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To address the problem of cyan-green light deficiency in fluorescent converters for laser diode (LD) illumination applications, Ca 3-x Sc 2 Si 3 O 12 :xCe3+ (CSS:xCe3+) cyan-green fluorescent ceramics and CSS:Ce3+ phosphor in glass (CSS:Ce3+-PiG) fluorescent converter were successfully prepared. Among them, the CSS:0.08Ce3+ cyan-green fluorescent ceramic and 20 wt% CSS:Ce3+-PiG fluorescent converter had the highest luminescence intensity. At 450 nm excitation, the emission spectra of both materials showed an asymmetric broadband band between 470 nm and 690 nm. And the two fluorescent converters are not appear of luminescence temperature quenching until more than 538 K. The performance of the white LDs synthesized with ceramic and PiG converters was investigated. Under different power excitation, the green emission intensity of both wLD is enhanced with increased incident laser power. The wLDs based on CSS:Ce3+ fluorescent ceramics have a luminous flux of 880 l m and the maximum luminescence efficiency of 176 l m/W at an incident power of 5 W. And the wLDs of PiG fluorescent converters have a maximum luminous flux of 584 l m and luminescence efficiencies of up to 117 l m/W. CSS:Ce3+ ceramics and CSS:Ce3+-PiG are green fluorescent converter with good luminescence performance and thermal stability. It will play an important role in the compensation of the cyan light in LD illumination. [ABSTRACT FROM AUTHOR]

Aluminum garnets display exceptional adaptability in incorporating mismatching elements, thereby facilitating the synthesis of novel materials with tailored properties. This study explored Ce3+-doped Tb3Al5−xScxO12 crystals (where x ranges from 0.5 to 3.0), revealing a novel approach to control luminescence and photoconversion through atomic size mismatch engineering. Raman spectroscopy confirmed the coexistence of garnet and perovskite phases, with Sc substitution significantly influencing the garnet lattice and induced A1g mode softening up to Sc concentration x = 2.0. The Sc atoms controlled sub-eutectic inclusion formation, creating efficient light scattering centers and unveiling a compositional threshold for octahedral site saturation. This modulation enabled the control of energy transfer dynamics between Ce3+ and Tb3+ ions, enhancing luminescence and mitigating quenching. The Sc admixing process regulated luminous efficacy (LE), color rendering index (CRI), and correlated color temperature (CCT), with adjustments in CRI from 68 to 84 and CCT from 3545 K to 12,958 K. The Ce3+-doped Tb3Al5−xScxO12 crystal (where x = 2.0) achieved the highest LE of 114.6 lm/W and emitted light at a CCT of 4942 K, similar to daylight white. This approach enables the design and development of functional materials with tailored optical properties applicable to lighting technology, persistent phosphors, scintillators, and storage phosphors. [ABSTRACT FROM AUTHOR]

In recent times, there has been significant interest in Mn4+-activated red phosphors in double perovskite oxide materials. However, the practical use of these materials is hindered by concerns related to their thermal and humidity stability. In this research, we have synthesized deep red-emitting phosphors with the composition La 2 LiNb (1- x) O 6 : x Mn4+ using a conventional high-temperature solid-phase method. The microstructures and luminescence properties of these phosphors have been thoroughly investigated. All the samples consist of irregular microcrystals with an average size ranging from 3 to 7 μm, and they exhibit excellent phase purity and crystallinity. Under excitation by 335 nm ultraviolet light, the La 2 LiNb (1- x) O 6 : x Mn4+ phosphors emit a narrow and sharp red band (centered at ∼710 nm), and the emission intensity initially increases and then decreases with increasing Mn4+-doping concentration, peaking at x = 0.5%. The La 2 LiNb 0.995 O 6 : 0.5%Mn4+ phosphor exhibits exceptional thermal stability, with a normalized emission intensity of 66.24% maintained at 150 °C. More importantly, the La 2 LiNb 0.995 O 6 :0.5%Mn4+ phosphor exhibits excellent humidity stability and can maintain more than 90% of its initial emission intensity after immersion in deionized water for 24 h. The La 2 LiNb 0.995 O 6 : 0.5%Mn4+ phosphor demonstrates an impressive resistance to humidity-induced luminescence quenching. It maintains a significantly higher far-red emission intensity at relative humidities exceeding 65%. These newly developed La 2 LiNb (1- x) O 6 : x Mn4+ phosphors hold great potential as red phosphors for high-power plant growth LEDs in extended outdoor, high-humidity conditions. [ABSTRACT FROM AUTHOR]

X-ray luminescent nanoparticles have gained significant attention as promising tools for implementing multimodal imaging and radiation-based treatments in theragnostics. The intricate comprehension of their properties and the underlying mechanisms driving the conversion of X-rays into light is critical for their success in various applications. LaPO 4 nanoparticles doped with various individual luminescence centers, gadolinium (Gd3+), europium (Eu3+), dysprosium (Dy3+), and terbium (Tb3+), were produced via co-precipitation and investigated for their behavior upon X-ray excitation using energies of up to 225 kV. These materials evidenced a radioluminescent response dependent on the dopant concentrations, with emission lines from 300 to 700 nm, providing insights into the luminescence quenching effect in these structures. The luminescent characteristics of the nanoparticles were studied under continuous irradiation, evidencing the materials' ability to withstand high absorbed doses and preserve their properties. Furthermore, the influence of dopant concentrations on crystallite size and the dependence of luminescence on thermal treatments was investigated. The assessment of nanoparticle stability in aqueous suspension was evaluated over a broad pH range, revealing a tendency of the LaPO 4 surface to selectively interact with electropositive species. This insight enhances our comprehension of the colloidal stability of the material, positioning it for extended applications and in vitro evaluations, along with further surface functionalization. [ABSTRACT FROM AUTHOR]

Different concentrations of B2O3 in zinc–aluminum–sodium–phosphate (ZANP) glasses were synthesized by the conventional melt-quenching method and analyzed using X-ray diffraction (XRD), optical absorption, excitation, visible luminescence, decay lifetime, and chromaticity methods. The amorphous nature of the glasses was confirmed by the absence of sharp diffraction peaks in the XRD profile. In the visible emission spectra blue, yellow, and red bands were observed and the intensity of the yellow band was superior. Furthermore, the samples show a luminescence quenching beyond 20 mol.% of B2O3 concentration. The decay lifetime of 4F9/2 of Dy3+ ions was found to be maximal in ZANP Dy0.5:20B2O3 glass. [ABSTRACT FROM AUTHOR]

