Blue-shift Phenomenon Research Articles

Anomalous Pressure-Induced Blue-Shifted Emission of Ionic Copper-Iodine Clusters: The Competitive Effect between Cuprophilic Interactions and Through-Space Interactions.

Developing ionic copper-iodine clusters with multiple emitting is crucial for enriching lighting and display materials with various colors. However, the luminescent properties of traditional ionic copper-iodine clusters are often closely associated with low-energy cluster-centered triplet emission, which will redshift further as the Cu⋅⋅⋅Cu bond length decreases. This article utilizes a pressure-treated strategy to achieve an anomalous pressure-induced blue-shifted luminescence phenomenon in ionic Cu4I6(4-dimethylamino-1-ethylpyridinium)2 crystals for the first time, which is based on dominant through-space charge-transfer (TSCT). Herein, we reveal that the more advantageous through-space interactions in the competition between cuprophilic interactions and through-space interactions can lead to a blue-shifted luminescence. High-pressure angle-dispersive X-ray diffraction and high-pressure infrared experiments show that the enhanced through-space interactions mainly originate from forming new intermolecular C-H⋅⋅⋅I hydrogen bonds and the enhancement of van der Waals interactions between organic cations and anionic clusters. Theoretical calculations and experimental studies of excited-state dynamics confirm that the blue-shifted emission is due to the increased energy gap between the excited triplet and ground states caused by the electron delocalization under stronger through-space interactions. This work deepens previous understanding and provides a new avenue to design and synthetic ionic copper-iodine clusters with high-energy TSCT emission.

A four core fiber temperature and strain dual parameter sensor based on T-shaped taper

A four core fiber temperature and strain dual parameter sensor based on T-shaped taper is proposed and prepared. The sensor is composed of single-mode fiber (SMF), multi-mode fiber (MMF), and four core fiber (FCF). Among them, MMF plays a role in beam expansion, and FCF is tapered and fused with SMF to form a T-shaped taper structure, thereby preparing a sensor based on Mach Zehnder interference principle. When the external environmental temperature and strain change, due to thermal effect and elastic optical effect, the refractive index of the FCF cladding and fiber core changes differently, resulting in shift in the interference spectrum. Based on the temperature and strain sensitivity at different interference valleys, the temperature and strain dual parameter matrix equation of the sensor can be obtained. The experimental results indicate that when the temperature rises within the range of 30 ℃ to 90 ℃, the sensor spectrum shows a red shift phenomenon, and the maximum temperature sensitivity can reach 55 pm/ ℃. When the strain increases within the range of 0 με∼ 2000 με, the transmission spectrum of the sensor exhibits a blue shift phenomenon, and the maximum strain sensitivity can reach −2.6 pm/ με. Finally, based on the experimental results, the matrix equation for dual parameter sensing can be obtained. This sensor is easy to manufacture and has high sensitivity. It can measure sensing parameters normally in micro magnetic and micro electric field environments.

Tunable Band Alignment and Optoelectronic Structure of Cu2Se/PtX2 (X=Se,Te) Heterostructures: under Strain and Electric Field

Two-dimensional (2D) material-based van der Waals heterostructures (vdWHs) are an emerging strategy for regulating the electronic properties of two-dimensional materials. This study investigated the effects of a vertical electric field and strain on the band alignment transition and optoelectronic properties of Cu2Se/PtSe2 (PtTe2) vdWHs using density functional theory calculations. Cu2Se/PtSe2 vdWHs exhibited type-I to type-II band alignment transformation under an in-plane strain, interlayer distance, and electric field of 2%, 2.40 Å, and -0.40 V/Å, respectively. Moreover, Cu2Se/PtTe2 vdWH demonstrated a rich transition of types I, II, and III band alignments with in-plane strain. The absorption spectra of Cu2Se/PtSe2 (PtTe2) vdWHs show a certain degree of blue and red shift phenomenon upon the application of strain and electric fields. The predicted power conversion efficiencies at 3% in-plane strain with an interlayer distance of 3.40 Å for Cu2Se/PtSe2 (PtTe2) vdWHs were observed to be as high as 22.58% (19.80%). Thus, our work demonstrated that both strain and electric field can effectively and flexibly control the electronic properties of Cu2Se/PtSe2 (PtTe2) vdWHs, making them a promising candidate material for applications in photodetectors and field-effect transistors.

