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Development of ultra‐broadband visible‐to‐near‐infrared (VIS‐NIR) luminescent materials is a challenging but rewarding endeavor, as they are highly desirable for a number of applications in photonics, optoelectronics, and biological sciences. Nevertheless, to date, rare earth‐doped phosphors that can be efficiently excited by blue light and produce broadband emission in the VIS‐NIR regions remain scarce. In this study, a series of Ce3+‐doped Ba3M4O9 (M = Sc, Lu, Y) broadband luminescent materials are designed based on low‐coordination crystallographic lattice engineering. Among these materials, Ba3Y4O9:Ce3+ produces a continuous ultra‐wide VIS‐NIR emission (λem = 660 nm) in the range of 500–950 nm under 410 nm light excitation. This emission wavelength is the longest among those observed in Ce3⁺‐doped oxide materials. Structural refinement, theoretical calculation, and spectral analysis demonstrate that this VIS‐NIR broadband emission is attributed to the occupying multiple distorted octahedral lattice sites by Ce3+ in Ba3Y4O9. Several strategies are employed to enhance the luminescence intensity and thermal stability of this material, including the use of carbon paper coating, the incorporation of co‐solvents, and the addition of GeO₂ or ZrO₂. Furthermore, the as‐prepared materials demonstrate multifunctional applications in white light‐emitting diodes (WLED), night vision, and fluorescent thermometers. This study offers insights into the design of Ce3+‐doped ultra‐wide VIS‐NIR light‐emitting materials. [ABSTRACT FROM AUTHOR]

A series of red-emitting phosphors, Na3.6Y1.8−x(PO4)3:xEu3+, have been synthesized by a high-temperature solid-phase method. The impact of the partial Li+/K+ ion substitution on the crystal structure and photoluminescence (PL) performance of Na3.6Y1.05(PO4)3:0.75Eu3+ phosphor have been investigated. Various techniques have been used for characterization of the as-obtained materials. X-ray diffraction (XRD) analysis was utilized to confirm the composites of these samples, and the morphology and element distribution were examined by scanning electron microscope (SEM) and transmission electron microscope (TEM). This study found that the developed Na3.6Y1.8−x(PO4)3:xEu3+ phosphors exhibited a prominent emission peak at ~620 nm when excited at 393 nm, which corresponded to 5D0 → 7F2 transitions of Eu3+ ions. Furthermore, the robust emission peak at ~705 nm (5D0 → 7F4) of these phosphors enables a better match with plant pigment absorption. Beyond that, the partial substitution of Li+/K+ ions probably changed the crystal structure, and reduces the symmetry around Eu3+, leading to significantly enhanced luminous intensities by 23.24% and 18.29%, with the highest quantum yields (QYs) reaching 99.85% and 96.29%, respectively. Additionally, the prepared phosphors show non-thermal quenching and superior thermal stability at elevated temperatures from 298 to 473 K. These findings and results suggest that Li⁺/K⁺-substituted Na3.6Y1.05(PO₄)₃:0.75Eu3⁺ phosphors can serve as promising red-emitting phosphors for plant lighting applications. [ABSTRACT FROM AUTHOR]

Uncovering new ways for light localization at the micro‐ and nanoscale is essential for the development of state‐of‐the‐art photonic devices. Nowadays the most advances in this area are achieved using near‐field resonators, providing extreme light confinement in nanoscale volume. However, the boosting of device performance in some practical applications, for example, luminescent sensing, optical tweezing, and super‐resolution optical microscopy require light localization at distances beyond near‐field range. This issue can be addressed by employing dielectric microstructures that produce photonic nanojets (PNJs), representing an intermediate state between near‐field localization and geometric optics. Despite the promising benefits of PNJ implementation in various optical applications, their practical studies are scarce and mostly limited to numerical simulations. Here, a new type of PNJ is introduced and studied both numerically and experimentally. Contrary to the conventional case, wherein PNJ is generated by a single microstructure, the reported PNJ is produced through collective effects in a densely packed array of dielectric microstructures. The studies reveal that these collective PNJs can reach an unprecedented length of >60 λ, while maintaining a high localization intensity. Under certain configurations of the array, collective PNJ can enhance the electromagnetic field by up to sevenfold, being a versatile tool for various photonic applications. [ABSTRACT FROM AUTHOR]

A novel near-infrared emitting Ga 2 O 3 : Ni2+ phosphor was prepared, and its emission characteristics were improved through melting aid and charge balance. Under 410 nm excitation, the Ga 2 O 3 : Ni2+ phosphor exhibits broadband near-infrared emission in the second region, with a peak at 1455 nm and a half maximum width of up to 300 nm. At the same time, the crystallinity of the sample was improved and the charge imbalance during substitution between Ga3+ and Ni2+ was eliminated through melting assistance and charge compensation. The results show that the emission intensity of Ga 1.97 O 3 : 0.015Ni2+, 0.015Ge4+ phosphor (with added flux H 3 BO 3) is 10 times higher than that of Ga 1.985 O 3 : 0.015Ni2+ sample. Its quantum yield is as high as 31.2 %, significantly higher than the reported Ni2+ ion doped phosphors. According to the distinct absorptions of C–H, O–H as well as N–H bonds in the shortwave near-infrared range, samples of ethanol, n-hexanol, water and ammonia demonstrated different absorption peaks under the penetration of the constructed phosphor conversion light-emitting diode, which proved the potential application of Ga 2 O 3 : Ni2+, Ge4+-H 3 BO 3 phosphor in composition analysis and detection. [ABSTRACT FROM AUTHOR]

Luminescent CuI complexes are an important class of coordination compounds due to their relative abundance, low cost and ability to display excellent luminescence. The title Cu2I2P2S2‐type binuclear complex, di‐μ‐iodido‐bis[(thiourea‐κS)(triphenylphosphine‐κP)copper(I)], [Cu2I2(CH4N2S)2(C18H15P)2], conventionally abbreviated as Cu2I2TPP2TU2, where TPP and TU represent triphenylphosphine and thiourea, respectively, is described. In this complex, each CuI atom adopts a CuI2PS four‐coordination mode and pairs of atoms are connected to each other by two μ2‐I ligands to form a centrosymmetric binuclear cluster. It was also found that the paper‐based film of this complex exhibited obvious luminescence light‐up sensing for pyridine and 4‐methylpyridine. [ABSTRACT FROM AUTHOR]

The importance of aluminum usage in our everyday life and its adverse impact on health and the environment stimulate the development of excellent probes for the detection of Al3+ ions. In this study, we developed a luminescence enhancement-based detection probe for the selective detection of Al3+ ions. For this purpose, we developed water-dispersible 2-furoic acid-capped LaF3:5%Tb3+ nanocrystals (NCs) via the microwave irradiation method. Here, 2-furoic acid acts as a surfactant and an antenna for the Tb3+ ions. Oxygen in the furan ring has a hard base nature and prefers to bind with hard acid-natured metal ions. Upon excitation at 258 nm, the NCs show characteristic Tb3+ emissions via 2-furoic acid sensitization. The excitation and emission spectra of the NCs increased continuously with the gradual addition of Al3+ ions from 1 to 700 μm in the aqueous medium. More than 2-fold enhancement was found for 700 μM Al3+ ions. The luminescence enhancement results from aggregation caused by hard acid and hard base interactions between Al3+ ions and oxygen atoms in the furan ring. In this way, the quenching of nonradiative energy transfer by solvent molecules was reduced, and the efficiency of energy transfer from ligand to Tb3+ ions was increased. The luminescence increment is highly selective toward Al3+ ions with very minimal interference. The developed method shows a remarkably high sensitivity for Al3+ ion detection, and the calculated LOD was 1.67 μM, which is much lower than the maximum aluminum content allowable by the WHO in drinking water. Furthermore, we applied this method for the determination of Al3+ ions in actual water samples. [ABSTRACT FROM AUTHOR]

