-Counterfeiting and 4D information encryption-decryption were demonstrated. Luminescent materials with engineered optical properties play an important role in anti-counterfeiting and information security technology. However, conventional luminescent coding is limited by fluorescence color or intensity, and high-level multi-dimensional luminescent encryption technology remains a critically challenging goal in different scenarios. To improve the encoding capacity, we present an optical multiplexing concept by synchronously manipulating the emission color and decay lifetimes of room-temperature phosphorescence materials at molecular level. Herein, we devise a family of zero-dimensional (0D) hybrid metal halides by combining organic phosphonium cations and metal halide tetrahedral anions as independent luminescent centers, which display blue phosphorescence and green persistent afterglow with the highest quantum yields of 39.9 % and 57.3 %, respectively. Significantly, the luminescence lifetime can be fine-tuned in the range of 0.0968–0.5046 μs and 33.46–125.61 ms as temporary time coding through precisely controlling the heavy atomic effect and inter-molecular interactions. As a consequence, synchronous blue phosphorescence and green afterglow are integrated into one 0D halide platform with adjustable emission lifetime acting as color- and time-resolved dual RTP materials, which realize the multiple applications in high-level anti-counterfeiting and information storage. The color-lifetime-dual-resolved encoding ability greatly broadens the scope of luminescent halide materials for optical multiplexing applications. [ABSTRACT FROM AUTHOR]

Bi3+-doping luminescent materials have recently evoked considerable interest in versatile applications. In this work, we have developed a series of Bi3+-activated CaSrMSbO 6 (M = La, Gd, Y) phosphors with double perovskite structures, exhibiting blue emission from 350 nm to 500 nm. The emission spectral position and intensity of Bi3+ ions can be tuned by changing excitation wavelength and doping concentrations. The relationship between the local crystal field environment and the luminescence properties is comprehensively analyzed. Importantly, optical temperature properties of CaSrLaSbO 6 : Bi3+ were investigated and were found to reach a maximum relative sensitivity of 4.57 % K−1 at 298 K. Furthermore, the anti-counterfeiting ink was prepared using CaSrLaSbO 6 : Bi3+ phosphors, and it showed tunable emission under different light stimulation. These results indicate that CaSrLaSbO 6 : Bi3+ phosphors have application potential in optical temperature sensing and anti-counterfeiting. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel phosphorescence light-harvesting system with sequential two-step energy transfer processes was constructed. • The tunable multicolor emission was employed for the information anti-counterfeiting and storage. • The sequential two-step energy transfer processes facilitate the conversion of photosensitizer types. • The PLHS was employed to enhance the photooxidation of styrene derivatives and CDC reaction. Making full use of the captured energy by phosphorescence light-harvesting systems (PLHSs) and the tunable photoluminescence in energy transfer process to realize the multiple applications is still the challenge of PLHSs research. In this study, we have successfully constructed a highly effective PLHS with tunable multicolor luminescence and efficient conversion of photosensitizer types, which can further be used in photocatalytic organic conversion, information anti-counterfeiting and storage. The supramolecular polymer of BDBP-CB[8], which is generated by cucurbit[8]uril (CB[8]) and 4-(4-bromophenyl)-pyridine derivative (BDBP), realizes a phosphorescence emission and a change in luminescence color. Notably, white light emission was achieved and the logic gate systems were constructed utilizing the application of adjustable luminescence color. More interestingly, PLHS can be constructed by employing BDBP-CB[8] as energy donors, Sulforhodamine 101 (SR101) and Cyanine5 (Cy5) as energy acceptors, which results in a remarkably tunable multicolor photoluminescence to achieve the information storage. Furthermore, we have also found that BDBP-CB[8] can serve as type II photosensitizer for the effective production of singlet oxygen (1O 2) during the photooxidation process of styrene in aqueous environments, attaining a remarkable output rate reaching as high as 89 %. Particularly, compared with 1O 2 produced by type II photosensitizer BDBP-CB[8], the construction of PLHS can effectively convert type II photosensitizer to type I photosensitizer and efficiently generate superoxide anion radical (O 2 •−), which can be used for photocatalytic cross-dehydrogenative coupling (CDC) reaction in the aqueous solution with a yield of 90 %. Thus, we have created a PLHS that not only achieves tunable multicolor emission for information anti-counterfeiting and storage, but also realizes the conversion of reactive oxygen species (ROS) for different types photocatalytic oxidation reactions. [ABSTRACT FROM AUTHOR]

