Shift Of Emission Research Articles

Achieving Thermally Stable YAl3-xGax(BO3)4:Cr3+ Near-Infrared Emitting Phosphors via Chemical Substitution for Plant Growth LEDs.

Indoor plant cultivation has been receiving increased attention due to concerns about sustainable agricultural production. Phosphor-converted light-emitting diodes (pc-LEDs) offer substantial promise as lighting solutions for regulating plant growth. However, the quest for high-performance phosphors with precise responsiveness to far-red phytochromes poses a challenge. Our study proposes a chemical substitution strategy to develop near-infrared (NIR) phosphors, YAl3-xGax(BO3)4:Cr3+. Benefiting from Ga3+ replacement of Al3+, a red shift in the NIR emission of YAl3-xGax(BO3)4:Cr3+ is realized to attain a good alignment with far-red phytochrome absorption centering at 730 nm. The optimized YAl2.5Ga0.5(BO3)4:Cr3+ exhibits a favorable quantum yield of 71.8% and robust thermal stability of 101.0%@423 K, owing to local structural distortion and thermal repopulation caused by Ga3+ incorporation. The fabricated pc-LED combined with the phosphor yields an NIR output power of 40.9 mW and a photoelectric conversion efficiency of 15.4% at 100 mA. Plant growth experiments demonstrate that under NIR illumination from the devices, the average lengths of pea roots and stems gain 127 and 225% promotion, respectively, further highlighting the potential of YAl2.5Ga0.5(BO3)4:Cr3+ phosphors for applications in plant cultivation.

Encapsulation-induced hypsochromic shift of emission properties from a cationic Ir(III) complex in a hydrogen-bonded organic cage: A theoretical study.

Encapsulation of coordination complexes within the confined spaces of self-assembled hosts is an effective method for creating supramolecular assemblies with distinct chemical and physical properties. Recent studies with calix-resorcin[4]arene hydrogen-bonded hexameric capsules revealed that encapsulated metal complexes exhibit enhanced and blue-shifted photoluminescence compared to their unencapsulated forms. The photophysical change has been hypothetically attributed to encapsulation-induced confinement, which isolates the metal complex from the solvent, suppressing stabilization of the excited state of the guest by solvent reorganization and structural relaxation, and altering the local environment, such as solvent polarity and viscosity, around the guest. In this study, density-functional theory calculations were conducted to explore how encapsulation affects the photophysical properties of a cationic iridium complex within a hydrogen-bonded hexameric capsule. The encapsulation-induced emission shift was analyzed by separating it into three factors: suppression of solvent reorganization, suppression of structural relaxation of the complex, and electronic interactions between the complex and the capsule. The findings indicate that the photoluminescence modulation is driven by the electronic interaction between the host and guest, which affects the energy levels of the molecular orbitals involved in the T1 excited state and the suppression of excited-state structural relaxation of the Ir complex due to the presence of the host. This study advances our understanding of the photophysical dynamics of coordination complexes within the confined spaces of hexameric capsules, providing a valuable approach for tuning the excited state properties of guest molecules.

Satellite Data and Machine Learning for Benchmarking Methane Concentrations in the Canadian Dairy Industry

Amid escalating climate change concerns, methane—a greenhouse gas with a global warming potential far exceeding that of carbon dioxide—demands urgent attention. The Canadian dairy industry significantly contributes to methane emissions through cattle enteric fermentation and manure management practices. Precise benchmarking of these emissions is critical for developing effective mitigation strategies. This study ingeniously integrates eight years of Sentinel-5P satellite data with advanced machine learning techniques to establish a methane concentration benchmark and predict future emission trends in the Canadian dairy sector. By meticulously analyzing weekly methane concentration data from 575 dairy farms and 384 dairy processors, we uncovered intriguing patterns: methane levels peak during autumn, and Ontario exhibits the highest concentrations among all provinces. The COVID-19 pandemic introduced unexpected shifts in methane emissions due to altered production methods and disrupted supply chains. Our Long Short-Term Memory (LSTM) neural network model adeptly captures methane concentration trends, providing a powerful tool for planning and reducing emissions from dairy operations. This pioneering approach not only demonstrates the untapped potential of combining satellite data with machine learning for environmental monitoring but also paves the way for informed emission reduction strategies in the dairy industry. Future endeavors will focus on enhancing satellite data accuracy, integrating more granular farm and processor variables, and refining machine learning models to bolster prediction precision.

