Information Storage Materials Research Articles

Hydrolytic‐Resistance Long‐Persistent Luminescence SrAl2O4:Eu2+,Dy3+ Ceramics for Optical Information Storage

AbstractSrAl2O4:Eu2+, Dy3+ (SAED) is one of the most popular materials for information storage and night display applications because it has a wide excitation range and long afterglow duration. However improving the hydrolytic resistance of SAED remains a challenge. In this study, the SAED is presented to be the ceramic type by a solid‐state reaction in a vacuum ambiance. The achieved SAED ceramic has 8200 mcd m−2 initial luminescence intensity. It can also obtain long‐persistent luminescence after UV light irradiation even soaking in water for more than 30 days. This ceramic demonstrates sustained imaging capability irradiated under 365 nm UV light and X‐ray, as well as erasability and reproducibility of storage by lighting and heating. These results indicate the promising applications of SAED ceramics in optical information storage and night display in complex environments. The phase evolution in the SAED ceramic is identified directly in the micromorphology for the first time based on scanning electron microscopy coupled with a cathodoluminescence system.

Second-Harmonic-Generation Switching via Pressure-Suppressed Dynamical Disorder.

Second-harmonic-generation (SHG) switching is an emerging phenomenon with potential applications in bistable storage and optical switches while also serving as a sensitive probe for inversion-symmetry. Temperature-induced disorder-order phase transition has been proven to be a rational design strategy for achieving SHG bi-state switching; however, pressure-sensitive SHG switching via a disorder-order structural transition mechanism is rarely reported and lacks sensitivity and cyclicity as practical switching materials. Herein, we demonstrate the pressure-induced "dynamical disorder-order" phase transition as an effective strategy for triggering SHG and SHG switching in NH4Cl. The "dynamical disorder-order" phase transition of NH4Cl occurring at as low as 1 GPa is confirmed by comprehensive in situ high-pressure XRD, molecular vibrational spectra, and Brillouin scattering spectra. The pressure-induced SHG is responsive to a wide excitation wavelength region (800-1500 nm), and the "off-on" switching is reversible for up to 50 cycles, setting a record for pressure-driven switching materials. It is worth noting that when pressure is further increased to 14 GPa, NH4Cl exhibits another SHG "on-off" switching, which makes it the first triplet SHG "off-on-off" switching material. Molecular dynamics simulations reveal the key role of N-H···Cl hydrogen bonding in the pressure-induced "dynamic disorder-order" mechanism. Finally, we verified that chemical pressure and physical pressure can jointly regulate the SHG switching behavior of NH4X (X = Cl, Br). The pressure-driven "dynamic disorder-order" transition mechanism sheds light on the rational design of multistable SHG switching materials for photoswitches and information storage.

Effect of Metal-Organic Frameworks with Different Ligand Structures (ZIF-11 & ZIF-23) on the Optoelectronic Performance of Perovskite Photodetectors.

Crystal engineering using passivation to reduce perovskite defects is crucial to improving the quality of perovskite crystals and optoelectronic properties. Because of their unique properties, metal-organic framework materials have been used as an emerging and effective passivator for perovskite materials and optoelectronic devices. This paper focuses on the differences in the optoelectronic properties of zeolite imidazolium ester framework materials (ZIF-11 & ZIF-23) doped with different conjugated ring ligands for perovskite photodetectors. This paper proposes a simple and effective method to dope zeolite imidazolium ester framework nanoparticles (ZIF-11 & ZIF-23) into organic-inorganic perovskite MAPbI3 films. The crystalline quality of the perovskite films was improved after doping with ZIF-11 and ZIF-23. Meanwhile, the performance of the planar photoconductive devices was significantly improved. The photoresponsivity of the photodetector doped with ZIF-23 was 0.185A/W, and the detectivity was 4.22 × 1012 Jones. The photoresponsivity of the photodetector doped with ZIF-23 was 0.164 A/W, and the detectivity was 3.27 × 1012 Jones. The devices maintained long-time operational stability, operating without significant degradation for 480 s under the 1.2 V bias voltage operating condition. In addition, we observed a significant suppression of the ion migration process in ZIF-23 for a voltage-controlled ion migration process. The potential application of perovskite and MOF heterojunction materials for image information acquisition and storage is demonstrated.

