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Alcohol-Guided Growth of Two-Dimensional Narrow-Band Red-Emitting K2TiF6:Mn4+ for White Light-Emitting Diodes
摘要： The use of red phosphors with low light-scattering loss could improve the luminous efficacy and color rendering of white light-emitting diodes (LEDs). Thus, the discovery of such phosphors is highly desired. In this work, high-efficiency two-dimensional red-emitting K2TiF6:Mn4+ (KTFM) were synthesized via an alcohol-assisted coprecipitation route. The synergistic effects of 1-propanol and hydrofluoric acid (HF) on the growth of KTFM microsheets (MSs) were studied through the first-principles calculations, which revealed that 1-propanol promoted the growth of KTFM MSs by preferentially adsorbing on the H-terminated K2TiF6 (001) surface. The photoluminescence quantum efficiency (QE) of Mn4+-activated K2TiF6 MSs was highly related to their size and thickness. The morphology-optimal KTFM MSs presented high internal QE (> 90 %), external QE (> 71%), and thermal quenching temperature (102% at 150 °C relative to that at 25 °C). A prototype phosphor-converted LED with KTFM as the red-emitting component showed an excellent color rendition (Ra = 91, R9 = 79) and high luminous efficacy (LE =156 lm/w).
关键词： light emitting diode,two-dimensional material,Narrow band,K2TiF6:Mn4+,backlight,red emission
更新于2025-11-14 17:04:02
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The red persistent luminescence of (Sr,Ca)AlSiN3:Eu2+ and mechanism different to SrAl2O4:Eu2+,Dy3+
摘要： (Sr,Ca)AlSiN3:Eu2+ phosphors have been widely used in phosphor-converted white light emitting diodes. Herein, we reported the strong red persistent luminescence in (Sr,Ca)AlSiN3:Eu2+ under UV light excitation. The Sr0.8Ca0.2AlSiN3:0.15% Eu2+ shows the strongest red persistent luminescence with a peak emission wavelength at ~628 nm and a persistent time of ~9600 s at the 0.32 mcd/m2 threshold value. A new persistent luminescence mechanism, which is different to that of SrAl2O4:Eu2+,Dy3+, was proposed by comparing the thermoluminescence excitation spectrum (TLES) and the photoluminescence excitation spectrum (PLES) of Sr0.8Ca0.2AlSiN3:0.15% Eu2+. The electrons are directly excited from 4f ground states to the conduction band or from valence band to conduction band in (Sr,Ca)AlSiN3:Eu2+; while, in SrAl2O4:Eu2+,Dy3+, they are first excited to 5d level and then stimulated thermal process to the conduction band. The effect of Eu2+ concentration on red persistent luminescence in (Sr,Ca)AlSiN3:Eu2+ were discussed. The proposed mechanism of persistent luminescence can help us to design and find new persistent luminescence materials.
关键词： Persistent luminescence,SrAl2O4:Eu,Dy,Red emission,(Sr,Ca)AlSiN3:Eu,Persistent luminescence mechanism
更新于2025-09-23 15:23:52
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Red-emissive conjugated oligomer/silica hybrid nanoparticles with high affinity and application for latent fingerprint detection
摘要： Latent fingerprint detection plays a great role in forensic science, and considerable efforts have been made on developing efficient and simple strategy to realize clear visualization of latent fingerprints. Among them, fluorescent nanoparticles have attracted increasing interests due to their easy fabrication, good photostability, and low toxicity, but insufficient affinity toward fingerprints has limited their further application. Herein, we report a red-emissive conjugated oligomer/silica hybrid nanoparticle with enhanced affinity toward fingerprints, showing a promising performance on fluorescent detection on latent fingerprints. The conjugated oligomer is covalently doped into the silica nanoparticles, which effectively guarantee its fluorescent quantum yield and photostability. Moreover, the red emission of these nanoparticles also enables the latent fingerprint detection on substrates with fluorescent background, such as plastic and various papers. Most importantly, the introduction of epoxy groups on the silica surface largely enhances its affinity toward fingerprints, compared to that with hydroxy or amino groups, which possibly can be ascribed to its electrostatic attraction and hydrophobic interaction with amino acids and sebaceous substances of fingerprints, respectively.
