Luminescence Properties Research Articles

A novel red-emitting InScW3O12:Eu3+ phosphor with anti-thermal-quenching performance for high-power WLED applications

A series of red-emitting InScW3O12:Eu3+ (ISWO:Eu3+) phosphors with anti-thermal-quenching performance were successfully synthesized by conventional solid-state reaction. The phase structure and luminescent properties of ISWO:Eu3+ were systematically studied. The photoluminescence excitation (PLE) spectrum showed that ISWO:Eu3+ phosphor can be effectively matched with commercial ultraviolet (UV), violet and blue light chips. The main emission peak of the phosphor was located at 613 nm, which was attributed to the electric dipole transition 5D0 → 7F2. Under the optimal excitation, the prepared ISWO:0.08Eu3+ phosphor showed excellent anti-thermal-quenching performance, its photoluminescence (PL) intensity at 180 °C reached 157.4 % of initial intensity at room temperature. At 465 nm excitation, it also exhibited the anti-thermal-quenching property and the PL intensity remained 115.1 % at 150 °C of that at room temperature. In situ XRD analysis revealed that the lattice contraction resulting in an increase in structural rigidity as the temperature rising, which caused the change of Eu3+ local environment and improved the PL intensity. Finally, a series of warm white LED devices under varying power density conditions with stable output were prepared using the red ISWO:0.08Eu3+ phosphor, indicating that the ISWO:Eu3+ phosphor with excellent anti-thermal-quenching performance has potential application prospects in high-power white light-emitting diodes (WLEDs).

Two new Mn-LMOF based on an AIEgens ligand for selective detection of Al3+ and other ions in aqueous solution

Two novel multifunctional chemical sensor Mn-LMOF, namely, [Mn2(TPPE)(ndc)2(H2O)]n (LMOF-1) and [Mn2(TPPE)(oba)2]n (LMOF-2) were solvothermally synthesized by introducing an AIE luminogens (AIEgens) ligand, 1,1,2,2-tetra[4-(pyridin-4-yl)phenyl]ethylene(TPPE), and analyzed by single crystal X-ray diffraction, thermogravimetric and powder X-ray diffraction and other methods. LMOF-1 and LMOF-2 have high stability and strong luminescence properties in solutions. The sensing experiments testify that LMOF-1 can be used as a selectively sensor for Al3+, with the limit of detection is 1.83 × 10−5 M. And LMOF-1 and LMOF-2 can identify Fe3+, CrO42− and Cr2O72− ions in aqueous solution, and LMOF-1 has a higher Ksv for all three ions than LMOF-2.

Luminescence Thermochromism of a Noncluster Copper Iodide Complex.

Hybrid copper(I) halide materials are currently attracting significant attention due to their exceptional luminescence properties, offering great potential for the development of multifunctional emissive materials with, in addition, eco-friendly features. A binuclear copper iodide complex, based on the [Cu2I2L4] motif with phosphite derivatives as ligands, has been synthesized and structurally characterized. Photophysical investigations indicate that this complex displays luminescence thermochromic properties, which are characterized by a temperature-dependent change in the relative intensity of two emission bands. The high-contrast luminescence thermochromism, with an important color variation from purple to cyan, is ascribed to the thermal equilibrium of two different excited states. While thermochromism is relatively known for multimetallic complexes, the perfectly controlled thermochromism of the studied compound is unprecedented for a binuclear complex. From theoretical investigations, this original feature is due to the coordination of phosphite ligands, which induces a specific energy layout of the complex, presenting vacant orbitals of varying nature. This single-component, dual-emissive binuclear complex, displaying relevant sensitivity temperature response, presents great potential for luminescence ratiometric thermometry applications. This study underlines the relevance of the ligand engineering strategy in developing original, emissive, and sustainable copper-based materials.

Creation of Excitation-Driven Hypervalent Tin(IV) Compounds For Aggregation-Induced Emission and Application to Thermoresponsive Luminescent Films Below Freezing Point.