Ab initio investigation of the geometrical behavior in solution and electronic structure of the anion complexes [bis(1,3-dithiole-2-thione-4,5-dithiolate)M], for M = Bi(III), Sb(III), and Zn(II).

1,3-Dithiole-2-thione-4,5-dithiolate (dmit) ligands are known for their conductive and optical properties. Dmit compounds have been assessed for use in sensor devices, information storage, spintronics, and optical material applications. Associations with various metallic centers endow dmit complexes with magnetic, optical, conductive, and antioxidant properties. Optical doping can facilitate the fabrication of magnetic conductor materials from ground-state nonmagnetic cations. While most studied complexes involve transition-metal centers due to their diverse chemistry, compounds with representative elements are less explored in the literature. This study investigated the structural and electronic properties of bisdmit complexes with representative Bi(III), Sb(III), and Zn(II) cations. AIMD calculations revealed two new geometries for Bi(III) and Zn(II) complexes, diverging from the isolated geometry typically used in quantum chemical calculations. The coordination of acetonitrile molecules to the cationic centers of the complexes resulted in unstable structures, while the dimerization of the complexes was stable. SA-CASSCF/NEVPT2 calculations were applied to the structures of the isolated complexes and stable dimers, confirming the multireference character of the electronic structure of the three systems and the multiconfigurational character of the Bi(III) complex. The electronic spectra simulated by the STEOM-DLPNO-CCSD calculations accurately reproduced the experimental UV‒Vis spectra indicating the participation of the isolated Bi(III) dmit complex and its dimeric form in solution. AIMD calculations of the dmit salts were conducted using the GFN2-xTB method with 60 explicit acetonitrile molecules as the solvent at 300K for a total simulation time of 50.0ps, with printing intervals of 0.5fs. The final geometries were optimized employing the PBEh-3c compound method, incorporating implicit conductor-like polarizable continuum model (CPCM) solvation for acetonitrile. Local energy decomposition (LED) analysis at the DLPNO-CCSD(T)/Def2-TZVP level of theory was utilized to investigate the stability of the complex geometries identified by AIMD. The electronic structures of the complexes were assessed using the SA-CASSCF/NEVPT2/Def2-TZVP method to confirm the multiconfigurational and multireference nature of their electronic structures. Electronic spectra were analyzed using the STEOM-DLPNO-CCSD/Def2-TZVP method, with CPCM used to simulate an acetonitrile medium.

Large valley splitting induced by spin-orbit coupling effects in monolayer Hf3N2O2

Valleytronics is an emerging field of electronics that aims to utilize valley degrees of freedom in materials for information processing and storage. Nowadays, the valley splitting of 2D materials is not particularly large, therefore, the search for large valley splitting materials is very important for the development of valleytronics. This work theoretically predicts that MXene Hf3N2O2 is a 2D material with large valley splitting. It is an indirect bandgap semiconductor with a bandgap of 0.32 eV at the PBE level and increases to 0.55 eV at the HSE06 level. Since Hf3N2O2 breaks the symmetry of spatial inversion, when we consider spin–orbit coupling (SOC), there is a valley splitting at K/K′ of the valence band with a valley splitting value of 98.76 meV. The valley splitting value slightly decreases to 88.96 meV at the HSE06 level. In addition, The phonon spectrum and elastic constants indicate that it is both dynamically and mechanically stable. According to the maximum localization of the Wannier function, it is obtained that the Berry curvature is not zero at K/K′. When a biaxial strain is applied, Hf3N2O2 transitions from metal to semiconductor. With increasing biaxial strain, the valley splitting value increased from 70.13 meV to 109.11 meV. Our research shows that Hf3N2O2 is a promising material for valleytronics.