Emission from metal–organic frameworks (MOFs) made from Eu3+ and 1,3,5‐benzenetricarboxylic acid (BTC) is enhanced eightfold by doping with Y3+ and Ca2+ ions. The Ca2+ ions are shown to substitute into the MOFs, and the MOFs structure is shown to be retained at high Y3+ doping levels. The emission enhancement is shown to be associated with variations in the local electric field at the Eu3+ centers in the MOFs. Calculations indicate that the HOMO and LUMO levels vary considerably with both Y3+ doping and with low‐level Ca2+ doping. These then modulates Eu3+ concentration quenching, ligand‐metal energy transfer processes, and the local electric field at the Eu3+ centers, qualitatively accounting for the primary observed features. For UV excitation (250, 295, and 393 nm, respectively), the greatest emission enhancement comes from the doped MOFs with 10% Eu3+, 89% Y3+, and 1% Ca2+. In a photonic barcode application, the doped MOFs are shown to facilitate increased information storage density, and in a fingerprinting application, they are displayed to lead to higher photostability and reduced materials demand. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDC) are a family of atomic‐layer 2D materials (2dMs). Many researches have attempted to reinforce the unique properties by incorporating artificially designed nanostructures. Here, a highly photoluminescence (PL) enhancing platform is reported that is formed by combining high‐emittance plasmo–photonic metasurfaces with a large‐area 2dM, which is a continuous monolayer of TMDC of cm2 dimension. It is experimentally demonstrated that the 2dM‐PL intensity at room temperature is enhanced by more than 1030‐fold in comparison with that observed on the flat gold film regions. The enhancement is associated with spectral transformation indicating a resonant effect of the metasurfaces. It is moreover revealed that the confocal PL image originates from a coherent single‐mode emission that forms a photon number distribution obeying the Poisson probability distribution. Thus, the 2dM‐fused metasurfaces function as efficient coherent quantum light sources. PL decay‐time analysis also reveals the coexistence of two components in the enhanced PL. The fast component exhibits a lifetime of 18 ps whereas the slow component decays at 4.4 ns. Both components are most likely to undergo radiative processes, which indicates that metal‐induced PL quenching is suppressed on these 2dM‐fused metasurfaces. The long lifetime component is ascribed to an excitonic intervalley transition. [ABSTRACT FROM AUTHOR]

In this work,60TeO 2 -(35-x)ZnO-xNb 2 O 5 –5SrF 2 -0.5Dy 2 O 3 glasses was prepared to use a high-temperature melting method, where x represents the Nb 2 O 5 content (x = 0,5,7.5,10).Raman spectra studies revealed that increasing the concentration ratio of Nb 2 O 5 to TeO 2 resulted in the gradual transformation of [TeO 3 ] and [TeO 3+1 ] units in the glass network to [TeO 4 ] units. This transformation also enhanced the stability of the network structure. The emission peaks of the samples were observed at 481 nm (blue), 576 nm (yellow), and 663 nm (red), which is crucial for white light materials. The luminescent intensity increased with the increase of Nb 2 O 5 concentration, reaching its maximum at 7.5% mol. The CIE 1931 chromaticity coordinates fell within the range of white light, with corresponding color temperatures ranging from 5063 K to 5877 K. All the results show that the fluorescent materials used in high-brightness illumination can be obtained by adding an appropriate amount of Nb 2 O 5 to Dy3+-doped tellurate glass. [ABSTRACT FROM AUTHOR]

A series of novel phosphors, specifically Eu3+-doped and Eu3+/M+ co-doped (M = Li+, Na+, K+) SrLaNaTeO 6 , were synthesized via a high-temperature solid-state process. The luminous properties and thermal stability of these phosphors were thoroughly investigated. When subjected to the appropriate excitation wavelengths (395 and 465 nm), all phosphors demonstrate a pronounced red light emission, corresponding to the 5D 0 →7F 2 transition of Eu3+. The researchers found that the most effective concentration of Eu3+ doping in the Sr 1-x LaNaTeO 6 :xEu3+ phosphor was discovered to be x = 0.25. It was shown that excessive doping leads to concentration quenching, which can be attributed to the energy transfer interaction between Eu3+ ions. The incorporation of Li+, Na+, and K+ as charge compensation ions in conjunction with Eu3+ in Sr 0.75 LaNaTeO 6 :0.25Eu3+ phosphor leads to a notable enhancement in light intensity. Notably, the phosphor co-doped with Na+ exhibits the highest luminous intensity among the alkali metal charge compensation ions. The near proximity of the ion radius of the charge compensation ion Na+ to that of Sr2+ in the host facilitates the occupation of the Na + ion in the Sr2+ lattice location. Sodium ions (Na+) have the ability to counteract the positive defects resulting from the substitution of europium ions (Eu3+) with strontium ions (Sr2+), hence maintaining charge neutrality. Additionally, it should be noted that Sr 0.5 LaNaTeO 6 :0.25Eu3+,0.25Na+ phosphor exhibits a remarkable quantum yield of 71.26 % and lacks thermal quenching. These characteristics suggest that this particular phosphor holds promising potential for utilization in developing white-light-emitting diodes. This research adopted a strategy on alkali metal ions (Li+, Na+, K+) as charge compensators to improve luminescence properties and quantum yield of phosphor. Li+, Na+, K+ co-doped significantly improve the luminescence intensity of phosphor. Meanwhile, this phosphor exhibits excellent thermal stability and a strong negative thermal quenching. Significantly, Sr 0.5 LaNaTeO 6 :0.25Eu3+,0.25Na+ phosphor demonstrates excellent color purity (98.6 %) and quantum yield (71.26 %). [Display omitted] • Alkali metal charge compensation ions Li+, Na+ and K+ co-doped significantly improve the luminescence intensity of Sr 1-x LaNaTeO 6 :xEu3+ phosphor. • A series of Sr 0.5 LaNaTeO 6 :0.25Eu3+,0.25M+ (M+ = Li+, Na+, K+) red-emitting phosphor has remarkable negative thermal quenching. • Sr 0.5 LaNaTeO 6 :0.25Eu3+,0.25Na+ phosphor demonstrates excellent quantum yield (71.26 %) and color purity (98.6 %). [ABSTRACT FROM AUTHOR]

A series of red-emitting phosphors, Na3.6Y1.8−x(PO4)3:xEu3+, have been synthesized by a high-temperature solid-phase method. The impact of the partial Li+/K+ ion substitution on the crystal structure and photoluminescence (PL) performance of Na3.6Y1.05(PO4)3:0.75Eu3+ phosphor have been investigated. Various techniques have been used for characterization of the as-obtained materials. X-ray diffraction (XRD) analysis was utilized to confirm the composites of these samples, and the morphology and element distribution were examined by scanning electron microscope (SEM) and transmission electron microscope (TEM). This study found that the developed Na3.6Y1.8−x(PO4)3:xEu3+ phosphors exhibited a prominent emission peak at ~620 nm when excited at 393 nm, which corresponded to 5D0 → 7F2 transitions of Eu3+ ions. Furthermore, the robust emission peak at ~705 nm (5D0 → 7F4) of these phosphors enables a better match with plant pigment absorption. Beyond that, the partial substitution of Li+/K+ ions probably changed the crystal structure, and reduces the symmetry around Eu3+, leading to significantly enhanced luminous intensities by 23.24% and 18.29%, with the highest quantum yields (QYs) reaching 99.85% and 96.29%, respectively. Additionally, the prepared phosphors show non-thermal quenching and superior thermal stability at elevated temperatures from 298 to 473 K. These findings and results suggest that Li⁺/K⁺-substituted Na3.6Y1.05(PO₄)₃:0.75Eu3⁺ phosphors can serve as promising red-emitting phosphors for plant lighting applications.

