Phosphor For Light-emitting Diodes Research Articles

Proliferating optoelectronic properties of doped ZnO nanoparticles

Ag-doped ZnO nanocomposites were synthesized precisely by adopting a wet chemical method to explore their optoelectronic characteristics for LED applications. Characterization studies have progressed for substantiation of its structural, and functional characteristics in conjugation with the optical properties of nanocomposites before and after doping. The metal-oxygen bonding was affirmed from IR spectra and excitation characteristics were detailed from UV–visible absorption spectra. The SEM images along with Energy dispersive X-ray analysis deliberates hexagonal morphology for pure ZnO which was surprisingly reformed into poly hexagon structures after doping with silver ions. The pertinence of the target material for LED application was verified by performing photoluminescence and charge density measurements. The doping of silver ions into ZnO presents a novel avenue in the field of optronics and serves as appropriate phosphors for light-emitting diodes. The application of the title compound was established by providing nano coating to LED bulb and emission efficiencies was recorded before and after coating. The present research recommends a unique method of nanocoating of LED bulb for efficient light intensity.

Hetero atom-based metal complexes as emitters in organic light-emitting diodes

The new, more energy-efficient lighting systems and high-quality displays for new age digital devices is the demand of the current generation. In this regard, focused and deliberated research has been done on transition metal complexes as effective building blocks for organic light-emitting diodes (OLEDs). The activity of divalent metallic compounds was investigated through spotlighting Co (II), Ni (II), and Cu (II) metal ions with guanidinium naphthoate as blue phosphors in OLEDs. Using spectroscopic and diffraction techniques, the phosphors produced at the optimal temperature were studied both structurally and thermally. Additionally, the target compound's photophysical investigations in a variety of organic solvents with differing polarities were examined, and the findings were presented. Because of their quick photoluminescence response time and high emission quantum efficiency, Ni (II) complexes have drawn specific attention. Ni (II) complexes precisely exhibit thermally activated delayed fluorescence (TADF) and found to be the most promising materials for future lighting technology. We compared the efficiencies of various complexes in this study to provide an overview of the development of OLEDs. To affirm the pertinency of the synthesized compounds as phosphors, studies like photoluminescence, correlated color temperature, color purity, Duv, and the Television Lighting Consistency Index (TLCI) were performed and their photometric properties were also deliberated. Ni (II) shows an magnificent luminescence character and maximum coloring index for light sources and found to be an essential component for OLEDs.

Spectroscopic investigation of K5La(MoO4)4:Sm3+ red phosphor with excellent thermal stability and color purity for white LEDs

In this study, a series of innovative red-emitting Sm3+-doped K5La(MoO4)4 phosphors were synthesized using the solid-state reaction method. The X-ray powder diffraction patterns and Rietveld refinement confirmed the single-phase structure of the synthesized K5La(MoO4)4:Sm3+ samples with trigonal system (space group R3‾m (#166)). The phosphors demonstrated a strong red emission at 644 nm, corresponding to the electric dipole transition 4G5/2 → 6H9/2 of Sm3+ ions. The optimal doping concentration for K5La(1-x) (MoO4)4:xSm3+ was found to be approximately 5 mol%. The temperature-dependent emission of phosphors was examined and found that the luminescence intensity remained at 86 % even at 480 K, showing the exceptional thermal stability of this material. K5La(1-x) (MoO4)4:xSm3+ phosphors displayed remarkable color stability with chromaticity coordinates falling within the red region in 1931 CIE diagram. K5La(MoO4)4:5 mol%Sm3+ exhibited a high color purity of 99.9 % and internal quantum efficiency (IQE) was measured as 66.8 %. Light-emitting diodes (LEDs) were constructed using InGaN chips and the synthesized red phosphors. The chromaticity coordinates of the fabricated w-LED (white light-emitting diode) were (0.330, 0.351), closely resembling the typical white point of the National Television System Committee (NTSC) at (0.333, 0.333). The color rendering index (CRI, Ra) and correlated color temperature (CCT) of w-LED were 87 and 5627 K. These findings strongly suggest the potential use of K5La(MoO4)4:Sm3+ phosphors as red phosphors in LEDs.