Trap engineering in bismuth activated NaLu(Gd)GeO4 persistent phosphors by doping Ln3+

Persistent phosphors, as a promising material for information storage and encryption, have garnered considerable attention owing to their rapid access and low-energy consumption. However, the lack of effective trap control in storage phosphors has resulted in limited storage capacity. In this study, we have prepared a series of NaLu(Gd)GeO4:Bi3+,Ln3+ (Ln = Eu, Tb, Dy, Pr, Sm, Er, Nd, Ho, Tm, and Yb) materials exhibiting tunable multimode and multicolor stimuli-responsive luminescence. The enhanced thermo-stimulated luminescence of five times is obtained in NaLuGeO4:Bi3+,Eu3+ relative to NaLuGeO4:Bi3+, where Bi3+ not only serves as the luminescent center but also as the hole trap center, and trace amounts of Eu3+ act as electron traps to form stable electron-hole pair traps together with Bi3+ hole traps. We propose a new method to improve trap density by constructing electron-hole pair traps via utilizing Bi3+ and Ln3+ as both trap makers and luminescence centers. Density functional theory calculations provide detailed information on the band structures of the matrix and electronic properties, which has confirmed the types of traps and then supports persistent luminescence mechanisms. Particularly, our phosphors are used as optical storage medium for multilevel optical data recording in a single physical layer through managing traps via setting the temperature. This study provides valuable insights for the design and fabrication of next-generation optical information storage and encryption materials.

Multilevel Information Encryption Based on Thermochromic Perovskite Microcapsules via Orthogonal Photic and Thermal Stimuli Responses.

Increasing modal variations of stimulus-responsive materials ensure the high capacity and confidentiality of information storage and encryption systems that are crucial to information security. Herein, thermochromic perovskite microcapsules (TPMs) with dual-variable and quadruple-modal reversible properties are designed and prepared on the original oil-in-fluorine (O/F) emulsion system. The TPMs respond to the orthogonal variations of external UV and thermal stimuli in four reversible switchable modes and exhibit excellent thermal, air, and water stability due to the protection of perovskites by the core-shell structure. Benefiting from the high-density information storage TPMs, multiple information encryptions and decryptions are demonstrated. Moreover, a set of devices are assembled for a multilevel information encryption system. By taking advantage of TPMs as a "private key" for decryption, the signal can be identified as the corresponding binary ASCII code and converted to the real message. The results demonstrate a breakthrough in high-density information storage materials as well as a multilevel information encryption system based on switchable quadruple-modal TPMs.

In‐situ controllable synthesis of carbon dots for patterned fluorescent wood films rapid fabrication strategy

AbstractFluorescent‐patterned materials are widely used in information storage and encryption. However, preparing a patterned fluorescent display on a matrix currently requires a time‐consuming (hours or even days) and complex multi‐step process. Herein, a rapid and mild technique developed for the in‐situ controllable synthesis of fluorescent nitrogen‐doped carbon dots (NCDs) on eco‐friendly transparent wood films (TEMPO‐oxidized carboxyl wood film [TOWF]) within a few minutes was developed. A wood skeleton was employed as the carbon precursor for NCD synthesis as well as the matrix for the uniform and controlled distribution of NCDs. Moreover, the in‐situ synthesis mechanism for preparing NCDs in TOWF was proposed. The resulting fluorescent wood films have excellent tensile strength (310.00 ± 15.57 MPa), high transmittance (76.2%), high haze (95.0%), UV‐blocking properties in the full ultraviolet (UV) range, and fluorescent performance that can be modified by changing the heating parameters. Fluorescent patterning was simply achieved by regulating the in‐situ NCD synthesis regions, and the fluorescent patterns were formed within 10 s. These fluorescent‐patterned wood films can effectively store and encrypt information, and they can interact with external information through a transparent matrix. This work provides a green and efficient strategy for fabricating fluorescent information storage and encryption materials.

"Cell Disk" DNA Storage System Capable of Random Reading and Rewriting.