Wearable technology has seen rapid advancement, yet the integration of responsive materials into wearable devices poses significant challenges, particularly in maintaining fabric integrity and user comfort while ensuring sensitivity and responsiveness to environmental stimuli. In this work, these challenges are addressed by developing an ultra‐stable hydrochromic fabric that exhibits both hydro‐ and halochromic responsiveness. Utilizing a bimolecular fluoran dye system composed of a black leuco dye (ODB‐2) and a weak acid developer (benzyl 4‐hydroxybenzoate, B4H), these materials are embedded into a robust fibrous matrix constructed through an electrospinning process with thermoplastic polyurethane (TPU). This approach ensures the breathability, flexibility, and structural integrity of the fabrics, while the hydrophobic nature of TPU contributes to the stability and reversibility of the hydro/halochromic properties. The strategy allows for immediate, high‐contrast color changes upon exposure to water and acidic/basic vapors. These fabrics are also applied in rewritable data encryption, demonstrating their potential in anti‐counterfeiting. Furthermore, the investigation into the mechanical properties of these fabrics confirms their durability and resilience, making them ideal for wearable technology. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs), with their accessible nanoscale porosity, selectable building blocks, and precisely engineered topology, offer unique benefits in the design of room‐temperature phosphorescent (RTP) materials. However, their potential has been limited by phosphorescence quenching caused by interlayer π–π stacking interactions. This paper presents a novel strategy to enhance RTP in heavy‐atom‐free COFs by employing a donor–acceptor (D–A) system that leverages the Förster resonance energy transfer (FRET) and Dexter energy transfer (DET) mechanisms. Among the materials investigated, the best‐performing COF exhibits a phosphorescence lifetime of 4.35 ms at room temperature. Spectral analysis, structural analysis, and theoretical calculations indicate the presence of intralayer FRET processes as well as interlayer DET processes within the D–A COF system. Potential anti‐counterfeiting applications are explored by exploiting the unique phosphorescent properties of these materials. Additionally, the inherent permanent porosity of COFs presents new opportunities for future development and application. This strategy offers many promising prospects for advancing the RTP technology in COF materials and broadens their potential applications in various fields. [ABSTRACT FROM AUTHOR]

A multi‐stimuli responsive tetraphenyl substituted tripehnylamine‐based aggregation induced emissive (AIE) material coupled with spiropyran was prepared. Owing to the presence of AIE and photochromic moiety, the molecule exhibits emissive aggregates, photochromism, and acidochromism. The multiple stimuli sensitive behavior of the molecule was explored for anti‐counterfeiting behavior on TLC plate and commercial banknotes. The fluorogenic and photogenic response under UV and visible light established the potential of the candidate as a new generation encryption material. [ABSTRACT FROM AUTHOR]

With growing threats from counterfeiting‐based security breaches, multi‐level and specific stimuli‐responsive anti‐counterfeiting devices and message encryption methods have attracted immense research interest. Fluorescence‐based encryption from aggregation‐induced emission (AIE)‐based materials solves the problems to a considerable extent. However, the development of smarter patterns with hierarchical security levels alongside dynamic display is still challenging. To screen out this complication, we bring forward a pH‐switchable fluorescent assembly of an AIEgen and an aliphatic acid. We later temporally direct the molecular assembly with the aid of a chemical trigger‐regulated pH clock, generating a transitory multicolor emission, including transient white light generation. The pH‐dependent emissions were further implemented in constructing smart multi‐input fluorescent chemical AND gates. Subsequently, we integrate the time‐gated emissive system to develop an advanced multi‐dimensionally secure data encryption strategy. This novel approach enhances anti‐counterfeiting measures by introducing an additional layer of security based on temporal characteristics. [ABSTRACT FROM AUTHOR]

The spatially resolvable multicolored microrods have potential applications in many fields. However, achieving spatially resolved multicolor luminescence tuning on the microrod with a fixed composition remains a daunting challenge. Herein, a strategy is proposed that allows for the tuning of spatially resolved, multicolored upconversion (UC) luminescence (UCL) along a 1D heterogeneous microrod by modifying the pulse width of an external laser. NaYbF4:1 % Ho is identified as an UCL color‐adjustable material, exhibiting pulse width‐dependent multicolored UCL, resulting in a significant regulation of the red/green (R/G) ratio from 0.1 to 10.3 as the pulse width is varied from 0.1 to 10 ms. Such variability can be ascribed to differences in the number of photons incident upon the microrod throughout the period necessary for the UC process to occur. Additionally, NaYbF4:1 %Tm and NaYF4:20 %Yb,1 %Ho are employed as materials that emit blue and green light, respectively, with their UCL colors largely unaffected by changes in the pulse width. Subsequently, a tip‐modified epitaxial growth method is utilized to integrate both UCL color‐adjustable and non‐adjustable segments within the same microrod. Comparing with single‐color or fixed multicolor microrods, our developed multisegmented emissive color adjustable 1D heterogeneous microrods have unique optical characteristics and can carry more optical information. [ABSTRACT FROM AUTHOR]