Tunable broadband near-infrared photoluminescence of Mg2LaTaO6:Cr3+ phosphors for light-emitting diodes

Near-infrared phosphor-converted light-emitting diodes (NIR pc-LED) prepared with near-infrared (NIR) phosphors have potential applications in various aspects. In this paper, Cr3+-activated Mg2LaTaO6 (MLTO: Cr3+) phosphors were prepared by the conventional high-temperature solid-phase method. The structure, morphology, and photoluminescence (PL) spectra of MLTO: Cr3+ phosphor were investigated. There is broadband NIR emission and the emission peak is red-shifted with the increase of doping concentration. The crystal field strengths of the samples were calculated and the relationship between the emission peak positions of the samples and the crystal field strengths was investigated. In addition, the concentration quenching mechanism of the samples was discussed, which is mainly attributed to dipole-dipole interactions. The internal quantum efficiency (IQE) of the MLTO: 0.4 mol% Cr3+ sample was measured with an IQE value of 76.48 %. NIR pc-LED devices were fabricated by combining the prepared MLTO: Cr3+ phosphor and blue-emitting LED chips, which are capable of emitting NIR light.

Novel solution and solid-state emissive long-wavelength carbon dots for water sensing and white LED applications

Carbon dots (CDs) are among the most popular nanomaterials due to their remarkable fluorescent and electronic properties, as well as their good biocompatibility and low cytotoxicity. Currently, CDs with aggregation-induced emission (AIE) are relatively rare and have become a significant research hotspot. This is because most conventional CDs suffer from severe quenching in a solid state. Herein, novel CDs with both solution and solid-state emissions were obtained using a facile one-step hydrothermal synthesis. Specifically, the CDs exhibit yellow solvent-dependent fluorescence in solution state (λem = 580 nm) and red AIE emission in solid state (λem = 640 nm). CDs powder is utilized as a red phosphor for light-emitting diode (LED). The resulting fabricated white LEDs (WLEDs) demonstrate good performance metrics, including a Color Rendering Index (CRI) of 89.5, Correlated Color Temperature (CCT) of 3876 K, and commission Internationale d’Éclairage (CIE) coordinates of (0.350, 0.331). Furthermore, the solvent-dependent phenomenon observed in AIE-CDs can be exploited to apply their solution as a highly sensitive fluorescence sensor for quantitatively detecting amounts of water in various organic solvents. The method offers both high accuracy and sensitivity, with R2 values varying from 0.853 to 0.994 and a low detection limit ranging from 0.296 to 3.23 % across a wide linear range. This inherent versatility makes the CDs suitable for a wide range of applications, including sensing and LED devices.

Thermally stable near-infrared emission from a double perovskite K2LiScF6:Cr3+ phosphor for light-emitting diodes

The exploration of Cr3+-doped near-infrared (NIR) phosphors for light-emitting diodes has attracted widespread attention. In this work, we present a fluoride double perovskite K2LiScF6:Cr3+ NIR-emitting phosphor through a co-precipitation method. It was found that the Cr3+ activators undergo a weak crystal field and present a NIR emission band peaking at 768 nm under blue light excitation (430 nm). Meanwhile, the K2LiScF6:Cr3+ exhibits a high activation energy (0.537 eV), a weak electron-phonon coupling (EPC) effect and a remarkable photoluminescence thermal stability at 423 K, with an intensity of 95.1% of that at room temperature. Profiting from the luminescent properties, clear night vision images and human palm vein photographs were realized by coating the K2LiScF6:Cr3+ phosphor on a blue InGaN chip and using it as a lighting source, suggesting its applicability in light-emitting diodes for NIR spectroscopy applications.