DNA has emerged as an appealing material for information storage due to its great storage density and durability. Random reading and rewriting are essential tasks for practical large-scale data storage. However, they are currently difficult to implement simultaneously in a single DNA-based storage system, strongly limiting their practicability. Here, a "Cell Disk" storage system is presented, achieving high-density in vivo DNA data storage that enables both random reading and rewriting. In this system, each yeast cell is used as a chamber to store information, similar to a "disk block" but with the ability to self-replicate. Specifically, each genome of yeast cell has a customized CRISPR/Cas9-based "lock-and-key" module inserted, which allows selective retrieval, erasure, or rewriting of the targeted cell "block" from a pool of cells ("disk"). Additionally, a codec algorithm with lossless compression ability is developed to improve the information density of each cell "block". As a proof of concept, target-specific reading and rewriting of the compressed data from a mimic cell "disk" comprising up to 105 "blocks" are demonstrated and achieve high specificity and reliability. The "Cell Disk" system described here concurrently supports random reading and rewriting, and it should have great scalability for practical data storage use.

Deep-trap persistent materials for future rewriteable optical information storage.

Deep-trap persistent luminescent (PersL) materials with enriched traps, which allow signals to quickly write-in and read-out with low-energy consumption, are one of the most promising materials for information storage. In this review, considering the demand for optical information storage, we provide comprehensive insights into the data storage mechanism of PersL materials. Particularly, we focus on various "trap-state tuning" strategies involving doping to design new deep-trap persistent phosphors with controlled carrier trapping-de-trapping for non-volatile and high-capacity information storage. Subsequently, various recent significant strategies, including wavelength-multiplexing, intensity-multiplexing, mechanical-multiplexing, and three-dimensional and multidimensional trap-multiplexing technologies for improving the information storage capacity of PersL phosphors are highlighted. Finally, the challenges and opportunities regarding optical information storage by PersL materials are discussed. We hope that this review will provide new insights for the future development of PersL materials in the field of optical data storage.

A novel viologen-based hybrid crystalline material for photochromic glass films, information storage and anti-counterfeiting.

Information storage and anti-counterfeiting are two very important applications of photochromic materials. Photochromic materials with both information storage and anti-counterfeiting should meet the requirements including fast coloration, good stability and reversibility, low storage cost, and practical application value. Herein, a novel viologen-based coordination polymer, Cd[(pbpy)0.5(HBTC)Cl]·2H2O (1) (pbpy = 1,1'-[1,4-phenylenebis-(methylene)]bis(4,4'-bipyridinium); HBTC2- = 1,3,5-benzenetricarboxylic acid), has been constructed. Compound 1 not only exhibits selective amine sensing properties, but also shows excellent photochromic properties, and the anti-counterfeiting of a two-dimensional code can be also realized through the color-changing behavior. Meanwhile, photochromic glass films of compound 1 were prepared, and compared to traditional optical information storage technology, these photochromic glass films have better water resistance and stability, improving their practical application stability. This work has further enriched the application of photochromic materials in the field of sensing, anti-counterfeiting and information storage.

Multi-stimuli responsive behavior of two Zn(ii) complexes based on a Schiff base with high contrast

Two zinc(ii) complexes, [Zn(HL)X2]·CH3OH (X = I, Br) prepared through one-pot method exhibit high contrast NH3-induced discoloration properties, acidochromic properties and mechanochromic luminescence properties, and are made into test papers capable of detecting HCl and NH3 vapor.

A Multiconfigurational Wave Function Theoretical Study on Electronic Structure and Magnetic Susceptibility of Dilanthanide Single Molecule Magnet.

Single molecule magnets (SMMs) have been a promising material for next-generation high-density information storage and molecular spintronics. N23--bridged dilanthanide complexes, {[(Me3Si)2N]2Ln(THF)(μ-η2:η2-N2)(THF)Ln[(Me3Si)2N]2}1-, exhibit high blocking temperatures and have been one of the promising candidates for future application. Rational understanding should be established between the magnetic properties and electronic structure. However, the theoretical study is still challenging due to the complexities in their electronic structures. Here, we theoretically studied the magnetic susceptibility of dilanthanide SMMs based on the state-of-the-art multistate-complete active space self-consistent field and perturbation theory at the second order and restricted active space state interaction with spin-orbit coupling calculations. Temperature dependence of the magnetic susceptibility (χmT-T curve) was quantitatively reproduced by the theoretical calculations. The complexities in the electronic states of these dilanthanide complexes originate from significantly strong static electron correlations in the lanthanide 4f and N2 π* orbitals and the SOC effect. The temperature dependence of the magnetic susceptibility results from the energy levels and magnetic properties of the low-lying excited state. The χmT values below 50 K are dominated by the ground state, while thermal distribution in the low-lying excited state affects the χmT values over 50 K. Saturation magnetization at low temperatures was also evaluated, and the result agrees with the experimental observation.

