Ultraviolet Chip Research Articles

Designing of Eu2+-activated single-phase white-emitting phosphor through modifying cationic sites for high color rendering full-spectrum illumination

Single-phase full-spectrum white-emitting phosphors with individual activator are of great significance for avoiding unnecessary energy loss and realizing high luminescence efficiency. Herein, a novel Na2Ca17Al2(PO4)14:Eu2+ phosphor is designed and the strategy of cation substitution is functioned in regulating the luminescence. The Na2Ca17Al2(PO4)14:Eu2+ phosphor could realize basic full-spectrum emission under the excitation of 335 nm, but the lack of red-light component and the CIE color coordinates of (0.2291, 0.2302) can not meet the requirements for white light-emitting diodes (WLEDs). With partial or even full replacement of Na+ in the host with Li+ ions, the red-light component in the emission is efficiently improved and each emitting color reaches the appropriate proportion, achieving the cold white light at (0.3330, 0.3179). By further regulating the excitation wavelength, Li2Ca17Al2(PO4)14:Eu2+ phosphor finally exhibits bright warm white emission with the color coordinates of (0.3551, 0.3448) upon 360 nm excitation and the internal quantum efficiency is 33.2 %. It is due to the substitution of Na+ by Li+ ions that contributes to the redistribution of Eu2+ in different crystal sites and regulates the photoluminescence of this phosphor, further realizing the full-spectrum white light emission. The fabricated two WLED devices by this material with near ultraviolet chips show outstanding color rendering index of 92.7 and 96.8, respectively, revealing that this material has a promising prospect in the field of full-spectrum illumination.

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

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

Photoluminescence properties of Mn2+-activated red-emitting phosphors with superior thermal stability for backlighting display applications

The red-emitting phosphors, Na2Mg1-x(PO3)4:xMn2+ with concentrations ranging from 0.01 to 0.11, have been successfully synthesized using a simple solid-state method. The as-synthesized phosphors are crystallized in an orthorhombic structure. The luminescence mechanism of Mn2+ ions in Na2Mg(PO3)4 lattice has been deeply explained using the Tanabe-Sugano (T-S) energy level diagram for the d5 electron configuration. The typical photoluminescent emission (PL) and photoluminescent excitation (PLE) spectra were measured. Several excitation peaks in the spectral range of 250–550 nm on the PLE spectrum and a strong emission peak at 613 nm indicate that the as-synthesized phosphors can be effectively excited using ultraviolet (UV) and near-UV LED chips. Several photometric characteristics were measured, such as the Commission International de'LEclarirage (CIE) chromaticity coordinate (x, y), color purity (CP), and correlated color temperature (CCT), corresponding to the concentration-dependent PL spectra. Furthermore, the thermal stability of the Na2Mg1-x(PO3)4:xMn2+ phosphors was investigated through temperature-dependent PL spectra and decay curves from 10 to 500 K. All results confirm that the as-synthesized red-emitting phosphors exhibit excellent thermal stability, which are attractive characteristics for white light emitting diodes (W-LEDs) applications.

Yellow light emitting Cs2Zr0.99Te0.01Cl6 with high efficiency emission via modified co-precipitation method synthesis for the light-emitting device

While lead-free perovskite has attracted widespread interest in the optical field by overcoming their toxicity and stability disadvantages compared to conventional lead-based perovskite, the low photoluminescence quantum yield (PLQY) of lead-free perovskite has greatly limited their commercialization path. In this research, a modified co-precipitation method was used to prepare Cs2ZrCl6, which was achieved by the addition of TeCl4 to shift the emission wavelength from 436 to 556 nm with bright yellow emission, the optimal PLQY of 98.2% was achieved by the addition of Te4+ in the amount of 1 % and the optimization of the reaction concentration. First-principles calculations and spectral analysis of Cs2Zr1-xTexCl6 show that the broadband yellow light emission comes from self-trapped excitons (STEs) in Cs2Zr1-xTexCl6. In addition, the luminous intensity of the prepared Cs2Zr1-xTexCl6 was 57.3, 63.3 and 90.1% of the initial intensity after exposure to air for 30 d, cyclic intermittent heating to 200°C and ultraviolet (UV) irradiation for 7 d, respectively. Finally, Cs2Zr1-xTexCl6 and Cs2ZrCl6:10% Bi were used as phosphors and encapsulated with a UV chip to make three different colors of light-emitting diodes (LED), where the white LED (WLED) had CIE coordinates of (0.3061 0.3244), color temperatures, color rendering indices as well as color tolerances of 6921 K, 84 and 6.52 respectively. This research provides a new approach to improve the performance of lead-free perovskite.

