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"information encryption"
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Precise Regulation Strategy for Fluorescence Wavelength of Aggregation‐Induced Emission Carbon Dots
Aggregation‐induced emission (AIE) carbon dot (CDs) in solid state with tunable multicolor emissions have sparked significant interest in multidimensional anti‐counterfeiting. However, the realization of solid‐state fluorescence (SSF) by AIE effect and the regulation of fluorescence wavelength in solid state is a great challenge. In order to solve this dilemma, the AIE method to prepare multi‐color solid‐state CDs with fluorescence wavelengths ranging from bright blue to red emission is employed. Specifically, by using thiosalicylic acid and carbonyl hydrazine as precursors, the fluorescence wavelength can be accurately adjusted by varying the reaction temperature from 150 to 230 °C or changing the molar ratio of the precursors from 1:1 to 1:2. Structural analysis and theoretical calculations consistently indicate that increasing the sp2 domains or doping with graphite nitrogen both cause a redshift in the fluorescence wavelength of CDs in the solid state. Moreover, with the multi‐dimensional and adjustable fluorescence wavelength, the application of AIE CDs in the fields of multi‐anti‐counterfeiting encryption, ink printing, and screen printing is demonstrated. All in all, this work opens up a new way for preparing solid‐state multi‐color CDs using AIE effect, and further proposes an innovative strategy for controlling fluorescence wavelengths. Herein, they proposed an efficient and precise wavelength tuning mechanism for the Aggregation‐induced emission (AIE) carbon dots (CDs). Specifically, by using thiosalicylic acid and carbonyl hydrazine as precursors, they can accurately adjust the fluorescence wavelength by varying the reaction temperature or changing the molar ratio of the precursors. Moreover, the application of AIE CDs in the fields of multi anti‐counterfeiting encryption has been demonstrated.
Journal Article
Excitation‐Dependent Quadruple‐Level Emission from an Isolated Molecule for Dynamic Information Encryption
Stimuli‐responsive single‐molecule multi‐emission materials have long attracted considerable attention due to their great potential in non‐phase‐separated smart luminescence. Here, a new strategy is demonstrated for manipulating electron transfer based on donor‐acceptor decoupling to regulate energy levels, aiming to achieve excitation‐dependent (Ex‐De) single‐molecule emission with switchable multiple fluorescence and phosphorescence. The synthesized 10‐phenyl‐10H,13'H‐spiro[acridine 9,6'‐pentacen]‐13'‐one (ACRSP) exhibits anti‐Kasha quadruple‐level emission and opposite Ex‐De afterglow in different environments. The high‐energy emission bands of multi‐fluorescence in solution respond to excitation, whereas in poly(methyl methacrylate) (PMMA), phosphorescence‐fluorescence multi‐emission causes Ex‐De to appear in the low‐energy emission band. Experimental and computational results indicate that exciton spin ratios and emissive state compositions vary with excitation modes, leading to dual Ex‐De behavior from three fluorescence and one phosphorescence emissions. Donor‐acceptor decoupling separates locally excited (LE) and charge transfer (CT) states, while triplet level inversion enables Ex‐De behavior and room‐temperature phosphorescence (RTP) coexistence (τ = 770.54 ms). By tuning the excitation mode of ACRSP, we achieve Ex‐De long afterglow emission from an isolated molecule, enabling time‐resolved and excitation‐responsive multi‐dimensional information encryption. This work offers design guidelines for purely organic Ex‐De systems and paves the way for next‐generation single‐molecule responsive luminophores. By manipulating the quadruple decoupled radiative transitions of donor and acceptor units, dual‐phase excitation‐dependent afterglow emission is achieved for the first time in a single isolated molecule. The decoupled donor‐acceptor units precisely manipulate the electron transfer pathways in ACRSP, endowing it with intrinsic single‐molecule Ex‐De properties, resulting in anti‐Kasha quadruple emission levels. The precise control over exciton spin ratios and excited‐state components enables time‐resolved and wavelength‐responsive multidimensional information encryption.
Journal Article
Recent Progress in Photoresponsive Room-Temperature Phosphorescent Materials: From Mechanistic Insights to Functional Applications
Room-temperature phosphorescence (RTP) materials with photo-responsive properties have attracted increasing attention for applications in smart luminescent switches, optical logic control, and multidimensional information storage. Compared to other external stimuli, light offers the advantages of non-contact control, high spatiotemporal resolution, and excellent programmability, making it an ideal strategy for reversible and dynamic modulation of RTP. This review summarizes recent advances in light-triggered RTP systems coupled with photochromism. From a structural design perspective, we discuss strategies to integrate photochromic and RTP units within a single material system, covering photoisomerizable molecules, metal–organic complexes, organic–inorganic hybrids, and purely organic radicals. These materials demonstrate unique advantages in fields such as information encryption, bioimaging, and light-controlled upconversion. Finally, future design directions and challenges are proposed, aiming toward high-security, long-lifetime, and multi-channel collaborative luminescent systems.