Unraveling Luminescent Energy Transfer Pathways: Futuristic Approach of Miniature Shortwave Infrared Light-Emitting Diode Design

Phosphor-converted shortwave infrared phosphor light-emitting diodes (pc-SWIR LEDs, 900–1700 nm) are promising next-generation portable light sources for spectroscopy, security, optical communication, and medical applications. A typical design strategy involves energy transfer from Cr3+ to Ni2+, and thus, energy transfer from Cr3+–Cr3+ pairs to Ni2+ ions is important but challenging. Here, we report a Sr1–xLaxAl5.92Cr0.08Ga6–xO19:xNi2+ (x = 0–0.09) series for the SWIR emissions range of 900–1600 nm due to an energy transfer from Cr3+ and Cr3+–Cr3+ pair to Ni2+. Short-range structural studies using electron paramagnetic resonance and magnetometry measurements reveal that Ni2+ ions likely exist as isolated Ni2+ ions and Cr3+–Ni2+ pairs rather than forming Ni2+–Ni2+ pairs. The fabricated prototype SWIR pc-LED delivers a radiant flux of 12.43 mW under a 350 mA driving current. This work provides insights into the codopant strategy for energy transfer and the design of promising next-generation SWIR phosphors.

Luminescence enhancement of Mn4+‐activated double‐perovskite phosphors for LEDs through a co‐replacement strategy

AbstractPhosphors doped with Mn4+ ions have strong emission in the red and far‐red light regions and are therefore used as red phosphors for indoor plant cultivation light‐emitting diodes (LEDs) and white LEDs (w‐LEDs). This paper introduces La2Mg(Mg1/3Ta2/3)O6: Mn4+ (Mg2La3TaO9: Mn4+) red phosphors prepared by conventional high‐temperature solid‐phase method. The broad excitation band of Mg2La3TaO9: Mn4+ phosphor is effectively excited by ultraviolet and blue light in the range of 250–600 nm, with the emission of 707 nm centered on far‐red light. The phosphor has a high color purity of 99.07% and an internal quantum efficiency of 59.87%. To further enhance the performance of the phosphor, a cation substitution method was adopted in this paper to synthesize La2Mg(Al1/2Ta1/2)O6: Mn4+ phosphor by replacing [1/3Mg2+–2/3Ta5+] in La2Mg(Mg1/3Ta2/3)O6: Mn4+ with [1/2Al3+–1/2Ta5+]. The luminescence intensity and thermal stability of the samples were enhanced. The emission spectrum of the Mg2La3TaO9: Mn4+ samples matched well with the phytochrome PFR (phytochrome that absorbs far‐red light) and is suitable for the preparation of LEDs for indoor plant cultivation. The concentration quenching effect of the samples was investigated, the main mechanism of which is the electric dipole–dipole interaction. Red LEDs and w‐LEDs devices were prepared with the synthesized phosphors that produce light stably at different currents. The w‐LEDs have a correlated color temperature of 5310 K and a color rendering index of 80.1. Therefore, these samples are expected to be used as red components for w‐LEDs.

Anionic Regulation toward Bi3+ Selective Occupation for Full-Spectrum White Light Emission.

An activator's selective occupation of a host is of great significance for designing high-quality white light-emitting diode phosphors, while achieving a full-spectrum single-phase white light emission phosphor is challenging. In this study, a boron phosphate solid-solution Na2Y2(BO3)2-x(PO4)xO:0.005 Bi3+ (NYB2-xPxO:0.005 Bi3+) white phosphor was designed by selectively occupying Bi3+ activators in the mixed anionic groups. The substitutes of the anionic unit (BO3)3- by the (PO4)3- unit are supposed to force part of the Bi3+ ion to enter the Na lattice site, which produces an intense orange-red emission peaked at 590 nm. In parallel, spectral tuning from blue to white light and an internal quantum efficiency of 56.42% was obtained, and the thermal stabile luminescence intensity remains at 94.2% of the initial intensity after four heating-cooling cycles from 30 to 210 °C (luminescent intensity is 83.6% of room temperature (RT) at 150 °C, with excellent thermal stability and recovery performance). Finally, an excellent color rendering index (Ra = 90.8 and R9 = 85) was demonstrated for white light-emitting diode devices using only an NYB1.5P0.5O:0.005 Bi3+ phosphor and a near-ultraviolet (n-UV) 365 nm LED chip. This work delves into the different selective occupancy of Bi3+ ions and explores a new avenue for the design of phosphors for full-spectrum white light emission.