Phosphor-converted white light emitting diodes (pc-WLEDs) as a new green lighting source have attracted considerable attention around the world. Single-component white light emitters are particularly attractive for fabricating economical solid-state devices for display and lighting. However, the emission loss of phosphors caused by thermal quenching is one of the important factors limiting its application. Herein, a series of single-phase Li 3 Ba 2 Y 3 (WO 4) 8 :Dy3+,Tm3+ phosphors were synthesized by solid state reaction. The crystal structure, electronic structure, morphology, temperature dependent photoluminescence and decay lifetimes were systematically studied by experimental and theoretical calculations. Under the UV excitation, the phosphor could easily emit yellow, blue and white light by simply tuning the ratio of Dy3+ to Tm3+ ions. Notably, the obtained phosphors showed an anti-thermal quenching at 422 K, and the luminous intensity remained 93.09 % of that at room temperature even up to 472 K. Moreover, the CIE chromaticity coordinates hardly changed with the increase of temperature. Ultimately, by combining the phosphor with a 365 nm NUV chip, a high-performance pc-WLED device with a correlation color temperature of 4333 K and CIE coordinates of (0.328,0.396) was successfully realized. This work indicates that the designed single-phase Li 3 Ba 2 Y 3 (WO 4) 8 :Dy3+,Tm3+ may be potential candidates for efficient single-phased white emission in pc-WLED lighting applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Currently, the unique 5D 4 energy level of terbium (Tb3+) can contribute to narrow-band green light emission, which has high application prospects. However, due to its poor thermal stability at high temperatures, how to enhance the antithermal-quenching properties of Tb-doped phosphors has become a research difficulty in the field of solid-state lighting and temperature sensing. In this contribution, the antithermal-quenching green-emitting of terbium was achieved by Nb/Ta substitution to form GdNb 1-x Ta x O 4 :Tb3+ phosphors with various components. Photoluminescence analyses reveal an increasing trend in both the optical band gap and the intervalence charge transfer (IVCT) energy level positions with substitution. Variable-temperature spectrums observed that the phosphors under different compositions presented a large discrepancy in thermal quenching performance. It is elucidated that the elevated position of the IVCT energy level (IVCT-EL) predominantly influences thermal quenching, bolstering its role as a compensatory luminescence channel of 5D 3 →5D 4 far more than functioning as a quenching luminescence channel for Tb3+5D 3 /5D 4. Delving into the perspective of IVCT-EL positioning unveils the intrinsic mechanism through which IVCT-EL positions modulate the thermal quenching properties of phosphors with varying compositions due to the substitution of Ta for Nb. This insight facilitates the realization of enhanced thermal quenching resistance in phosphors. Furthermore, the antithermal-quenching property of Tb3+ in single-phase phosphors can be effectively modulated by excitation at different wavelengths. This tuning scheme not only advances the exploration of terbium-doped antithermal-quenching phosphors but also provides a novel strategy and reference for designing green-emitting phosphors in the fields of lighting and sensing. [Display omitted] [ABSTRACT FROM AUTHOR]

Fluoroborates have garnered significant research interest due to their intricate structure and unique nonlinear optical properties. In this work, pure and Eu-activated Ba 5 B 4 O 10 F 2 were prepared via the high-temperature solid-state ceramic method. Ba 5 B 4 O 10 F 2 is a wide band semiconductor (E g = 4.51 eV) with an indirect transition characteristic. The optical absorption, photoluminescence, and dynamic spectra of Eu2+/3+ activators were investigated. Luminescence intensities of Eu2+ and Eu3+ had distinctly different responses to doping content. The residual Eu3+ centers in Ba 5-5 x Eu 5 x B 4 O 10 F 2 (x > 0.03) cannot be avoided even it was sintered in a reducing atmosphere. Time-resolved spectra and decay curves also confirm the presence of Eu3+ with Eu2+. Under near-UV light excitation, a strong emission band from the 5d→4f transition of Eu2+ was detected overlapping with sharp peaks from (5D 0 →7F 0,1,2,3,4) of Eu3+ in Ba 5-5 x Eu 5 x B 4 O 10 F 2 (x > 0.03). As the Eu-doping level increases, the intensity ratio of Eu2+ and Eu3+ changes regularly, and the luminescent intensity of Eu3+ obviously and systematically becomes stronger. As the temperature changes from 25 °C to 150 °C, the luminescent intensity of Eu3+ increases, while that of Eu2+ gradually decreases. The results confirm the energy transfer (ET) from Eu2+ to Eu3+ in Ba 5 B 4 O 10 F 2. Eu3+ can act as killers, leading to the luminescence quenching of Eu2+ activators. The heterovalent substitution of Eu and NaF in Ba 5 B 4 O 10 F 2 not only reduces the content of Eu3+ but also significantly enhances the efficiency of Eu2+. The experiments demonstrate that to improve the luminescence efficiency of Eu2+, it is important to focus on reducing the residual Eu3+ in the lattice through enhancing the reduction from Eu3+ to Eu2+. [ABSTRACT FROM AUTHOR]

Combination of affordable organic dyes of high quantum yield with silicon can be an interesting way for development of highly efficient thin film photovoltaic cells utilizing silicon sensitisation. This work is focused on investigating the energy transfer processes including photon tunnelling from photosensitive molecules of BASF R305 high quantum yield dye to silicon substrate. Energy transfer from dye molecules to silicon substrate is evaluated by measuring the quenching of molecular photoluminescence lifetime using time-correlated single photon counting (TCSPC) technique. Energy transfer is further studied in dependence on dye layer thickness. The results can be useful for further studies leading to design of ultrathin silicon solar cells. [ABSTRACT FROM AUTHOR]

The novel red-emitting phosphors Ba 3 Lu 1– x Eu x B 9 O 18 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.85) belonging to the Ba 3 REE B 9 O 18 (REE – Y, Pr–Lu) family were successfully obtained by a multistep solid-phase synthesis. X-ray diffraction experiments revealed no phase transitions caused by the Eu3+ → Lu3+ isomorphic substitution in this series of solid solutions. An increase in the Eu3+ content leads to an expectable increase of hexagonal unit cell parameters and volume. Optical properties of the Ba 3 Lu 1– x Eu x B 9 O 18 (x = 0–0.85) phosphors were investigated. The highest emission intensity was demonstrated by Ba 3 Lu 0.6 Eu 0.4 B 9 O 18. The concentration quenching of luminescence was revealed for the x (Eu3+) > 0.4 samples. Concentration quenching, quantum yield and structural data were compared between three red-emitting Ba–Lu borates-phosphors (BLBO:Eu3+) containing independent crystallographic sites for the REE ions (n = 1–3) in crystal structure. It was revealed that the higher the number of nonequivalent cationic REE sites suitable for the Eu3+ → Lu3+ substitution, the higher the quantum yield taking into account practically equal amount of an optimal concentration of the activator-ion. Such an observation could be useful for a crystal chemical design of novel phosphors. [Display omitted] • Novel red-emitting phosphors Ba 3 LuB 9 O 18 :Eu3+ are synthesized. • Optical properties of the phosphors are studied. • Luminescence and structural data of three Ba–Lu borates-phosphors are compared. • Dependence of quantum yield on number of nonequivalent REE cationic sites is discussed. [ABSTRACT FROM AUTHOR]

So far, overcoming thermal quenching remains a huge challenge in the application of phosphor materials. The intervalence charge transfer (IVCT) state has an inestimable role in the compensation of antithermal-quenching effects and is widely used in the research of applications in optical temperature sensing, yet little study has been reported on its modulation of thermal quenching properties. In this contribution, the thermal quenching properties of praseodymium-activated solid-solution substituted GdNb 1-x Ta x O 4 phosphors were investigated systematically for the inaugural time from the perspective of IVCT energy level positions. According to the empirical formula, the IVCT level positions in the phosphor increase sequentially from 32960.71 cm−1 to 33442.15 cm−1, the DFT calculates the extension of the substrate band gap from 3.6408 eV to 4.3066 eV, and the contributing energy level of the conduction band is determined. The variation in the position of the IVCT energy level explains the alteration of the luminescence intensity at room temperature for different composition phosphor 3P 0 and 1D 2 energy levels. More particularly, it was analyzed that in the variable temperature spectra, x = 0–0.75 exhibited different degrees of efficient antithermal-quenching properties at 303–523 K, while no antithermal-quenching was presented at x = 1. By analyzing the IVCT energy level position and other influencing factors such as band gap, the feasibility of the IVCT energy level position as a competing model for the compensation and quenching channels is established, and the internal mechanism of regulating thermal quenching property is revealed. Effective control of the phosphor resistance to thermal quenching performance was achieved, which directly determines whether enhanced or diminished thermal quenching can be obtained. This finding provides a new effective strategy for the tuning of thermal quenching luminescence of Pr3+-doped Nb/Ta system phosphors. [Display omitted] [ABSTRACT FROM AUTHOR]

