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Component Regulation and Crystallization Mechanism of CsPbBr3/Cs4PbBr6 Perovskite Composite Quantum Dots-Embedded Borosilicate Glass for Light Emitting Application
摘要： Cesium lead bromide CsPbBr3/Cs4PbBr6 perovskite composite QDs-embedded borosilicate glass (QDs@glass) have been prepared by using the conventional melting-quenching and heat-treatment technique. The effect of raw components and melting condition on the crystallization process, phase transition and crystal growth of CsPbBr3/Cs4PbBr6 QDs in the glass matrix were discussed in details. The formation of Cs4PbBr6 in glass has a significant impact on the optical properties of CsPbBr3 QDs. Excellent QDs@glass with high photoluminescence quantum yield (PLQY) of ～58% was achieved by optimizing the raw components and melting condition. The obtained QDs@glass shows outstanding thermal stability, photostability and water resistance stability. The PL intensity of QDs@glass remains 80% of the original one after being stored in a chamber with high-temperature and high-humidity (85 °C/RH 85%) for 70 hours, and shows little decrease (2%) after being soaked into deionized water for 70 hours. The white LED fabricated by using the as-synthesized green QDs@glass powder and red K2SiF6: Mn4+ phosphor on the surface of a blue LED chip displays luminous efficiency of 25 lm/W with CIE coordinates of (0.3328, 0.3442) at 100 mA and exhibits a wide color gamut (130% of the National Television System Committee standard).
关键词： Quantum dots,Borosilicate glass,White LED,Display,Cesium lead bromide
更新于2025-09-19 17:13:59
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Preparation of red-emitting BaSiF6:Mn4+ phosphors for three-band white LEDs
摘要： BaSiF6:Mn4t phosphors were synthesized to improve the color purity of phosphor-converted white light-emitting diodes (LEDs). The optimal synthesis conditions for attaining the brightest red emission spectrum from BaSiF6:Mn4t were investigated. The BaSiF6:Mn4t phosphor exhibited a strong absorption band at approximately 465 nm because of the 4A2g → 4T2g transition of Mn4t ions. In addition, the phosphor exhibited three strong emission peaks, at 615, 632, and 650 nm, because of a combination of vibrational shifts and the 2Eg → 4A2g transition in Mn4t is suitable for use as the red-emitting phosphor in three-band white LEDs pumped by a blue LED. The optical properties of BaSiF6:Mn4t were examined under excitation from a commercial blue LED by coating the phosphor onto the blue LED. Similarly, a three-band white LED was also fabricated by coating the red-emitting phosphor BaSiF6:Mn4t and green-emitting phosphor CsPbBr3 onto a commercial blue LED.
关键词： Photoluminescence,Three-band white LED,BaSiF6:Mn4t,phosphor
更新于2025-09-19 17:13:59
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Neoteric Mn <sup>2+</sup> ‐activated Cs <sub/>3</sub> Cu <sub/>2</sub> I <sub/>5</sub> dazzling yellow‐emitting phosphors for white‐LED
摘要： Neoteric Mn2+‐activated Cs3Cu2I5 yellow‐emitting halides were achieved by the simple solid‐state reaction route. The near‐ultraviolet light was the suitable excitation lighting source for the resultant halides. The resultant halides exhibited bright yellow emission under the excitation of 378 nm and the optimum dopant content was 11 mol%. The multipole‐multipole interaction contributed to the concentration quenching mechanism and the critical distance was 28.65 ?. The thermal resistance of the prepared compounds was identified by the temperature‐dependent emission spectra. Ultimately, the designed light‐emitting diode showed bright white light with satisfied color rendering index, proper color coordinate, and suitable correlated color temperature. These results indicated that the prepared yellow‐emitting halides were suitable for indoor illumination.
关键词： white‐LED,phosphors,Mn2+ ions,luminescence
更新于2025-09-19 17:13:59
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Come to light: detailed analysis of thermally treated Phenyl modified Carbon Nitride Polymorphs for bright phosphors in lighting applications
摘要： Carbon Nitride and its polymorphs have recently gained large interests for their huge properties and applications in different fields, from lighting to photocatalysis. Further, several attempts were recently devoted to tune and control its optical and electrical properties. In this report we analyze phenyl modified Carbon Nitride structures obtained by simple thermal polymerization at different temperatures (250 to 400 °C) of the starting precursor: 2,4-diamino-6-phenyl-1,3,5-triazine. A multi-technique experimental data (XRD patterns, Raman, TGA and DTG, steady- time and time resolved Luminescence, Photoluminescence Excitation spectra, Reflectivity spectra) was applied to analyze the relationship between structural and optical properties and to give more insight on the effect of synthesis procedure on the final polymer. The optical properties evidenced an interesting shift towards the visible region of the absorption spectrum of the phenyl modified g-C3N4 polymer that, associated with the high optical quantum yield (about 60%) and to a broad emission in the green-red spectral region, makes the samples very suitable for lighting applications. Indeed, we report a first prototype of white LED emission by assembly of a commercial blue LED and the Phenyl modified g-C3N4 powders as phosphor, verifying the structural and optical stability over about 10000 working hours.