Efficient and ultra-broadband Cr3+/Ni2+ co-doped phosphors for light-emitting diodes with spectral output over NIR-I and NIR-II regions

A blue-light excitable near-infrared (NIR) MgGa2(O,F)4:Cr3+,Ni2+ phosphor is developed, which exhibits an ultrabroad NIR emission from 700 to 1500 nm and an internal quantum efficiency of up to 83.3%.

U-type π-conjugated phosphorescent ligand sensitized lanthanide metal-organic frameworks for efficient white-light-emitting diodes.

Lanthanide metal-organic framework (Ln-MOF) based phosphors for light-emitting diodes (LEDs) play an important role in the fields of solid-state lighting and display. The rational design of organic antennae to address the drawback of low extinction coefficients of the lanthanide ions is highly desired. In this work, we provide a new design strategy to achieve an energy transfer molecule with a through-space conjugated folded structure, which can strengthen the skeleton rigidity and facilitate triplet state energy transfer. Consequently, one U-type π-conjugated molecule 2,6-bis(3,5-dicarboxylphenoxy) pyridine (H4L) was selected as a light gatherer to sensitize lanthanide ions for the construction of Ln-MOFs [Ln(HL)(H2O)3]n (Eu-MOF and Tb-MOF), which exhibit a long-lived luminescence lifetime (0.88 ms for Eu-MOF and 1.31 ms for Tb-MOF) and high quantum yields (50.87% for Eu-MOF and 85.64% for Tb-MOF). Furthermore, a white LED device with a colour rendering index (89) was fabricated using the mixture of Ln-MOFs with a commercial blue phosphor.

Hue dual-chromatic calcium chlorosilicate phosphor for light-emitting diode having yellow and white illumination

<p><span>High-thermal solid phase reactions produced a series of bright green-yellow phosphors called Ca<sub>3</sub>SiO<sub>4</sub>Cl<sub>2</sub>,Eu<sup>2+</sup>,Mn<sup>2+ </sup>(CaM). For example, powder dispersed reflection, photoluminescence excitation (PE), and along with emission spectra, were used to determine their luminous characteristics at between 10 K and 450 K of temperature. While the CaM exhibits wide absorption bands in the 250-450 nm range, which matches the near-uv of the InGaN-based chips, they also display two dominant absorptions, attributed to the 5d → 4f Eu<sup>2+</sup> transformation, as well as the <sup>4</sup>T<sub>1g</sub>(<sup>4</sup>G) → <sup>6</sup>A<sub>1g</sub>(<sup>6</sup>S) transfer of the two ions Eu<sup>2+</sup> and Mn<sup>2+</sup>, respectively. Increasing the concentration of Mn<sup>2+</sup> ion reduces the lifespan of the Eu<sup>2+</sup> ion. This encourages an efficient energy exchange between these two ions. The UV light leakage issue in yellow LEDs was resolved by intergrating with n-UV InGaN chips and CaM. Powerful white LEDs were then created by mixing blue chlorophosphate with CaM. Its color coordinate was (0.3281,0.3071), and the associated color temperature (TC) was 6065 K, while the general hue rendering (Ra) and illuminating effectiveness (11 lm/W) were respectively 84.5 and 11 lm/W.</span></p>