So far, overcoming thermal quenching remains a huge challenge in the application of phosphor materials. The intervalence charge transfer (IVCT) state has an inestimable role in the compensation of antithermal-quenching effects and is widely used in the research of applications in optical temperature sensing, yet little study has been reported on its modulation of thermal quenching properties. In this contribution, the thermal quenching properties of praseodymium-activated solid-solution substituted GdNb 1-x Ta x O 4 phosphors were investigated systematically for the inaugural time from the perspective of IVCT energy level positions. According to the empirical formula, the IVCT level positions in the phosphor increase sequentially from 32960.71 cm−1 to 33442.15 cm−1, the DFT calculates the extension of the substrate band gap from 3.6408 eV to 4.3066 eV, and the contributing energy level of the conduction band is determined. The variation in the position of the IVCT energy level explains the alteration of the luminescence intensity at room temperature for different composition phosphor 3P 0 and 1D 2 energy levels. More particularly, it was analyzed that in the variable temperature spectra, x = 0–0.75 exhibited different degrees of efficient antithermal-quenching properties at 303–523 K, while no antithermal-quenching was presented at x = 1. By analyzing the IVCT energy level position and other influencing factors such as band gap, the feasibility of the IVCT energy level position as a competing model for the compensation and quenching channels is established, and the internal mechanism of regulating thermal quenching property is revealed. Effective control of the phosphor resistance to thermal quenching performance was achieved, which directly determines whether enhanced or diminished thermal quenching can be obtained. This finding provides a new effective strategy for the tuning of thermal quenching luminescence of Pr3+-doped Nb/Ta system phosphors. [Display omitted] [ABSTRACT FROM AUTHOR]

Novel and high-security anti-counterfeiting technology has always been the focus of attention and research. This work proposes a nanocomposite combination of upconversion nanoparticles (UCNPs) and perovskite quantum dots (PeQDs) to achieve color-adjustable dual-mode luminescence anti-counterfeiting. Firstly, a series of NaGdF4: Yb/Tm UCNPs with different sizes were synthesized, and their thermal-enhanced upconversion luminescence performances were investigated. The upconversion luminescence (UCL) intensity of the samples increases with rising temperature, and the UCL thermal enhancement factor rises as the particle size decreases. This intriguing thermal enhancement phenomenon can be attributed to the mitigation of surface luminescence quenching. Furthermore, CsPbBr3 PeQDs were well adhered to the surfaces and surroundings of the UCNPs. Leveraging energy transfer and the contrasting temperature responses of UCNPs and PeQDs, this nanocomposite was utilized as a dual-mode thermochromic anti-counterfeiting system. As the temperature increases, the color of the composite changes from green to pink under 980 nm excitation, while it displays green to non-luminescence under 365 nm excitation. This new anti-counterfeiting material, with its high security and convenience, has great potential in anti-counterfeiting applications. [ABSTRACT FROM AUTHOR]

In this paper, Fe 3 O 4 /α-Fe 2 O 3 /Y 2 O 3 :Eu3+ multifunctional nanocomposites were synthesized using a hydrothermal method. Fe 3 O 4 /α-Fe 2 O 3 /Y 2 O 3 :Eu3+ nanocomposites are core-shell nanostructures consisting of a superparamagnetic nanomagnetite core, which is converted to hematite during the synthesis. As a theranostic material, hematite could be used in drug-release processes, while nanomagnetite generates heat in a hyperthermia cancer treatment. An outer shell of Y 2 O 3 :Eu3+ nanophosphor is added to give nanocomposites photoluminescent properties and to render them visible in bioimaging. Structural, optical, and magnetic features of nanocompositesare studied using X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FTIR), Raman, photoluminescence (PL), vibrating-sample magnetometer (VSM), and high-resolution transmission electron microscope (HRTEM) techniques. Photoluminescence properties of nanocomposites show a quenching effect related to the proportion of magnetite and Y 2 O 3 :Eu3+. A luminescence quenching mechanism is proposed based on the optical effects of a core-shell structure. Magnetic saturation grows proportionally with the amount of magnetite present, which indicates that Fe 3 O 4 magnetic structure is not altered, even by the hematite that forms around it. The synthesized nanocomposites possess a core-shell morphology modified by the different proportions of their components. The optical, structural, and magnetic nanocomposite properties found will be of interest in theranostic materials research in the biomedical field. [ABSTRACT FROM AUTHOR]

Two Al-MOFs, i.e., MIL-53 (Al) and (NH2)-MIL-53 (Al) have been synthesized using aluminium nitrate as metal ligands and 1,4 benzene dicarboxylic acid, amino 1,4 benzene dicarboxylic acid as organic linkers in aqueous medium at room temperature, respectively. Both Al-MOFs have been confirmed through different microscopy and spectroscopy tools. Afterwards, the optical properties of Al-MOFs have been confirmed in polar and non-polar solvents using photoluminescence spectroscopy. Finally, both Al-MOFs have been explored for optical nitrobenzene (NB) sensing. Interestingly, we have found excellent optical ability of NH2-MIL-53 (Al) over MIL-53 (Al) due to structural π–π* transitions. The photo-induced electron transfer mechanism has been found during the MOF–analyte interaction. Importantly, we confirmed that NH2-MIL-53 (Al) is an excellent sensing material for NB with a 0.28 ppb limit of detection over MIL-53 (Al). [ABSTRACT FROM AUTHOR]

The effect of modifying the composition of a glass matrix based on the Ga2S3-GeS2:Pr3+ system due to the addition of La2S3 on the structure and the optical and luminescent properties of these glasses has been studied. It has been shown that the addition of La2S3 leads to changes in the nearest structural environment of Ga, Ge, and S and increases the degree of ionicity of the bonds of the Pr3+ ion. Despite the existence of a large glass formation region in the Ga2S3-GeS2-La2S3 system and the structural and chemical similarity of La and Pr, La2S3 does not promote a more uniform distribution of Pr3+ ions in the glass matrix, and thus does not reduce the concentration quenching of the luminescence of Pr3+ ions. However, the addition of La2S3 increases the probability of emission of Pr3+ ions and decreases the radiative lifetime. Additionally, it was shown that, when studying the structure and luminescent properties of glasses with La, it is necessary to take into account a significant concentration of rare earth traces (Pr and Nd). [ABSTRACT FROM AUTHOR]

Structural and thermal stability are two essential conditions in phosphor research, which are related to the structure of the host and the position of 4T 2 energy lever in Mn4+-activated phosphors. Here, Mn4+-activated CaGdAlO 4 phosphor with superior structural stability was synthesized through systematically screening the aluminate family of ABAlO 4 (A = Mg, Ca, Sr, Ba; B Sc, Lu, Y, Gd, La). Sr2+ was subsequently introduced to modulate the 4T 2 state level of Mn4+ for achieving better thermal stability in CaGdAlO 4 :Sr2+,Mn4+ phosphor. The luminescence quenching temperature T 1/2 show a parabolic trend with the increasing of Sr2+ dopant in Ca 1-y GdAlO 4 :ySr2+, Mn4+ phosphors, and change from 403 K to 426 K and 387 K in CaGdAlO 4 :Mn4+, Ca 0.4 GdAlO 4 :0.6Sr2+,Mn4+ and SrGdAlO 4 :Mn4+ three samples, respectively. The corresponding crystal-field calculations confirm that a certain amount of Sr2+ doping can improve the 4T 2 state of Mn4+ and obtain better thermal stability in the phosphor. All the samples have deep-red emission located at 712 nm, which matches well with the absorption spectra of green vegetables. This deep-red light accelerate morphological formation and increase vegetable biomass. This work is expected to stimulate more exploration of Mn4+-doped oxide phosphors with better structural and thermal stability for emerging applications of agricultural lighting. [ABSTRACT FROM AUTHOR]

Complexes of lanthanide ions, such as Eu(III) (red light emission) and Tb(III) (green light emission), with proper ligands can be highly luminescent and color-tunable, also attaining yellow and orange emission under UV radiation. The ligands employed in this work were poly(sodium acrylate), working as polymeric matrix, and 1,10-phenanthroline, taking advantage of its antenna effect. Possibilities of color display were further enhanced by incorporating a cationic polyfluorene with blue emission. This strategy allowed for obtaining cyan and magenta, besides the aforementioned colors. Uncoated cellulose paper was impregnated with the resulting luminescent inks, observing a strong hypsochromic shift in excitation wavelength upon drying. Hence, while a cheap UV-A lamp sufficed to reveal the polyfluorene's blue emission, shorter wavelengths were necessary to visualize the emission due to lanthanide ions as well. The capacity to reveal, with UV-C radiation, a full-color image that remains invisible under natural light is undoubtedly useful for anti-counterfeiting applications. Furthermore, both lanthanide ion complexes and polyfluorenes were shown to have their luminescence quenched by Cu(II) ions and nitroarenes, respectively. [ABSTRACT FROM AUTHOR]