The influence of coordination mode differences on the structural diversity and fluorescence properties of Zn(II)/Cd(II) Schiff base complexes

Four metal complexes 1 : Zn2Cl2L2, 2 : Zn2(CH3OO)2L2·MeCN, 3 : Zn(NO3)2HL, 4 : CdCl2HL were obtained by coordinating the flexible Schiff‐base ligand 4‐amino‐N'‐(di(pyridin‐2‐yl)methylene)benzohydrazide (abbreviated as HL) with the Zn(II) and Cd(II). X‐ray single crystal diffraction confirms that the four complexes 1‐4 employ two different coordination modes. Moreover, the structures of complexes 1 and 2 are accompanied by deproton behavior, and these structural differences not only increase the fluorescence quantum yield but also produce a red shift in fluorescence emission. TD‐DFT calculations confirm that these performance changes are related to the coordination mode and coordination environment. This work not only construct the four fluorescent complexes, but also further deepen the understanding of the structure‐activity relationship between the structure of the complexes and the fluorescence properties.

Pressure-Engineered Through-Space Conjugation for Precise Control of Clusteroluminescence.

Clusteroluminogens (CLgens) represent an innovative class of nonconjugated luminophores that address the limitations of conventional π-conjugated molecules. Different from the through-bond conjugation mechanism in π-conjugated luminophores, through-space conjugation (TSC) plays dominant roles in CLgens. However, precisely controlling TSC to customize the optical properties of CLgens remains a significant challenge. This work proposes a novel strategy of high pressure to engineer TSC within tetraphenylalkanes (TPAs)-based CLgens at molecular level. High-pressure exploration enables accurate manipulation of clusteroluminescence and elucidates the intrinsic structure-property relationships involved. Upon initial compression, the predominant molecular distortions marked by increased interfacial angles between benzene rings diminish TSC, resulting in anomalous hypochromatic shift in emission. Subsequently, considerable structural contraction enhances TSC and suppresses molecular motion, resulting in a pronouncedly enhanced and bathochromic-shifted emission. Notably, a series of TPAs-based CLgens exhibit intense white-light emission upon pressure release, attributed to irreversible structural distortion and destruction. This study not only advances the understanding of CLgens, but also underscores the crucial structural factors for effective TSC control, paving the way for establishing new photophysical theories for aggregate science.

Pressure‐Engineered Through‐Space Conjugation for Precise Control of Clusteroluminescence

Clusteroluminogens (CLgens) represent an innovative class of nonconjugated luminophores that address the limitations of conventional π‐conjugated molecules. Different from the through‐bond conjugation mechanism in π‐conjugated luminophores, through‐space conjugation (TSC) plays dominant roles in CLgens. However, precisely controlling TSC to customize the optical properties of CLgens remains a significant challenge. This work proposes a novel strategy of high pressure to engineer TSC within tetraphenylalkanes (TPAs)‐based CLgens at molecular level. High‐pressure exploration enables accurate manipulation of clusteroluminescence and elucidates the intrinsic structure‐property relationships involved. Upon initial compression, the predominant molecular distortions marked by increased interfacial angles between benzene rings diminish TSC, resulting in anomalous hypochromatic shift in emission. Subsequently, considerable structural contraction enhances TSC and suppresses molecular motion, resulting in a pronouncedly enhanced and bathochromic‐shifted emission. Notably, a series of TPAs‐based CLgens exhibit intense white‐light emission upon pressure release, attributed to irreversible structural distortion and destruction. This study not only advances the understanding of CLgens, but also underscores the crucial structural factors for effective TSC control, paving the way for establishing new photophysical theories for aggregate science.

