Up to now, PersL materials emitting visible light have been extensively studied and applied in emergency signage, optical data storage and anti-counterfeiting, energy-saving catalysis, and many other aspects. [10][11][12][13][14][15][16][17][18][19] Recently, near-IR (NIR) PersL materials have received particular interest due to their great application prospects in various biomedical applications, such as autofluorescence-free bioimaging, longterm biomolecule tracking. [20][21][22][23][24][25][26][27] However, in stark contrast to the evolving progress in the research of the PersL materials in visible region, the study concerning the design and development of NIR PersL materials is still lacking. [28,29] Hence, it is significantly important to develop and make up the number of NIR PersL materials.The luminescent materials are composed of matrixes and activators, the activators exist as emission centers while the matrixes provide an appropriate crystal environment for activators. [30] At present, most reported NIR PersL materials are based on Cr 3+ emitters. [28] Nevertheless, the toxicity of chromium might lead to biosafety and biodistribution issues of these Cr 3+ -activated materials in organisms, which would severely hindered further practical bioapplications. [31][32][33] As an essential element of the human body, the promising and so far rarely investigated ferric ions can be a considerable candidate for activator ions to address the toxicity issue of Cr 3+ . [34] Unfortunately, the number of studies on the rational design of Fe 3+doped NIR PersL remains very quiet. [35,36] Hitherto, the majority of the research concerning Fe 3+ -activated luminescent materials is devoted to their photoluminescence (PL) properties and the related luminescence thermometer application. [37,38] This may be because Fe 3+ is usually regarded as a luminescent quencher, and it is hard to control the crystal environments of the matrixes for achieving PersL of Fe 3+ . Therefore, it is vital importance to explore a special crystal structure and regulate the defect properties for the development of Fe 3+ -activated NIR PersL materials.Spinel configuration can be one of the best host material candidates when designing PersL materials owing to the easy formation of vacancies and anti-site defects. [39,40] However, the PersL from Fe 3+ doped in spinel-type compounds has never been reported before. [41] Herein, we propose a new strategy of defect enrichment for the activation of PersL, and in contrast to the normal spinel configuration, we demonstrate that the crystal structure of near inverse spinel ensures more numerous Spinel configuration is a kind of broadly considered host candidate when designing persistent luminescence (PersL) materials due to the easy generation of vacancies and anti-site defects. Here, a new strategy of defect enrichment for the activation of PersL is proposed, and in contrast to the spinel configuration, it is demonstrated that the crystal structure of near inverse spinel ensures more numerous defects to activat...
nanorods) show strong polarized absorption and emission due to the dielectric confinement effect and intrinsic optical anisotropy of their asymmetric shapes. [5][6][7] CsPbBr 3 QD is a cubic crystalline phase with high symmetry at room temperature, resulting in almost no optical anisotropy in the single particle and colloidal solution. [8,9] However, many strategies, such as polymer stretching, electrospinning, nanoimprinting, and photolithography, have been utilized to align semiconductor QDs to generate and improve polarized absorption and emission of semiconductor QDs by implementing orientation arrangement. [10][11][12][13][14][15][16][17] By rotating coating CsPbBr 3 QDs on a silica substrate, the silica substrate induced charge redistribution in CsPbBr 3 QDs, resulting in anisotropic dipole transition distribution and overcoming the population averaging effect to produce polarized emission. [18] Furthermore, It is reported that patterned anti-counterfeiting applications can be achieved by directional recombination of CsPbX 3 (X = Cl, Br, I) nanowires in different directions. [17] Under different polarization excitation, the anti-counterfeiting pattern will present different patterns, because of the PL intensity difference under different polarized angles. Although the above methods can endow CsPbBr 3 QDs with polarization emission The pursuit of high-resolution and advanced anti-forgery technology has stimulated a growing demand for anti-counterfeiting and encryption strategies with real-time response and high security. Polarized patterns taking the advantage of high security, rapid response, simple operation, and great selectivity enable real-time and non-invasive detection by monitoring in different polarization directions. Here, a new strategy to design and fabricate the polarized CsPbBr 3 quantum dot (QD) line arrays by femtosecond (fs) laser writing in a transparent glass matrix is proposed. The obtained line array structures endow isotropic CsPbBr 3 QDs with macroscopic polarized emission with a polarization degree up to 0.189. Through programable design, the authors have created 2D and 3D polarized luminescent patterns made up of vertical and horizontal lines inside the glass for polarization-sensitive optical anti-counterfeiting patterns. The CsPbBr 3 QD line arrays used in anti-counterfeiting can be well maintained in the water environment. The successful demonstration of the laser writing CsPbBr 3 QD polarization structures in glass highlights the versatility of anti-counterfeiting and encryption.
With the fast‐growing amount of data, the state‐of‐the‐art optical data storage has become a front‐runner in the competing data storage technologies. However, two‐dimensional (2D) spatial resolution in the conventional optical data storage media has almost reached the limit. Herein, LiGa5O8:Cr3+ nanoparticles (NCs) precipitated in situ from a transparent medium are prepared. The transparent LiGa5O8:Cr3+ glass ceramics show excellent deep‐trap carriers storage ability under blue light irradiation and can realize the bit‐by‐bit optical data in 3D space for write‐in and read‐out in a photon trapping/detrapping mode. Moreover, this optical storage mechanism is also extended to 4D by realizing temperature optical encryption. Notably, the written information can still be clearly displayed even after being recorded for 200 days. This work enables 4D high‐precision storage of information and provides new insights into the design and fabrication of next‐generation storage materials.
The low formation energies of metal halide perovskites endow them with potential luminescent materials for applications in information encryption and decryption. However, reversible encryption and decryption are greatly hindered by the difficulty in robustly integrating perovskite ingredients into carrier materials. Here, we report an effective strategy to realize information encryption and decryption by reversible synthesis of halide perovskites, on the lead oxide hydroxide nitrates (Pb 13 O 8 (OH) 6 (NO 3 ) 4 ) anchored zeolitic imidazolate framework composites. Benefiting from the superior stability of ZIF-8 in combination with the strong bond between Pb and N evidenced by X-ray absorption spectroscopy and X-ray photoelectron spectroscopy, the as-prepared Pb 13 O 8 (OH) 6 (NO 3 ) 4 −ZIF-8 nanocomposites (Pb−ZIF-8) can withstand common polar solvent attack. Taking advantage of blade-coating and laser etching, the Pb−ZIF-8 confidential films can be readily encrypted and subsequently decrypted through reaction with halide ammonium salt. Consequently, multiple cycles of encryption and decryption are realized by quenching and recovery of the luminescent MAPbBr 3 −ZIF-8 films with polar solvents vapor and MABr reaction, respectively. These results provide a viable approach to integrate the state-of-the-art materials perovskites and ZIF for applications in information encryption and decryption films with large scale (up to 6 × 6 cm 2 ), flexibility, and high resolution (approximate 5 μm line width).
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