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Recently, lanthanide (Ln) luminescent nanocrystals have attracted increasing attention in various fields such as biomedical imaging, lasers, and anticounterfeiting. However, due to the forbidden 4f–4f transition of lanthanide ions, the absorption cross‐section and luminescence brightness of lanthanide nanocrystals are limited. To address the challenge, we constructed an optical oscillator‐like system to repeatedly simulate lanthanide nanocrystals to enhance the absorption efficiency of lanthanide ions on excitation photons. In this optical system, the upconversion luminescence (UCL) of Tm3+ emission of ~450 nm excited by a 980 nm laser can be amplified by a factor beyond 104. The corresponding downshifting luminescence of Tm3+ at 1460 nm was enhanced by three orders of magnitude. We also demonstrated that the significant luminescence enhancement in the designed optical oscillator‐like system was general for various lanthanide nanocrystals including NaYF4:Yb3+/Ln3+, NaErF4@NaYF4 and NaYF4:Yb3+/Ln3+@NaYF4:Yb3+@NaYF4 (Ln = Er, Tm, Ho) regardless of the wavelengths of excitation sources (808 and 980 nm). The mechanism study revealed that both elevated laser power in the optical system and multiple excitations on lanthanide nanocrystals were the main reason for the luminescence amplification. Our findings may benefit the future development of low‐threshold upconversion and downshifting luminescence of lanthanide nanocrystals and expand their applications. [ABSTRACT FROM AUTHOR]

Glyphosate is one of the most effective herbicides and is extensively used in agriculture to improve crop production. However, its toxicity and carcinogenicity stimulate the development of potent, rapid, and highly selective sensors for glyphosate. In this study, we have successfully developed a rational and effective method for detecting glyphosate concentrations in the nanomolar range through luminescence enhancement. For this purpose, we synthesized NH2-MIL-88B (Fe) (MIL = Material Institute Lavoisier) metal–organic framework (MOF)-based nanocrystals (NCs) using the hydrothermal method and applied it for glyphosate detection in an aqueous medium. The MOF NCs contain coordinative ligands (2-aminoterephthalic acid) and metal clusters. The Fe clusters act as luminescence quenchers, suppressing emission from the MOF due to photoinduced electron transfer (PET) from the ligand to Fe3+ ions. The phosphate group of glyphosate competes with the carboxylate of the ligand in the MOF. As a result, the coordination between ligand molecules and Fe metal clusters in the MOF weakens, causing the ligand molecules to separate from the Fe cluster. This process diminishes the PET and regenerates the ligand emission at 450 nm. The luminescence enhancement exhibits high selectivity toward glyphosate and shows minimal interference from various pesticides and metal ions. The limit of detection was calculated as 198 nM, and the performance of the detection probe was evaluated in drinking water. Finally, MOF NCs-coated circular paper strips were prepared and successfully applied to detect glyphosate at femtomolar concentrations. [ABSTRACT FROM AUTHOR]

Ethylene glycol (EG), citrate and EDTA stabilized Eu(III) doped CaF2 nanoparticles were synthesized following colloidal precipitation method. With EDTA, highly monodisperse cubic nanoparticles (NPs) were formed which changes to quasi-spherical morphology when the capping ligand changes to TSC and EG associated with a broader size distribution. Generations of larger NPs were produced through kinetically controlled seeded-growth method where the ligands directly affect the size tunability. The homogeneity of the growth process was maximized by the adjustment of reaction parameters like temperature and concentration of precursor. Under the same reaction conditions, better kinetic control of the growth process and the ease of tuning the size by the ligands follow the order: EDTA > citrate > EG. The Eu3+ emission intensities characteristic of 5D0 → 7Fn for the NPs increases when the ligand changes from EG to EDTA through citrate. Among the generations of NPs capped by a particular ligand, the dependence of luminescence intensity on size is observed. With decreasing size, there is luminescence enhancement for NPs stabilized by citrate and EDTA while the trend is opposite for EG stabilized particles. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDs) like molybdenum disulfide (MoS2) have unique optical properties such as strong luminescence and a tunable bandgap. However, the small interaction distance due to the atomically thin nature of these materials is a limitation for applications. In this study, a significant enhancement of the A‐ and B‐exciton emission in MoS2 flakes through coupling with plasmonic Au nano‐pyramid arrays fabricated by a colloidal lithography technique is reported. This study experimentally maps local emission enhancement from the structure with a nanometer spatial resolution by cathodoluminescence (CL) technique. Strongly enhanced emission intensity within the MoS2‐Au pyramids is achieved due to the localized surface plasmon resonance confined in nano‐pyramids and its interaction with the periodicity‐based resonance of the array structure. The results provide an approach to significantly improve the luminescence intensity of MoS2 through optical interaction with the local plasmonic field, which is promising for applications in optoelectronic devices and nanophotonics. [ABSTRACT FROM AUTHOR]

Pr-doped metal oxide polycrystalline transparent ceramics are highly desirable for photothermal window systems served in extreme environments; however, obtaining efficient photoluminescence (PL) together with high transparency in these ceramics is still posing serious challenges, which undoubtedly limits their applications. Here, Pr-doped Y2Zr2O7 (YZO) transparent ceramics, as an illustrative example, are prepared by a solid-state reaction and vacuum sintering method. Owing to the elimination of defect clusters [PrY4+−O2−−PrY4+] and [PrY4+−e′] without the introduction of impurities and additional defects, the fabricated YZO:Pr ceramics exhibit high transparency (74%) and efficient PL (39-fold enhanced) after air annealing plus vacuum re-annealing treatment. Moreover, upon 295/450 nm excitation, the emission bands (blue, green, red, and dark red) from YZO:Pr ceramics present different temperature-dependent properties due to the thermal-quenching channel generated by the intervalence charge transfer (IVCT) state between Pr3+ and Zr4+ ions. Furthermore, a self-calibrated temperature feedback window with the same fluorescence intensity ratio (FIR) model (I613/I503, where I represents the intensity) under different excitation light sources (295 and 450 nm) is designed. The developed photothermal window operated in a wide temperature range (303–663 K) shows relatively high sensitivities (absolute sensitivity (Sa) and relative sensitivity (Sr) reach 0.008 K−1 at 663 K and 0.47% K−1 at 363 K, respectively), high repeatability (> 98%), and low temperature uncertainty (δT < 3.2 K). This work presents a paradigm for achieving enhanced PL along with elevated transparency of lanthanide (Ln)-doped ceramics through vacuum re-annealing treatment engineering and demonstrates their promising potential for photothermal window systems.