Thermal quenching (TQ) that weakens luminescent intensity is crucial for the application value of a phosphor. Here, we report a series of color-tunable phosphors Na 2 MgAl 10 O 17 : x Eu2+ (NMA: x Eu2+) from green to cyan. For optimized Eu2+ concentration of x = 0.15, its internal and external quantum efficiency can reach up to 86% and 43%, respectively. In addition, it is unexpected that NMA:0.15Eu2+ exhibits anti-temperature quenching (TQ) luminescence even up to 300 °C, which is due to the ability of the defect energy levels to counteract the usual loss of emission by TQ through EPR and TL spectral analysis. Then, a prototype w-LED lamp by using NMA:0.15Eu2+ cyan phosphor, CaAlSiN 3 :Eu2+ red phosphor, and 380 nm LED chip is fabricated. This work not only reports a new phosphor with high efficiency and good thermal stability of luminescence, but also brings forward a defect engineering approach for enhancing the thermal quenching resistance of a phosphor. [Display omitted] [ABSTRACT FROM AUTHOR]

Photoluminescence from the surface of Nafion polymer membrane upon swelling in water under irradiation by electromagnetic waves at a frequency of 100 MHz was studied. In these experiments, natural deionized (DI) water with a deuterium content of 157 ppm and deuterium-depleted water (DDW, deuterium content is 1 ppm) were explored. We have studied for the first time the effect of linearly and randomly polarized low-frequency electromagnetic radiation on the luminescence excitation. To obtain low-frequency electromagnetic radiation with random polarizations, anisotropic solid submicron-sized particles, which result in depolarization effects upon scattering of the initially linearly polarized radiation, were used. We compared two types of colloidal particles: spherically symmetric (isotropic) and elongated (anisotropic). If the radiation is linearly polarized, the intensity of luminescence from the Nafion surface decreases exponentially as the polymer is soaked, and such a behavior is observed both in natural DI water and DDW. When spherically symmetric submicron-sized particles are added to a liquid sample, the luminescence intensity also decreases exponentially upon swelling in both natural DI water and DDW. At the same time, when anisotropic submicron-sized particles are added to DI water, random jumps in the luminescence intensity appear during swelling. At the same time, the exponential decrease in the luminescence intensity is retained upon swelling in DDW. A qualitative theoretical model for the occurrence of random jumps in the luminescence intensity is presented. [ABSTRACT FROM AUTHOR]

A novel fluorescent probe (C460@Tb-MOFs) was designed and synthesized by encapsulating the fluorescent dye 7-diethylamino-4-methyl coumarin (C460) into a terbium-based metal–organic framework using a simple ultrasonic impregnation method. It is impressive that this dye-modified metal–organic framework can specifically detect styrene and temperature upon luminescence quenching. The sensing platform of this material exhibits great selectivity, fast response, and good cyclability toward styrene detection. It is worth mentioning that the sensing process undergoes a distinct color change from blue to colorless, providing conditions for the accurate visual detection of styrene liquid and gas. The significant fluorescence quenching mechanism of styrene toward C460@Tb-MOFs is explored in detail. Moreover, the dye-modified metal–organic framework can also achieve temperature sensing from 298 to 498 K with high relative sensitivity at 498 K. The preparation of functionalized MOF composites with fluorescent dyes provides an effective strategy for the construction of sensors for multifunctional applications. [ABSTRACT FROM AUTHOR]

Quantum dot light-emitting diodes (QLEDs) are considered as the ideal candidate for next-generation displays, solid-state lighting, and optical communication applications. Although the efficiency of QLEDs has been significantly improved to the level comparable to that of organic light-emitting diodes in recent years, simultaneously achieving high efficiency and high brightness still remains challenging for QLEDs. In this work, we report a facile and effective electron-transport-layer interface control strategy of incorporating 3-aminopropyl triethoxysilane (APTES) into a ZnO nanocrystal-solution to enhance charge injection balance and suppress interfacial exciton quenching via in-situ formation of ZnO/organic silica (hereinafter referred to as ZnO/SiO 2) quasi core/shell nanoparticles in the solution, enabling red QLEDs to exhibit a maximum luminance intensity of 261,700 cd m−2, a peak external quantum efficiency (EQE) of 19.0%, and low efficiency roll-off at high luminance (an EQE up to 16.8% remained at a brightness of 200, 000 cd m−2). Our results demonstrate that substituting quasi core/shell-structured ZnO/SiO 2 nanoparticles for traditional ZnO nanocrystals as electron transport materials is a simple and effective means of fabricating QLEDs with both high efficiency and high luminance, which is expected to facilitate the development of QLED technology toward practical applications in lighting, displays and optical communication. [ABSTRACT FROM AUTHOR]

Gd3+ and Sm3+ co-activation, the effect of cation substitutions and the creation of cation vacancies in the scheelite-type framework are investigated as factors influencing luminescence properties. AgxGd((2−x)/3)−0.3−ySmyEu3+0.3☐(1−2x)/3WO4 (x = 0.50, 0.286, 0.20; y = 0.01, 0.02, 0.03, 0.3) scheelite-type phases (AxGSyE) have been synthesized by a solid-state method. A powder X-ray diffraction study of AxGSyE (x = 0.286, 0.2; y = 0.01, 0.02, 0.03) shows that the crystal structures have an incommensurately modulated character similar to other cation-deficient scheelite-related phases. Luminescence properties have been evaluated under near-ultraviolet (n–UV) light. The photoluminescence excitation spectra of AxGSyE demonstrate the strongest absorption at 395 nm, which matches well with commercially available UV-emitting GaN-based LED chips. Gd3+ and Sm3+ co-activation leads to a notable decreasing intensity of the charge transfer band in comparison with Gd3+ single-doped phases. The main absorption is the 7F0 → 5L6 transition of Eu3+ at 395 nm and the 6H5/2 → 4F7/2 transition of Sm3+ at 405 nm. The photoluminescence emission spectra of all the samples indicate intense red emission due to the 5D0 → 7F2 transition of Eu3+. The intensity of the 5D0 → 7F2 emission increases from ~2 times (x = 0.2, y = 0.01 and x = 0.286, y = 0.02) to ~4 times (x = 0.5, y = 0.01) in the Gd3+ and Sm3+ co-doped samples. The integral emission intensity of Ag0.20Gd0.29Sm0.01Eu0.30WO4 in the red visible spectral range (the 5D0 → 7F2 transition) is higher by ~20% than that of the commercially used red phosphor of Gd2O2S:Eu3+. A thermal quenching study of the luminescence of the Eu3+ emission reveals the influence of the structure of compounds and the Sm3+ concentration on the temperature dependence and behavior of the synthesized crystals. Ag0.286Gd0.252Sm0.02Eu0.30WO4 and Ag0.20Gd0.29Sm0.01Eu0.30WO4, with the incommensurately modulated (3 + 1)D monoclinic structure, are very attractive as near-UV converting phosphors applied as red-emitting phosphors for LEDs. [ABSTRACT FROM AUTHOR]