Effects of monosaccharides glycation on structural characteristics and functional properties of coconut protein isolate based on molecular docking

The study examined the impact of glycation with five-carbon and six-carbon monosaccharides on the structure and physicochemical properties of coconut protein isolate (CPI). Compared to native CPI, CPI/monosaccharide complexes exhibited higher absorbance ratios (A294/A420) and glycation degrees. Structural analysis revealed an increase in disordered structures (β-turn and random coil), a blue shift in fluorescence emission, and elevated UV absorbance, indicating protein unfolding and exposure of hydrophobic groups. Glycation significantly enhanced CPI's solubility, emulsifying capacity, oil holding capacity, and thermal stability. Molecular docking simulations emphasized the importance of hydrogen bonding in complex formation. These findings provide insights into protein-carbohydrate interactions, offering potential for diverse industrial applications and guiding future research.

A Novel Colon-Targeting Ratiometric Probe with Large Emission Shift for Imaging Peroxynitrite in Ulcerative Colitis.

Ulcerative colitis (UC) is an inflammatory disease that leads to the overexpression of peroxynitrite (ONOO-). Up to now, it has been a challenge to design a colon-targeted fluorescent probe with a large emission shift that can detect and image ONOO- in UC mice. Here, a fluorophore (pyran-coumarin) is linked with cholic acid to develop a colon-targeted fluorescent probe (CPC) for the detection of ONOO-. The fluorescent probe showed strong near-infrared emission at 725 nm. After reacting with ONOO-, it can be observed that the fluorescence intensity at 725 nm decreases obviously, and the signal at 490 nm increases clearly with an obvious emission shift (235 nm). This response mechanism causes the probe to have good sensitivity and selectivity. Additionally, the probe CPC shows good targeting ability for the cells with overexpressingTGR5 receptors and displays good results for detecting exogenous and endogenous ONOO- in the cells. More importantly, the probe CPC can be especially assembled in the colon site to distinguish normal and UC mice and provide significant information for the diagnosis of UC.

Organic BODIPY based gels: Optical, electrochemical and self-assembly properties.

Two novel BODIPY dyes, BOC3 and BC12, were synthesized with variable alkyl chains at terminal amide functional units. BC12, featuring a longer alkyl chain (-C12H25), formed a gel compared to BOC3, which has a shorter alkyl chain (-CH2OCH3), due to supra molecular self-assembly in film. Both dyes exhibited absorption peaks around 530 nm in the visible region, with a red shift of about 30 nm in the film state, essential for organic electronic applications. Concentration variation studies revealed π-π stacking/aggregates in the solid state causing red shifts in absorption and emission. BC12 exhibited more significant red shifts in film compared to its solution state due to supra molecular self-assembly. Electronic structure analysis using density functional theories (BMK and O3LYP) showed better correlation with absorption using the O3LYP method. Both dyes displayed quasi-irreversible oxidation and reduction couples with suitable HOMO (5.46 eV) and LUMO (3.32 eV) energy levels for organic electronic applications. Transient photoluminescence studies indicated a longer lifetime for BC12 (5.28 ns) than BOC3 (4.50 ns), suggesting π-π aggregation and supra molecular self-assembly. BC12's gelation, attributed to its long alkyl chain and two-dimensional motifs of the BODIPY core, forms spherical-shaped nano networks.

Two-Photon Cellular and Intravital Imaging of Hypochlorous Acid by Fluorescent Probes That Exhibit a Synergistic Excited-State Intramolecular Proton Transfer-Intramolecular Charge Transfer Mechanism Enabling Near-Infrared Emission with a Large Stokes Shift.