In this work, the effect of Nb 2 O 5 oxide on the ∼2.0 μm band luminescence of Ho3+/Tm3+/Ce3+ tri-doped tellurite glass with composition of TeO 2 –ZnO–La 2 O 3 was studied. The doped tellurite glass was synthesized by using the melt-quenching method. Under the pumping of 808 nm laser diode (LD), a broad and relatively flat fluorescence emission ranging from 1600 to 2200 nm with a full width at half maximum (FWHM) of 374 nm was obtained by optimizing the concentration combination of Ho3+, Tm3+ and Ce3+ ions. The observed broad luminescence was attributed to the spectral overlapping between the energy level transitions from 3F 4 to 3H 6 of Tm3+ at 1.82 μm and that from 5I 7 to 5I 8 of Ho3+ at 2.0 μm. Further, an increment by about 143% in peak intensity of 1600∼2200 nm broad luminescence was found after the introduction of Nb 2 O 5 oxide, which is due to the enhanced energy transfer from Tm3+ to Ho3+ ions, and the increased multi-phonon relaxation (MPR) rate from higher levels to fluorescence emitting levels. It can be inferred from the results that a potential gain medium suitable for applications in optoelectronic devices operating at ∼2.0 μm band can be produced by incorporating an appropriate amount of Nb 2 O 5 oxide into Ho3+/Tm3+/Ce3+ tri-doped tellurite glass. [ABSTRACT FROM AUTHOR]

Luminescence is an essential signal for many plants, insects, and marine organisms to attract the opposite sex, avoid predators, and so on. Most luminescent living organisms have ingenious optical structures which can help them get high luminescent performances. These remarkable and efficient structures have been formed by natural selection from long-time evolution. Researchers keenly observed the enhanced luminescence phenomena and studied how these phenomena happen in order to learn the characteristics of bio-photonics. In this review, we summarize the optical structures for enhancing luminescence and their applications. The structures are classified according to their different functions. We focus on how researchers use these biological inspirations to enhance different luminescence processes, such as chemiluminescence (CL), photoluminescence (PL), and electroluminescence (EL). It lays a foundation for further research on the applications of luminescence enhancement. Furthermore, we give examples of luminescence enhancement by bio-inspired structures in information encryption, biochemical detection, and light sources. These examples show that it is possible to use bio-inspired optical structures to solve complex problems in optical applications. Our work will provide guidance for research on biomimetic optics, micro- and nano-optical structures, and enhanced luminescence. [ABSTRACT FROM AUTHOR]

The preparation of high-efficiency phosphor is the key to the construction of white light-emitting diode (WLED) devices and their application in indoor photovoltaics. Compared with YVO4, InVO4 is not suitable as the host material of lanthanide ions because of its strong self-luminescence. Here, the work focused on combining the broadband emission from InVO4 and the red luminescence from YVO4:Eu3+ to obtain enhanced and stable multicolor luminescence. The band structure, density of state, and optical properties were studied by density functional theory. The spectral configuration of YVO4:In3+/Eu3+ with (112) surface appears to be broadening and redshifts with increasing layer number. When the In3+ concentration is 3.5 mol%, the YVO4:30%Eu3+/In3+ emits the strongest light. The Judd-Ofelt parameter Ω2 of YVO4:In3+/Eu3+ increases with increaing In3+ concentration, indicating that the symmetry decreases. By adjusting In3+/Eu3+ contents, the YVO4:In3+/Eu3+ not only can emit white light with a color rendering index of 95, but also can be used as high-efficiency red phosphor to build WLED devices with blue emitting N/Tb codoped carbon quantum dots (CQDs-N:Tb3+) and green emitting MOF:Tb3+ (MOF = metal organic framework), for which the color rendering index can also reach 95 and the color temperature is 5549 K. The manufactured WLED devices were further used to excite the silicon solar cell and make it show good photoelectric characteristics. [ABSTRACT FROM AUTHOR]

A novel far‐red emitting phosphor Sr2MgWO6: Mn4+ was fabricated using high‐temperature solid‐state reaction. X‐ray diffraction patterns, scanning electron microscopy images, and photoluminescence excitation and photoluminescence spectra for this phosphor were analyzed in detail. The analysis revealed that its emission ranged from 600 to 800 nm and peaked at 699 nm, which was attributed to the 2Eg→4A2g transition of Mn4+ under 314 nm excitation. Moreover, we introduced rare‐earth Yb3+ ions into the Sr2MgWO6:Mn4+ to improve its far‐red emitting intensity. The photoluminescence (PL) intensity of the Yb3+ co‐doped phosphor was three times higher than that of the single‐doped phosphor. Therefore charge compensation is an efficient approach to improving PL intensity. The phosphor emitted a far‐red light that resembled the pigments essential for plant growth in terms of the absorption spectrum. Therefore, the obtained phosphor, Sr2MgWO6:0.006Mn4+,0.2Yb3+, had the potential to be a new type of far‐red luminescent powder for indoor plant growth LEDs. [ABSTRACT FROM AUTHOR]

Tellurite glasses doped with Tm3+, Ho3+ and Ce3+ ions were prepared via melt-quenching to realise broadband and fluorescence enhancement in near-infrared (NIR) band. Under the pumping of a commercial 808 nm laser diode (LD), the emission bands at 2.0 μm, 1.85 μm, 1.47 μm, and 705 nm were observed in the Tm3+/Ho3+ co-doping glass samples, which originated from the transitions of Ho3+:5I 7 →5I 8 and Tm3+:3F 4 →3H 6 , 3H 4 →3F 4 , 3F 2,3 → 3H 6 , respectively. The existence of 2.0 μm band fluorescence is due to the energy transfer from the Tm3+:3F 4 level to the Ho3+:5I 7 level. This band overlaps with the 1.85 μm band which forms a broadband fluorescence spectrum in the range of 1600–2200 nm. In glass samples co-doped with Tm3+/Ho3+ with 0.085 mol% Ho 2 O 3 and 1 mol% Tm 2 O 3 , the full width at half maximum (FWHM) of this broadband spectrum (1600–2200 nm) was as high as ∼370 nm. After introducing 0.6 mol% CeO 2 , the emission intensity of broadband fluorescence increased by ∼50%, which was caused by the cross-relaxations between Ce3+ and Tm3+ ions. The lifetime of fluorescence decay was determined to prove the interactions among the doped rare-earth ions, the radiative parameters such as transition probability, branching ratio and radiative lifetime were calculated from the absorption spectra based on the Judd-Ofelt theory to better understand the observed luminescence phenomena. In addition, X-ray diffraction (XRD) confirmed the amorphous state structure of the synthesised glass samples, while Raman spectrum revealed the different vibrational structural units forming the glass network. [ABSTRACT FROM AUTHOR]

Eu3+ activated zinc titanate red-emitting phosphors have been synthesized by a solid state reaction, and Li+ is added as the charge compensator to tune the optical performances of the phosphors. The structure of samples synthesized at different temperature reveals temperature dependence. The crystallization of particles is improved with increasing calcination temperature. The surface morphology and element distribution of the samples are observed by scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDS). Various elements are evenly distributed in the matrix materials. The luminescence intensity of Eu3+ is effectively improved by co-doping Li+, and the luminescence intensity of the phosphor with Li+ content of 5 mol% and 7 mol% is twice than that of the phosphor without Li + when the annealing temperature is 600 °C. While the influence of Li + on the photoluminescence performance becomes weaker with the annealing temperature increasing. The highest relative sensitivity of 0.65%/K is obtained in the sample annealed at 1000 °C, which is not affected by the Li+ dopants. [ABSTRACT FROM AUTHOR]