Although many researchers have devoted their much effort to establish the strategy for developing a stimuli-responsive molecule and tuning of their properties according to the preprogrammed design, it is still challenging to create desired molecules from the scratch. We recently demonstrated that the molecules with a large structural difference between the theoretically optimized structures in the ground and excited states have a potential to exhibit stimuli-responsive luminescent properties. We defined these molecules as an excitation-driven molecule and have shown that they are a versatile platform for designing stimuli-responsive luminescent molecules. Herein, based on the concept of excitation-driven molecules, we show that the hypervalent tin-fused azomethine (TAm) compounds possessing aggregation-induced emission (AIE) properties can be obtained by simple chemical modification with a methyl group although conventional TAm derivatives are well known to be highly luminescent compounds in solution. Furthermore, by combining the solid-state luminescence property of AIE and the coordination number shifts of the hypervalent tin atom, the thermoresponsive films operating below the freezing point are fabricated with the polymer. In this study, we apply the concept of excitation-driven molecules to the hypervalent compounds and demonstrate to obtain the novel functional materials.

A Dual‐Purpose Non‐Canonical Amino Acid for the Expanded Genetic Code: Combining Metal‐Binding and Click Chemistry

AbstractA rationally designed dual‐purpose non‐canonical amino acid (Trz) has been synthesised and successfully incorporated into a protein scaffold by genetic code expansion. Trz contains a 5‐pyridyl‐1,2,4‐triazine system, which allows for inverse‐electron‐demand Diels–Alder (IEDDA) reactions to occur on the triazine ring and for metal ions to be chelated both before and after the click reaction. Trz was successfully incorporated into a protein scaffold and the IEDDA utility of Trz demonstrated through the site‐specific labelling of the purified protein with a bicyclononyne. Additionally, Trz was shown to successfully coordinate a cyclometallated iridium(III) centre, providing access to a bioorthogonal luminogenic probe. The luminescent properties of the Ir(III)‐bound protein blue‐shift upon IEDDA click reaction with bicyclononyne, providing a unique method for monitoring the extent and location of the labelling reaction. In summary, Trz is a new dual‐purpose non‐canonical amino acid with great potential for myriad bioapplications where metal‐based functionality is required, for example in imaging, catalysis, and photo‐dynamic therapy, in conjunction with a bioorthogonal reactive handle to impart additional functionalities, such as dual‐modality imaging or therapeutic payloads.

A Dual-Purpose Non-Canonical Amino Acid for the Expanded Genetic Code: Combining Metal-Binding and Click Chemistry.

A rationally designed dual-purpose non-canonical amino acid (Trz) has been synthesised and successfully incorporated into a protein scaffold by genetic code expansion. Trz contains a 5-pyridyl-1,2,4-triazine system, which allows for inverse-electron-demand Diels-Alder (IEDDA) reactions to occur on the triazine ring and for metal ions to be chelated both before and after the click reaction. Trz was successfully incorporated into a protein scaffold and the IEDDA utility of Trz demonstrated through the site-specific labelling of the purified protein with a bicyclononyne. Additionally, Trz was shown to successfully coordinate a cyclometallated iridium(III) centre, providing access to a bioorthogonal luminogenic probe. The luminescent properties of the Ir(III)-bound protein blue-shift upon IEDDA click reaction with bicyclononyne, providing a unique method for monitoring the extent and location of the labelling reaction. In summary, Trz is a new dual-purpose non-canonical amino acid with great potential for myriad bioapplications where metal-based functionality is required, for example in imaging, catalysis, and photo-dynamic therapy, in conjunction with a bioorthogonal reactive handle to impart additional functionalities, such as dual-modality imaging or therapeutic payloads.

Luminescent Radical Polymers.

Organic radicals are gaining significant interest in luminescent materials due to their unique properties, which present unprecedented opportunities for innovation across various fields, from display technology to biomedical applications. However, addressing challenges related to stability and low fluorescence efficiency is crucial to unlocking their full potential for practical applications. Polymerization has emerged as an effective strategy to enhance intra- and interchain through-space interactions, enabling the creation of stable luminescent radicals with excellent processing and multifunctional properties. This concept emphasizes the strategic use of polymerization in designing and synthesizing stable main-chain and side-chain radical polymers. This approach not only broadens the scope of stable radicals but also improves their luminescence properties as photofunctional materials.

Vacancy Effect on the Luminescent and Water Responsive Properties of Vacancy-Ordered Double Perovskite Derivatives.