Bi4BPO10:Dy3+: a single-phase white-emitting phosphor for light-emitting diodes

We reported a single-phase white-emitting phosphor Bi4BPO10 (BBP):Dy3+ developed via a solid-state reaction route. Dy3+ activator is introduced into the BBP host by replacing Bi3+ ion with optimal content of 7 mol%. Under 390 nm excitation, due to the suitable combination of characteristic yellow and blue-emitting from Dy3+, the phosphor generates white light. The working temperature-dependent photoluminescence data confirms that it owns a satisfactory thermostability. Finally, the representative BBP:0.07Dy3+ phosphor-converted WLED device is pumped by a n-NV chip to display white light with a CCT of 3731 K. The report indicates that the studied phosphor could be potentially employed for solid-state white lighting source.

Self-Reduction Mechanism and Luminescence Properties of Eu2+-Eu3+Doped Ca(PO3)2 Phosphor

A series of Ca(PO3)2 phosphors mono-doped with Eu3+ were successfully synthesized by the conventional high-temperature solid-phase method. Rietveld correction of the X-ray diffraction shows that Eu3+ ions occupy Ca2+ positions in the Ca(PO3)2 lattice and have no effect on the matrix structure. In this work, the self-reduction of Eu3+ was observed and verified by photoluminescence (PL), excitation spectroscopy (PLE) and X-ray photoelectron spectroscopy (XPS). Under excitation at 238 nm, Ca(PO3)2: Eu exhibits a broad blue Eu2+ emission band in addition to the usual orange-red emission of Eu3+. The fact that europium ions exist in divalent and trivalent forms was further confirmed, and the corresponding mechanism of the anomalous reduction of Eu3+ to Eu2+ is discussed. On this basis, the effect of Eu concentration on the structure and luminescence properties of Ca(PO3)2 phosphor was investigated in detail. The luminescence of the phosphor exhibited bright tunable emission in the blue region and the red region. These results indicate that the Ca(PO3)2: Eu phosphors have potential applications as a n-UV convertible phosphor for light-emitting diodes.