This work demonstrates the simultaneous control of three separate optical responses, i.e., phase, amplitude, and luminescence, using anisotropic gap-plasmon metasurfaces. Due to the incorporated geometric anisotropy, the designed structure exhibits distinct responses under x - and y -polarized light, revealing either a color image, or a holographic projection in the far-field as well as a luminescence image when pumped with NIR laser. Inserting upconversion nanoparticles (UCNPs) into the dielectric gaps of the structures, creates a unique "fingerprint", achieving a physically unclonable function (PUF) layer. Our triple-mode metasurface paves the way towards highly secure and easy-to-authenticate metasurface-driven optically variable devices (mOVDs). [Display omitted] In optical anti-counterfeiting, several distinct optically variable devices (OVDs) are often concurrently employed to compensate for the insufficient security level of constituent OVDs. Alternatively, metasurfaces that exhibit multiple optical responses effectively combine multiple OVDs into one, thus significantly enhancing their security and hindering fraudulent replication. This work demonstrates the simultaneous control of three separate optical responses, i.e., phase, amplitude, and luminescence, using anisotropic gap-plasmon metasurfaces. Due to the incorporated geometric anisotropy, the designed structure exhibits distinct responses under x - and y -polarized light, revealing either a color image, or a holographic projection in the far-field. Furthermore, inserting upconversion nanoparticles (UCNPs) into the dielectric gaps of the structures, the designed metasurface is able to generate a third luminescent image upon illumination with the near-infrared light. The stochastic distribution of the UCNPs constitutes a unique "fingerprint", achieving a physically unclonable function (PUF) layer. Crucially, our triple-mode metasurface requires only readily attainable equipment such as a macro-lens/camera and a laser pointer to read most of the channels, thus paving the way towards highly secure and easy-to-authenticate metasurface-driven OVDs (mOVDs). [ABSTRACT FROM AUTHOR]

• Tellurite glasses doped with Er3+ and Au NPs were synthesized. • Heat treatment was applied to promote the growth of the Au NPs. • Coupling between Er3+ and Au NPs exert prominent enhancement in NIR emission. • Luminescence enhancement was improved under cooling conditions. • Semiempirical calculations explain the Er3+-Au NPs coupling. The plasmonic applications at low temperatures of metallic nanoparticles in glasses doped with rare-earth ions are not yet covered in-depth analysis in the literature. This paper insights into the coupling between gold nanoparticles and Er3+ embedded in tellurite glasses via luminescence enhancement of the emission centred at 1.53 µm under controlled temperature. This enhancement is obtained for the sample with 24 h of heat treatment (TErAu24) concerning the Er3+ single doped (TEr) at room temperature under 980 nm excitation. The enhancement remains under cooling conditions, consequence of the strong coupling between the plasmon and the Er3+, attributed to an increment of the localized plasmon mode volume at low temperatures. Further, the band area increment of the TErAu24 sample comparing the spectra at 98 and 348 K is 414 %, whereas for the TEr is about 348 %. These findings provide advanced understanding of the plasmonics on quantum emitters engineering. [Display omitted] [ABSTRACT FROM AUTHOR]

The blue-emitting KBaYSi 2 O 7 :Bi3+ phosphor was prepared via the high-temperature solid-phase method, and the structural Si4+ was partially substituted by Al3+ and Ge4+ to improve its luminescence properties. A blue emission peak of the KBaYSi 2 O 7 :Bi3+ phosphor appears at 418 nm under an excitation of 370 nm, which is attributed to the 3P 1 →1S 0 electron transition of Bi3+. The luminescence intensity (λ em = 418 nm) of KBaYSi 1.94 Al 0.06 O 7 :0.03Bi3+ and KBaYSi 1.96 Ge 0.04 O 7 :0.03Bi3+ was 1.81 and 1.94 times that of KBaYSi 2 O 7 :0.03Bi3+, respectively. The luminescence intensity of phosphors at 423 K remained at 62.5 % (KBaYSi 1.94 Al 0.06 O 7 :0.03Bi3+) and 65.7 % (KBaYSi 1.96 Ge 0.04 O 7 :0.03Bi3+) of the initial values (at 303 K), respectively. The actual w -LEDs were fabricated with these blue-emitting phosphors, emitting a warm and bright white light. Therefore, the KBaYSi 2-x Al x O 7 :0.03Bi3+ and KBaYSi 2-y Ge y O 7 :0.03Bi3+ blue-emitting phosphors with excellent luminescence performance can be potential applied in w -LEDs and display fields. • Al3+ and Ge4+ substituted KBaYSi 2 O 7 :Bi3+ was first prepared for excellent blue emission. • The luminescence intensity of KBaYSi 2 O 7 :Bi3+ was enhanced by 1.81 and 1.94 times by Al3+ and Ge4+ substitution. • The combined w -LEDs with KBaYSi 2-x Al x O 7 :Bi3+ and KBaYSi 2-y Ge y O 7 :Bi3+emit a warm and bright white light. [ABSTRACT FROM AUTHOR]

[Display omitted] • A strategy to boost low-temperature persistent luminescence by forming a NaNbO 3 -LiNbO 3 heterostructure with Pr3+ dopants. • Prominent persistent luminescence is realized after the cessation of charging at 253 K. • The enhancement mechanism is explained through structural characterization and density functional theory calculations. • Promising applications in dynamic info encryption and anti-counterfeiting at low temperatures are demonstrated. We report a strategy to enhance the low-temperature persistent luminescence (LT PersL) in perovskite oxides through the formation of a heterostructure, i.e. NaNbO 3 -LiNbO 3 with Pr3+ dopants, via the defect engineering method. Prominent LT PersL was realized when the Na/Li ratio was 0.6/0.4, with the red emission still visible over 1 h after the cessation of charging at 253 K. The PersL-enhancement mechanism is elucidated with elaborate structural characterization and density functional theory calculations. The introduction of the heterostructure increased electron–hole recombination efficiency, generated long-distance photogenerated carriers, and created a pathway for successive shifts in the band structure between NaNbO 3 and LiNbO 3 to form shallow broad traps with broad distribution. The promising applications of these materials in dynamic information encryption and anti-counterfeiting fields at low temperatures are demonstrated. [ABSTRACT FROM AUTHOR]