GdAl 3 (BO 3) 4 :Dy3+, Sm3+, Eu3+, and Tb3+ samples were successfully achieved via a sol-gel combustion method. The observed XRD analysis confirms the formation of the desired GAB host, indicating rhombohedral structures that agree well with JPCD card number 72–1985. The FTIR analyses show the detection of B − O stretching and B − O − B bending modes as well as Al − O and Gd − O bonds in the phosphor samples. Energy dispersive spectroscopy (EDS) analysis reveals that Sm, Eu, Dy, and Tb have been successfully doped into GdAl 3 (BO 3) 4. The observed broad intrinsic luminescence band can be caused by oxygen-induced luminescence defects in the GAB host with hydrous precursors. The luminescence properties of rare earth ion-doped GdAl 3 (BO 3) 4 samples are analysed by photoluminescence spectra, showing their optimal doping concentrations and critical distances of Dy3+, Eu3+, Sm3+ and Tb3+ are 2 wt% − 25.8 Å, 7 wt% − 17 Å, 1 wt% − 32.59 Å, and 7 wt% − 17.03 Å. Additionally, the energy transfer mechanism for luminescence quenching was determined as dipole-dipole (for Dy3+, Eu3+, and Tb3+) or dipole-quadrupole (for Sm3+) and the cross-relaxation process. GdAl 3 (BO 3) 4 samples obtained by doping with different RE3+ ions exhibit intense light emissions with different colors originating from different RE3+ ions under 349 nm excitation. When doped with different concentrations of RE3+ ions, the luminescence properties of the samples changed. The synthesized luminescence materials have potential applications in lighting and display technologies. [ABSTRACT FROM AUTHOR]

Nitrogen-doped carbon nanodots (CNDs) were synthesized and utilized as sensing probes to detect different anions and metallic ions within aqueous solutions. The pristine CNDs were developed through a one-pot hydrothermal synthesis. o-Phenylenediamine was used as the precursor. A similar hydrothermal synthesis technique in the presence of polyethylene glycol (PEG) was adopted to form the PEG-coated CND clusters (CND-100k). Through photoluminescence (PL) quenching, both CND and PEG-coated CND suspensions display ultra-high sensitivity and selectivity towards HSO4− anions (Stern–Volmer quenching constant (KSV) value: 0.021 ppm−1 for CND and 0.062 ppm−1 for CND-100k) with an ultra-low detection limit (LOD value: 0.57 ppm for the CND and 0.19 ppm for CND-100k) in the liquid phase. The quenching mechanism of N-doped CNDs towards HSO4− ions involves forming the bidentate as well as the monodentate hydrogen bonding with the sulfate anionic moieties. The detection mechanism of metallic ions analyzed through the Stern–Volmer formulation reveals that the CND suspension is well suited for the detection of Fe3+ (KSV value: 0.043 ppm−1) and Fe2+ (KSV value: 0.0191 ppm−1) ions, whereas Hg2+ (KSV value: 0.078 ppm−1) sensing can be precisely performed by the PEG-coated CND clusters. Accordingly, the CND suspensions developed in this work can be employed as high-performance PL probes for detecting various anions and metallic ions in the liquid phase. [ABSTRACT FROM AUTHOR]

Herein, we report strategies combining component adjustment and ion doping for the development of photochromic materials with high color-changing contrast. Sr 0.05 Ba 0.95 HfO 3 : Eu3+ ceramics showed reversible photochromism from off-white to dark brown under the alternating action of 254 nm UV light and heat treatment at 300 °C. This is caused by the capture and release of electrons by defects in the Sr 0.05 Ba 0.95 HfO 3 : Eu3+ host such as oxygen vacancies. Under this strategy, the maximum photochromic contrast ratio of 44.81% is achieved, which is a great improvement compared to pure SrHfO 3 (15.91%) and BaHfO 3 (14.98%). The luminescence quenching behavior based on the photochromic reaction can effectively modulate the emission of Eu3+. The reversible photochromic properties of Sr 0.05 Ba 0.95 HfO 3 : Eu3+ ceramics can be used for repeated writing and erasing of optical information, and the significant body color change improves its resolution in pattern information storage. [ABSTRACT FROM AUTHOR]

Experimental temperature dependences (77–293 K) of absorption and photoluminescence spectra of CdSe/ZnS semiconductor quantum dots (QDs) were analyzed based on modern models of exciton–phonon coupling. It was proven that the first excitonic transition absorption band formed with participation primarily of optical phonons of the CdSe core while the photoluminescence properties reflected the interaction of the ZnS layer with optical phonons. Photoluminescence quenching for CdSe/ZnS QDs of various diameters upon formation of nanoassemblies with porphyrin molecules was analyzed in the framework of a quantum-mechanical model. It was shown that the quenching rate constant decreased with increasing QD diameter and that the quenching process under quantum confinement conditions was due to the electron of an excited electron–hole pair tunneling onto the QD surface with subsequent localization on surface traps. [ABSTRACT FROM AUTHOR]

In this work, the formation, structural properties, and energy spectrum of novel self-assembled GaSb/AlP quantum dots (SAQDs) were studied by experimental methods. The growth conditions for the SAQDs' formation by molecular beam epitaxy on both matched GaP and artificial GaP/Si substrates were determined. An almost complete plastic relaxation of the elastic strain in SAQDs was reached. The strain relaxation in the SAQDs on the GaP/Si substrates does not lead to a reduction in the SAQDs luminescence efficiency, while the introduction of dislocations into SAQDs on the GaP substrates induced a strong quenching of SAQDs luminescence. Probably, this difference is caused by the introduction of Lomer 90°-dislocations without uncompensated atomic bonds in GaP/Si-based SAQDs, while threading 60°-dislocations are introduced into GaP-based SAQDs. It was shown that GaP/Si-based SAQDs have an energy spectrum of type II with an indirect bandgap and the ground electronic state belonging to the X-valley of the AlP conduction band. The hole localization energy in these SAQDs was estimated equal to 1.65–1.70 eV. This fact allows us to predict the charge storage time in the SAQDs to be as long as >>10 years, and it makes GaSb/AlP SAQDs promising objects for creating universal memory cells. [ABSTRACT FROM AUTHOR]

A new strategy for the easy polymerization of anionic [Ln(Qcy)4]− (HQcy-4-(cyclohexanecarbonyl)-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one) into two-dimensional layers of [AgLn(Qcy)4]n (Ln = Sm, Eu, Gd, Tb and Dy) is proposed by binding the single molecular anions [Ln(Qcy)4]− to silver cations through the coordination of the pyridinic nitrogen atoms of the pyrazolonate rings. The luminescent properties of [AgLn(Qcy)4]n have been studied in detail, and it was shown that the previously described low photoluminescence quantum yield (PLQY) of [Eu(Qcy)4]− is due to Ligand-To-Metal Charge Transfer (LMCT) quenching, which is effectively suppressed in the heterometallic [AgEu(Qcy)4]n polymer. Sensibilization coefficients for H3O[Eu(Qcy)4], [AgEu(Qcy)4]n, and H3O[Sm(Qcy)4] complexes (n ≈ 1) were estimated via theoretical analysis (also by using Judd-Ofelt theory for Sm3+) and PLQY measurements. [ABSTRACT FROM AUTHOR]

Perovskite quantum dots (QDs) have been considered as excellent luminescent materials that can replace traditional phosphors in backlit display field due to their narrow emission and high photoluminescence quantum yield (PLQY). However, the problems of rapid aging and luminescence quenching seriously affect their practical applications. One of the effective strategies to improve the stability is to prepare the QDs in glass. Herein, highly quality perovskite QDs embedded borosilicate glasses have been successfully prepared with the introduction of alkaline earth metals. With the help of alkaline earth, the further precipitation of perovskite QDs from glass can be promoted and then the heat-treatment temperature and time decreased. The crystallization principle, luminescence performance, and stability are studied in detail. The intrinsic PLQY of the optimal perovskite QDs glass powder exceeds 95%. The perovskite QDs glass powder was mixed with epoxy resin to form a flexible film. Both the QDs glass powder and film could still emit bright light under ultraviolet light when immersed in 90 °C hot water. The color gamut of LED based on QDs glass film reaches 112% of the NTSC standard, 158% of the sRGB standard, showing its strong potential applications in the backlit display field. [ABSTRACT FROM AUTHOR]