Ln-HOF Nanofiber Organogels with Time-Resolved Luminescence for Programmable and Reliable Encryption.

Developing tunable luminescent materials for high throughput information storage is highly desired following the explosive growth of global data. Although considerable success has been achieved, achieving programmable information encryption remains challenging due to current signal crosstalk problems. Here, we developed long-lived room-temperature phosphorescent organogels enabled by lanthanum-coordinated hydrogen-bonded organic framework nanofibers for time-resolved information programming. Via modulating coassembled lanthanum concentration and Förster resonance energy transfer efficiency, the lifetimes are prolonged and facilely manipulated (20-644 ms), realizing encoding space enlargement and multichannel data outputs. The aggregated strong interfacial supramolecular bonding endows organogels with excellent mechanical toughness (36.16 MJ m-2) and self-healing properties (95.7%), synergistically achieving photostability (97.6% lifetime retention in 10000 fatigue cycles) via suppressing nonradiative decays. This work presents a lifetime-gated information programmable strategy via lanthanum-coordination regulation that promisingly breaks through limitations of current responsive luminescent materials, opening unprecedented avenues for high-level information encryption and protection.

Seven-channel nanoprinting and meta-holography based on metasurface-space and angular multiplexing

Metasurfaces have emerged as crucial materials for optical information encryption and storage, lauded for their ease of operation and high programmability. However, the inherent inflexibility following metasurface fabrication leaves room for improvement in terms of information storage capacity. Incorporating multiplexed channels in metasurface boasts independent coding degrees of freedom, which bolsters the utility of metasurfaces for optical information storage and encryption. Most multiplexed metasurfaces conventionally rely on optical variables that can be controlled, such as wavelength, orbital angular momentum (OAM), forward/backward incidence of light, and polarization state, etc. However, there has been limited attention given to the inherent spatial properties of metasurfaces, let alone to combine these spatial properties with optical variables for multiplexing. To address this gap, we proposes a combined approach to develop a nanoprinting and meta-holography metasurface, which harnesses both metasurface-space and angular multiplexing to store seven independent holographic and nanoprinted images. This work not only unlocks new avenues for advanced optical information storage and encryption, but also pushes the boundaries of metasurface technology.

Multicolor photochromic material with dual protection of anti-counterfeiting and waterproofing

Optical information storage materials with dual protectiveness of anti-counterfeiting and waterproofing are critical to store information and improve paper utilization in a safe and accurate way. A novel multifunctional material with efficient photo-responsiveness and hydrophobicity was herein developed. Wherein, a system of silver ion (Ag+)/polyoxometalates/polymer was creatively formed as a photochromic layer, achieving different color variations by different contents of Ag+ and UV irradiation doses. This functional surface can maintain colored state for a long time in indoor environments, which is favorable to long-term information storage. It can be quickly blenched within 20 min under a hydrogen peroxide-containing atmosphere, achieving controllability of fading time. In addition, a multifunctional transparent coating formed by PDMS and fine particles composed of ytterbium compound and silica was applied on photochromic layer. This coating rapidly generates dazzling green light under infrared radiation, laying a foundation for the safe transmission of information. Its microstructures effectively capture air in gaps and low surface energy avoids wetting of water, achieving excellent hydrophobicity with a surface contact angle of 152°. In a word, this elaborately designed strategy for information storage via photochromism and dual protection shows enormous application potentials in optical information storage and encryption.

Engineering Isomeric AIEgens Containing Tetraphenylpyrazine for Dual Memory Storage.