关键词： Thermal polymerization,Optical properties,Polymorphs,Carbon Nitride,White LED,Lighting applications
更新于2025-09-19 17:13:59
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Synthesis, energy transfer mechanism, and tunable emissions of novel Na3La(VO4)2:Re3+ (Re3+ = Dy3+, Eu3+, and Sm3+) vanadate phosphors for near-UV-excited white LEDs
摘要： In this study, novel Eu3+-, Dy3+-, and Sm3+-activated Na3La(VO4)2 phosphors were synthesized using a solid state reaction method. X-ray diffraction analysis results indicated that the Na3La(VO4)2 phosphors had an orthorhombic crystal structure with the Pbc21 space group. There were two different La(1)O8 and La(2)O8 polyhedra with high asymmetry in the crystal structure. Scanning electron microscopy revealed that the product had a sheet morphology with an irregular particle size. Further, the luminescence properties, including the excitation and emission spectra, and luminescence decay curve, were investigated using a fluorescence spectrometer. The results showed that the Na3La(VO4)2 compound was an excellent host for activating the luminescence of Eu3+ (614 nm), Dy3+ (575 nm), and Sm3+ (647 nm) ions. Further, Dy3+/Eu3+ co-doped Na3La(VO4)2 phosphors were exploited, and the energy transfer from Dy3+ to Eu3+ was demonstrated in detail by the photoluminescence excitation, photoluminescence spectra, and luminescent decay curves. The results showed that the energy transfer efficiency from Dy3+ to Eu3+ was highly efficient, and the energy transfer mechanism was dipole–dipole interactions. Finally, tunable emissions from the yellow region of CIE (0.3925, 0.4243) to the red region of CIE (0.6345, 0.3354) could be realized by rationally controlling the Dy3+/Eu3+ concentration ratio. These phosphors may be promising materials for the development of solid-state lighting and display systems.
关键词： Vanadate phosphor,White LED,Energy transfer,Lighting and display,Near ultraviolet excitation,Tunable emissions
更新于2025-09-16 10:30:52
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Realization of white LED using plasmonic-based photonic structure through reflection, absorption and transmission analysis
摘要： A novel notion is proposed in the present research to generate white color LED using plasmonic-based one-dimensional photonic crystal structure. The entire work manipulates with three distinct colors of the red, blue and green light-emitting diode to realize the aforementioned application. The physics behind the research deals with the effective refractive indices of the proposed photonic crystal, pertaining to the red, blue and green where the mathematics of the same is integrated with Maxwell’s differential equation and subsequently through the Helmholtz second order differential equation. However, the principle of operation deals with the reflection, absorption and transmission characteristics. The reflection and transmission can be studied through-plane wave expansion method whereas absorption is discussed through numerical investigation. Further, the generation of three distinct signal and white signal can be made using different photonic structure. Moreover, the combination of said one-dimensional photonic structure generates a signal of 350 nm–530 nm wavelength, which is the signal of white LED. Finally it is inferred that the efficiency of the proposed structures is high as compared to both cold and warm LED.
关键词： 1-D photonic,White LED,Plasmonic,Structure
更新于2025-09-16 10:30:52
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Machine-learning assisted prediction of spectral power distribution for full-spectrum white light-emitting diode
摘要： The full-spectrum white light-emitting diode (LED) emits light with a broad wavelength range by mixing all lights from multiple LED chips and phosphors. Thus, it has great potentials to be used in healthy lighting, high resolution displays, plant lighting with higher color rendering index close to sunlight and higher color fidelity index. The spectral power distribution (SPD) of light source, representing its light quality, is always dynamically controlled by complex electrical and thermal loadings when the light source operates under usage conditions. Therefore, a dynamic prediction of SPD for the full-spectrum white LED has become a hot but challenging research topic in the high quality lighting design and application. This paper proposes a dynamic SPD prediction method for the full-spectrum white LED by integrating the SPD decomposition approach with the artificial neural network (ANN) based machine learning method. Firstly, the continuous SPDs of a full-spectrum white LED driven by an electrical-thermal loading matrix are discretized by the multi-peak fitting with Gaussian model as the relevant spectral characteristic parameters. Then, the Back Propagation (BP) and Genetic Algorithm-Back Propagation (GA-BP) NNs are proposed to predict the spectral characteristic parameters of LEDs operated under any usage conditions. Finally, the dynamically predicted spectral characteristic parameters are used to reconstruct the SPDs. The results show that: (1) The spectral characteristic parameters obtained by fitting with the Gaussian model can be used to represent the emission lights from multiple chips and phosphors in a full-spectrum white LED; (2) The prediction errors of both BP NN and GA-BP NN can be controlled at low level, that is to say, our proposed method can achieve a highly accurate SPD dynamic prediction for the full-spectrum white LED when it operates under different operation mission profiles.