To develop highly effective molecular tools for intravital imaging of hypochlorous acid (HOCl), in this study, we initially designed two-photon hybrid fluorophores, SDP and P-SDP, by conjugating the classical dye 2-(2'-hydroxyphenyl)benzothiazole with the two-photon hydroxylphenyl-butadienylpyridinium fluorophore. The designed fluorophores exhibit a synergistic interaction between excited-state intramolecular proton transfer and intramolecular charge transfer mechanisms, enabling near-infrared (NIR) emission and significant Stokes shifts. Subsequently, using these fluorophores, we developed two HOCl fluorescent probes, SDP-SN and P-SDP-SN, by further incorporating N,N-dimethylthiocarbamate as a specific recognition group for HOCl. Toward HOCl, both SDP-SN and P-SDP-SN demonstrate an ultrafast response (less than 3 s), NIR emission at wavelengths of 714 and 682 nm, and remarkable Stokes shifts of 303 and 271 nm, respectively. Leveraging these advantages in conjunction with their ability to cross the blood-brain barrier, the probes find successful application in two-photon cellular and intravital imaging of HOCl. This includes visualizing endogenous generation of HOCl in cellular models related to inflammation, hyperglycemia, and ferroptosis, as well as mapping in vivo generation of HOCl within the brain and abdominal cavity using a murine model of systemic inflammation.

Carbazole-pyrimidine-based novel ratiometric fluorescent probe with large Stokes shift for detection of hydrazine in real environments and organisms

Widespread application of hydrazine results in serious harm on the natural environments and human health because of its highly toxic, mutagenic, carcinogenic and teratogenic properties. Hence, it is very emergent to develop a convenient and efficient method for detection of hydrazine existed in real environments and living organisms. In this work, a novel ratiometric fluorescent probe PKZ-IN from the natural monoterpenoid 2-hydroxy-3-pinanone was designed and synthesized to detect trace hydrazine. The detection performance of probe PKZ-IN for hydrazine was investigated, and the results showed that this probe possessed excellent performance including large Stokes shift (211 nm), fast response time (<30 s), remarkable emission shift (136 nm), and a wide pH range (5 −13). This probe was successfully used to detect hydrazine existed in three different soil samples (humus soil, sandy soil and loess soil). In addition, probe PKZ-IN was also used to prepare nanofibrous membrane for detecting gaseous hydrazine qualitatively and quantitively by the mobile phone platform. Furthermore, PKZ-IN was successfully applied in living organisms and plants imaging for detection of the residual hydrazine.

Preparation of Red-Emitting CDs for Glioma Imaging and Fe3+ Sensing.

Red-emitting fluorescent carbon dots (CDs) have garnered significant attention due to their wide-ranging applications in biological fields. However, challenges such as complex precursors, labor-intensive preparation processes, and low quantum yields have hindered their broader utilization. In this study, we developed a simple and efficient solvothermal method to synthesize fluorescent CDs with tunable emission wavelengths using aniline derivatives as precursors. The emission wavelengths of the synthesized CDs were influenced by the functional groups at the para-position of the aniline derivatives with stronger electron-donating effects leading to a red shift in emissions. Notably, bright red-emitting CDs with a quantum yield of 19.42% and excellent photobleaching resistance were obtained by using p-phenylenediamine as the sole precursor. These CDs exhibited sensitivity to Fe3+ ions, demonstrating a strong linear detection range (R 2 = 0.999) from 0 to 50 μM. Additionally, the CDs were uniform in size (2-5 nm), emitted stable red fluorescence in pH conditions ranging from 4 to 10, and were successfully internalized by glioma cells, enabling precise fluorescence imaging of gliomas both in vitro and in vivo.

Intramolecular Charge Transfer Inhibition Strategy toward a Desired Solvatochromic Fluorescent Platform: Visualization of Duple Organelles and Detection of Carbon Dioxide.