关键词： Latent fingerprint detection,High affinity,Red emission,Fluorescence,Conjugated oligomer
更新于2025-09-23 15:23:52
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Synthesis and photoluminescence properties of high thermal stability Mn4+ in orthorhombic SrLa2Mg2W2O12 red phosphor for warm w-LEDs
摘要： We successfully synthesized SrLa2Mg2W2O12:xMn4+ (x = 0.002, 0.004, 0.006, 0.008, 0.010, 0.012, 0.014) phosphors through a high-temperature solid-state reaction. The phase of sample was shown by X-ray powder diffraction (XRD). The morphology of the sample was observed by field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM), which showed the irregular morphology of SrLa2Mg2W2O12 (SLMW) powders. Additionally, the photoluminescence excitation (PLE), emission (PL) and ultraviolet–visible reflection spectra were also presented. As shown in results, the phosphor could be stimulated by the ultraviolet (UV) and near ultraviolet (NUV) light and then exhibited far-red emission (697?nm). The optimum doping concentration of Mn4+ is 1?mol%. The thermal stability of phosphors has been investigated and discussed (I423K/I298K = 64.6%), and the internal quantum efficiency (IQE) of SLMW:0.01Mn4+ phosphors is as high as 51.2%. Finally, a far-red light-emitting diodes (LEDs) was fabricated by combining a 365?nm near-ultraviolet InGaN chip with SLMW:0.01Mn4+ phosphor. The Color Rendering Index (CRI), correlated color temperature (CCT) and luminescent efficiency (LE) values were 29.5, 1159?K and 5.6?lm/W, respectively. All of these indicated that SLMW:Mn4+ as a far-red phosphor can be applied to LEDs lamp and it has enormous potential applications in white light-emitting diodes (w-LEDs).
关键词： SrLa2Mg2W2O12:Mn4+,far-red emission,thermal stability,w-LEDs,phosphor
更新于2025-09-23 15:21:01
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A novel double-perovskite LiLaMgTeO6: Mn4+ far-red phosphor for indoor plant cultivation white LEDs: Crystal and electronic structure, and photoluminescence properties
摘要： Deep-red-emitting Mn4t activated oxide phosphors are the hot research topic due to their potential applications in indoor plant cultivation LEDs. In this paper, a novel double-perovskite LiLaMgTeO6:Mn4t phosphor was firstly prepared by high-temperature solid-state reaction method and its structure of the phosphor was determined by X-ray diffraction (XRD) and Rietveld refinement. Density functional theory (DFT) calculations using VASP provide an insight into the bandgap and electronic structures of the LiLaMgTeO6 host. Under UV or blue excitation, LiLaMgTeO6:Mn4t shows a good stability and bright far-red light in the 540e800 nm range with the maximum at 708 nm, which matches well with the absorption band of phytochrome PFR, indicating its potential application in improving plant growth. The optimal Mn4t doping concentration was approximately 0.6 mol%. Furthermore, a white-LEDs device made of a 365 nm chip coated with present phosphor and commercial green, blue phosphors was designed for indoor plant cultivation. The results indicate that the LiLaMgTeO6: Mn4t phosphor possesses great application prospect in white-LEDs for plant cultivation.
关键词： Far red emission,Phytochrome,Double perovskite,LEDs,Thermal stability,Indoor plant cultivation
更新于2025-09-23 15:21:01
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Molecular isomeric engineering of naphthyl-quinoline-containing dinuclear platinum complexes to tune emission from deep red to near infrared
摘要： Four isomeric dinuclear platinum complexes of (C^N)2Pt2(m-OXT)2 are synthesized and characterized with different C^N cyclometalating ligands and the same ancillary ligand of 5-(4-octylphenyl)-1,3,4-oxadiazole-2-thiol (m-OXT). These isomeric C^N ligands are 1-naphthyl-1-isoquinoline (niq), 2-naphthyl-1-isoquinoline (2niq), 1-naphthyl-2-quinoline (nq) and 2-naphthyl-2-quinoline (2nq). The isomeric effect on the photophysical, electrochemical and electroluminescence properties of (C^N)2Pt2(m-OXT)2 was systematically studied. It is found that the emissions were easy to tune from deep red to near infrared for (C^N)2Pt2(m-OXT)2 by changing the C^N isomers. Furthermore, the complexes with 2-naphthyl in these presented better electroluminescence (EL) properties than the complexes with 1-naphthyl. In contrast to the (2nq)2Pt2(l-OXT)2-doped devices displaying a deep-red emission peaked at 686 nm with an external quantum efficiency (EQE) of 3.21%, the (2niq)2Pt2(l-OXT)2-doped devices exhibited a near-infrared emission peaked at 704 nm with a significantly increased EQE of 8.86% and a radiant emittance of 986 mW cm?2. Our research provides an efficient strategy to tune emission from deep red to near infrared by a simple isomeric engineering of dinuclear platinum(II) complexes.
关键词： deep red emission,isomeric engineering,near infrared emission,dinuclear platinum complexes,electroluminescence
更新于2025-09-19 17:15:36
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Luminescent properties of Zn2+-doped CaAl12O19:Mn4+ deep-red phosphor for indoor plant cultivation
摘要： A series of CaAl12O19: 0.5%Mn4+ phosphors doped with different concentrations of Zn2+ were prepared via solid state reaction process. The micrographs and phases of powders were analyzed by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD), respectively. The Photoluminescence excitation spectra(PLE) and emission spectra(PL) of CaAl12O19: 0.5%Mn4+ with varying Zn2+ concentrations were investigated, the result indicated that prepared samples after Zn2+-doping exhibited deep red emission (658 nm) under the excitation of ultraviolet (UV), near ultraviolet (NUV). PL spectra indicated that Zn2+-doping could remarkably enhance the luminescent intensity of CaAl12O19:0.5%Mn4+. When the doping concentration of Zn2+ was 4%, the emission intensity of Ca0.96Zn0.04Al12O19:0.5%Mn4+ was improved up to 2.2 times that of pure CaAl12O19:0.5%Mn4+. In addition, the emission band of phosphor is highly compatible with the absorption band of phytochrome PR(660 nm). Besides, the internal quantum efficiency (IQE) was up to 67.1%. All the obtained results indicated that CaAl12O19:Zn2+, 0.5%Mn4+ has potential application value in indoor plant cultivation.