Vacancy-ordered perovskites and derivatives represent an important subclass of hybrid metal halides with promise in applications including light emitting devices and photovoltaics. Understanding the vacancy-property relationship is crucial for designing related task-specific materials, yet research in this field remains sporadic. For the first time, we use the Connolly surface to quantitatively calculate the volume of vacancy (V□, □=vacancy) in vacancy-ordered double perovskite derivatives (VDPDs). A relationship between void fraction and the structure, photoluminescent properties and humidity stability was established based on zero-dimensional (0-D) [N(alkyl)4]2Sb□Cl5□'-type VDPDs. Compared with the more commonly studied A2M(IV)X6□-type double perovskite (A=cation, M=metal ion, X=halide), [N(alkyl)4]2Sb□Cl5□' features double vacancy sites. Our results demonstrate an inverse relationship between the photoluminescent quantum yield and V□ in 0-D VDPDs. Additionally, structural transformation from A2SbCl5 to A3Sb2Cl9 was first reported, during which the novel 'gate-opening' gas adsorption phenomenon was observed in VDPDs for the first time, as evidenced by 'S'-shaped sorption isotherms for water vapor, indicating a cation-controlled water-vapor response behavior. A mixed-cation strategy was developed to modulate the humidity stability of VDPDs. Characterized by controllable water-responsive behavior and unique 'on-off-on' luminescent switching, A2M(III)□X5□'-type materials show great promise for multi-level information anti-counterfeiting applications.

Vacancy Effect on the Luminescent and Water Responsive Properties of Vacancy‐Ordered Double Perovskite Derivatives

AbstractVacancy‐ordered perovskites and derivatives represent an important subclass of hybrid metal halides with promise in applications including light emitting devices and photovoltaics. Understanding the vacancy‐property relationship is crucial for designing related task‐specific materials, yet research in this field remains sporadic. For the first time, we use the Connolly surface to quantitatively calculate the volume of vacancy (V□, □=vacancy) in vacancy‐ordered double perovskite derivatives (VDPDs). A relationship between void fraction and the structure, photoluminescent properties and humidity stability was established based on zero‐dimensional (0‐D) [N(alkyl)4]2Sb□Cl5□′‐type VDPDs. Compared with the more commonly studied A2M(IV)X6□‐type double perovskite (A=cation, M=metal ion, X=halide), [N(alkyl)4]2Sb□Cl5□′ features double vacancy sites. Our results demonstrate an inverse relationship between the photoluminescent quantum yield and V□ in 0‐D VDPDs. Additionally, structural transformation from A2SbCl5 to A3Sb2Cl9 was first reported, during which the novel ‘gate‐opening’ gas adsorption phenomenon was observed in VDPDs for the first time, as evidenced by ‘S’‐shaped sorption isotherms for water vapor, indicating a cation‐controlled water‐vapor response behavior. A mixed‐cation strategy was developed to modulate the humidity stability of VDPDs. Characterized by controllable water‐responsive behavior and unique ‘on‐off‐on’ luminescent switching, A2M(III)□X5□′‐type materials show great promise for multi‐level information anti‐counterfeiting applications.

Enhancement of Circularly Polarized Luminescence Brightness of Schiff‐Base Diphenylboron and 9‐Borafluoren‐9‐yl Complexes

AbstractA series of diphenylboron and 9‐borafluoren‐9‐yl complexes with chiral Schiff‐base ligands was synthesized and characterized by NMR spectroscopy. X‐ray diffraction analysis revealed that their boron centers were adapted to tetrahedral coordination geometry. Although boron complexes with salicylideneimine backbones exhibited a weak circularly polarized luminescence (CPL), the CPL brightness (BCPL) was enhanced more than 9‐fold by the π‐extension of the Schiff base ligands. Time‐resolved emission decay analysis and theoretical calculations based on density functional theory (DFT) were conducted to further understand their luminescent properties.

Lantern-Shaped Structure Induced by Racemic Ligands in Red-Light-Emitting Metal Halide with Near 100 % Quantum Yield and Multiple-Stimulus Response.