Tetraphenylpyrazine (TPP) is a promising heterocycle-based aggregation-induced emission luminogen (AIEgen) which has sparked multiple applications in organic light-emitting diodes, sensors, and biotherapy. However, the utility of it in developing information storage materials is relatively rare. Moreover, TPP is mostly employed as an electronic acceptor in molecular design, while the consideration of it as an electronic donor is attractive in studies which may provide a full understanding of its property to tailor the materials. In this work, we synthesize three TPP-based molecules by decorating it with acrylonitrile and isomeric pyridine units, which show AIE behavior by property inheritance from their parent unit. Interestingly, the effective intramolecular charge transfer takes place from the TPP electronic donor to the acrylonitrile and pyridine electronic acceptor, therefore inducing a remarkable solvatochromic effect as the solvent polarity improves. Moreover, it is revealed that the isomeric effect of the nitrogen atom in the pyridines may pose an influence on the absorption, solvatochromism, and AIE behavior. In addition, the acrylonitrile and pyridine groups are reactive to light and acid-base stimuli with irreversible and reversible responses, respectively. Combined with the high light-harvesting ability of these AIEgens, they show great potential in the stimuli-responsive materials for dual information storage.

“Acrostic” Encryption: Stress‐Manipulation on Information Display

AbstractPolymers are ideal materials for information printing and storage and encryption through multiple channels. In this study, the visible color, fluorescent, and stress‐color are combined to print information. Stress‐color is achieved using an acid‐tunable dynamic reaction between a β‐diketone and an amine group via the light‐induced transformation of spiropyran (SP), which also directly prints the visible color information. The color and fluorescent patterns are stable via the reaction between SP and amine released from a dynamic enaminone structure. By achieving the stress‐color information coding, the data is further encrypted in an “acrostic” form by programmatically coding the information at several stages. The pattern or information in stress‐color is closely related to the decoding strain, whereas the fluorescent and color patterns display all the information written in various strains. As a result, the secret information is hidden among public data, resulting in acrostic encryption.

Bio-Inspired Electro-Thermal-Hygro Responsive Rewritable Systems with Temporal/Spatial Control for Environment-Interactive Information Display.

Utilization of rewritable luminescent materials for secure information storage and delivery has long been envisaged to reduce the cost and environmental wastes. However, it remains challenging to realize a temporally/spatially controlled display of the written information, which is crucial for secure information encryption. Here, inspired by bioelectricity-triggered skin pattern switching in cephalopods, an ideal rewritable system consisting of conductive graphene film and carbon dots (CDs) gel with blue-to-red fluorescence-color changes via water-triggered CDs aggregation and re-dispersion is presented. Its rewritability is guaranteed by using water ink to write on the CDs-gel and employing Joule heat of graphene film to evaporate water. Due to the highly controlled electrical stimulus, temporally/spatially controlled display is achieved, enabling on-demand delivery and duration time regulation of the written information. Furthermore, new-concept environment-interactive rewritable system is obtained by integrating sensitive acoustic/optical sensors and multichannel electronic time-delay devices. This work opens unprecedented avenues of rewritable systems and expands potential uses for information encryption/delivery.

Photocontrol of Exchange Bias Using Cobalt–Iron Prussian Blue Analogues for Applications in Spintronics

Multiphysics manipulation of the exchange bias (EB) effect to achieve spin-valve-type spintronic device versatility has begun to attract increasing attention recently. Light-controlled EB is considered to be an attractive approach because the photon mode allows access to a wide variety of materials with high speed, remote control, noncontact, and superior resolution. In this work, we report a detailed photocontrolled EB effect in the well-defined CoO@CoFePBA core–shell heteronanostructure, where the EB effect of this composite can be permanently changed after being exposed to light. As demonstrated, such an interesting photocontrolled effect is actually affected by the composition of the CoFePBA shell. More deeply, the alkali-metal-ion content in the CoFePBA shell is the major factor in controlling these hybrids’ EB effects. Different alkali-metal insertions result in different ratios of the FeIII–CoII magnetic pair to the FeII–CoIII diamagnetic pair in the CoFePBA shell, where FeIII–CoII and FeII–CoIII control the magnetic and photomagnetic effects of CoFePBA, respectively. Therefore, the photocontrolled EB effect of the whole nanohybrid can be adjusted by the amount of alkali-metal insertion in the CoFePBA shell. This study is an advance in the research of light-controlled EB effects, which are useful for the evolution of new functional spintronic devices, such as photomagnetic switches, photomagnetic sensors, and photointelligent information storage materials.