Mn4+-activated fluoride phosphors exhibiting broadband excitation and sharp line emission within the sensitivity range of the human eye are extensively utilized as supplementary red phosphors for white light-emitting diodes (WLEDs), and the K 2 SiF 6 :Mn4+ phosphor has achieved considerable commercial success. However, the K 2 SiF 6 :Mn4+ phosphor has defects in long fluorescence decay life and poor moisture resistance owing to its Mn-doped fluoride composition, which severely restricts its application in fast response commercialized backlight LEDs. Hence, we selected the monoclinic crystal K 2 NbF 7 :Mn4+ phosphor with higher zero phonon line (ZPL) emission. Using density functional theory (DFT) calculations, we identified the optimal sensitizer Sc3+ and improved the original synthesis method to develop a new K 2 NbF 7 :0.06Mn4+-0.02Sc3+ (KNFMSc) phosphor successfully. The KNFMSc phosphor has an integral luminescence intensity 2.63 times that of K 2 SiF 6 :Mn4+, superior moisture resistance performance, which is characterized by maintaining 60.78 % of its initial luminescence intensity after a 12 h water immersion, and a faster fluorescence decay lifetime of 3.79 ms. After being assembled into LEDs, the KNFMSc phosphor emits warm white light with a color rendering index of 93.5 and a correlated color temperature of 3924 K, representing enhanced luminous stability under varying driving currents. Therefore, the prepared KNFMSc phosphor holds considerable potential for application in WLEDs and backlighting LEDs, offering a new alternative to commercial phosphors. [Display omitted] • A novel K 2 NbF 7 :0.06Mn4+-0.02Sc3+ phosphor has be successfully developed with the help of DFT calculations. • Sample perfectly meets the requirements of commercial fast response WLEDs and backlight LEDs due to its short lifetime. • The doping of Sc3+ dramatically improves the luminescence and moisture resistance of phosphors. [ABSTRACT FROM AUTHOR]

Control over the radiative and non-radiative channels of the IR-emitting quantum dots (QDs) is crucially important to improve performance of related devices. Here, we study spontaneous photoluminescence (PL) enhancement of mercury telluride QDs coupled to plasmonic nanoantenna arrays supporting collective plasmon mode spectrally matching QD's PL spectrum. Our systematic studies revealed how PL enhancement varies with QDs layer thicknesses as well as laser excitation and emission collection conditions, providing deeper insight into the QD/plasmonic arrays interaction. We demonstrated that careful adjustment of excitation and emission collection parameters leads to more than an order of magnitude enhancement of spontaneous emission of HgTe QDs coupled with periodical plasmonic arrays with resonances spectrally matched to QDs absorption and emission bands. The region of QDs layer thickness, wherein plasmon-related quenching and dot-to-dot resonance energy transfer have the minimal impact and, hence the PL enhancement has the maximal factor, had been determined. [ABSTRACT FROM AUTHOR]

Abstract We utilized a seeded growth method to synthesize SiO2@Ag NPs with tunable plasmonic resonance peak to investigate the effect of spectral overlap between the SiO2@Ag plasmonic resonance spectrum and the PtTFPP‐based oxygen sensors’ absorbance spectra on luminescence enhancement and performance optimization. An organic silicate was used as the matrix. Oxygen‐sensors were produced by directly casting the mixture of NPs and dyes with silicate gels onto glass slides. Oxygen‐induced spectral response of the PtTFPP was obtained as the analytical signal. Our results show that when the plasmonic resonance spectrum of SiO2@Ag has a maximum wavelength overlap with the absorbance spectra of dyes, the Stern‐Volmer slopes were enhanced by almost an order of magnitude. At 21% O2, the Stern‐Volmer plot achieved a maximum seven‐fold increase over the oxygen sensor without the metal‐enhanced luminescence. Our results also show that 10% wt NPs is the optimal amount for the PtTFPP‐SiO2@Ag based oxygen sensors that can eliminate self‐quenching and the NRET process. These data confirm that the spectral overlap between the dyes and noble metal NPs and how to eliminate self‐quenching and the NRET process are vital to high‐sensitive oxygen sensors. We have also shown that our fabrication process of these oxygen sensors is repeatable.

[Display omitted] • The obviously and uniformly luminescence enhancement for Au NRs embedded Eu-PMMA films is realized. • The enhanced luminescence can be used to improve the detection of MG based on the FRET from Eu to MG. The detected lowest concentration for MG is reduced from 0.01 mg L-1 to 0.001 mg L-1. • The prepared detection platform can realize the sensitive, reusable and the single droplet (<10 μL) detection of MG. The sensitively detection of malachite green (MG) is very important because it is a low-cost and effective fungicide and insecticide in the aquatic industry. In this study, the gold nanorods (Au NRs) are prepared and incorporated into Eu-poly(methylmethacrylate) (PMMA) films in a simple and convenient way. The Au NRs embedded Eu-PMMA films reveal a significant and uniform luminescence enhancement due to the LSPR effect of plasmonic nanostructures. Based on the enhanced luminescence, the sensitive and single droplet (<10 μL) detection of malachite green is achieved through the fluorescence resonance energy transfer between Eu and MG. The detected lowest concentration for MG is reduced from 0.01 mg L-1 to 0.001 mg L-1. Further more, the Au NRs embedded Eu-PMMA films as the platform exhibits the excellent recyclability and stability, which not only reduces waste but also enhances the platform's environmental friendliness. This work not only provides an enhanced fluorescence for the detection of MG, but also provides a novel strategy for the design of fluorescent sensor toward different biomolecules. [ABSTRACT FROM AUTHOR]

A series of Ca 19 Zn 2 (PO 4) 14- y AG y :Dy3+ (AG = BO 3 3−, SiO 4 4−) white-emitting phosphors with partial PO 4 3− substitution were synthesized through high-temperature solid-state reaction. The BO 3 3− and SiO 4 4− anionic groups were introduced into Ca 19 Zn 2 (PO 4) 14 :Dy3+ for enhancing the luminescence of Dy3+. The X-ray diffraction results exhibited that all samples were assigned to the standard trigonal Ca 19 Zn 2 (PO 4) 14 structure with R3c (161) space group. The white emission spectrum of Dy3+-doped phosphors was composed of several characteristic peaks located at 484 nm, 575 nm and 665 nm, corresponding to 4F 9/2 → 6H 15/2 , 6H 13/2 and 6H 11/2 electron transitions, respectively. After partial SiO 4 4− and BO 3 3− substituting PO 4 3−, the luminescence intensity of Ca 18.62 Zn 2 (PO 4) 13.75 (SiO 4) 0.25 :0.38Dy3+ and Ca 18.62 Zn 2 (PO 4) 13.65 (BO 3) 0.35 :0.38Dy3+ samples were higher by 1.68 and 1.49 times than that of Ca 18.62 Zn 2 (PO 4) 14 :0.38Dy3+ sample, respectively, due to the charge compensation and crystal field environment effect. The actual w -LEDs fabricated with as-prepared Ca 18.62 Zn 2 (PO 4) 13.75 (SiO 4) 0.25 :0.38Dy3+ and Ca 18.62 Zn 2 (PO 4) 13.65 (BO 3) 0.35 :0.38Dy3+ phosphors showed excellent optical performances. All results indicated that the single component Ca 18.62 Zn 2 (PO 4) 14- y AG y :0.38Dy3+ white-emitting phosphors could have a potential application in w -LEDs. [Display omitted] [ABSTRACT FROM AUTHOR]