Porphyrin (TMPyP) functionalized carbon quantum dots (CQDs-TMPyP), a novel and efficient carbon nanocomposite material, were developed as a novel luminescent material, which could be very useful for the sensitive detection of copper ions in the Cu2+ quenching luminescence of functionalized carbon quantum dots. Therefore, we constructed a sensitive "signal off" ECL biosensor for the detection of Cu2+. This sensor can sensitively respond to copper ions in the range of 10 nM to 10 μM, and the detection limit is 2.78 nM. At the same time, it has good selectivity and stability and a benign response in complex systems. With excellent properties, this proposed ECL biosensor provides an efficient and ultrasensitive method for Cu2+ detection. [ABSTRACT FROM AUTHOR]

The detection of infrared radiation through a CMOS detector has recently intrigued the scientists and engineers all over the world. This could lower the cost, simplify the operation, and improve the pixel of the conventional infrared detection technology. To achieve this objective, the infrared light is converted into visible light via up-conversion nanoparticles or LED, which, however, suffers from complicated device fabrication. Herein, we report a type of simple infrared detection via a CMOS detector based on quantum dots (QDs). Inspired by the temperature effect of luminescence QDs, we design a setup that modulates the luminescence intensity of QDs via infrared radiation, which can be read out through a CMOS camera. Furthermore, the underlying mechanism of thermal quenching behavior is investigated through measurements of transient photoluminescence. Compared with traditional IR detectors, our infrared detection system possesses the advantages of facile fabrication and scalability, showing great potential for infrared detection. [ABSTRACT FROM AUTHOR]

Green coffee is coming into vogue as a food that contains remarkable contents of antioxidants like chlorogenic acid (ChA) and induces mild stimulation to the consumer. While most methods for determination of ChA require chromatographic separation prior its quantitation, we present the first probe and a simple, sensitive and validated luminescence method for the determination of chlorogenic acid in green and roasted coffee infusion samples that does not require a chromatographic separation. ChA can remarkably quench the luminescence intensity of the Tb3+ complex with 1-(furan-2-ylmethyl)-4-hydroxy-N-(4-methylpyridin-2-yl)-2-oxo-1,2,5,6,7,8-hexahydroquinoline-3-carboxamide (R3) in aqueous solution containing urotropine buffer at a near neutral pH 7.5 at λexc = 315 nm and λem = 545 nm. Under optimal conditions, the quenching of the luminescence intensity is directly proportional to the concentration of ChA in the range of 0.5–30 μg/mL, and the detection limit is 180 ng/mL. From measurements of luminescence decay time, it was determined that both static and dynamic quenching is induced upon coordination of ChA to Tb-R3. The related quenching constants are KS = 5.97∙104 M−1 and KD = 1.05⋅104 M−1. Finally, the method was applied successfully to the determination of ChA in real green and roasted coffee infusion samples and validated by HPLC to yield very closely matching concentrations of both methods. Therefore, this method can serve for a simple quality control of total ChA contents in coffee prior and after roasting. [ABSTRACT FROM AUTHOR]

In this paper, the effect of the GeO2:TiO2 molar ratio in glass composition on the spectroscopic properties of germanate glasses was systematically investigated. The visible luminescence bands associated with characteristic 1D2 → 3H4 (red), 5S2, 5F4 → 5I8 (green), and 1D2 → 3F4 (blue) transitions of Pr3+, Ho3+, and Tm3+ ions in systems modified by TiO2 were well observed, respectively. It was found that the luminescence intensity of glasses containing Pr3+ and Ho3+ ions increases, whereas, for Tm3+-doped systems, luminescence quenching with increasing content of TiO2 was observed. Based on Commission Internationale de I'Eclairage (CIE) chromaticity coordinates (x, y) analysis, it was demonstrated that the value of chromaticity coordinates for all glasses depends on the GeO2:TiO2 molar ratio. The addition of TiO2 to system compositions doped with Tm3+ ions shifts the (x, y) to the center of the CIE diagram. However, chromaticity coordinates evaluated for glasses containing Pr3+ ions move to a purer red color. Our results confirm that the spectroscopic properties of the studied glasses strongly depend on TiO2 content. Moreover, it can be stated that germanate-based glass systems modified by TiO2 can be used for optoelectronics in RGB technology as red (Pr3+), green (Ho3+), and blue (Tm3+) emitters. [ABSTRACT FROM AUTHOR]

Mixed-ligand complexes of Co(II) and Cu(II) with rutin and glycine were synthesized and studied by the method of "block" synthesis. The composition and structure of the synthesized compounds in solutions and in the solid state were studied, and their spectral and luminescent properties were determined. It is shown that the mixed-ligand complexes have the composition MII(Gly)2(Rut), while the coordination of 3-d metal ions occurs through the catechol fragment of rutin and the carboxyl and amino groups of two glycine molecules. For complexes in solutions, luminescence was detected in the visible region of the spectrum (~500-540 nm). It is shown that 3-d metal ions quench the luminescence of rutin, but in the presence of glycinate ion, the luminescence intensity of the complexes increases. The antibacterial activity of the complexes against pathological bacteria Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, P. Aeruginosa was studied. It has been shown that the synthesized compounds have an antimicrobial effect. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs) were synthesized in this study by hydrothermally treating cow milk. The procedure is simple, non-hazardous to the environment, and does not necessitate the use of any special instruments or chemicals. CQDs were practically almost circular when they were manufactured and had an average size of 7 nm. Carbon (67.36%), oxygen (22.73%), and nitrogen (9.91%) comprised the majority of their composition. They feature broad excitation-emission spectra, excitation-dependent emission, and temperature-dependent photoluminescence. They remained quite stable in the presence of a lot of salt, UV radiation, and storage time. Because luminescence quenching mechanisms are sensitive to and selective for Sn2+, they can be employed to create a nanosensor for detecting Sn2+. [ABSTRACT FROM AUTHOR]

A new family of perylenediimide (PDI) silver and copper complexes has been successfully synthesized by reacting ortho- and bay-substituted (dipyrid-2′,2″-ylamino)perylenediimide ligands with metal phosphine fragments. The coordination of the metal center did not reveal a significant effect on the photophysical properties, which are mainly due to the PDI ligands, and in some cases quenching of the luminescence was observed. The antiproliferative effect of the free perylenediimide ligands and the metalloPDI complexes against the cervix cancer cell line HeLa was determined by MTT assay. The free perylenediimide ligands exhibited a moderate cytotoxic activity, but the coordination of silver or copper to the dypyridylamino fragment greatly enhanced the activity, suggesting a synergistic effect between the two fragments. In attempts to elucidate the cellular biodistribution of the PDIs and the complexes, a colocalization experiment using specific dyes for the lysosomes or mitochondria as internal standards revealed a major internalization inside the cell for the metal complexes, as well as a partial mitochondrial localization. [ABSTRACT FROM AUTHOR]

Light emission from the M-type enantiomer of a helicene derivative (2,13-bis(hydroxymethyl)[7]-thiaheterohelicene) adsorbed on the clean Au(111) and the C60-covered Au(111) surfaces were investigated by tunneling-current-induced light-emission technique. Plasmon-originated light emission was observed on the helicence/Au(111) surface and it was strongly suppressed on the area where the helicene molecules were adsorbed at the edges of the Au(111) terraces. To avoid luminescence quenching of excited helicene molecules and to suppress strong plasmon light emission from the Au(111) surface, C60 layers were used as decoupling buffer layers between helicene molecules and the Au(111) surface. Helicene molecules were adsorbed preferentially on the Au(111) surface rather than on the C60 buffer layers due to the small interaction of the molecules and C60 islands. This fact motivated us to deposit a multilayer of helicene molecules onto the C60 layers grown on the Au(111) surface, leading to the fact that the helicene/C60 multilayer showed strong luminescence with the molecules character. We consider that such strong light emission from the multilayer of helicene molecules has a plasmon origin strongly modulated by the molecular electronic states of (M)-[7]TH-diol molecules. [ABSTRACT FROM AUTHOR]