Zero‐dimensional (0D) hybrid metal halides have been emerged as room‐temperature phosphorescence (RTP) materials, but synchronous optimization of multiple phosphorescence performance in one structural platform remains less resolved, and stable RTP activity in aqueous medium is also unrealized due to serious instability toward water and oxygen. Herein, we demonstrated a photophysical tuning strategy in a new 0D hybrid zinc halide family of (BTPP)2ZnX4 (BTPP=benzyltriphenylphosphonium, X=Cl and Br). Infrequently, the delicate combination of organic and inorganic species enables this family to display multiple ultralong green afterglow and efficient self‐trapped exciton (STE) associated cyan phosphorescence. Compared with inert luminescence of [BTPP]+ cation, incorporation of anionic [ZnX4]2− effectively enhance the spin‐orbit coupling effect, which significantly boosts the photoluminescence quantum yield (PLQY) up to 30.66 % and 54.62 % for afterglow and phosphorescence, respectively. Synchronously, the corresponding luminescence lifetime extend to 143.94 ms and 0.308 μs surpassing the indiscernible phosphorescence of [BTPP]X salt. More importantly, this halide family presents robust RTP emission with nearly unattenuated PLQY in water and harsh condition (acid and basic aqueous solution) over half a year. The highly efficient integrated afterglow and STE phosphorescence as well as ultrahigh aqueous state RTP realize multiple anti‐counterfeiting applications in wide chemical environments. [ABSTRACT FROM AUTHOR]

The nonconventional polymer luminophores (NPLs) with white emission are scarce due to the challenges in regulating their clustering structures. In this work, polystyrene is employed to develop a new kind of broad‐emitting clusteroluminescence (CL) through suitable cross‐linking and sulfonation. The sulfonated porous poly(styrene‐co‐divinylbenzene) microspheres (SPDMs) exhibit broad emission spectra (400–700 nm) in the visible light region. Further characterization and theoretical calculations show that through‐space conjugation (TSC) enhanced with high cross‐linking and sulfonation degrees (SD) is the main factor affecting the luminescence of microspheres. Monodisperse SPDMs with a low fluorescence distribution (CV < 5%) across 13 flow channels. Additionally, SPDMs microspheres is employed to construct binary, Cu2+, and pH‐responsive microarrays to encrypt and decode important information. Finally, SPDMs are developed for utilization as single‐component white and warm white light‐converting light emitting diodes (LEDs). These LEDs demonstrate Commission International de L’Eclairage (CIE) coordinates and correlate color temperatures (CCT) of (0.31, 0.321) and (0.383, 0.41), 6611 and 4100 K, respectively. Notably, the color rendering index (CRI) value for SPDMs‐50‐2 in white LED applications reaches an impressive 92. This study provides an economical, simple, and effective design strategy for developing NPLs with both monodispersity and broad emission. [ABSTRACT FROM AUTHOR]

Advanced multifunctional photochromic materials have important significance in the fields of anti-counterfeiting and optical information storage. Herein, we report novel Li doped NaNbO 3 :Er3+/Eu3+ multifunctional materials. Tunable multicolor emission, photochromism, and reversible multimode luminescence modulation are integrated in a single matrix through Li doping and defect engineering strategies. Real-time visualized emission colors dynamically change from green, yellow, orange to red by controlling the excitation wavelengths or photochromic processes. Notably, Li doping synergistically boosts the photochromic efficiency (46.2 % from 15.6 %) and luminescent modulation ratio (93.7 % from 10.1 %). The multimodal luminescence can be reversibly modulated by alternating ultraviolet light (379–397 nm), near infrared light (980 nm), or thermal stimulation. Based on multicolor emission and luminescent modulation behaviors, the designed patterns can realize real-time and differentiation displays in the dark or bright fields, significantly improving the anti-counterfeiting level and storage ability. These findings offer new insights into the development of multifunctional integrated materials for advanced anti-counterfeiting and optical storage applications. [ABSTRACT FROM AUTHOR]