Solvatochromic fluorescent probes are crucial molecular tools to investigate and aggregate proteins' fold, visualize fine structures in biomembranes, and label different organelles in dual emission colors. However, solvatochromic fluorogens often displayed a weak emission at high polarity, hindering their bioimaging applications. To resolve this problem, herein, we propose an intramolecular charge transfer (ICT) inhibition strategy. The probe was designed with a single electronic donor and two acceptors in order to split and inhibit the ICT procedure. As a result, the probe displayed an intense emission at both low and high polarities and showed a large emission shift (84 nm) upon polarity change. Using the probe, we successfully imaged lipid droplets and the endoplasmic reticulum in different fluorescence colors. Moreover, the different degrees of lipid accumulation by oleic acid, stearic acid, and cholesterol (oleic acid > stearic acid > cholesterol) have been revealed. The lipid accumulation induced by the three lipids could be rapidly consumed under lipid-less conditions, and the lipids with stearic acid were the most difficult to be consumed. The biological results could facilitate the understanding and treatment of lipid accumulation and obesity. Furthermore, utilizing the polarity increase of diethylamine after the reaction with CO2, the ratiometric detection of CO2 has been achieved for the first time with the probe.

Versatile photoluminescence behavior of polycyclic hydroxybenzimidazoles driven by intermolecular hydrogen bonding

Herein, the synthesis of polycyclic hydroxybenzimidazole based on 4-hydroxyphthalimide is presented and two isomeric structures are formed. The isomeric structures are capable of forming intermolecular hydrogen-bonded molecular associates. Hydroxybenzimidazole hydrogen-bonded organic frameworks have been shown to be sensitive to different solvent polarity, particularly in proton donor media, resulting in a blue shift in emission. The role of proton donor media has been evaluated using the binary mixture of acetonitrile/water and protonation by trifluoroacetic acid. The results show that by tuning the environment, the aggregation induced emission has appeared in the blue region and larger aggregates are formed compared to the less polar aprotic solvents. Under acidic conditions, the disruption of the hydrogen-bonded dimers was estimated, resulting in deep blue emission. This provides an opportunity to control the molecular associates and tune the optical behavior.

Visual colorimetric label for real-time monitoring of SO2 concentration change in grape and mango during storage

Sulfur dioxide (SO2) is widely utilized as a preservative in food transportation and storage, but excessive consumption poses health risks. This study presents a novel and efficient method for the real-time detection of SO2 using a sensor named TK, synthesized from triphenylamine and 2-cyanomethyl-1-methyl-quinolinium. The core mechanism involves the Michael addition reaction of the CC bond in TK with SO2, which disrupts the intramolecular charge transfer process, resulting in a significant color change and a blue shift in fluorescence emission. Methodologically, the sensor's response was quantified by the change in fluorescence intensity ratio (I425/I647) within a SO2 concentration range of 0–180 μM. The sensor exhibited high sensitivity and selectivity. For practical application, TK was incorporated into hydrophilic polyvinyl alcohol to create a smart label capable of visual colorimetry and fluorescence analysis. SO2 concentration changes were monitored by using this label, demonstrated by the color transition from burgundy red to colorless, yielding a maximum color difference (ΔE) of 73.6. The smart label was successfully used to monitor the quality of various grapes and mangoes during long-term storage, providing a reliable, equipment-independent method suitable for household use. The study offers a new tool for enhancing food safety and mitigating health risks associated with SO2 exposure.

Development of Donor-acceptor-type Molecules and Their Application as Analytical Reagents

π-Extended donor-acceptor (D-A)-type molecules, which bear both electron-donor and electron-acceptor substituents on the backbone, exhibit unique optical properties, such as bathochromic shifts in absorption and emission, large Stokes shifts, solvatochromic behavior, and fluorescence quenching in polar solvents. These unique properties are attributed to intramolecular charge transfer (ICT) or twisted intramolecular charge transfer (TICT) in the ground and excited states. This review article introduces three types of D-A-type molecules that are used as detection reagents for (1) methanol, (2) amino acids during solid-phase peptide synthesis (SPPS), and (3) amines present in the biological environment. For methanol detection, D-A-type fluorophores with basic guanidine moieties were developed to differentiate between methanol (MeOH) and ethanol (EtOH) based on the small difference in their pKa values (ΔpKa=0.4). Selective protonation of the guanidine moiety in methanol disrupts the D-A structure, allowing emission in the resultant polar environment. Similarly, an acid-base reaction between the hydrogen chloride (HCl) salts of the D-A-type molecules and amines is applied to detect amines during SPPS. In this method, a colorless solution of an HCl salt of the D-A-type molecule is deprotonated by amines, forming a yellow solution. This is the first reported quantitative and non-destructive colorimetric method for detecting amines. Finally, a turn-on-type amine-labeling reagent was developed for the nucleophilic aromatic substitution (SNAr) reaction. This new reagent enables protein staining of living cells with a large Stokes shift and without solvent-polarity-dependent fluorescence quenching.