Quantum efficiency of europium doped LaPO4 phosphors for UV sensing applications

The radiation conversion phenomenon is used for UV sensing applications with rare earth doped phosphors. This paper presents the results of structural and optical measurements of undoped and europium doped LaPO4 phosphors. LaPO4 phosphors with 1% mol, 2% mol, and 5% mol of europium were fabricated by the co-precipitation method. The effect of Eu3+ concentrations on the luminescence characteristics under UV LED excitation was investigated. The maximum quantum efficiency of luminescence (c.a. 82%) was obtained in sampled doped with 5% of europium. Full Text: PDF ReferencesM. Runowski, "Nanotechnologia – nanomateriały, nanocząstki i wielofunkcyjne nanostruktury typu rdzeń/powłoka", Chemik 68, 9, 766-775 (2014). DirectLink J. Zhou, J.L. Leano Jr., Z. Liu, D. Jin, K.-L. Wong, R.S. Liu, et al., "Impact of Lanthanide Nanomaterials on Photonic Devices and Smart Applications", Small 14, 1801882 (2018). CrossRef Z. Li, Y. Zhang, G. Han, "Lanthanide-Doped Upconversion Nanoparticles for Imaging-Guided Drug Delivery and Therapy", Springer Series in Biomater. Sci. Eng. 6, 139-164, (2016). CrossRef M. Lin, Y. Zhao, S. Wang, M. Liu, Z. Duan, Y. Chen, et al., "Recent advances in synthesis and surface modification of lanthanide-doped upconversion nanoparticles for biomedical applications", Biotechnol. Adv. 30, 1551-1561 (2012). CrossRef H. Su, Y. Nie, H. Yang, D. Tang, K. Chen, T. Zhang, "Improving the thermal stability of phosphor in a white light-emitting diode (LED) by glass-ceramics: Effect of Al2O3 dopant", J. Eur. Ceram. Soc. 38, 2005-2009 (2018). CrossRef J. Huang, X. Hu, J. Shen, D. Wu, C. Yin, R. Xiang, et al., "Facile synthesis of a thermally stable Ce3+:Y3Al5O12 phosphor-in-glass for white LEDs", Cryst. Eng. Comm 17, 7079-7085 (2015). CrossRef R. Zhang, H. Lin, Y. Yu, D. Chen, J. Xu, Y. Wang, "A new-generation color converter for high-power white LED: transparent Ce3+:YAG phosphor-in-glass", Laser Photon. Rev. 8, 158-164 (2014). CrossRef B. Zheng, Y. Bai, H. Chen, H. Pan, W. Ji, X. Gong, et al., "Near-Infrared Light-Excited Upconverting Persistent Nanophosphors in Vivo for Imaging-Guided Cell Therapy", ACS Appl. Mater. Interfaces 10, 19514 (2018). CrossRef J. Qiao, G. Zhou, Y. Zhou, Q. Zhang, Z. Xia, "Divalent europium-doped near-infrared-emitting phosphor for light-emitting diodes", Nature Communications 10 (1), 5267 (2019). CrossRef V. Singh, A. Kumar, C. Mehare, H. Jeong, S. Dhoble, "UV/VUV excited photoluminescence of Tb3+ doped LaPO4 green emitting phosphors for PDP applications", Optik 206, 163733 (2020). CrossRef G. Han, Y. Wang, C. Wu, J. Zhang, "Hydrothermal synthesis and vacuum ultraviolet-excited luminescence properties of novel Dy3+-doped LaPO4 white light phosphors", Mat. Res. Bull. 44 (12), 2255-2257 (2009). CrossRef K. S. Gupta, P. S. Ghosh, M. Sahu, K. Bhattacharyya, R. Tewari, V. Natarajan, "Intense red emitting monoclinic LaPO4:Eu3+ nanoparticles: host–dopant energy transfer dynamics and photoluminescence properties", RSC Adv. 5, 58832-58842 (2015). CrossRef

Evaluation of the novel Blue Emitting Phosphor with High Thermal Stability and High Color Purity for Solid State Lighting Applications - Ca2MgSi2O7: Eu2 +

This study deals with the new blue release LED phosphor activated by Eu2+. The luminescence properties of blue-emitting phosphor di-Calcium magnesium di-Silicate (Ca2MgSi2O7) doped with europium Eu2+are extensively investigated. This phosphor is produced by the high-temperature solid-state reaction method. The phase structure and crystalline size, surface morphology and elemental analysis were investigated by X-ray diffraction technique (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX). The optical properties are investigated by photoluminescence (PL) properties. Phase structure of Ca2MgSi2O7: Eu2 + is a carbonite-type structure belonging to tetragonal crystallography with the space group P4̅21m; this structure forms a member and layered compound in the Myelite group. The surface of the prepared phosphors is not detected uniformly and the particle distribution is within the nanometer range. EDX ensures components of Eu2 + doped Ca2MgSi2O7 phosphor. Under UV induction, the main emission peak appeared at 470 nm. This emission peak is attributed to the typical emission of Eu2+ due to the 4F9/2 → 6H15/2 transition. The blue light-emitting properties and excellent light response of these silicate phosphors make them suitable for photonic applications and open new avenues for solid-state lighting, cathode ray tubes, fluorescent lamps and scintillators etc. The phosphor system has been researched as a new candidate for phosphor-converted white light-emitting diode (LED) applications.

Disorder-Order Conversion-Induced Enhancement of Thermal Stability of Pyroxene Near-Infrared Phosphors for Light-Emitting Diodes.