Clustering-triggered emission mechanism of carboxymethyl β-cyclodextrin aqueous solution and efficient recognition of Fe3+ in mixed ions.

Most nonconventional luminogens enjoy good water solubility and biocompatibility, showing unique application prospects in fields like biological imaging. Although clustering-triggered emission (CTE) mechanisms have been proposed to explain such emissions, the have not been thoroughly elucidated, which limits their development and application. Here, the photoluminescence properties of carboxymethyl β-cyclodextrin (CM-β-CD) aqueous solution are utilized to further investigate the effects of changes in concentration, in order to elucidate the emission mechanism through cryo-transmission electron microscopy (cryo-TEM), small-angle X-ray scattering (SAXS), molecular interaction analysis, and theoretical calculation. The results showed that the size distribution, morphology, and distance between water aggregates were successfully correlated with the cluster emission centers. The emission mechanism of nonconventional luminogen solutions was more clearly and intuitively elucidated, which has a promoting effect on the emission and application of this field. It is interesting that temperature-dependent emission spectra show the blue-shift phenomenon of PL with increasing excitation wavelengths. Moreover, due to its strong static quenching effect for Fe3+, CM-β-CD can efficiently detect Fe3+ in mixed-ion aqueous solutions. It provides a strategy to clarify the CTE mechanism of nonconventional luminogen solutions more clearly and its application of mixed-ion detection.

Hybrid Amino Acid Ligand-Regulated Excited Dynamics of Highly Luminescent Perovskite Quantum Dots for Bright White Light-Emitting Diodes.

Organic-inorganic hybrid perovskite quantum dots (QDs) have garnered significant research interest owing to their unique structure and optoelectronic properties. However, their poor optical performance in ambient air remains a significant limitation, hindering their advancement and practical applications. Herein, three amino acids (valine, threonine and cysteine) were chosen as surface ligands to successfully prepare highly luminescent CH3NH3PbBr3 (MAPbBr3) QDs. The morphology and XRD results suggest that the inclusion of the amino acid ligands enhances the octahedral structure of the QD solutions. Moreover, the observed blue-shifted phenomenon in the photoluminescence (PL) aligns closely with the blue-shifted phenomenon observed in the ultraviolet-visible (UV-Vis) absorption spectra, attributed to the quantum confinement effect. The time-resolved spectra indicated that the introduction of the amino acid ligands successfully suppressed non-radiative recombination, consequently extending the fluorescence lifetime of the MAPbBr3 QDs. The photoluminescence quantum yields (PLQYs) of the amino acid-treated MAPbBr3 QDs are increased by 94.8%. The color rendering index (CRI) of the produced white light-emitting diode (WLED) is 85.3, with a correlated color temperature (CCT) of 5453 K. Our study presents a novel approach to enhancing the performance of perovskite QDs by employing specially designed surface ligands for surface passivation.

Four-band terahertz perfect-absorption and high-sensitivity sensor based on tunable Dirac semimetal

In this paper, we designed a dynamically tunable four-band perfect sensor based on bulk Dirac semimetal (BDS). The sensor comprises a top BDS layer, a bottom Au layer, and an intermediate dielectric layer. Four resonant modes with >98 % absorption are achieved in the range of 9–11.8 THz. Due to the rotationally symmetric design, the sensor is polarization insensitive. The formation mechanism of perfect absorption is explained using the principles of impedance matching. We also determined the effects of structural parameters and Fermi energy of the BDS on the absorption spectra. We explain the blue-shift and red-shift phenomena of the resonant frequency based on equivalent circuits. Additionally, we define the refractive index sensitivity (S) and find that the maximum sensitivity is 516 GHz/RIU. Due to these excellent properties, our design provides a way of thinking about actively tunable terahertz sensors and expands their application scope.

Electronic structure and optical properties of alkali metal X (X=Li, Na, K, Rb, Cs) adsorbed in the Te vacancy-deficient molybdenum ditelluride system: A first-principles study

In the framework of density functional theory, based on first principles, the plane wave pseudopotential technique was utilized to investigate the electrical and optical properties of MoTe2 adjusted by alkali metal X adsorption on Te vacancy defects (X[Formula: see text]=[Formula: see text]Li, Na, K, Rb, Cs). The adsorption of alkali metals on Te vacancy-deficient MoTe2 monolayers has been computationally analyzed. Charge transfer, electronic structure, and optical properties of alkali metal adsorption were systematically studied. It is shown that the MoTe2 bandgap is significantly reduced under Te vacancies. Te vacancies are frequently active sites in TMDs materials. With the adsorption of alkali metal atoms X (X = Li, Na, K, Rb, Cs) in the Te vacancy MoTe2 system, Li atoms have the most substantial geometrical deformation and the minor adsorption energy and can improve the adsorption properties more effectively. The MoTe2 system undergoes a change from semiconductor to metal after adsorption. Regarding optical properties, firm absorption and reflection peaks appeared, and a blueshift phenomenon was observed in the mountains. It is expected that these discoveries are likely to guide the use of molybdenum ditelluride in optoelectronics.

A study on the electromagnetic mechanism of a flexible terahertz toroidal dipole metasurfaces

We have designed and fabricated metasurfaces structures generated toroidal dipole phenomenon by fabricating periodic metal pattern on polyimide substrate. The metasurfaces structure consists of two symmetric split rings along the Y-axis. The impact of structural parameters, gap, and SR, on the electromagnetic characteristics of metasurfaces at terahertz frequencies was investigated. An increase in gap results in a blue shift phenomenon in the amplitude transmission spectrum, while an increase in SR leads to a red shift phenomenon in the amplitude transmission spectrum. The intrinsic mechanism of the toroidal resonance is investigated more deeply by calculating the multipole scattering power and Q-factor. Q-factor values of 2.3 and 9.5 were obtained at low and high frequencies, respectively. Terahertz toroidal dipole metasurfaces made on flexible substrates like this have the potential for applications in terahertz functional devices, such as sensors and tuners.

The Modulation of the Optical Properties of Low‐Dimensional Hybrid Perovskite by Using Anchoring Groups and Biaxial Strain: A First‐Principles Study

AbstractIn this paper, using CsMA2Sn2I7 as an example, first‐principles calculations are performed to thoroughly investigate the crystal structures, electronic properties, and optical properties of 11 representative anchoring group/low‐dimensional hybrid perovskite systems. The results show that the addition of benzene, 4‐iodoaniline, aniline, and benzenethiol anchoring groups causes a blueshift phenomenon in the absorption spectra of CsMA2Sn2I7 perovskite. Furthermore, the involvement of the benzoic acid anchoring group has a minimal effect on the absorption spectra of the CsMA2Sn2I7 hybrid perovskites, which show better absorption intensity only in the ultraviolet. The addition of other anchoring groups leads to varying degrees of redshift in the absorption spectra of CsMA2Sn2I7 perovskite, which not only enhances absorption intensity but also lends to the improvement of the absorption efficiency in the visible range. In addition, the bandgap can be tuned by applying biaxial strain, which further effectively modulates the absorption intensity of the adsorption systems in different optical bands. Therefore, the selection of suitable anchoring groups has great potential for modulating the photovoltaic performance of organic–inorganic hybrid perovskites, which is helpful for the application of organic–inorganic perovskites in photovoltaics.

First-principles study of the effect of doping on the optoelectronic properties of defective monolayers of MoSe2.

In this paper, the structural stability, electronic structure, and optical properties of monolayer MoSe2 doped with C, O, Si, S, and Te atoms, respectively, under defective conditions are investigated based on first principles. It is found that the system is more structurally stable when defecting a single Se atom as compared to defecting a single Mo or two Se atoms. The electronic structure analysis of the system reveals that intrinsic MoSe2 is a direct bandgap semiconductor. The bandgap value of the system decreases with a single Se atom defect and introduces two new impurity energy levels in the conduction band. The defective systems doped with C and Si atoms all exhibit P-type doping. The total density of states of intrinsic MoSe2 is mainly contributed by the Mo-d and Se-p orbitals, and new density of state peaks appears near the conduction band after the defects of Se atoms. The total density of states of the defective system doped by each atom is mainly contributed by Mo-d, Se-p, and the result of the p orbital contribution of each dopant atom. By analyzing the dielectric function of each system, it is found that the intrinsic MoSe2 has the lowest static permittivity and the C-doped defect system has the highest static permittivity, which reaches 21.42. The C- and Si-doped defect systems are the first to start absorbing the light, and the intrinsic MoSe2 absorbs the light later, with its absorption edge starting at 1.25eV. In the visible range, the reflection peaks of the systems move toward the high-energy region and the blue-shift phenomenon occurs. It is hoped that applying modification means to modulate the physical properties of the two-dimensional materials will provide some theoretical basis for broadening the application of monolayer MoSe2 in the field of optoelectronic devices. This study utilizes the first principle computational software package MS8.0 (Materials studio8.0) under density functional theory (DFT). The exchange-correlation potential (GGA-PBE) is described by the Perdew-Burke-Ernzerhof correlation function in CASTEP, and the potential function adopts the ultrasoft pseudopotential in the inverse space formulation. The plane wave truncation energy Ecut is set to 400eV, the K-point is taken as 5 × 5 × 1, and the force convergence criterion is 0.05eV/Å. The convergence accuracy of the total energy of the system is less than 1.0 × 10-5eV/atom, the tolerance shift is less than 0.002Å, and the stress deviation is less than 0.1 GPa. The vacuum layer is taken as 15Å, which is intended to minimize the interlayer force. The vacuum layer was set to 15Å to avoid the effect of layer-to-layer interaction forces in the crystal cell.

Banana peels based zinc oxide doped silver nanoparticles for enhanced photocatalytic degradation of paracetamol

Paracetamol (PCM) is a common drug for daily use in each household and considering PCM’s availability and huge production, traces of waste PCM present in water sources are concerned. Photocatalysis technology shows promising results with the utilization of semiconductor materials and light energy to degrade and remove organic pollutants. In this study, zinc oxide/silver nanoparticles (ZnO/Ag NPs) photocatalyst were synthesized via sol-gel and co-precipitation technique with the aid of banana peels extract (BPE) for photodegradation of PCM. The produced photocatalysts were characterized by UltravioletVisible Spectroscopy (UV-Vis), X-ray Diffraction (XRD), surface area and pore analysis and Field Emission Scanning Electron Microscope (FESEM). Results shows that a blue shift phenomenon occurs between ZnO NPs and ZnO/Ag NPs while XRD analysis suggested that all samples exhibit hexagonal wurtzite structure. ZnO/Ag NPs portrayed a spherical and hexagonal surface morphology with average particles size of 25.68 nm and mesoporous structure. ZnO/Ag NPs shows the highest photodegradation of PCM with 96 % with five repeated cycles compared to pristine ZnO NPs. The main species responsible for PCM degradation via ZnO/Ag are hydroxyl radical and electron. The prepared BPE based ZnO/Ag has a high potential as advanced materials for pharmaceutical wastewater treatment.

Paying Comprehensive Attention to the Temperature-Dependent Dual-Channel Excited-State Intramolecular Proton Transfer Mechanism of Fluorescence Ratio Probe BZ-DAM.

The mechanism of fluorescence detection of diethyl chlorophosphate (DCP) based on 2-substituted benzothiazole (BZ-DAM) was studied by a theoretical calculation method. It should not be ignored that both the BZ-DAM and the detection product BZ-CHO have two excited-state intramolecular proton transfer (ESIPT) channels. Density functional theory (DFT) and time-dependent DFT (TDDFT) theory were used to study the photophysical mechanism of two compounds in two channels in (acetonitrile) ACN solvent, and the temperature dependence of the two channels was given. Channel 1 is more likely to exist at low temperatures and channel 2 is more likely to exist at high temperatures. By theoretical analysis of the constructed potential energy curve, the hydrogen bond energy and electron-hole analysis, we confirmed that both molecules undergo ESIPT and intramolecular charge transfer (ICT) processes in channel 1 and ESIPT and twisted intramolecular charge transfer (TICT) coupling processes in channel 2. The formation of product BZ-CHO molecules led to a significant fluorescence blue-shift phenomenon and inhibited the ICT process, which confirmed that BZ-DAM could be used as a fluorescence probe for fluorescence detection. We sincerely hope that this work will not only help to clarify the excited-state dynamics behavior of the BZ-DAM probe but also provide a new idea for designing and optimizing a new chemical dosimeter.

3D printed self-calibrating on-site sensing platform based on bimodal excitation carbon dots for visual 4-nitrophenol detection by means of the localization of inner filter effect and pH regulation

For facile and rapid detection of 4-nitrophenol (4-NP), we synthesize nitrogen-doped carbon dots (N-CDs) through microwave radiation treatment using melamine and o-phenylenediamine as precursors. We employed N-CDs as an ingenious ratiometric fluorescence sensor via a novel bimodal excitation behavior. As the concentration of N-CDs increases, the broad excitation peak splits into two excitation peaks. The blue-shift phenomenon appears at the short-wavelength excitation peak, while the long-wavelength excitation peak presents the red-shift. Consequently, 4-NP can be sensitively detected by N-CDs owing to the localization of inner filter effect (L-IFE) with the detection limit of 83 nM ranging from 0.083 to 80 µM. Moreover, a self-calibrating on-site sensing platform constructed by 3D printing technique realizes the visual 4-NP detection in actual samples based on bimodal excitation behavior and RGB analysis. Our work not only presents a novel perspective for visual 4-NP sensing, but also renders the integration of 3D printing technology and the CDs industry.

Red InGaN Micro-LEDs on Silicon Substrates: Potential for Multicolor Display and Wavelength Division Multiplexing Visible Light Communication

Red micro light-emitting diodes (micro-LEDs) on silicon substrates are crucial for the realization of large-scale, high-quality, low-cost micro-LED displays, and are also beneficial for high-speed visible light communication (VLC). In this letter, micro-LEDs with different sizes were fabricated. The maximum light output power density of the 20 μm pixel can reach 3.36 W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , which is 14 times higher than that of the largest pixel (150 μm). By adjusting the pixel size and injection current, a direct color shift from red to green can be observed. Moreover, multicolor emission with uniform brightness can be realized by adjusting duty cycle, which has broad application prospect in monolithic, multicolor displays. Despite the significant blue shift phenomenon, the peak wavelength of all pixels is still greater than 630 nm at the current density of 100 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , which means that red light can be emitted in a large current density range to meet various application scenarios requiring different driving conditions. We have realized red, yellow and green micro-LED transmitters on Si substrate by changing the driving current density and modulation bandwidth up to 533.15 MHz is achieved when emitting green light. This is the report of red-emission micro-LEDs on Si substrates for visible light communication for the first time. And we proposed a proof-of-concept monolithic, multicolor wavelength division multiplexing scheme that achieved a total allowable transmission data rate of 2.35 Gbps. Such micro-LED is expected to be applied in multicolor displays, high-speed multi-channel VLC, color-tunable light sources, etc. In particular, due to its high integration and miniaturization, it is expected to be used in future practical application scenarios such as wearable communication devices and smartwatches.