This work reports fabrication of polylactide (PLA) films doped with various additives of an amorphous Eu(III) complex. We study the temperature behavior of the luminescence intensity and lifetime of the PLA-Eu(III) composites in the range of 298–353 K and investigate the mechanism of luminescence temperature quenching. The peak relative sensitivity of the films reaches 20.1 %×K−1 and exceeds the respective characteristics of all known lanthanide-containing thermosensors designed for the range of physiological temperatures. The produced films can be potential novel materials for luminescent thermosensors. [ABSTRACT FROM AUTHOR]

In this work, Ba2MgWO6: Eu3+ (BMW: Eu3+) ceramic materials with a double perovskite structure were sintered using the High-Pressure Low-Temperature sintering (HPLT) technique. As part of the research, the influence of pressure (CP), sintering temperature (CT), and sintering time (CTS) on the structure and luminescence of the doped BMW were determined. Structural analysis via XRD and SEM + EDS and spectroscopic analysis via emission and excitation spectra, decay time, and absorption spectra of the obtained ceramics were performed. Dense double perovskite ceramics were obtained with a cubic structure with optimal sintering parameters: T = 500 °C, p = 8 GPa, and t = 1 min. The increase in temperature caused an increased extinction of the luminescence due to the diffusion of carbon into the ceramics. The increase in pressure led to the formation of the amorphous phase, which increased the speed of non-radiative transitions and also led to the extinction of the luminescence. The increase in sintering time from 1 to 3 min enhanced the luminescence output, but when the ceramic was sintered for 5 min, the luminescence was quenched, most likely by increasing the rate of the non-radiative process, as evidenced by reduced decay time. [ABSTRACT FROM AUTHOR]

A new luminescent CdII compound, poly[[μ2‐1,4‐bis(1H‐imidazol‐1‐yl)benzene]{μ2‐5‐[(3‐carboxylphenoxy)methyl]isophthalato}cadmium(II)], [Cd(C16H10O7)(C12H10N4)]n or [Cd(HL)(1,4‐bib)]n {H3L is 5‐[(3‐carboxyphenoxy)methyl]isophthalic acid and 1,4‐bib is 1,4‐bis(1H‐imidazol‐1‐yl)benzene}, I, has been synthesized successfully from CdII and a semirigid tricarboxylic ligand under hydrothermal conditions. Structure analysis shows that I is a two‐dimensional structure with the point symbol {44.62}. The three‐dimensional framework is constructed by O—H...O hydrogen bonds and π–π stacking interactions. Furthermore, the obtained CdII compound displays high solvent stability and excellent thermal stability, as shown by powder X‐ray diffraction and thermogravimetry measurements. Studies of the luminescence properties reveal that compound I can act as a promising luminescent sensor for detecting FeIII cations and CrVI oxyanions with high selectivity and low detection limits (0.19 µM for Fe3+ and 1.13 µM for Cr2O72−), and is additionally free from the interference of other ions. The mechanism of selective quenching was studied by measuring the UV–Vis absorption of the host compound and the target analytes. [ABSTRACT FROM AUTHOR]

A water-stable Zn-MOF was constructed based on H2PBA and 1, 10-phenanthroline under solvothermal conditions. The compound exhibited a 3D (2,3,8)-connected (43)2(46.66.815.12)(8) topology framework. The crystal structure and phase purity of the compound was verified by single crystal X-ray diffraction. Subsequently, some studies on the morphology, structure, and luminescent properties were carried out. The results showed that this compound could be used as a versatile chemosensor for Fe3+/Cu2+, trinitrophenol and colchicine via a luminescence quenching effect in an aqueous medium. [ABSTRACT FROM AUTHOR]

Discovering bismuth based smart materials that can respond to thermal, mechanical, and wide range X-ray to infrared photon excitation remains a challenge. Such materials have various uses like in advanced information encryption. In this work, valence state change between Bi2+, Bi3+, and Bi4+, and the dual role of Bi3+ in trapping electrons and holes have been studied in Bi3+ or/and Ln3+ (Ln=Tb or Pr) doped LiScGeO 4 family of compounds by vacuum referred binding energy (VRBE) diagram construction, thermoluminescence, and spectroscopy. Electron release from Bi2+ has been evidenced. It can be used to experimentally determine the VRBE in the Bi2+ 2P 1/2 ground state and to realize Bi3+ negative quenching luminescence. Particularly, a new force induced charge carrier storage phenomenon has been discovered for non-real-time force recording. Wide range of emission tailorable afterglow, unique Bi3+ ultraviolet-A, white, and infrared afterglow have been demonstrated by using Bi3+ as a hole trapping and recombination center and using energy transfer processes from Bi3+ to Tb3+, Pr3+, Dy3+, or Cr3+. Proof-of-concept advanced anti-counterfeiting, information encryption, and X-ray imaging will be demonstrated. This work not only develops smart storage phosphors, but more importantly unravels the valence change between Bi2+, Bi3+, or Bi4+ and how it can affect the trapping and release of charge carriers with thermal, optical, or mechanical excitation. This work therefore can promote the discovery and development of Bi3+ based smart materials for various applications. Discovering bismuth based smart materials that can respond to thermal, mechanical, and wide range X-ray to infrared photon excitation remains a challenge. Such materials have various uses like in advanced information encryption. In this work, valence state change between Bi2+, Bi3+, and Bi4+, and the dual role of Bi3+ in trapping electrons and holes have been studied in Bi3+ or/and Ln3+ (Ln=Tb or Pr) doped LiScGeO 4 family of compounds by vacuum referred binding energy (VRBE) diagram construction, thermoluminescence, and spectroscopy. Electron release from Bi2+ has been evidenced. [Display omitted] [ABSTRACT FROM AUTHOR]

Developing new hybrid materials is critical for addressing the current needs of the world in various fields, such as energy, sensing, health, hygiene, and others. C-dots are a member of the carbon nanomaterial family with numerous applications. Aggregation is one of the barriers to the performance of C-dots, which causes luminescence quenching, surface area decreases, etc. To improve the performance of C-dots, numerous matrices including metal-organic frameworks (MOFs), covalent-organic frameworks (COFs), and polymers have been composited with C-dots. The porous crystalline structures, which are constituents of metal nodes and organic linkers (MOFs) or covalently attached organic units (COFs) provide privileged features such as high specific surface area, tunable structures, and pore diameters, modifiable surface, high thermal, mechanical, and chemical stabilities. Also, the MOFs and COFs protect the C-dots from the environment. Therefore, MOF/C-dots and COF/C-dots composites combine their features while retaining topological properties and improving performances. In this review, we first compare MOFs with COFs as matrices for C-dots. Then, the recent progress in developing hybrid MOFs/C-dots and COFs/C-dots composites has been discussed and their applications in various fields have been explained briefly. [Display omitted] • Comparison of MOF and COF as support for C-dots is presented. • Methods for hybridization of MOF and COF with C-dots have been discussed. • Described are the generated and synergistic properties of the hybrid materials. • The main applications of MOF/C-dots and COF/C-dots have been addressed. [ABSTRACT FROM AUTHOR]