关键词： Phosphor,Deep-red emission,CaAl12O19:Zn2+,Plant cultivation,Luminescence,Mn4+
更新于2025-09-19 17:15:36
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Eu3+ doped (Li, Na, K) LaMgWO6 red emission phosphors: An example to rational design with theoretical and experimental investigation
摘要： Various theoretical methods were comprehensively applied in (Li, Na, K) LaMgWO6: Eu3+ phosphors to achieve the rational design of phosphors. The detailed structural characteristics were analyzed by using geometric optimization and Rietveld analysis for the first time. The plane-wave density functional theory (DFT) was used for all electronic structure, electronic distribution, and phonon dispersion calculations. The evolution of the octahedral tilting in the (Li, Na, K) LaMgWO6 crystal structures was studied in detail. The relationship between crystal structure, environmental factors, Judd-Ofelt intensity parameters and fluorescence properties were analyzed. Combined with experimental results and theoretical calculations, the detailed luminescence process is deduced starting from the different ionic radius of Li+, Na+, and K+. Notably, the redshift of CTB can be ascribed to the value variation of environmental factors, which can represent the ionic radius, coordination number, covalency, and polyhedral tilting to qualify comparison and even quantify analysis.
关键词： Red emission,Phosphor,Double perovskite tungstate,Luminescence,CASTEP,Environmental factor
更新于2025-09-19 17:15:36
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Pulsed laser deposition of a ZnO:Eu3+ thin film: study of the luminescence and surface state under electron beam irradiation
摘要： A highly c-axis orientated Eu3+ doped ZnO (ZnO:Eu3+) thin film was successfully deposited by pulsed laser deposition in an oxygen working atmosphere. The structure, morphology, chemical analysis and luminescence properties of the sample were investigated. The effect of electron beam irradiation on the surface state, chemical and luminescence properties of the sample were studied. Successful incorporation of Eu3+ ions in the ZnO matrix was confirmed by X-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) analysis. XPS measurements revealed traces of the divalent (Eu2+) on the film surface while the trivalent (Eu3+) oxidation state in the bulk of the film. XPS depth profile confirmed that the film contained excess oxygen throughout the film. The film exhibited exciton and defect emission of ZnO as well as 4f – 4f characteristic emission of Eu3+ ions superimposed on the defect emission when excited at 325 nm using a He-Cd laser. Whereas only 4f – 4f characteristic emission of Eu3+ ions was recorded when the film was excited at 464 nm and also when excited with the electron beam. XPS high resolution spectra of the O 1s peak confirmed the creation of new defects during electron beam irradiation. In general, ZnO:Eu3+ films show potential for applications as a source of red light in optoelectronic devices.
关键词： Degradation,PLD,ZnO thin film,Eu3+ ions,Cathodoluminescence,Red emission,Electron beam irradiation
更新于2025-09-19 17:13:59
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Orange-red-emitting CaTi4(PO4)6:Eu3+ phosphor for white LEDs: synthesis and luminescence properties
摘要： CaTi4(PO4)6:xEu3+ phosphors are successfully synthesized under air condition by high-temperature solid-state method. The crystal structure, morphology, energy spectrum, atomic percentage, elemental mapping, and luminescence properties are investigated, respectively. Monitored at 594 nm, the excitation spectral bands of CaTi4(PO4)6:Eu3+ phosphor in the range of 210–550 nm are assigned to the O2?–Eu3+ charge transfer band (CTB) and the 7F0 → 5H3, 5L7, 5L6, 5D1, 5D2, 5D3, and 5D4 transitions of Eu3+ ion. With excitation at 394 nm, CaTi4(PO4)6:Eu3+ phosphor emits orange-red light with the chromaticity coordinates (0.548, 452), and the emission spectral bands in the region from 575 to 720 nm are attributed to the 5D0 → 7F1, 7F2, 7F3, and 7F4 transitions of Eu3+ ion. The optimal doping concentration of Eu3+ ion is ~ 8 mol%. The lifetime of CaTi4(PO4)6:Eu3+ phosphors decreases from 1.87 to 0.97 ms with increasing Eu3+ concentrations from 1 to 10 mol%. CaTi4(PO4)6:Eu3+ phosphor has a good thermal stability. The experimental results indicate that CaTi4(PO4)6:Eu3+ phosphor has an application prospect in white light-emitting diodes (LEDs) based on the near ultraviolet (~ 394 nm) LED chip.
关键词： Phosphors,Eu3+ ion,CaTi4(PO4)6,Luminescence properties,Orange-red emission
更新于2025-09-19 17:13:59