Two substitution strategies realize single-phase full-spectrum emission in Ca10Na(PO4)7:Eu2+ phosphors for WLED

Herein, a variety of single-phase full-spectrum emission phosphors doped with Eu2+ were synthesized. Under the 350 nm excitation, as K+ and Y3+ were introduced into Ca10Na(PO4)7 (CNP):1.5%Eu2+, respectively, the emission color of Ca9.85KyNa(1-y) (PO4)7:1.5%Eu2+ (0 ≤ y ≤ 1.0) was tuned from yellow to cyan, while that of Ca(9.85-z)NaY0.667z (PO4)7:1.5%Eu2+ (0 ≤ z ≤ 1.0) was tuned from yellow to green. The internal quantum yield (QY) of Ca9·85K0·4Na0·6(PO4)7 (CKNP):1.5%Eu2+ and Ca9·45NaY0·267(PO4)7 (CNYP):1.5%Eu2+ reached 47.47 % and 27.11 %, respectively. The introduction of K+ or Y3+ made Eu2+ selectively occupy the Ca sites and led to changes in the local environment of Eu2+, allowing for spectral tuning emission. In addition, the luminescence intensity of the samples retained 54.59 % and 31.34 % of their room temperature values. Eventually, two white light emitting diode (WLED) devices were fabricated, combining the synthesized white emitting phosphors with 365 nm ultraviolet (UV) chips. They exhibited high color rendering indices of 84.7 and 77.0, along with low correlated color temperatures of 5435 K and 5023 K. The Commission Internationale de L'Eclairage (CIE) color coordinates were (0.3349, 0.3975) and (0.3517, 0.4366), respectively. The results pointed to the phosphors' potential suitability for use in the WLED sector.

Synthesis and properties of naphthylamine derivative functionalized spiro-[fluorene-9,9′-xanthene] for single-component white light-emitting diodes

White light-emitting diodes (LEDs) with high color purity and color-rendering index have elicited much interest in many fields. In this work, a spirotype molecule SFX-PNA was designed and synthesized by combining a spiro[fluorene-9,9′-xanthene] (SFX) core with naphthylamine derivative functionalized at the 2,3′,6′,7-positions. Studies revealed that the highly twisted configuration allowed SFX-PNA to exhibit good thermal stability and a broad blue-emissive band (λem = 466 nm) in the solid state. In combination with the intrinsic yellow luminescence (λem = 556 nm) of commercially available GaN ultraviolet LED chips, a white LED with SFX-PNA as the phosphor was successfully obtained, which showed high color purity with Commission Internationale de L’Éclairage coordinates of (0.30, 0.33) and a color-rendering index of 86.

Folic Acid Passivated Efficient Cerium Doped Perovskite Nanocrystals for High‐Performance Light‐Emitting Diodes