Photoluminescence of GaAsSb/AlAsSb superlattices for investigating band structure

To study the band structure of GaAsSb/AlAsSb systems grown on InP substrates, optical absorption and photoluminescence (PL) measurements were performed. The measurements utilized GaAsSb/AlAsSb superlattice (SL) samples to investigate the optical properties of the system. By comparing optical absorption and photoluminescence (PL) measurements, it was determined that the non-radiative transition occurred at lower energy levels than the PL transition energy in the sample with the narrowest well width. The excitation power dependence of PL measurements exhibited an almost linear power law of peak intensity, suggesting high-quality luminescence properties of GaAsSb/AlAsSb SLs. In addition, the sample with the narrowest well width exhibited a blueshift of the PL transition energy as a function of the excitation power between square and cubic root laws. To explain these experimental observations, quantized energies in SLs were calculated using the band structures that were suggested and modified using an established band parameter. The most plausible band structure was revealed by comparing experimental observations with the calculations. PL from the SL samples was found to occur within the GaAsSb well (type I) in between the gamma point (Γ) of the conduction band and the heavy hole (HH) energy level in the valence band. To understand the underlying causes of the blueshift phenomenon, a self-consistent calculation that solves the Schrödinger and Poisson equations was performed iteratively as a function of carrier density. As a result, the blueshift of transition energy with an increase in the carrier density was confirmed in the type-I transition between Γ and HH bands if the lowest transition was type II between L for AlAsSb and HH for GaAsSb bands. The Hartree potential due to the separately confined electrons and holes in the SLs slightly narrowed the GaAsSb well width by modifying the conduction band.

A water-soluble colorimetric and ratiometric fluorescent probe based on phenothiazine for the detection of hypochlorite ion

A new water-soluble colorimetric and ratiometric fluorescent probe for detecting hypochlorite ion (ClO−) based on a phenothiazzine group was designed and synthesized. As ratiometric fluorescent probe, LD-Lyso showed rapid, accuracy, and selective fluorescence sensing effect for ClO− in PBS buffer solution with a large Stokes shift (195 nm), it displayed a significant blue-shift phenomenon and a 25-fold enhancement of the fluorescence intensity ratio (I550/I635) toward ClO−, fluorescence notably changing from red to green, the detection limit as low as 8.74 μM; As colorimetric probe, LD-Lyso also showed a significant shift in absorption band (from 450 to 395 nm) upon treatment with ClO− along with the visible color changed from faint yellow to colorless, the detection limit as low as 0.01 μM. In addition, the detecting mechanism of LD-Lyso towards ClO− via the intramolecular charge transfer (ICT) mechanism was proved by ESI-MS and DFT calculation, and the application as testing strips for detecting ClO− was realized.

Pyrene-Fused Poly-Aromatic Regioisomers: Synthesis, Columnar Mesomorphism, and Optical Properties.