Organic-inorganic metal halides (OIMHs) have become a research hotspot in recent years due to their excellent luminescent properties and tunable emission wavelengths. However, the development of efficient red-light-emitting OIMHs remains a significant challenge. This work reports three Mn-based OIMHs derived from 1-methyl-1,2,3,4-tetrahydroisoquinoline hydrobromide: racemic one (Rac-TBM) and chiral ones (R-TBM and S-TBM). As a result of the synergism of chiral organic ligands inducing a unique lantern-shaped hybrid structure containing both tetrahedra and octahedra, Rac-TBM exhibits red-light emission with near-unity luminescence quantum yield. In comparison, the chiral counterparts R/S-TBM display strong green emission and circularly polarized luminescence (CPL) with a glum value up to ±2.5×10-2. Interestingly, a mixture of R- and S-TBM can transform into Rac-TBM, successfully achieving a sensitive and reversible switch between red light of octahedra and green light of tetrahedra under external stimuli. The outstanding luminescent properties allow Rac-TBM to be utilized not only for X-ray radioluminescence with a detection limit down to 46.29 nGys-1, but also for advanced information encryption systems to achieve leak-proof decryption.

Lantern‐Shaped Structure Induced by Racemic Ligands in Red‐Light‐Emitting Metal Halide with Near 100 % Quantum Yield and Multiple‐Stimulus Response

AbstractOrganic‐inorganic metal halides (OIMHs) have become a research hotspot in recent years due to their excellent luminescent properties and tunable emission wavelengths. However, the development of efficient red‐light‐emitting OIMHs remains a significant challenge. This work reports three Mn‐based OIMHs derived from 1‐methyl‐1,2,3,4‐tetrahydroisoquinoline hydrobromide: racemic one (Rac‐TBM) and chiral ones (R‐TBM and S‐TBM). As a result of the synergism of chiral organic ligands inducing a unique lantern‐shaped hybrid structure containing both tetrahedra and octahedra, Rac‐TBM exhibits red‐light emission with near‐unity luminescence quantum yield. In comparison, the chiral counterparts R/S‐TBM display strong green emission and circularly polarized luminescence (CPL) with a glum value up to ±2.5×10−2. Interestingly, a mixture of R‐ and S‐TBM can transform into Rac‐TBM, successfully achieving a sensitive and reversible switch between red light of octahedra and green light of tetrahedra under external stimuli. The outstanding luminescent properties allow Rac‐TBM to be utilized not only for X‐ray radioluminescence with a detection limit down to 46.29 nGys−1, but also for advanced information encryption systems to achieve leak‐proof decryption.

Enhanced Quantum Efficiency via Co-substitution in Sr2[MgAl5N7]:Eu2+ for Spectroscopic Applications including Laser Displays with Ultra-high Luminescence Saturation Threshold.

A series of Sr2[Mg1-xLixAl5-xSixN7]:0.01Eu2+ (SMAN-xLS, 0≤x≤0.5) red phosphors were devised and synthesized via the high temperature solid state reaction and the effects of the co-substitution of [Mg-Al]5+ by [Li-Si]5+ on structural and luminescence properties is investigated. With the entry of [Li-Si]5+ into theSr2[MgAl5N7]:0.01Eu2+ (SMAN) lattice, the substitution of Al3+ by Si4+ shifts the emission peak from 657 nm to 647 nm and reduces the excitation in green region. When the amount of [Li-Si]5+ co-substitution is x=0.1, the luminescence intensity and thermal stability of the sample are enhanced, in which the external quantum efficiency is elevated by 49.6%. The increase in lattice rigidity gives rise to higher luminescence intensity, and the introduced trap levels for the compensation of luminescence enhances the thermal stability. Under blue laser excitation, the SMAN-0.1LS can achieve an ultra-high luminescence saturation threshold of 52.22W/mm2, which is a breakthrough performance that has enormous potential for application in high-power laser display light sources. By measuring the pressure-dependent luminescence of SMAN-0.1LS, the emission peak can be shifted from 650 nm to 702 nm with the increase of pressure, and the sensitivity dλ/dP is 5.07 nm/GPa, which is indicative of the potential application of this system as an optical pressure sensor.