The minimization of thermal quenching, which leads to luminescence loss at high temperatures, is one of the most important issues for near-infrared phosphors. In the present work, we investigated the properties of near-infrared Ca(Sc,Mg)(Al, Si)O6 : Cr3+ phosphors with a pyroxene-type structure under blue light excitation. The CaScAlSiO6 : Cr3+ end member of Ca(Sc,Mg)(Al,Si)O6 : Cr3+ phosphor led to broadband emission at a full-width half maximum of 215 nm, whereas the CaMgSi2 O6 : Cr3+ end member exhibited high thermal stability at 150 °C, with an intensity of 88.4 % of that at room temperature. The structural analysis and density functional theory calculations revealed the absence of soft conformations and local space confinement contributed to the high structural rigidity and weakened the thermal quenching effect.

Eu2+ Doping Concentration-Induced Site-Selective Occupation and Photoluminescence Tuning in KSrScSi2O7:Eu2+ Phosphor.

Regulation of Eu2+ dopants in different cation sites of solid-state materials is of great significance for designing multicolor phosphors for light-emitting diodes (LEDs). Herein, we report the selective occupation of Eu2+ for multiple cationic sites in KSrScSi2O7, and the tunable photoluminescence from blue to cyan is realized through Eu2+ doping concentration-dependent crystal-site engineering. Eu2+ preferably occupies the K and Sr sites in KSrScSi2O7 at a low doping concentration, resulting in a 440 nm blue emission. As the Eu2+ concentration increases, a new Eu2+ substitution pathway is triggered, that is, Eu2+ enters the Sc site, leading to the red-shifted emission spectra from 440 to 485 nm. The doping mechanism and photoluminescence properties are corroborated by structural analysis, optical spectroscopy study, and density functional theory calculations. The optical properties of the as-fabricated white LEDs are studied, which demonstrates that these phosphors can be applied to full-spectrum phosphor-converted LEDs. This study provides a new design strategy to guide the development of multicolor Eu2+-doped oxide phosphors for lighting applications.

Nitridated CaSiO3: Eu and SrSiO3: Eu phosphors for LEDs

Eu2+-activated single-phase CaSi(O,N)3 and SrSi(O,N)3 oxonitridosilicate phosphors were synthesized by a conventional solid-state reaction method at 1100 °C and 1200 °C. For comparative purposes, their oxide equivalents, CaSiO3 and SrSiO3, doped with Eu2+ were obtained using the same synthesis method. The XRD patterns for the obtained phosphors indicate the formation of single-phase oxide and oxynitride phosphors. Energy Dispersive Spectroscopy (EDS) confirmed the incorporation of nitrogen in the phosphor host lattices. The formation of Ca/Sr-N and Si-N bonds can be observed in the FT-IR spectra. The oxonitridosilicate phosphors showed intense emission from Eu2+ in the green-red spectral region. The emissions were redshifted compared to their oxide counterparts described in the scientific literature. The thermal stability and quantum yields (QY) of oxonitridosilicate phosphors were significantly improved compared with respective oxide phosphors. This shows the high potential of oxynitrides as phosphors for light-emitting diodes (LEDs).

New red-emitting phosphor of Eu3+-doped Ba2Gd0.67W1−xMoxO6 for solid state lighting

In recent years, white light emitting diodes (LEDs) as a typical green lighting source have attracted great attention. A promising red phosphor for LEDs, (Ba0.8Eu0.1Li0.1)2Gd0.67W1 − x Mo x O6 solid solution, was synthesized by a high-temperature solid-state reaction. The excitation spectra of phosphors can be broadened by substituting Mo for W, which has good absorption in the near ultraviolet region. We measured the X-ray diffraction, absorption spectra, excitation spectra and emission spectra of these solid solutions, and analyzed their crystal structures. This series of phosphors present a relatively effective excitation band in the near-UV region (370–425 nm) from the charge transfer state of MoO6 and orange-red luminescence at 596 nm from the 5D0 → 7F1 transition. With increasing molybdate content, the luminescence intensity of (Ba0.8Eu0.1Li0.1)2Gd0.67W1−x Mo x O6 (x = 0.15–0.6), increases first and then decreases, and reaches a maximum at x = 0.4. The red phosphor excited by near ultraviolet light provides a reference value for white LEDs.