AbstractThe 5d→4f transition of Ce3+ is allowed by the electric dipole and the parity selection rule and the position/intensity of the 5d excited state is strongly dependent on the materials’ composition and atomic structure. Herein, the composition‐dependent luminescence properties of Ce3+ in CsPbCl3‐xBrx (0 ≤ x ≤ 3) perovskite nanocrystals (PeNCs) are systematically revealed. It's observed that the 5d‐4f broadband emission of Ce3+ is greatly improved by optimizing the Cl:Br ratio due to the efficient energy transfer from excitons to Ce3+. Folic acid, a vitamin which is an extremely important cofactor, is introduced to regulate the film formation by interacting with uncoordinated ions. The modified CsPbCl1.5Br1.5 PeNCs with photoluminescence quantum yield of 91% represent a novel and extremely efficient white nanophosphor. Then, white light‐emitting diodes (WLEDs) are constructed by combining Ce3+‐doped PeNCs with 400‐nm ultraviolet chips with a luminous efficiency of 120.3 lm W−1, which is the most efficient perovskite single‐component WLED. Moreover, the blue‐violet LEDs are fabricated with external quantum efficiency of 0.84%, representing extremely high level of 400–435 nm perovskite LEDs. This work demonstrates the strategy in realizing high‐efficiency wavelength‐tunable PeNCs, motivating the further exploration of Ce3+‐doped perovskites in optoelectronic devices.

Luminescent properties of Y2LaCaGa3ZrO12: Bi3+, Al3+ cyan phosphors for application in white light emitting diodes

High-quality white light can be obtained from a mixture of blue, green, and red phosphors excited by ultraviolet chips. However, this approach suffers from the presence of a cyan gap in the emission spectra, which hinders further improvement in the color rendering index (CRI). The obvious solution to this problem should be the development of efficient ultraviolet-excited cyan phosphors to fill this gap. Therefore, a series of Y2LaCaGa3ZrO12: xBi3+ (x = 0–0.1) cyan phosphors were synthesized via high-temperature solid-state reaction method, and their properties were systematically characterized. The Bi3+ ion in Y2LaCaGa3ZrO12 exhibits dual-mode luminescence with emission bands peaking at 356 nm and 483 nm, originating from the 3P1→1S0 transitions of Bi3+ at different sites. The ultraviolet emission is attributed to Bi3+ occupying 8 coordination sites, while the cyan emission arises from Bi3+ in 6 coordination sites. It is noteworthy that the emission intensity and thermal stability of the phosphors can be further improved by partially substituting Ga3+ with Al3+. By incorporating Y2LaCaGa3ZrO12: 0.02Bi3+ or Y2LaCaGa2.7Al0.3ZrO12: 0.02Bi3+ with commercial phosphors and depositing them onto a 365 nm ultraviolet chip, the prototype white light emitting diodes (w-LEDs) exhibits white light with high CRI of 89.6 and 90.4, respectively. These results validate the potential of Bi3+ activated Y2LaCaGa3-yAlyZrO12 (y = 0–1) cyan phosphor as a promising candidate material for application in UV-excited w-LEDs.

White carbon dots with high quantum yield and multicolor carbon dots synthesized by the microwave method in one step

In the field of optics, carbon dots (CDs) have been extensively studied and have made rapid advancements in related fields, including bioimaging, optoelectronic devices and optical probes. However, it is difficult to efficiently synthesize high quantum yield (QY) white fluorescence CDs and multicolor CDs, which restricts their development in the field of optics. In this work, we chose formamide as the reaction solvent and used citric acid (CA) and 4-bromo-1,2-diaminobenzene to synthesize high-performance white fluorescent CDs20 with a QY of up to 87.5% and excellent stability (28 days). The reaction solvents (water, N,N-dimethylformamide and ethanol) were changed to obtain colorful CDs20 (orange, green and yellow) covering a broader visible spectrum via a microwave method. The solid model, which combines white fluorescent CDs20 and polyvinyl alcohol (PVA), exhibits strong white fluorescence as well as a solution state. To develop white-emitting diodes suitable for indoor use, a white CDs20 / PVA mixture with brilliant white fluorescence might be placed on ultraviolet (UV) chips (365 nm). The white LED had a high color purity (0.34, 0.25), excellent correlation color temperature (4250 K) and color rendering index (72.5). The results above show that white CDs have great promise for use in optical device fields.