Synthesis and Properties of a Red Na5Zn2Gd1−x(MoO4)6: xEu3+ Phosphor

Novel Eu3+-doped Na5Zn2Gd(MoO4)6 triple molybdate phosphors were fabricated by the sol-gel method. The structure, morphology, and luminescent properties have been characterized by X-ray diffraction (XRD), thermogravimetric differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), FTIR spectroscopy, and luminescence spectroscopy. The results indicated that the synthesized Na5Zn2Gd1−x(MoO4)6: xEu3+ phosphor consisted of a pure phase with monoclinic structure. Under excitation at 465 nm, the Na5Zn2Gd1−x(MoO4)6: xEu3+ phosphor exhibits an intensive red emission band around 610 nm corresponding to the transition of 5D0→7F2 which is much higher than that 5D0→7F1 at 594 nm, which was appropriate for a blue LED. According to the influence of the synthesis conditions, the phosphors showed the highest emission intensity when the doping concentration of Eu3+ was 25 mol.% and the molar ratio of citric acid to metal ions was 2:1. Na5Zn2Gd0.75(MoO4)6: 0.25 Eu3+ with the color coordinates (x = 0.658, y = 0.341) is a more stable red phosphor for blue-based white LEDs than the commercial Y2O2S: Eu3+ red phosphor (0.48, 0.50) due to its being closer to the NTSC standard values (0.670, 0.330).

Enhanced Quantum Efficiency via Co‐substitution in Sr2[MgAl5N7]:Eu2+ for Spectroscopic Applications including Laser Displays with Ultra‐high Luminescence Saturation Threshold

A series of Sr2[Mg1‐xLixAl5‐xSixN7]:0.01Eu2+ (SMAN‐xLS, 0≤x≤0.5) red phosphors were devised and synthesized via the high temperature solid state reaction and the effects of the co‐substitution of [Mg‐Al]5+ by [Li‐Si]5+ on structural and luminescence properties is investigated. With the entry of [Li‐Si]5+ into theSr2[MgAl5N7]:0.01Eu2+ (SMAN) lattice, the substitution of Al3+ by Si4+ shifts the emission peak from 657 nm to 647 nm and reduces the excitation in green region. When the amount of [Li‐Si]5+ co‐substitution is x=0.1, the luminescence intensity and thermal stability of the sample are enhanced, in which the external quantum efficiency is elevated by 49.6%. The increase in lattice rigidity gives rise to higher luminescence intensity, and the introduced trap levels for the compensation of luminescence enhances the thermal stability. Under blue laser excitation, the SMAN‐0.1LS can achieve an ultra‐high luminescence saturation threshold of 52.22W/mm2, which is a breakthrough performance that has enormous potential for application in high‐power laser display light sources. By measuring the pressure‐dependent luminescence of SMAN‐0.1LS, the emission peak can be shifted from 650 nm to 702 nm with the increase of pressure, and the sensitivity dλ/dP is 5.07 nm/GPa, which is indicative of the potential application of this system as an optical pressure sensor.

Synthesis, crystal structure, DNA studies, DFT calculation and luminescence properties of a new one dimensional copper(II) compound with 4,4′- trimethylenedipyridine and 2,2′-bipyridine

Synthesis, crystal structure, DNA studies, DFT calculation and luminescence properties of a new one dimensional copper(II) compound with 4,4′- trimethylenedipyridine and 2,2′-bipyridine

Influence of Chelants and Catalyst on Luminescence of CaAl<sub>2</sub>O<sub>4</sub>:Eu<sup>2+</sup> Phosphors for Optical Temperature Sensing Applications

This study synthesized CaAl2O4:Eu2+ blue phosphors using the sol-gel method. The effects of incorporating citric acid, poly (oxyethylene) (PEG), and HCl in the precursor on the luminescent properties of phosphors were investigated. No significant changes were observed in the photoluminescence (PL) spectra of the phosphors when different precursor solutions were used. However, the use of PEG and citric acid led to a noticeable decrease in the PL intensity. Notably, the use of HCl resulted in an increase in PL. In addition, upon heating the phosphors from room temperature to 110 °C, the PL spectrum remained unchanged, whereas the PL intensity decreased linearly with increasing temperature. This indicated the suitability of CaAl2O4:Eu2+ for optical temperature-sensing applications.