Vacancy‐ordered perovskites and derivatives represent an important subclass of hybrid metal halides with promise in applications including light emitting devices and photovoltaics. Understanding the vacancy‐property relationship is crucial for designing related task‐specific materials, yet research in this field remains sporadic. For the first time, we use the Connolly surface to quantitatively calculate the volume of vacancy (V□, □=vacancy) in vacancy‐ordered double perovskite derivatives (VDPDs). A relationship between void fraction and the structure, photoluminescent properties and humidity stability was established based on zero‐dimensional (0‐D) [N(alkyl)4]2Sb□Cl5□′‐type VDPDs. Compared with the more commonly studied A2M(IV)X6□‐type double perovskite (A=cation, M=metal ion, X=halide), [N(alkyl)4]2Sb□Cl5□′ features double vacancy sites. Our results demonstrate an inverse relationship between the photoluminescent quantum yield and V□ in 0‐D VDPDs. Additionally, structural transformation from A2SbCl5 to A3Sb2Cl9 was first reported, during which the novel ‘gate‐opening’ gas adsorption phenomenon was observed in VDPDs for the first time, as evidenced by ‘S’‐shaped sorption isotherms for water vapor, indicating a cation‐controlled water‐vapor response behavior. A mixed‐cation strategy was developed to modulate the humidity stability of VDPDs. Characterized by controllable water‐responsive behavior and unique ‘on‐off‐on’ luminescent switching, A2M(III)□X5□′‐type materials show great promise for multi‐level information anti‐counterfeiting applications. [ABSTRACT FROM AUTHOR]

Multi‐excitonic emitting materials in luminescent metal halides are emerging candidates for anti‐counterfeiting and information encryption applications. Herein, ATPP2SnCl6 (ATPP=acetonyltriphenylphosphonium) phase was designed and synthesized by rationally choosing emissive organic reagent of ATPPCl and non‐toxic stable metal ions of Sn4+, and Sb3+ was further doped into ATPP2SnCl6 to tune the photoluminescence with external self‐trapped excitons emission. The derived non‐toxic ATPP2SnCl6 shows multi‐excitonic luminescent centers verified by optical study and differential charge‐density from density functional theory calculations. Incorporation of Sb3+ dopants and the increasing concentrations induce the efficient energy transfer therein, thus enhancing photoluminescence quantum yield from 5.1 % to 73.8 %. The multi‐excitonic emission inspires the creation of information encryption and decryption by leveraging the photoluminescence from ATPPCl to ATPP2SnCl6 host and ATPP2SnCl6 : Sb3+. This study facilitates the anti‐counterfeiting application by employing solution‐processable luminescent metal halides materials with excitation‐dependent PL properties. [ABSTRACT FROM AUTHOR]

Phosphors with multifunctional applications have attracted extensive research, especially in thermometer and anti‐counterfeiting fields. Herein, a series of Pr3+‐doped YNbO4 (YNO) phosphors with adjustable photoluminescence and red persistent luminescence (PersL) performances are developed. YNO host exhibits the blue self‐activated luminescence, and the different Pr3+ emission peaks possess various thermal stability properties due to the thermal quenching channel generated by the intervalence charge transfer state between Pr3+ and Nb5+ ions. Two kinds of fluorescence intensity ratio models with high absolute and relative sensitivities are realized to measure the temperature under dual‐wavelength excitation. Moreover, YNO:Pr3+ exhibits the red PersL with a duration of about 120 s upon ceasing the UV excitation light source. The fabricated YNO:Pr3+‐polydimethylsiloxane films display different luminescence patterns with the passage of time after turning off UV light, which can cleverly achieve dynamic conversion. These results demonstrate that YNO:Pr3+ phosphor has potential applications in dual‐wavelength excited thermometry and dynamic anti‐counterfeiting fields. [ABSTRACT FROM AUTHOR]

Asphaltene, often regarded as an undesirable by‐product of petroleum processing, possesses abundant reserves but limited market value. In this study, a simple and environmentally friendly solvent extraction method is conducted under ambient conditions to convert low‐value asphaltene into high‐value asphaltene‐based fluorescent carbon nanosheets (a‐FCS). This approach yields dual‐switch a‐FCS capable of emitting orange‐red fluorescence in solid‐state or water environment and exhibiting blue‐to‐yellow fluorescence in organic solvents. Moreover, the redshift observed in the fluorescence emission wavelength in the solvent is attributed to its intrinsic self‐assembly behavior, which becomes more pronounced with increasing concentration. Upon introduction to water, hydrophobic interactions induce the aggregation of a‐FCS. This aggregation triggers the orange‐red fluorescence by restricting intramolecular rotation on the surface, a phenomenon facilitated by the entanglement of aliphatic chains from asphaltene molecules. This unique property makes them applicable in anti‐counterfeiting and determination of ethanol content in aqueous solution. [ABSTRACT FROM AUTHOR]