Near‐unity quantum efficiency wavelength‐tunable NIR phosphors (Sr2−yCay)Sc1−xSbO6: xFe3+ with excellent thermal stability

AbstractFe3+ ions as near‐infrared (NIR) activators are emerging as an alternative to Cr3+.1–5 However, it is a challenge to develop Fe3+‐activated NIR phosphors featuring tunable optical properties, high efficiency, and thermal stability. Herein, we present a series of near‐unity internal quantum efficiency (IQE), wavelength‐tunable and thermal stability NIR‐emitting phosphors Sr2−yCaySc1−xSbO6:xFe3+ (S2−yCyS1−xS:xFe3+). Sr2ScSbO6:1%Fe3+ (SSS:1%Fe3+) phosphor shows broadband NIR emission at 904 nm and near‐unity IQE under excitation at 300 nm. Experimental and theoretical calculation results demonstrate that introduced Ca ions could increase the bandgap value and Debye temperature (ΘD) of host from Eg = 3.702 eV, ΘD = 609 K of y = 0 to Eg = 3.801 eV, ΘD = 692 K of y = 2. Significantly, the resultant S2−yCyS1−xS:1%Fe3+ NIR phosphors show wavelength‐tunable emission from 904 to 952 nm and high IQE of 84.6%–97.5% as well as enhanced thermal stability (I423K/I298K = 76.9%) of Ca2ScSbO6:1%Fe3+ (CSS:1%Fe3+) in comparison with that (I423K/I298K = 70.6%) of pristine sample. We fabricated an NIR light‐emitting diodes (LED) device by using CSS:1%Fe3+ NIR phosphors with ultraviolet LED chip and demonstrated its potential applications in anticounterfeiting, information encryption, and night vision.

Double Perovskite Single Crystals with High Laser Irradiation Stability for Solid-State Laser Lighting and Anti-counterfeiting.

Laser lighting devices, comprising an ultraviolet (UV) laser chip and a phosphor material, have emerged as a highly efficient approach for generating high-brightness light sources. However, the high power density of laser excitation may exacerbate thermal quenching in conventional polycrystalline or amorphous phosphors, leading to luminous saturation and the eventual failure of the device. Here, for the first time, we raise a single-crystal (SCs) material for laser lighting considering the absence of grain boundaries that scatter electrons and phonons, achieving high thermal conductivity (0.81 W m-1 K-1) and heat-resistance (575 °C). The SCs products exhibit a high photoluminescence quantum yield (89%) as well as excellent stability toward high-power lasers (>12.41 kW/cm2), superior to all previously reported amorphous or polycrystalline matrices. Finally, the laser lighting device was fabricated by assembling the SC with a UV laser chip (50 mW), and the device can maintain its performance even after continuous operation for 4 h. Double perovskite single crystals doped with Yb3+/Er3+ demonstrated multimodal luminescence with the irradiation of 355 and 980 nm lasers, respectively. This characteristic holds significant promise for applications in spectrally tunable laser lighting and multimodal anticounterfeiting.

Enhancing the luminescence of Mn4+-doped double perovskite oxide Ca2LuNbO6 phosphor by utilizing A-site cationic fluoride as a flux

Supplement illumination is indispensable in the indoor plant cultivation domain. In this research work, double perovskite Ca2LuNbO6:Mn4+ phosphors were produced. A strategy of enhancing luminescence performance by utilizing A-site cationic fluoride as a flux was proposed. The structure and morphology of Ca2LuNbO6:Mn4+ phosphor was characterized. Under the excitation of 360 nm, the emission spectra of Ca2LuNbO6:Mn4+ phosphor cover from 600 nm to 750 nm peaking at 683 nm. It benefits the red section of chlorophyll absorption band and possesses the wavelengths of 680 nm and 700 nm demanded by photosystem I (PS I) and photosystem II (PS II) to realize Emerson enhancement effect. After adding CaF2 as flux, the emission intensity increases by 2.5 times. Due to its compatibility with the A-site cation of host, CaF2 agent not only lower the sintering temperature but also increase the crystallite size, which result in the enhancement of luminescence. The Dq/B and optical band gap of Ca2LuNbO6 host is 2.32 and 3.79 eV, respectively, which show that Mn4+ ions locate in the [NbO6] octahedra of strong crystal field and host has the suitable optical band gap for Mn4+ ions. With the help of CaF2, the thermal stability, activation energy ΔEa, internal quantum efficiency of Ca2LuNbO6:Mn4+ phosphors are promoted at 373 K from 64.8% to 70.7% of that at 273 K, from 0.33 to 0.36 eV, and from 9.1% to 23.5%. The luminescence lifetime of Ca2LuNbO6:Mn4+ is the order of a fraction of a millisecond. Finally, the as-prepared Ca2LuNb0.996O6:0.004Mn4+ phosphor was successfully fabricated through a 365 nm near ultraviolet (NUV) chip, which has the peak wavelengths of 683 nm and possesses 680 nm and 700 nm demanded by PS I and PS II. It is implied that Ca2LuNbO6:Mn4+ phosphor-converted light emitting diode has prospective market in the domain of supplement illumination of plant cultivation.