Impact of Pre-Silica-Coating on the Luminescence Properties of Silica-Coated Indium Phosphide Nanoparticles

This study examined the impact of silica-coating on the luminescence characteristics of indium phosphide (InP) nanoparticles. Silica-coated InP nanoparticles were prepared using three different techniques. The first method utilized tetraethoxysilane (TEOS) as the silica source, resulting in the encapsulation of multiple InP nanoparticles within silica spheres. This approach caused a red-shift in the luminescence peak wavelength of the InP colloidal solution post-TEOS coating, compared to the original InP colloidal solution. Conversely, the second method employed tetramethoxysilane (TMOS), resulting in the formation of irregularly shaped silica-coatings on multiple InP nanoparticles, which reduced the red-shift in the luminescence peak wavelength of the silica-coated InP colloidal solution. The third method involved pre-coating InP nanoparticles with TMOS, followed by thickening the silica shells using TEOS. This technique successfully encapsulated multiple InP nanoparticles within silica spheres, maintaining the luminescence peak wavelength of the InP colloid solution post-coating with TMOS and TEOS nearly identical to that of the original solution. This method merged the advantageous outcomes of the first two methods. Additionally, silica spheres containing InP nanoparticles synthesized using both TMOS and TEOS exhibited the highest luminescence intensity. In summary, this study introduces a novel approach in nanoparticle engineering, enhancing the functional properties of InP nanoparticles and expanding their potential applications in optoelectronic devices.

Aggregation-induced emissive copper nanoclusters with peroxidase-like activity for colorimetric detection of cholesterol

Accurate and point-of-care cholesterol detection is of paramount significance for the prevention of cardiovascular diseases. The colorimetric assay based on peroxidase is a commonly used approach for cholesterol detection, without requiring any complicated biomolecular labeling or sophisticated instrumentation. Copper nanoclusters (CuNCs), exhibiting luminescent properties and peroxidase activity, have garnered significant attention in biomedical application recently. Herein, the glutathione-stabilized copper nanoclusters (GSH-CuNCs) were prepared with an easy one-pot method, employing glutathione as both a reducing agent and stabilizer. An optimization of the GSH-CuNCs preparation was carried out to obtain the highest peroxidase-like activity. UV-Vis absorption was measured to explore the steady-state kinetics of the GSH-CuNCs-catalyzed oxidation of 3,3',5,5' - tetramethylbenzidine (TMB) by H2O2. A colorimetric method for cholesterol detection was developed by combining the catalytic reaction of CuNCs and the enzymatic oxidation of cholesterol with cholesterol oxidase (ChOx). Under the optimized conditions, the UV-Vis absorbance of oxidized TMB (oxTMB) is proportional to the concentration of cholesterol within the range of 6.2-187.5 μM, and the limit of detection (LOD) is determined to be 3.0 μM. More importantly, cholesterol levels can be directly distinguished with the naked eye. Furthermore, the practicality of the method for detecting cholesterol in human serum has been verified with promising results. As expected, this simple, cost-effective, and easy-to-operate colorimetric method for cholesterol detection has potential applications in clinical diagnosis and provides valuable insights into the colorimetric sensing based on CuNCs.

Benchmarking luminescent properties of the arylvinylpyrimidine scaffold.

The exploration of the photophysical properties of push-pull molecules incorporating pyrimidine rings as electron-attracting moieties in their structure continues to be a fascinating area of investigation. A thorough examination of these properties not only contributes to fundamental knowledge but also provides crucial insights for the rational design of emissive materials in prospective applications. In this context, this work conducts an in-depth analysis of four families of 4,6-bis(arylvinyl)pyrimidines, evaluating the influence of substituents on both the aryl groups and position 2 of the pyrimidine ring. While previous research has primarily focused on solution studies, this work emphasizes the importance of examining solid-state photophysics. Through a multidisciplinary approach encompassing optical techniques, x-ray diffraction, and quantum chemical calculations, a comprehensive understanding of the structure-property relationships is achieved. This study underscores the intricate interplay between molecular structure, aggregation, and fluorescence behavior in pyrimidines, offering valuable insights with broader implications beyond academic realms.