The Ca 5 (PO 4) 2 SiO 4 :Eu3+ and Ca 5 (PO 4) 2 SiO 4 :Sm3+ phosphors were obtained via solid-state reaction, and A3+ (A = La, Bi) ions were further co-doped in the host for luminescence enhancement. The XRD results showed that the samples have a Ca 5 (PO 4) 2 SiO 4 structure with good crystallinity. The characteristic peaks of Ca 5 (PO 4) 2 SiO 4 :Eu3+, A3+ and Ca 5 (PO 4) 2 SiO 4 :Sm3+, A3+ phosphors severely appeared at 616 nm and 605 nm, which is originating from the 4f-4f transitions of Eu3+ and Sm3+ ions. Compared with Ca 4.8 (PO 4) 2 SiO 4 :0.2Eu3+, the luminescence intensity of Ca 4.8- y (PO 4) 2 SiO 4 :0.2Eu3+, y A3+ was increased by 1.34- and 1.65-fold with La3+/Bi3+ co-doping, respectively. And the luminescence intensity reached 1.77- and 1.49-fold that of Ca 4.9 (PO 4) 2 SiO 4 :0.1Sm3+ for Ca 4.9- y (PO 4) 2 SiO 4 :0.1Sm3+, y A3+, Meanwhile, Ca 4.7 (PO 4) 2 SiO 4 :0.2Eu3+, 0.1Bi3+ and Ca 4.75 (PO 4) 2 SiO 4 :0.1Sm3+, 0.15La3+ phosphors had excellent thermal stability and the luminescence intensity at 210 °C still maintained at 75.16% and 93.02% of that at room temperature. In addition, some w -LEDs were manufactured via mixing the as-prepared phosphor with others, which exhibited a white light with excellent chromaticity parameters (CCT = 4726 K, Ra = 89.3). All results manifested that the excellent Ca 5 (PO 4) 2 SiO 4 :Eu3+, Bi3+ phosphor was expected to be used as a red component in solid-state lighting devices. [ABSTRACT FROM AUTHOR]

Functional materials with highly desirable properties have been highly pursued for a long time due to their potential applications in many fields. High pressure can effectively reduce the interatomic distances and modulate the bonding patterns of materials without changing their chemical compositons, which has been considered as a powerful and important approach to design new functional materials with desired structures and properties. Many interesting types of functional carbon materials, such as optical transparent carbon, super strong and elastic carbon, and ultrahard bulk amorphous carbon have been obtained from different carbon precuresors under high pressure. Recent progress on the high pressure research of low dimensonal carbon composite materials are introduced. Based on the predesigned carbon-based precursors, new carbon materials with superhard properties, covalent polymerization and anomalous photoluminescence enhancement by the application of high pressure have been obtained. [ABSTRACT FROM AUTHOR]

[Display omitted] A novel perovskite CaLa 4 Ti 4 O 15 :Eu3+ red-emitting phosphor was synthesized via a sol-combustion method, and Gd3+ was further co-doped into structure to improve the luminescence performance. The effects of Eu3+ doping and Gd3+ co-doping concentrations on the microstructure and luminescence properties were investigated. The red emission peaks of as-prepared phosphors originate from the 5D 0 →7F j electron transitions of Eu3+ ions. Under 273 nm excitation, the luminescence intensity of Eu3+ was significantly enhanced through the energy transfer between Gd3+ and Eu3+ in CaLa 4 Ti 4 O 15 , and the luminescence intensity was also improved even under the excitation of 394 nm. By combining red-emitting CaLa 4 Ti 4 O 15 :Eu3+, Gd3+ phosphor with commercial blue and green phosphors on n -UV chip (λ = 395 nm), an eye-friendly w -LEDs with appropriate correlated color temperature (4761 K) and high color rendering index (R a = 93.1) has been realized. The electroluminescence spectrum of the packaged red LED have an excellent match with the P R absorption of plants. In addition, when introducing CaLa 4 Ti 4 O 15 :Eu3+, Gd3+ phosphor into a commercial w -LED with YAG:Ce3+, the adjustable chromaticity parameters like CCT and CRI values can be obtained. These results demonstrated that the as-prepared CaLa 4 Ti 4 O 15 :Eu3+, Gd3+ phosphor is an outstanding candidate as the red component for the application of w -LEDs and plants lighting. [ABSTRACT FROM AUTHOR]

Assembling cellulose nanocrystals (CNCs) can induce solid-state photoluminescence based on Stokes scattering. Such photoluminescent materials are free of photo-quenching and show great potential in optical applications, whereas poor flexibility of assembled CNC arrays limits their applications. Here, a binary co-assembly of 1D nanoparticles and long-chain polymers was explored to produce the uniaxial CNC arrays into transparent poly(vinyl alcohol) (PVA) membranes, which enhanced the mechanical properties, especially ductility. Besides, the CNC assembly was controlled by adjusting the mass ratio between CNCs and PVA. The result indicated that co-assembling with PVA could improve the uniaxial orientation of CNC arrays, which played a crucial role in enhancing the emission quantum efficiency (EQE). Stretching the PVA/CNC membrane could further induce an enhancement in EQE together with a blue shift in excitation wavelength. The mechanism study on stimulation-response suggested that the EQE enhancement and blue shift came from the change in uniaxial orientation degree and periodicity of the CNC assembly, respectively. Since the stimulation-responsive enhancement in EQE (from ca. 40 to 60%) can even be observed by naked eyes, we believe such cellulose-based materials can be widely used in optical sensors. [ABSTRACT FROM AUTHOR]

The all‐inorganic metal halide perovskite CsPbX3 (X = Cl, Br, and I) has received extensive attention in the field of white light‐emitting diodes (WLEDs) due to its high luminous intensity and high color purity. However, the shortcoming of poor stability directly affects the luminous performance of the WLED devices and reduces their luminous efficiency, which has become an urgent problem to be solved. Here, three‐color lead halide perovskite phosphors (blue‐emitting CsPbBr3 synthesized at 20 °C (CPB‐20), green‐emitting CsPbBr3‐80 (CPB‐80)/CsPbBr3:SCN−(CPB:SCN−), and red‐emitting PEA2PbBr4 (PPB)/PEA2PbBr4:Mn2+ (PPB:Mn2+)) with higher stability and luminous intensity are simultaneously prepared and applied in WLEDs. Density functional theory is used to optimize the structures of CsPbBr3 and PEA2PbBr4, and to calculate the work function, optical properties, and charge density difference. Not only the WLED devices with three‐color lead halide perovskite phosphors are constructed, but also WLED devices from warm white to cold white are realized by tuning the ratio of the different emissions, and a superior color quality (color rendering index of 96) and ideal correlated color temperature (CCT of 9376 K) are achieved. This work will set the stage for exploring low‐cost, environmentally friendly, high‐performance WLEDs. [ABSTRACT FROM AUTHOR]

The influence of Mn2+ ion concentration (x = 0–20 mol%) as well as the role of thermal-annealing temperature (400–600°C) on the structural as well as luminescence properties of NaYF4:Yb, Er (Y: 78-x%, Yb: 20%, Er: 2%) microcrystals prepared via a coprecipitation method is investigated. The cubic phase of the as-prepared NaYF4:Yb, Er (Y: 78%, Yb: 20%, Er: 2%) was found to remain intact upon the addition of the Mn2+ ions, but the thermal-annealing elucidates that the phase of the sample depends upon the annealing temperature as well as the Mn2+ ion concentration. Among the Mn2+ ion co-doped samples, 3 mol% doped samples dominant to have a maximum positive influence on the upconversion luminescence of the sample, and a further increase in concentration leads to the concentration-induced quenching of the upconversion luminescence. Moreover, the enhancement factor of green ( 2 H 11 / 2 → 4 I 15 / 2 a n d 4 S 3 / 2 → 4 I 15 / 2 ), as well as red ( 4 F 9 / 2 → 4 I 15 / 2 ) emission, depend upon the annealing temperature, with a maximum enhancement factor of 5 and 3.12 times for the sample annealed at 400°C, 8.6 and 7.25 times for the sample annealed at 500°C, and 6 and 4 times for the sample annealed at 600°C, as compared to Mn2+ ion undoped samples. The maximum emission strength for the green as well as red is observed for the sample annealed at 600°C and co-doped with 3 mol Mn2+ ions. The laser power-dependent study on all the samples shows that the upconversion process is a multi-photon process, predominantly a two-photon process. [ABSTRACT FROM AUTHOR]