Luminescence properties and energy transfer of broadband NIR phosphor Li2MgZrO4: 1.0%Cr3+, y%Yb3+

The discovery of high thermal stability, broad-band near-infrared (NIR) fluorescent phosphors holds significant potential in applications such as non-destructive testing, promoting plant growth, and night vision devices. In this study, a novel broad-band NIR phosphors Li2MgZrO4 (LMZ): 1.0 %Cr3+, y%Yb3+ were synthesized via a high-temperature solid-state reaction method, with the optimal doping concentration found to be y = 1.5. These phosphors exhibited broad NIR emission in the range of 700–1050 nm by effective energy transfer from Cr3+ to Yb3+. The maximum full width at half maximum (FWHM) of the Cr3+/Yb3+ co-doped LMZ phosphor is 270 nm. The thermal stability of the phosphors was improved with Yb3+ co-doping. Additionally, energy transfer from Cr3+ to Yb3+ was confirmed through luminescence spectra and lifetime analysis. Finally, NIR pc-LED devices composed of a 460 nm ultraviolet chip and LMZ: 1.0 %Cr3+, 1.5 %Yb3+ phosphors were fabricated, offering a highly promising source of invisible light. These results demonstrate the wide-ranging potential applications of this novel, high thermal stability, and ultra-broad NIR emitting fluorescent phosphor.

Broadband Green-Yellow KGaSi2O6:Eu2+ Phosphor with Excellent Thermal Stability for Near Ultraviolet-Pumped White-Light-Emitting Diodes

Various types of Eu2+ activated phosphors show potential applications in light emitting diodes. In this work, the Eu2+ activated KGaSi2O6 phosphors were synthesized using high-temperature solid-state reactions. The crystallization and oxidation states, luminescence spectra, decay characteristics, and thermal stability were researched. Depending on excitation of NUV light, the Eu2+ activated KGaSi2O6 phosphors emitted green-yellow light originating from the 4f65d1 → 4f7 transitions of Eu2+. In the light of emission data measured at different temperatures, the activation energy was calculated as 0.33 eV. The warm white light with a correlated color temperature of 3909 K and a color rendering index of 81.9 was emitted by the WLED device consisting of near ultraviolet LED chips, KGaSi2O6:Eu2+ and CaAlSiN3:Eu2+ phosphors.

Superior Quantum Efficiency Blue‐Emitting Phosphors with High Thermal Stability toward Multipurpose LED Applications

AbstractSince Bi3+‐activated phosphor are widely reported in phosphors‐converted light‐emitting diodes (pc‐LEDs), developing new‐high efficiency phosphors is imperative. Herein, superior internal quantum efficiency (IQE = 93.7%) and external quantum efficiency (EQE = 70.5%) are achieved with blue‐emitting gallate phosphor CaGdGaO4:Bi3+. Particularly, the photoluminescence excitation (PLE) spectrum ranges from 200 to 400 nm with two peaks at 337 and 368 nm, which match well with the 365 nm near ultraviolet (n‐UV) chip. The blue emission is attributed to two luminescence centers caused by Bi3+ occupying GdO6 and CaO6 sites. Furthermore, the thermal stability (@ 150 °C) enhanced from 73.2% to 80.1% when Ca2+ doping. A white LED (WLED) with high color rendering index (Ra) of 93.8 is prepared by as‐synthesized phosphors, indicating the potential application in WLED. The blue and red dual‐emitting phosphors are achieved by co‐doping Bi3+ and Eu3+. Finally, the rice planting experiment presents that the blue‐emitting can efficiently enhance the photosynthesis and seeding index of rice, which indicated these phosphors have significance in plant fill light.

