Journal articles: 'White Phosphor'

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Chen, Bing-Mau, Shang-Ping Ying, Hsuan-Li Huang, and Yu-Chieh Cheng. "Cylindrical Rod Phosphor Structure for Laser-Driven White Lighting." Coatings 12, no. 11 (October 28, 2022): 1637. http://dx.doi.org/10.3390/coatings12111637.

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In this article, a cylindrical rod phosphor structure was developed and used for laser-driven white lighting. The blue light emitting from the laser diode (LD) with limited divergence enters the cylindrical rod containing phosphor and excites the yellow phosphor particles in the cylindrical rod to generate white light. Multiple phosphor blends with yellow and red phosphors were also applied to the cylindrical rod phosphor structure to enhance the red luminescence of white light with a low correlated color temperature (CCT). An advanced structure with a surrounding transparent layer around the central cylindrical rod containing phosphors was also investigated to enhance the possibility of the blue light absorption by phosphors in the cylindrical rod region away from the LD. The cylindrical rod phosphor structures with or without the surrounding transparent layer were fabricated to produce laser-driven white lighting, and the optical characteristics of the cylindrical rod phosphor structures with different phosphor concentrations or yellow-to-red phosphor weight ratios were examined.

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Trivellin, Nicola, Matteo Meneghini, Matteo Buffolo, Gaudenzio Meneghesso, and Enrico Zanoni. "Analysis and Reliability Study of Luminescent Materials for White Lighting." Proceedings 2, no. 17 (May 15, 2018): 1158. http://dx.doi.org/10.3390/ecms2018-05233.

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In this work, we report on the characterization and reliability/stability study of phosphorescent materials for lighting applications. More specifically, we investigated (a) phosphors directly deposited over light-emitting diodes (LED) chip, (b) remote phosphor (RP) solutions encapsulated in plastic medium for LED lighting, and (c) phosphors without binder for extreme high-intensity laser diode white lighting. The optical and thermal properties of phosphors were studied to develop a sample based on a mix of phosphor compounds in order to achieve different correlated color temperatures (CCT) and high color rendering index (CRI) LEDs. Thermal properties of cerium-doped YAG (Yttrium Aluminum Garnet) phosphor materials were evaluated in order to study thermal quenching. A maximum phosphor operating temperature of 190–200 °C was found to cause a sensible efficiency degeneration. Reduced efficiency and Stokes shift also caused a localized temperature increase in the photoluminescent materials. In the case of remote phosphors, heat did not find a low thermal resistance path to the heatsink (as occurred through the GaN LED chip for direct phosphor-converted devices) and thermal analysis indicated that material temperature might therefore increase to values in excess of 60 °C when a radiation of 435 mW/cm2 hit the sample template. Reliability was also investigated for both plastic-encapsulated materials and binder-free depositions. Pure thermal reliability study indicated that phosphors encapsulated in polycarbonate material were stable up to temperature of approximately 100 °C, while binder-free phosphor did not show any sensible degradation up to temperatures of 525 °C.

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Liu, Sheng, Bei Ying Zhou, Shi Jia Gu, Lian Jun Wang, Wan Jiang, and Wei Luo. "A Promising Energy-Saving and Environmental-Friendly Lighting Device: High CRI White LED with Phosphor Materials." Materials Science Forum 848 (March 2016): 446–53. http://dx.doi.org/10.4028/www.scientific.net/msf.848.446.

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Two kinds of commercial LED phosphors (green phosphor LuAG:Ce3+ and red phosphor CaAlSiN3:Eu2+) with polymethyl methacrylate (PMMA) powders were mixed to prepare film phosphors with tunable emission peak in photoluminescence spectrum by flat vulcanizing machine under the temperature of 170 oC and pressure of 2 MPa. The physical phase, surface morphology, transmittance, luminescence spectra of samples were characterized by means of X-ray diffraction (XRD), Environmental scanning electron microscopy (ESEM), Ultraviolet-Visible (UV-Vis) spectrophotometry and Fluorescence spectrometer. The results show that the film phosphors phase was consistent with raw phosphors, phosphor particles were uniformly distributed, and fluorescence spectra with different proportions of phosphors in different position can be adjusted. Tested by HSP 3000 spectrum analyzer, the white LEDs fabricated by blue chip and composite film phosphor containing 5 wt% green phosphor and 1.5 wt.% red phosphor, which refers to the remote excitation technique, possessed color coordinate of (0.3715, 0.3280) and color rendering index (CRI) of 87 when it was driven at power of 36 V/140 mA, reaching the international advanced level.

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Uheda, Kyota. "Application of Nitride and Oxynitride Compounds to Various Phosphors for White LED." Key Engineering Materials 403 (December 2008): 15–18. http://dx.doi.org/10.4028/www.scientific.net/kem.403.15.

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Multiternary nitride and oxynitride compounds doped with rare earth ions, such as Eu2+ and Ce3+ have been enthusiastically applied as various phosphors to white LED. New red and green phosphors, CaAlSiN3:Eu and Ba3Si6O12N2:Eu, have been successfully synthesized, recently. The red phosphor has intense emission around 650 nm under two different irradiations at 405 and 455 nm from blue- and near UV-LED chips, respectively; while strong emission is observed around 520 nm from the green phosphor. Both phosphors also show small thermal quenching over the temperatures up to 150 °C. In addition, both LaSi3N5:Ce and La3Si8O4N11:Ce in lanthanum silicon nitride and oxynitride were examined as candidates for a blue phosphor in white LED with near UV-LED chip.

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Ye, Shenrui, Yukun Li, Ming Qiang, Wenhui Lou, Bo Dai, Hui Lin, Zhaoxia Han, Ruijin Hong, and Dawei Zhang. "Color Tunable Composite Phosphor Ceramics Based on SrAlSiN3:Eu2+/Lu3Al5O12:Ce3+ for High-Power and High-Color-Rendering-Index White LEDs/LDs Lighting." Materials 16, no. 17 (August 31, 2023): 6007. http://dx.doi.org/10.3390/ma16176007.

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Lu3Al5O12:Ce3+ phosphor ceramics were fabricated by vacuum sintering. On this basis, a bi-layer composite phosphor was prepared by low-temperature sintering to cover the phosphor ceramics with a layer of SrAlSiN3:Eu2+-phosphor-in-glass (PiG). The optical, thermal, and colorimetric properties of LuAG:Ce3+ phosphor ceramics, SrAlSiN3:Eu2+ phosphors and SrAlSiN3:Eu2+-PiG were studied individually. Combining the bi-layer composite phosphors with the blue LED chip, it is found that the spectrum can be adjusted by varying the doping concentration of SrAlSiN3:Eu2+-PiG and the thickness of Lu3Al5O12:Ce3+ phosphor ceramics. The maximal color rendering index value of the white LED is 86, and the R9 is 61. Under the excitation of a laser diode, the maximum phosphor conversion efficacy of the bi-layer composite phosphors is 120 lm/W, the Ra is 83, and the correlated color temperature is 4534 K. These results show that the bi-layer composite phosphor ceramic is a candidate material to achieve high color rendering index for high brightness lighting.

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Yao, Qing, Xinyi Pan, