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White light emitting thermally stable bismuth phosphate phosphor Ca <sub/>3</sub> Bi( <scp>PO</scp><sub/>4</sub> ) <sub/>3</sub> :Dy <sup>3+</sup> for solid state lighting applications
摘要： White light emitting dysprosium doped Ca3Bi(PO4)3 phosphor was successfully synthesized via co-precipitation method for the first time and the structural, vibrational, morphological and luminescent properties have been investigated for solid state lighting applications. The X-ray diffraction (XRD) and structural refinement studies reveal that the synthesized phosphors consist of single phase with cubic structure. The field emission scanning electron microscopy (FE-SEM) images reveal that the as-synthesized phosphor has micron size with an irregular shape. Under near ultraviolet (n-UV) and blue excitation, the phosphor exhibits white light emission via a combination of blue (~451 nm) and yellow (~575 nm) emission bands. The optimized concentration of Dy3+ ions is 6.0 mol % after which the concertation quenching takes place. The process of energy transfer between Dy3+ ions is due to dipole-dipole interaction, which was confirmed by applying Dexter and Reisfeld’s Energy Transfer (ET) formula. The CIE chromaticity coordinates for the optimized phosphor were (0.329, 0.377), which lie in the white light region. The emission intensity remains to 83.41% at 373 K to that of at room temperature, which indicates good thermal stability. The above mentioned results demonstrate that Ca3Bi(PO4)3 is a potential phosphor for solid state lighting applications.
关键词： White LEDs,Structural and luminescent properties,White light emission,Phosphor,Thermally stable
更新于2025-11-21 11:18:25
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Highly efficient rare-earth-free deep red emitting phosphor La <sub/>2</sub> Li <sub/>1?y</sub> Sb <sub/>1?x</sub> O <sub/>6</sub> : <i>x</i> Mn <sup>4+</sup> , <i>y</i> Mg <sup>2+</sup> : application in high-power warm w-LEDs
摘要： Phosphor-in-glass (PiG), which serves as both a luminescent convertor and organic encapsulation material in high-power white light-emitting diodes (w-LEDs), has become a prospective research hotspot owing to its high transparency and thermal stability. However, YAG:Ce3+ PiG-based LED devices still suffer from a lack of a red component. Therefore, the development of red phosphors with excellent quantum efficiency and superior thermal stability is urgent. Herein, a highly efficient La2Li1?ySb1?xO6:xMn4+,yMg2+ red phosphor with a broadband emission ranging from 670 to 720 nm was fabricated via a conventional solid-state reaction. By co-doping Mg2+ in La2LiSbO6:Mn4+, the emission intensity was enhanced significantly, which reaches as high as 10 times that of the single-doped La2LiSbO6:Mn4+. It is proposed that the Mg2+ dopant can compensate imbalanced charges for the substitution of Sb5+ by Mn4+ and interrupt adverse energy transfer among the Mn4+ activators. Impressively, a maximum quantum yield of up to 80.3% is achieved and about 80% emission intensity is retained at the temperature of 423 K. Furthermore, the crystal field strength (Dq) and Racah parameters (B and C) together with the nephelauxetic ratio (b1) were calculated based on the obtained spectroscopic data. By embedding the red-emitting La2LiSbO6:Mn4+,Mg2+ phosphor and yellow-emitting YAG:Ce3+ phosphor into TeO2-based glass, an inorganic PiG composite as a color converter to replace organic silicone was acquired. The excellent optical parameters and tunable chromaticity feature of the fabricated w-LEDs were achieved by adjusting the mass ratio of La2LiSbO6:Mn4+,Mg2+ to YAG:Ce3+ in the PiG plate, where the correlated color temperature changed from cool white (6555 K) to warm (4130 K) and the color rendering index increased from 73.7 to 86.6 under an operating current of 300 mA.
关键词： Phosphor-in-glass,quantum yield,red phosphor,Mg2+,thermal stability,w-LEDs,Mn4+
更新于2025-11-20 15:33:11
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Enhancing optical performance of quantum dot-converted LEDs via electrospun fiber rods
摘要： Quantum dots (QDs) have been caught great concern for its excellent performance in the commercial white light-emitting diodes (LEDs). However, QDs show poor light scatter ability, limiting their luminous efficiency enhancement. In this study, a novel scattering structure via electrospinning fiber rods was designed to improve the usage efficiency of QDs in the packaging application. After studying the diffuse properties of the only fiber rod films, they were added into quantum dot-converted LEDs component to study the optical performance of LEDs. Results show that the luminous flux have been enhanced 3.42% when the fiber rod mass ratio is 0.065%, compared to the conventional structure.
关键词： Electrospinning,fiber rod,quantum dot-converted LEDs component,Scattering
更新于2025-11-19 16:46:39
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Ligand-assisted synthesis of monodispersed and small-sized ZnO nanoparticles and their application in electroluminescence device
摘要： ZnO nanoparticle thin film has been demonstrated to be the best electron transportation material in quantum dot-based light emitting diodes (QD-LEDs). Therefore, the synthesis of well-dispersed and size-controllable ZnO nanoparticles is highly desirable. In this work, we present a facile and reproducible approach for the controllable synthesis of well-dispersed and monodispersed ZnO nanoparticles by using short-chain ethanolamine as the capping agent. It was found that ethanolamine plays an important role in the synthesis of monodispersed ZnO nanoparticles by controlling the nucleation and growth process. As a result, well-dispersed and size-controllable ZnO nanoparticles can be obtained. Compared with ligand-free conventional methods, our ligand-assisted approach has a higher reproducibility and a better controllability. We notice that QD-LEDs based on ligand-assisted ZnO exhibit a superior electroluminescence (EL) performance than those of traditional ZnO.
关键词： nanoparticles,ZnO,QD-LEDs,electroluminescence
更新于2025-11-14 17:04:02
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Broadband emission of single-phase Ca3Sc2Si3O12:Cr3+/Ln3+ (Ln = Nd, Yb, Ce) phosphors for novel solid-state light sources with visible to near-infrared light output
摘要： Novel single-component phosphors Ca3Sc2Si3O12:Cr3+/Ln3+ (CSS:Cr3+/Ln3+, Ln = Nd, Yb, Ce) with broadband near-infrared (NIR) emissions are synthesized. Their phase structure, photoluminescence properties and energy transfer between Cr3+ and Ln3+ ions are investigated. In the CSS host, Cr3+ ions occupy Sc3+ sites with low-field octahedral coordination, and thus show a broadband emission in 700-900 nm under the blue light excitation. Nd3+, Yb3+ and Ce3+ ions substitute Ca2+ sites in CSS, where Nd3+ and Yb3+ ions emit the NIR light in 900-1100 nm and their excitation efficiencies at ~450 nm are greatly enhanced by utilizing the energy transfer from Cr3+ to Nd3+/Yb3+ ions. Ce3+ ions can further enhance the absorption of CSS:Cr3+/Ln3+ phosphors to the blue light, and at the same time contribute to the visible emission in 480-650 nm. Furthermore, CSS:Cr3+/Ln3+ phosphors show good thermal stability, and approximately 79% of the initial emission intensity is sustained at 150 oC. A phosphor-converted LED (pc-LED) prototype is fabricated by integrating the as-prepared phosphor CSS:Cr3+/Ln3+ and the commercial phosphor CaAlSiN3:Eu2+ with the blue LED chip, showing a super broadband emission ranging from 450 to 1100 nm. This finding shows the potential application of CSS:Cr3+/Ln3+ phosphors in broadband NIR pc-LEDs or super broadband LED sources with visible to NIR light output.
关键词： Near-infrared,Phosphor-converted LEDs,Photoluminescence,Ca3Sc2Si3O12
更新于2025-11-14 15:28:36
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Tunable white-light emission from Pr3+/Dy3+ co-doped B2O3 - TeO2 PbO - ZnO Li2O - Na2O glasses
摘要： In this paper, structural and optical analysis of boro-tellurite based glasses co-doped with Dy3+ and Pr3+ ions has been carried out. The glasses were fabricated by traditional melt quenching technique. XRD results confirm the amorphous-like nature of the glasses. FTIR spectroscopy was applied to explore the functional groups and interactions for the samples. The transition temperatures of glasses were identified by TGA/DSC analysis. Optical absorption and emission spectra of all the glasses have been recorded in the UVe Vis- NIR spectral range. Tauc's method was applied to determine the direct and indirect optical band gaps. Luminescence spectra show intense emission bands at ～482 nm and ～574 nm wavelengths under λexc = 388 nm corresponding to Dy3+: 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions. Decay time data revealed the occurrence of a non-radiative energy transfer from Dy3+ to Pr3+ ions. Intense emission bands are identified at ～602 nm (orange), ～487 nm (blue) and ～574 nm (yellow) observed upon λexc = 437 nm, corresponding to Pr3+:1D2→3H4, Pr3+:3P0,1,2 → 3H4/Dy3+: 4F9/2 → 6H13/2 and Dy3+: 4F9/2 → 6H13/2 transitions, respectively, where the Dy3+ emissions are due to energy transfer from Pr3+ to Dy3+ ions. The CIE chromaticity results confirm that different colors can be generated by tuning the exciting wavelength, where all the glasses are capable to emit white light under λexc = 388 nm, while at λexc = 437 nm the samples (S2eS4) emit reddish orange light. Accordingly, it is plausible to suggest these glasses for white LED and SSL applications.
关键词： Optical absorption,Photoluminescence,W-LEDs,Raman spectroscopy,Borotellurite glass,Energy transfer
更新于2025-09-23 15:23:52
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High concentration Eu3+-doped NaYb(MoO4)2 multifunctional material: Thermometer and plant growth lamp matching phytochrome PR
摘要： Phytochromes PR and PFR are distributed in various organs of plant, phytochrome PR absorbs red light and phytochrome PFR absorbs far-red light, respectively, so the flower induction, etc. can be controlled by changing the ratio of red light to far-red light. The emission of Eu3+ (transition from 5D0/7F2) is located at the red range and matches with the absorption band of PR. Herein, we synthesized successfully NaYb(MoO4)2: Eu3+ phosphors with the high doping concentration (50%) by hydrothermal method with further calcinations. The LED device was also fabricated by the blue InGaN chip combined with the red phosphors NaYb(MoO4)2: 50%Eu3+ based on the excellent luminescent intensity. Moreover, the effect of temperature on the excitation intensity ratio of MoO4 2- to Eu3+ has also been studied, which provided the possibility of simultaneous luminescence and temperature measurement. This work is the first time to use Eu3+ as a red source matching PR, and the red phosphors have potential value to control plant growth.
关键词： Down-conversion luminescence,Temperature sensing,LEDs,Plant cultivation,Red phosphors
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Kiev (2018.4.24-2018.4.26)] 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - A Device for Rapid Measurement of Nitrate Levels in Aqueous Solutions Based on Spectrophotometric Method
摘要： Method and device for rapid measurement of nitrate levels in aqueous solutions based on spectrophotometric method. The proposed method was realized with irradiation of test sample and measuring its optical density in the ultraviolet at three wavelengths.
关键词： UV-LEDs,nitrate-ions,water,measurement of nitrate,ultraviolet spectroscopy
更新于2025-09-23 15:22:29
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Simultaneously enhanced far-red luminescence and thermal stability in Ca3Al4ZnO10:Mn4+ phosphor via Mg2+ doping for plant growth lighting
摘要： Non-rare-earth-based Ca3Al4ZnO10:Mn4+,Mg2+ (CAZO:Mn4+,Mg2+) phosphors with admirable luminescence performance and great potential as far-red light source for plant growth light-emitting diodes (LEDs) were reported in this paper. The concentration-dependent optical properties of the as-prepared phosphors were investigated in detail. Under ultraviolet-light excitation at 358 nm, the composition-optimized CAZO:0.4%Mn4+,14%Mg2+ phosphor showed an intense broad far-red emission band in the 625-830 nm wavelength range with a maximum at 714 nm, which was due to the 2Eg→4A2g transition of Mn4+ ions. The luminescence intensity of the CAZO:0.4%Mn4+,14%Mg2+ phosphor was about 1.82 times higher than that of CAZO:0.4%Mn4+ phosphor, and the corresponding mechanism for the luminescence enhancement via Mg2+ doping was studied. Amazingly, the internal quantum efficiency of the CAZO:0.4%Mn4+ phosphor was increased from 31 to 60% after co-doping 14 mol% Mg2+. The CAZO:0.4%Mn4+,14%Mg2+ phosphor also showed enhanced thermal stability compared with the CAZO:0.4%Mn4+ counterpart. It was found that, for CAZO:0.4%Mn4+,14%Mg2+ phosphor, the emission intensity at 423 K (150 oC) was about 51% of that at 303 K (30 oC), while the corresponding activation energy was determined to be 0.245 eV.
关键词： thermal stability,plant growth,phytochrome,far-red emissions,LEDs.,Mn4+ ions
更新于2025-09-23 15:22:29
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Synthesis and photoluminescence properties of BaGeTeO6:Eu3+ red-emitting phosphor for n-UV Light Emitting Diodes
摘要： Novel red-emitting phosphors based on germanium tellurate host matrix, BaGeTeO6 doped with Eu3+, were prepared by solid-state reaction. X-ray diffraction analysis revealed that the phosphors consisted of hexagonal structure. The as-prepared BaGeTeO6:Eu3+ phosphors showed strong red emission at 610 nm corresponding to the 5D0–7F2 transition of Eu3+ upon 394 nm near UV wavelength. The optimal doping concentration of BaGeTeO6:xEu3+ was 5% and the critical distance of energy transfer between the Eu3+ ions was estimated to be about 17 ?. Temperature dependence of the Eu3+ emission intensity measured at T = 300–480 K was successfully analyzed. Due to their CIE coordinates with high color purity, BaGeTeO6:Eu3+ phosphors have potential application in the fabrication of WLED.
关键词： germanate,BaGeTeO6:Eu3+,Luminescence,LEDs
更新于2025-09-23 15:22:29