β -NaYF _4 : Yb ^3+ /Tm ^3+ /Zr ^4+ microcrystals are synthesized by a facile hydrothermal route. The up-conversion (UC) luminescence and photoelectric effects are enhanced simultaneously with the introduction of Zr ^4+ ions under IR excitation. With the Tm ^3+ ions fluorescence spectra under 980 nm excitation, the blue and red emissions reached the highest intensity in the case of 4 mol% Zr ^4+ doping. Taking the advantage of Zr ^4+ stimulates the free electrons transfer from the valence band (VB) to the conduction band (CB) in β -NaYF _4 :Yb ^3+ /Tm ^3+ /Zr ^4+ microcrystals, the photocurrent reached the highest intensity in the case of 4 mol% Zr ^4+ doping at 780 nm excitation. The β -NaYF _4 : Yb ^3+ /Tm ^3+ /Zr ^4+ microcrystals with both enhanced UC luminescence and photoelectric properties are highly potential to contribute in photovoltaic and infrared sensors application.

Luminescent Cu I complexes are an important class of coordination compounds due to their relative abundance, low cost and ability to display excellent luminescence. The title Cu 2 I 2 P 2 S 2 -type binuclear complex, di-μ-iodido-bis[(thiourea-κS)(triphenylphosphine-κP)copper(I)], [Cu 2 I 2 (CH 4 N 2 S) 2 (C 18 H 15 P) 2 ], conventionally abbreviated as Cu 2 I 2 TPP 2 TU 2 , where TPP and TU represent triphenylphosphine and thiourea, respectively, is described. In this complex, each Cu I atom adopts a CuI 2 PS four-coordination mode and pairs of atoms are connected to each other by two μ 2 -I ligands to form a centrosymmetric binuclear cluster. It was also found that the paper-based film of this complex exhibited obvious luminescence light-up sensing for pyridine and 4-methylpyridine.

Rare earth-doped upconversion nanoparticles (UCNPs) have achieved a wide range of applications in the sensing field due to their unique anti-Stokes luminescence property, minimized background interference, excellent biocompatibility, and stable physicochemical properties. However, UCNPs-based sensing platforms still face several challenges, including inherent limitations from UCNPs such as low quantum yields and narrow absorption cross-sections, as well as constraints related to energy transfer efficiencies in sensing systems. Therefore, the construction of high-performance UCNPs-based sensing platforms is an important cornerstone for conducting relevant research. This work begins by providing a brief overview of the upconversion luminescence mechanism in UCNPs. Subsequently, it offers a comprehensive summary of the sensors' types, design principles, and optimized design strategies for UCNPs sensing platforms. More cost-effective and promising point-of-care testing applications implemented based on UCNPs sensing systems are also summarized. Finally, this work addresses the future challenges and prospects for UCNPs-based sensing platforms., (© 2024 Wiley‐VCH GmbH.)

In the vicinity of metal nanostructures, phosphorescent intensity can be greatly enhanced through the localized surface plasmon resonance (LSPR). The enhancement of phosphorescence intensity in noble-metal nanoparticle (NP) systems is highly dependent on the overlap of the absorbance peak of a noble metal with that of phosphorescent dyes. When the peak of the NPs' absorption spectra has a maximum overlap with that of these dyes, the phosphorescence enhancement is the largest. Here, we use a seeded growth method to synthesize SiO2/Au NPs with tunable plasmonic resonance and compare their phosphorescence enhancement for an oxygen range of 0–21%. The measurement sensitivity of oxygen is strongly dependent on the enhancement of phosphorescence. When used with PtTFPP, when the absorbance peak of the SiO2/Au NPs has a maximum overlap with that of PtTFPP, the phosphorescence enhancement factor is as high as 7; the sensitivity of oxygen concentration is as high as 75. Moreover, we also optimize the performance by varying the number of NPs to eliminate the nonradiative energy-transfer (NRET) process and self-quenching. [ABSTRACT FROM AUTHOR]

A series of Sr 9 Y(PO 4) 7 :Eu3+ and Sr 9 Y(PO 4) 7 :Eu3+, Gd3+ red-emitting phosphors were prepared via a high-temperature solid-state method, Gd3+ ion was co-doped in Sr 9 Y(PO 4) 7 :Eu3+ as sensitizer to enhance the luminescence property. The X-ray diffraction results verify that the structure of the as-prepared samples is consistent with the standard Sr 9 Y(PO 4) 7 phase. All the Sr 9 Y(PO 4) 7 :Eu3+ samples show both characteristic emission peaks at 594 nm and 614 nm under near-ultraviolet excitation of 394 nm. The co-doping of Gd3+ significantly improves the luminescence intensity of the Sr 9 Y(PO 4) 7 :Eu3+ phosphors due to the crystal field environment effect and energy transfer of Gd3+→Eu3+ caused by the introduction of Gd3+, especially Sr 9 Y(PO 4) 7 :0.11Eu3+, 0.05Gd3+, which emission intensity is higher than that of Sr 9 Y(PO 4) 7 :0.11Eu3+ by 1.21 times. The color purity and lifetime of Sr 9 Y(PO 4) 7 :0.11Eu3+, 0.05Gd3+ phosphor are 88.26% and 3.7615 ms, respectively. A w -LED device was packaged via coating the as-prepared phosphor on n-UV chip of 395 nm with commercial phosphors. These results exhibit that the Sr 9 Y(PO 4) 7 :Eu3+, Gd3+ red-emitting phosphor can be used as a red component in the w -LEDs application. [ABSTRACT FROM AUTHOR]

We utilized a seeded growth method to synthesize SiO2@Ag NPs with tunable plasmonic resonance peak to investigate the effect of spectral overlap between the SiO2@Ag plasmonic resonance spectrum and the PtTFPP‐based oxygen sensors' absorbance spectra on luminescence enhancement and performance optimization. An organic silicate was used as the matrix. Oxygen‐sensors were produced by directly casting the mixture of NPs and dyes with silicate gels onto glass slides. Oxygen‐induced spectral response of the PtTFPP was obtained as the analytical signal. Our results show that when the plasmonic resonance spectrum of SiO2@Ag has a maximum wavelength overlap with the absorbance spectra of dyes, the Stern‐Volmer slopes were enhanced by almost an order of magnitude. At 21% O2, the Stern‐Volmer plot achieved a maximum seven‐fold increase over the oxygen sensor without the metal‐enhanced luminescence. Our results also show that 10% wt NPs is the optimal amount for the PtTFPP‐SiO2@Ag based oxygen sensors that can eliminate self‐quenching and the NRET process. These data confirm that the spectral overlap between the dyes and noble metal NPs and how to eliminate self‐quenching and the NRET process are vital to high‐sensitive oxygen sensors. We have also shown that our fabrication process of these oxygen sensors is repeatable. [ABSTRACT FROM AUTHOR]