关键词： Machine learning,Spectral power distribution,Genetic algorithm,Full-spectrum white LED,BP neural network
更新于2025-09-16 10:30:52
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Barbier Hyperbranching Polymerization-Induced Emission toward Facile Fabrication of White LED and Light Harvesting Film
摘要： Luminescent polymers are generally constructed through polymerization of luminescent moieties. Polymerization itself however is mainly used for constructing polymer main chain and the importance of polymerization on luminescence has yet to be explored. Here, we demonstrate a polymerization-induced emission strategy producing luminescent polymers by introducing Barbier reaction to hyperbranching polymerization, which allows luminescent properties to be easily tuned from the traditional type to an aggregation-induced emission type by simply adjusting the monomer structure and the polymerization time. When rotation about the phenyl groups in hyperbranched polytriphenylmethanols (HPTPMs) is hindered, HPTPMs exhibit traditional emission property. When all phenyl groups of HPTPM are rotatable, i.e., p,p’,p’’-HPTPM, it exhibits interesting aggregation-induced emission property with tunable emission colors from blue to yellow, by just adjusting polymerization time. Further applications of aggregation-induced emission type luminescent polymers are illustrated by the facile fabrication of white LED and light harvesting film with an antenna effect greater than 14. This Barbier hyperbranching polymerization-induced emission provides a new strategy for the design of luminescent polymers, and expands the methodology and functionality library of both hyperbranching polymerization and luminescent polymers.
关键词： white LED,luminescent polymers,aggregation-induced emission,polymerization-induced emission,light harvesting film,Barbier hyperbranching polymerization
更新于2025-09-16 10:30:52
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Ionic occupation sites, luminescent spectra, energy transfer behaviors in Y3MgAl3SiO12: Ce3+, Mn2+ phosphors for warm white LED
摘要： The Ce3t and Mn2t doped Y3MgAl3SiO12 (YMAS) phosphors were synthesized by the high-temperature solid-state reaction in 5%H2–95%N2 reduced atmosphere. Rietveld refinement of X-ray diffraction data indicated that co-doped YMAS phosphors had a garnet type cubic structure with the Ia3d space group. Ce3t occupies the lattice sites of Y3t. Mn2t occupies both lattice sites of MgO6 octahedron and AlO4 tetrahedron, emitting optical lights centered at 613 nm (Mn2t (I)) and 723 nm (Mn2t (II)), respectively. The orange-yellow light with the range of 450 nm–750nm was obtained by the energy transfer of Ce3t(cid:0) Mn2t with a maximum value of 69.2% of energy transfer efficiency. The integrated warm white LED produced white light with CRI of 85.4, CCT of 4502 K, and a CIE color coordinate (0.3542, 0.3269). It indicated that the phosphor might be suitable for blue light-excited white LEDs.
关键词： Phosphor,Y3MgAl3SiO12,White LED,Energy transfer,Garnet
更新于2025-09-16 10:30:52
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Green and red phosphor for LED backlight in wide color gamut LCD
摘要： Wide color gamut (WCG) backlight for liquid crystal display (LCD) utilizing white light-emitting diodes (LED) has attracted considerable attention for their high efficiency and color reduction. In this review, recent developments in crystal structure, luminescence and applications of phosphors for wide color gamut LED backlight are introduced. As novel red phosphors, Mn4+ activate fluoride and aluminate phosphors are advanced in quantum efficiency, thermal quenching and color saturation for their characteristic spectrum with broad excitation band and linear emission. The crystal structure and fluorescence properties of Mn4+ doped fluosilicate, fluorogermanate, fluotitanate, as well as Sr4Al14O25, CaAl12O19 and BaMgAl10O17 phosphors are discussed in detail. A serial of narrow-band red-emitting Eu2+, Eu3+ and Pr3+-doped nitride silicates and molybdate phosphors are also introduced. Rare-earth-doped oxynitride and silicate green-emitting phosphors have attracted more and more attention because of the wide excitation, narrow emission, high quenching temperature, high quantum efficiency, such as β-sialon:Eu2+, Ba3Si6O12N2:Eu2+, MSi2O2N2:Eu2+ (M=Ca, Sr, Ba), γ-AlON: Mn2+ and Ca3Sc2Si3O12:Ce3+. All above phosphors demonstrate their adaptability in wide color gamut LCD display. Especially for Mn4+ doped fluosilicate red phosphor and β-sialon: Eu2+ green phosphor. To achieve an ultra-high color gamut in white LED backlight and against the OLED, innovative narrow-band emission red and green phosphor materials with independent intellectual property rights are continuously pursed.
关键词： Rare earths,Liquid crystal display,Backlight,Wide color gamut,White LED,Phosphor
更新于2025-09-12 10:27:22