Stimuli‐responsive luminescent materials have attracted much research attention due to their wide application potential in various fields. Typically, the family of hydrated double perovskite A2MIIIX5·H2O shows unique emission color transformation between hydrated and dehydrated complexes, highlighting the application potential in advanced anti‐counterfeiting. Herein, two zero‐dimensional perovskites of Cs2YbCl5·H2O and Cs3YbCl6, are reported and broad‐band self‐trapped exciton recombination emission can be realized via external Sb3+ doping. Intriguingly, the Cs2YbCl5·H2O can be transformed to the dehydrated counterpart of Cs3YbCl6 through a facile methanol treatment at room temperature, leading to the emission color transformation from yellow to green. Notably, the green‐emissive Cs3YbCl6:Sb3+ delivers a high photoluminescence quantum yield of 67.3%. Leveraging the advantages of obvious methanol‐induced emission color transformation between Cs2YbCl5·H2O and Cs3YbCl6 at room temperature, Cs2YbCl5·H2O can be used in the field of high‐security‐level anti‐counterfeiting. [ABSTRACT FROM AUTHOR]

This manuscript describes the synthesis of green long afterglow nanophosphors SrAl2O4:Eu2+, Nd3+ using the combustion process. The study encompassed the photoluminescence behavior, elemental composition, chemical valence, morphology, and phase purity of SrAl2O4:Eu2+, Nd3+ nanoparticles. The results demonstrate that after introducing Eu2+ into the matrix lattice, it exhibits an emission band centered at 508 nm when excited by 365 nm ultraviolet light, which is induced by the 4f65d1→4f7 transition of Eu2+ ions. The optimal doping concentrations of Eu2+ and Nd3+ were determined to be 2% and 1%, respectively. Based on X-ray diffraction (XRD) analysis, we have found that the physical phase was not altered by the doping of Eu2+ and Nd3+. Then, we analyzed and compared the quantum yield, fluorescence lifetime, and afterglow decay time of the samples; the co-doped ion Nd3+ itself does not emit light, but it can serve as an electron trap center to collect a portion of the electrons produced by the excitation of Eu2+, which gradually returns to the ground state after the excitation stops, generating an afterglow luminescence of about 15 s. The quantum yields of SrAl2O4:Eu2+ and SrAl2O4:Eu2+, Nd3+ phosphors were 41.59% and 10.10% and the fluorescence lifetimes were 404 ns and 76 ns, respectively. In addition, the Eg value of 4.98 eV was determined based on the diffuse reflectance spectra of the material, which closely matches the calculated bandgap value of SrAl2O4. The material can be combined with polyacrylic acid to create optical anti-counterfeiting ink, and the butterfly and ladybug patterns were effectively printed through screen printing; this demonstrates the potential use of phosphor in the realm of anti-counterfeiting printing. [ABSTRACT FROM AUTHOR]

Lanthanide doped nanoparticles (NPs) exhibit tunable X‐ray‐excited optical luminescence and X‐ray‐excited persistent luminescence (XEPL), holding broad prospects for applications in display/anti‐counterfeiting and X‐ray imaging. The development of effective strategies for multi‐dimensional applications based on lanthanide‐doped fluoride NPs are a constant challenge. Here, core–shell structured fluoride NPs, in which the heavy metal fluoride shell effectively suppresses the non‐radiative relaxation and simultaneously improve the X‐ray absorption of the shell are designed and fabricated. Under X‐ray irradiation, the developed NPs exhibit an increased number of secondary electrons which migrate to Er3+ centers at the interface and greatly improve the XEPL intensity. Additionally, the introduction of Mn2+ further enhances the XEPL intensity and offers an effective route to control the red‐green ratio of the upconversion spectrum. The NPs co‐doped with Mn2+ exhibit a bright green XEPL under X‐ray irradiation and a red emission under 1532 nm laser excitation. It is further validated that these NPs can be utilized for advanced anti‐counterfeiting and high‐resolution delayed imaging based on a film containing NPs as a scintillation screen. These findings suggest a new strategy of designing Er3+ doped NPs for multi‐dimensional applications. [ABSTRACT FROM AUTHOR]