Interrupting the long-range energy migration among Eu3+ by the introduction of unequivalent [NaO8] units to achieve both high quenching concentration and quantum yield in NaY2Ga2InGe2O12

In the pursuit of optimizing white light-emitting diodes (WLEDs), Eu3+-doped phosphors have emerged as a key component in strategies that combine ultraviolet (UV) LED chips with red, green, and blue (RGB) tricolor phosphors. However, their application has been notably constrained by concentration quenching and thermal quenching. To address this challenge, we have developed a series of novel red phosphors, NaY2-xGa2InGe2O12:xEu3+. The powder X-ray diffraction (XRD) indicates that the NaY2Ga2InGe2O12(NYGIG) belongs to the garnet family. The [NaO8] unit replaces one-third of the eight-coordinated sites of garnet and leaves the other two-thirds for the [YO8], which helps to prevent long-range energy migration among Eu3+ especially when the eight-coordinated sites were highly substituted. Such a structure feature allowed the NaY2-xGa2InGe2O12:xEu3+ phosphor to achieve an optimal quantum yield of 95.6% at an extremely high Eu3+ doping x value up to 1.2. Moreover, further studies on the temperature-dependent luminescence spectra confirm that an anomalous thermal quenching phenomenon will occur when the NaY2-xGa2InGe2O12:1.2Eu3+ phosphor is properly excited. In application, the combination of the red-emitting NaY2-xGa2InGe2O12:1.2Eu3+, blue-emitting BaMgAl10O17:Eu2+, and green-emitting Zn2SiO4:Mn2+ phosphors can realize high color rendering (CRI∼93) white light with the with CIE coordinates of (0.353,0.350), indicating that the NYGIG:Eu3+ phosphor own a promising potential for WLEDs.

Electronic structure, colour-tunable emission and energy transfer in Li3Ba2Y3(WO4)8:Bi3+,Eu3+ phosphors for white light-emitting diodes.

Solid-state phosphor-converted white light-emitting diodes (pc-WLEDs) are the leading trend of the lighting industry in the 21st century. To pursue high quality WLED lighting, the development of highly efficient phosphors with tunable luminescence has become a hot research topic. Herein, we reported for the first time on Bi3+/Eu3+-doped Li3Ba2Y3(WO4)8 phosphors that exhibited tunable emission and high energy transfer efficiency of 89.90% from Bi3+ to Eu3+. The phase purity, microstructure, electronic structure and photoluminescence properties of these phosphors were studied in detail. Bi3+ and Eu3+ were effectively doped in Li3Ba2Y3(WO4)8 with an optical bandgap of 3.81 eV. The band structure and density of states were quantitatively evaluated by density functional theory simulation. At an excitation wavelength of 342 nm, the Bi3+-doped phosphor achieved yellow-green emission. By alloying Eu3+ into Li3Ba2Y3(WO4)8:Bi3+, the luminescence gradually turned red due to the energy transfer from Bi3+ to Eu3+. Moreover, the activation energy of the prepared phosphor was 0.1897 eV, demonstrating excellent thermal stability. Eventually, by combining Li3Ba2Y3(WO4)8:4%Bi3+,4%Eu3+ and a blue-emitting BAM:Eu2+ phosphor with a 365 nm ultraviolet chip, a WLED device with a high colour rendering index (Ra) of 78.7, chromaticity coordinates of (0.3401, 0.3131) and correlated colour temperature of 5080 K was successfully achieved. This work provided new insights into the design and development of color-tunable phosphors for white LEDs.