Simultaneous assessment of NAD(P)H and flavins with multispectral fluorescence lifetime imaging microscopy at a single excitation wavelength of 750nm.

Autofluorescence characteristics of the reduced nicotinamide adenine dinucleotide and oxidized flavin cofactors are important for the evaluation of the metabolic status of the cells. The approaches that involve a detailed analysis of both spectral and time characteristics of the autofluorescence signals may provide additional insights into the biochemical processes in the cells and biological tissues and facilitate the transition of spectral fluorescence lifetime imaging into clinical applications. We present the experiments on multispectral fluorescence lifetime imaging with a detailed analysis of the fluorescence decays and spectral profiles of the reduced nicotinamide adenine dinucleotide and oxidized flavin under a single excitation wavelength aimed at understanding whether the use of multispectral detection is helpful for metabolic imaging of cancer cells. We use two-photon spectral fluorescence lifetime imaging microscopy. Starting from model solutions, we switched to cell cultures treated by metabolic inhibitors and then studied the metabolism of cells within tumor spheroids. The use of a multispectral detector in combination with an excitation at a single wavelength of 750nm allows the identification of fluorescence signals from three components: free and bound NAD(P)H, and flavins based on the global fitting procedure. Multispectral data make it possible to assess not only the lifetime but also the spectral shifts of emission of flavins caused by chemical perturbations. Altogether, the informative parameters of the developed approach are the ratio of free and bound NAD(P)H amplitudes, the decay time of bound NAD(P)H, the amplitude of flavin fluorescence signal, the fluorescence decay time of flavins, and the spectral shift of the emission signal of flavins. Hence, with multispectral fluorescence lifetime imaging, we get five independent parameters, of which three are related to flavins. The approach to probe the metabolic state of cells in culture and spheroids using excitation at a single wavelength of 750nm and a fluorescence time-resolved spectral detection with the consequent global analysis of the data not only simplifies image acquisition protocol but also allows to disentangle the impacts of free and bound NAD(P)H, and flavin components evaluate changes in their fluorescence parameters (emission spectra and fluorescence lifetime) upon treating cells with metabolic inhibitors and sense metabolic heterogeneity within 3D tumor spheroids.

A terphenyl derivative-based colorimetric-fluorimetric probe for the detection of lysine and arginine and their bioimaging

Lysine (Lys) and arginine (Arg) play a crucial role in the human diets, medical diagnostics, and functional biomaterial synthesis. The imbalance of intake for these two amino acids causes various diseases. Although many analytical techniques have been reported for the detection of amino acids, there are still some issues such as the need for bulky instruments, professional operators, sensitivity to be improved, and real-time detection. Here, a novel colorimetric-fluorimetric probe based on a terphenyl derivative (TPT) has been synthesized for the precise detection of Lys and Arg. In the EtOH-H2O solution of TPT, the NH2 group at the chain end of Lys/Arg undergoes a nucleophilic addition reaction with CN groups of benzothiazole groups of the probe TPT, which breaks the initial long-conjugated system of the probe molecule. As a result, blue shifts can be observed for both UV–vis absorption spectra and fluorescence spectra, accompanying with color changes of the TPT solution. The UV–vis absorption peak of TPT solution shifts from ∼410 nm to ∼325 nm, and the solution color changes from light-yellow to colorless. The fluorescence emission shifts from ∼580 nm to ∼470 nm and the bright-yellow TPT solution changes to blue under the irradiation of 365 nm UV light. For colorimetric method, the limits of detection (LoD) are 0.82 μM and 0.90 μM for Lys and Arg, respectively. For fluorimetric method, they are 2.02 nM and 1.62 nM for Lys and Arg, respectively. In addition, TPT has good selectivity and anti-interference for Lys and Arg. The synthesized probe TPT has been successfully used for the precise detection of Lys and Arg in drugs and for fluorescence imaging of living cells. This work demonstrates that terphenyl-based derivatives are promising organic probes for the detection of Lys and Arg, providing a new way for designing other amino acids probes.