Lanthanide based coordination polymers (Ln-CPs) act as efficient chemo-sensors on interaction with the target analyte and show a detectable variation in their optical properties. This work demonstrates interaction of metal ions and nitroaromatic compounds with Eu based CP resulting in quenching of luminescence emission intensity. Approaching towards this aim, seven iso-structural lanthanide coordination polymers having the formulae, [Ln(diphen) 1.5 (1,10-phen)(H 2 O)] where Ln = Sm (1), Gd (3), Dy (5), {[Ln(diphen) 1.5 (1,10-phen)(H 2 O)]·OH} Ln = Eu (2), Er (7) and {[Ln(diphen) 1.5 (1,10-phen)(H 2 O)]·CH 3 CN·H 2 O} Ln = Gd (4), Ho (6) (diphen = diphenic acid, 1,10-phen = 1,10 Phenanthroline), were assembled solvothermally by using diphenic acid and 1,10-Phenanthroline as ligands. These lanthanide coordination polymers were characterized by Single-crystal X-ray diffraction, FTIR, Powder X-ray diffraction, Thermogravimetric analysis, UV–visible spectroscopy and Photoluminescence. The CPs 1–7 possess one-dimensional (1D) infinite chain-like structures which crystallize in the monoclinic C 2/ c space group. The photoluminescence properties of CP 2 exhibit its sensing ability to detect some toxic nitroaromatic compounds and d-block metal ions. However, CP 2 shows highly sensitive behavior for the recognition of Cu2+ and picric acid as indicated by efficient luminescence quenching with the low limit of detection. Other metal ions (viz., Cr3+, Cu2+, Co2+, Zn2+, Mn2+, Ni2+, Cd2+, and Hg2+), and nitro compounds (viz., PA, m -DNB, p-NP, p-NA and NB) were also screened for sensing potential of CP 2. [Display omitted] • Seven lanthanide coordination polymers with diphenic acid, 1,10-phenanthroline linkers are reported. • All coordination polymers are isostructural and crystallize in monoclinic C 2/ c space group. • All CPs possess one-dimensional (1D) infinite chain-like structures. • The synthesized CPs are isomorphous and possesses MFF (muffin) polyhedral geometry around Ln1 metal center. • The CP 2 shows highly sensitive behavior for detection of Cu2+ and picric acid. [ABSTRACT FROM AUTHOR]

Luminescent materials with desirable properties are in constant demand for lighting applications and as probes in bioimaging. In this study, we successfully synthesized nanosized strontium fluorapatite (SrFAp) powders doped with varying concentrations of Eu3+ ions via the hydrothermal method, targeting applications in lighting and bioimaging probes. Our focus was on understanding the impact of annealing temperature and dopant concentration on structural purity, particle morphology, photoluminescence, dopant ion occupancy, and temperature-dependent emission characteristics. The materials emit red light, with the most intense transition being 5 D 0 → 7 F 2. The asymmetry parameter (R) determination and CIE color coordinates provided insights into the spectroscopic attributes. Emission spectra were measured and discussed at four distinct excitation lines. Lower-energy excitation wavelengths, deemed favorable for organisms, make these materials particularly suitable for bioimaging applications. While the most intense emission occurred under 393 nm excitation, emissions were also detected at 464.5 nm and 525 nm, suggesting alternative excitation wavelengths better suited for bioimaging. Additionally, we conducted extensive studies to assess the effect of ambient temperature on the emission intensity of SrFAp materials doped with 1 mol% Eu3+ ions. Thermal quenching of luminescence was observed in both as prepared and annealed materials, providing insights into the temperature-dependent behaviour of the emission properties. • Nanosized Eu3+:Sr 10 (PO 4) 6 F 2 materials were synthesized by hydrothermal method. • The influence of Eu3+ content and annealing temperature on luminescence properties were studied. • Emission spectra were measured using two excitation wavelengths more friendly for bioimaging. • The emission intensity decreases as the ambient temperature increase. • A wide emission band around 430 nm was observed below 0°C that undergoes thermal quenching. [ABSTRACT FROM AUTHOR]

A new bioanalytical labeling system based on alloyed quantum dots' (QDs) photoluminescence quenching caused by an enzymatic reaction has been developed and tested for the first time. The catalytic role of the enzyme provides high sensitivity and the possibility of varying detecting time to improve assay sensitivity. Alloyed luminescent QDs were chosen in view of their small size (5–7 nm) and the high sensitivity of their optical properties to physicochemical interactions. Here, we described the synthesis of alloyed luminescent QDs and demonstrated the possibility of using them as a luminescent turn-off substrate for enzymatic assay. Synthesized alloyed QDs were found to be a sensitive turn-off substrate for glucose oxidase in homogeneous and heterogeneous assay models. CdZnSeS and CdZnSeS/ZnS QDs covered with dihydrolipoic acid and 2-mercaptoethanol were tested. A glucose oxidase limit of detection of 6.6 nM for the heterogenous high-throughput model assay was reached. [ABSTRACT FROM AUTHOR]

Monitoring the blood concentration of banoxantrone (AQ4N) is important to evaluate the therapeutic efficacy and side effects of this new anticancer prodrug during its clinical applications. Herein, we report a fluorescence method for AQ4N detection through the modulation of the molecule-like photoinduced electron transfer (PET) behavior of gold nanoclusters (AuNCs). AQ4N can electrostatically bind to the surface of carboxylated chitosan (CC) and dithiothreitol (DTT) co-stabilized AuNCs and quench their fluorescence via a Coulomb interaction-accelerated PET process. Under optimized experimental conditions, the linear range of AQ4N is from 25 to 200 nM and the limit of detection is as low as 5 nM. In addition, this assay is confirmed to be reliable based on its successful use in AQ4N determination in mouse plasma samples. This work offers an effective strategy for AQ4N sensing based on fluorescent AuNCs and widens the application of AuNCs in clinical diagnosis and pharmaceutical analysis. [ABSTRACT FROM AUTHOR]

The novel phosphors Ba 6 (Lu 1– x Eu x) 5 B 9 O 27 (x = 0.02, 0.04, 0.06, 0.08, 0.1, 0.14, 0.2) were obtained by cooling from a melt. Single-crystal X-ray diffraction experiments were provided for all the samples. No structural transitions caused by the Eu3+ → Lu3+ isomorphic substitution were revealed in this series of solid solutions. The data showed that an expected increase of cell parameters is caused by an increase in the Eu3+ content. First, the Eu3+ ions occupy large [Lu2O 6 ] and [Lu3O 6 ] polyhedra that are the most suitable ones for them, then (at x = 0.14) they start to occupy the smallest [Lu1O 6 ] polyhedra. Luminescent properties of the Ba 6 (Lu 1– x Eu x) 5 B 9 O 27 (x = 0.02–0.2) phosphors were investigated. The highest emission intensity with quantum yield of 28% was demonstrated by Ba 6 (Lu 0.92 Eu 0.08) 5 B 9 O 27. The concentration quenching effect was revealed for the 0.1 ≤ x ≤ 0.2 samples that could be caused by a beginning of the substitution of the smallest [Lu1O 6 ] polyhedra. It was shown that the successive substitution occurs at several cation positions of different sizes affects the quenching of luminescence. • Novel red-emitting phosphors Ba 6 Lu 5 B 9 O 27 :Eu3+ are synthesized. • Steady-state and kinetics luminescent properties of the phosphors are studied. • CIE coordinates are found to be close to those for the NTSC standard red phosphor. • Optimal concentration of Eu3+ depends on a sequential occupation of independent sites. [ABSTRACT FROM AUTHOR]

Upconversion luminescence materials have gained extensive attentions owing to their unique luminescence characteristics of converting near-infrared excitation to visible light emission. However, how to improve the doping concentration of activator (usually <3 mol%) in traditional sensitizer-activator system is still a great challenge due to the luminescence quenching effect. In this work, NaErF 4 crystals with diverse crystal phases and morphologies were prepared by simple hydrothermal method, constructing a 100% doping concentration system of activator (Er3+). With the increase of F− content, the phase of NaErF 4 transfers from cubic to hexagonal, and the morphology changes from nanospheres to hexagonal microflakes, meanwhile, the upconversion luminescence intensity also increases gradually. In addition, in order to further inhibit the luminescence quenching effect of NaErF 4 bare core, a series of NaErF 4 @SiO 2 core-shell samples with different SiO 2 shell thickness were successfully prepared. Compared with NaErF 4 bare core, the morphology and structure of the NaErF 4 @SiO 2 core-shell samples have no obvious change, but the UC luminescence intensity is significantly enhanced. Interestingly, the change of NaErF 4 crystal phase and SiO 2 shell thickness can both bring about multicolor luminescence. In addition, different from the traditional NaYF 4 :Yb, Er co-doping system, the as-prepared hydrophilic NaErF 4 and NaErF 4 @SiO 2 samples showed a greater red to green ratio (R/G > 1), which may expand their potential applications in biological imaging and sensing fields. [ABSTRACT FROM AUTHOR]