Journal Article
Photoresponsive Luminescent Polymeric Hydrogels for Reversible Information Encryption and Decryption
Conventional luminescent information is usually visible under either ambient or UV light, hampering their potential application in smart confidential information protection. In order to address this challenge, herein, light‐triggered luminescence ON‐OFF switchable hybrid hydrogels are successfully constructed through in situ copolymerization of acrylamide, lanthanide complex, and diarylethene photochromic unit. The open‐close behavior of the diarylethene ring in the polymer could be controlled by UV and visible light irradiation, where the close form of the ring features fluorescence resonance energy transfer with the lanthanide complex. The hydrogel‐based blocks with tunable emission colors are then employed to construct 3D information codes, which can be read out under a 254 nm UV lamp. The exposure to 300 nm UV light leads to the luminescence quenching of the hydrogels, thus erasing the encoded information. Under visible light (>450 nm) irradiation, the luminescence is recovered to make the confidential information readable again. Thus, by simply alternating the exposure to UV and visible lights, the luminescence signals could become invisible and visible reversibly, allowing for reversible multiple information encryption and decryption. Light‐triggered luminescence ON‐OFF switchable hybrid hydrogels are synthesized through in situ copolymerization. The hydrogel‐based blocks with tunable emission colors are then employed to construct 3D information codes, allowing for reversible multiple information encryption and decryption.
Journal Article
Synergistic Pyro‐Phototronics and Structural Anisotropy in CsAg2I3/GaN Heterostructures for High‐Performance Polarization‐Sensitive UV Photodetectors
Ultraviolet photodetectors capable of spectral selectivity, self‐powered operation, and polarization sensitivity are vital for next‐generation secure communication and sensing, yet their progress is hampered by material instability, interfacial losses, and the difficulty of multifunctional integration. Here, we report a groundbreaking CsAg2I3/GaN van der Waals (vdWs) heterojunction that uniquely integrates in‐plane structural anisotropy, pronounced pyro‐phototronic effect, and atomically sharp interface engineering. The CsAg2I3 single‐crystals, synthesized via chemical vapor deposition, exhibit a wide‐bandgap (∼3.38 eV), strong second‐order nonlinear response, and remarkable pyroelectricity, overcoming the stability and symmetry limitations of conventional perovskites and inorganic wide‐bandgap semiconductors. The CsAg2I3/GaN device delivers record‐breaking performance: an ultralow dark current of 0.3 pA, high responsivity of 0.28 A/W, specific detectivity of 1.7 × 1012 Jones, and ultrafast response speeds of 16/21 µs, outperforming most state‐of‐the‐art perovskites and wide‐bandgap photodetectors. Crucially, the pyro‐phototronic effect amplifies polarization sensitivity, achieving an unprecedented dichroic ratio of 10.5 under bias, the highest reported for all‐inorganic perovskite systems and other competitors. The device also demonstrates exceptional operational stability and robust performance in an information‐splitting encryption system, validating its real‐world applicability. This work establishes a new paradigm for synergizing pyro‐phototronics and structural anisotropy in heterostructures, enabling a versatile platform for high‐performance, self‐powered, polarization‐sensitive optoelectronics. The development of polarization‐sensitive ultraviolet photodetectors is limited by poor heterojunction quality and low polarization sensitivity. This study integrates synthesized CsAg2I3 single crystals with intrinsic non‐centrosymmetry into van der Waals heterojunction devices, demonstrating pronounced pyro‐phototronic effect. High dichroic ratio is validated via information‐splitting encryption system, establishing a novel paradigm for intelligent and secure optoelectronic technologies.
Journal Article
Advanced encryption method realized by secret shared phase encoding scheme using a multi-wavelength metasurface
Multi-channel information encryption technology has been implemented by optical metasurfaces owing to their superior ability to control the phase, amplitude, wavelength and polarization of incident light. However, current metasurface-based multi-channel encryption technologies suffer from information leakage in non-full channel decoding processes. To better increase the security of the encrypted information, we develop a secret shared phase encoding scheme by combining a visual secret sharing scheme with a metasurface-based phase-encoding technique. Our method achieves its high-concealment through mapping the target image into a set of unrecognizable phase-only keys that are subsequently encoded by a multi-wavelength metasurface. In the decryption process, the secret information can be reconstructed only by decoding and stacking all the wavelength channels of the metasurface. At the same time, chaotic images can be extracted from the other channels without revealing any original information. The simulated results and the theoretical analysis show the strong robustness and high security of our encryption setup, which is sure to find applications in emerging optical encryption schemes.
Journal Article