Fluorescence properties of novel deep-red phosphor LiMg4SbO7:Mn4+ with excellent quantum efficiency and color purity for warm white LEDs.

Red fluorescent materials have important application value in the background light and LED lighting fields of displays. In this work, a novel type of rare earth free deep-red phosphor LiMg4SbO7:Mn4+ was prepared successfully, and its crystal structure, microstructure, fluorescence spectrum, quantum yield, thermal stability, fluorescence lifetime, color coordinates and color purity were studied in detail. The excitation spectra of LiMg4SbO7:Mn4+ phosphors are located at 200-600 nm, which can be matched with ultraviolet, near-ultraviolet, and blue-light chips. The exciting result is that the LiMg4SbO7:0.002Mn4+ phosphor exhibits astonishing quantum efficiency, thermal stability and color purity. Finally, the developed LiMg4SbO7:Mn4+ and the yellow phosphor Y3Al5O12:Ce3+ (YAG:Ce3+) were mixed and coated on a blue light chip (460 nm) to produce a w-LED, which exhibited warm white luminescence with color coordinates of (0.3575, 0.3809), correlated colour temperature (CCT) of 4687 K, and color rendering index (CRI) of 83.6. It is reasonable to consider that LiMg4SbO7:Mn4+ phosphors with excellent photoluminescence performance have great application value in LED lighting fields.

A novel blue emitting phosphor Ca1-ySryScBO4:Bi3+ with zero-thermal quenching for multi-scenario application.

In recent years, Bi3+ activated phosphors have received a lot of attention from researchers; however, the performance and application areas of phosphors are yet to be developed. In this work, a series of CaScBO4(CSBO):xBi3+ phosphors were successfully prepared using a high-temperature solid-state method. Under UV excitation, blue light emission was achieved at 430 nm with a quantum yield of 91%, and at 423 K, the emission intensity retained 82.8% of the original intensity at 298 K. By crystal field engineering, the substitution of Sr2+ at the Ca2+ site enhances the temperature stability of the material, and at 423 K, 473 K and 573 K, the samples maintain 104%, 103% and 85% of the emission intensity at room temperature, respectively. It indicates that the cation substitution causes the increase in the oxygen vacancy concentration, and the oxygen vacancy defect compensates the energy lost in electrons at high temperature, producing resistance to anti-TQ performance. Finally, a blue-violet LED was fabricated by using the phosphor and an ultraviolet LED chip, and white LEDs (CCT = 4683 K, Ra = 89.7) were obtained by co-packaging this phosphor with commercial phosphors and a UV chip. Importantly, the great potential of this phosphor in the field of plant lighting and biocontrol can be demonstrated.

Tailoring Fe3+‐Activated Broadband NIR Phosphors: Enhancing External Quantum Efficiency and Spectrum Adjustability Through Crystal Field Engineering in Double Perovskite Antimonate Structures

AbstractFor near‐infrared (NIR) luminescent materials, it is a challenge to develop the next generation materials with high external quantum efficiency (EQE), low toxicity, and adjustable spectrum. The transition metal ion Fe3+ can act as a good activator and emit NIR light in oxide host lattice, but there is limited research on this topic. Herein, authors have developed a series of Fe3+ activated A2BSbO6:yFe3+ (A = Ca, Sr, Ba; B = Sc, Y, Ga) phosphors with a double perovskite structure, which can efficiently convert the exciting light into NIR emission in the range of 750–1200 nm with a full‐width half‐maximum (FWHM) of 1372−1525 cm−1. The NIR luminescence originates from the 4T1 (4G)→6A1 (6S) transition of the Fe3+ ions situated in the octahedral sites. By employing crystal field engineering, the emission spectra peak can be adjusted within the range of 842–944 nm, and the excitation spectra can be tuned from 334 to 374 nm. These spectral adjustments enable a good match between the phosphors and commercially ultraviolet chips. When excited at 334 nm, the Sr2ScSbO6:0.1%Fe3+ phosphor demonstrates a remarkably high EQE of 54.2% and high luminescent thermostability. These characteristics make it suitable for applications in NIR spectral detection.