Design and synthesis of dicyanoethylene derivatives functionalized with carbazole possessing the properties of obvious aggregation-induced emission and reversible high-contrast mechanofluorochromism

This study devotes to the design, preparation, and examination of two novel D-A structured molecules, designated as CCEDBF and BCCEDBF, which are derived from carbazole unit, dicyanoethylene segment, and dibenzofuran unit. The distinctive D-A molecular architectures and highly twisted spatial configurations of these compounds facilitate pronounced intramolecular charge transfer (ICT) while also imparting robust solid-state luminescence, exhibiting emission efficiencies of 0.518 and 0.739, respectively, and notable aggregation-induced emission (AIE) with AIE factors of 43 and 30. Significantly, both CCEDBF and BCCEDBF demonstrate reversible mechanofluorochromic (MFC) behavior characterized by high fluorescence contrast. Mechanical grinding of the initial powders results in a shift in their emission colors, transitioning from green and yellow-green to yellow and orange-red, respectively, alongside a corresponding shift in emission peaks from 525 nm to 536 nm–558 nm and 597 nm. Powder X-ray diffraction (PXRD) examination of the initially synthesized, mechanically processed, and vaporized samples reveals that the observed fluorescence color change is due to a structural transformation between ordered crystalline and disordered amorphous configurations induced by the application of the external force. The red shift in photoluminescence (PL) spectra post-grinding is attributed to a reduced band gap, driven by factors such as extended π-conjugation length, enhanced planar intramolecular charge transfer (PICT) effect, strengthened π-π interactions and exciton coupling, as well as the increase in the orbitals overlap between neighboring molecular. Moreover, the presence or absence of tert-butyl substituents attaching to the 3- and 6-positions of the carbazole units significantly impacts the photophysical properties of these materials.

New phase-construction phosphors ceramics for warm-white solid-state lighting: Orange-yellow-emitting (Lu,Gd)3(Sc,Al)5O12: Ce3+

Phosphor-converted white light-emitting diodes (pc-wLEDs) and phosphor-converted white laser diodes (pc-wLDs) are extensively utilized in lighting applications, with their quality and reliability heavily dependent on color converters. Recent progress in all-inorganic color converters, particularly phosphor ceramics (PCs), have markedly enhanced performance. However, due to the difficulty of managing emissive components, achieving warm white light with substantial red emission still remains challenging. In this work, a series of pure-phase Ce3+-activated garnet-structured solid-solution PCs, (Lu,Gd)3(Sc,Al)5O12: Ce (LGSAG: Ce), were fabricated using vacuum sintering technology for the first time. Through systematic analysis, it can be revealed that the addition of Gd3+ leads to a red shift in emission through changes in crystal-field splitting, whereas the inclusion of Sc3+ primarily focuses on improving the microstructure of the developed PCs. Particularly, the pc-wLED constructed from typical LGSAG: Ce PC generated significantly warmer light with a correlated color temperature (CCT) of 2916 K, compared to the 9557 K from LuAG: Ce PC. Meanwhile, under 40.0 W (15.7 W/mm2) blue laser excitation, the maximum luminous flux and luminescence efficiency of one typical LGSAG: Ce PG are 1172 lm and 29.3 lm/W, respectively. Therefore, the developed LGSAG: Ce PCs can show notable potential as color converters for future high-power warm-white solid-state lighting applications.