π-Extended pyrene compounds possess remarkable luminescent and semiconducting properties and are being intensively investigated as electroluminescent materials for potential uses in organic light-emitting diodes, transistors, and solar cells. Here, the synthesis of two sets of pyrene-containing π-conjugated polyaromatic regioisomers, namely 2,3,10,11,14,15,20,21-octaalkyloxypentabenzo[a,c,m,o,rst]pentaphene (BBPn) and 2,3,6,7,13,14,17,18-octaalkyloxydibenzo[j,tuv]phenanthro [9,10-b]picene (DBPn), is reported. They were obtained using the Suzuki-Miyaura cross-coupling in tandem with Scholl oxidative cyclodehydrogenation reactions from the easily accessible precursors 1,8- and 1,6-dibromopyrene, respectively. Both sets of compounds, equipped with eight peripheral aliphatic chains, self-assemble into a single hexagonal columnar mesophase, with one short-chain BBPn homolog also exhibiting another columnar mesophase at a lower temperature, with a rectangular symmetry; BBPn isomers also possess wider mesophase ranges and higher mesophases' stability than their DBPn homologs. These polycyclic aromatic hydrocarbons all show a strong tendency of face-on orientation on the substrate and could be controlled to edge-on alignment through mechanical shearing of interest for their implementation in photoelectronic devices. In addition, both series BBPn and DBPn display green-yellow luminescence, with high fluorescence quantum yields, around 30%. In particular, BBPn exhibit a blue shift phenomenon in both absorption and emission with respect to their DBPn isomers. DFT results were in good agreement with the optical properties and with the stability ranges of the mesophases by confirming the higher divergence from the flatness of DBPn compared with BBPn. Based on these interesting properties, these isomers could be potentially applied not only in the field of fluorescent dyes but also in the field of organic photoelectric semiconductor materials as electron transport materials.

First-principle studies of monolayer and bulk InSe1−xSx

S-substitution doped monolayer and bulk InSe exhibit opposite bandgap behaviors. The bandgap in the monolayer InSe1−xSx (x = 0, 0.125, 0,25) decreases with increasing S concentration. However, the bandgap in bulk InSe1−xSx increases with the increase of S concentration. It is mainly because In, and Se(S) at the Fermi level have different strengths of bonding and anti-bonding states. In addition, the first-neighbor interatomic force constant (IFC) of the dopant atom S is higher than that of Se. The enhanced IFC in bulk InSe1−xSx corresponds to the Raman spectral blueshift phenomenon observed in earlier experiments. The electro-acoustic interactions of the material are strongly correlated with dimensionality, which leads to differences in optical properties between monolayer and bulk InSe1−xSx. The optical dielectric functions indicate that monolayer and bulk InSe1−xSx can be applied in different fields. Substitutional doping could modulate pz-like orbital interactions, which provides clues for modulating the electronic orbital structure of InSe materials for optoelectronic and optical applications.

Finely regulated benzothiadiazole derivatives: Aggregation-induced emission (AIE), hypso- or bathochromic mechanofluorochromic behaviors, and multilevel information encryption applications

Six fluorescent dyes containing the same central benzothiadiazole skeleton were synthesized. Fluorogenic compounds 1 and 2 demonstrated typical aggregation-induced emission enhancement and aggregation-induced emission phenomena. These benzothiadiazole-modified dyes emitted different crystal-state fluorescence including green, yellow-green, yellowish brown, orange red and red colors, and these compounds displayed contrasting force-responsive fluorescence characteristics. More specifically, compound 1 exhibited red-shifted mechanofluorochromism behavior, and compounds 4–6 exhibited blue-shifted mechanofluorochromism phenomena, while compounds 2 and 3 showed no fluorescence change under mechanical stimulation. Among these benzothiadiazole derivatives, luminogens 1 and 6 presented mechanically triggered high-contrast bathochromic and hypsochromic fluorescence responses, respectively. Based on their various crystal fluorescence and force-sensitive emissive properties of fluorogenic molecules 1–6, an interesting multilevel information encryption system was successfully constructed. Indeed, this study not only provided a valuable reference for the preparation of luminophores possessing rich mechanoluminochromic natures, but also extended ideas for the development of advanced information encryption systems.

WP Nanocrystals on N,P Dual-Doped Carbon Nanosheets with Deeply Analyzed Catalytic Mechanisms for Lithium–Sulfur Batteries

WP Nanocrystals on N,P Dual-Doped Carbon Nanosheets with Deeply Analyzed Catalytic Mechanisms for Lithium–Sulfur Batteries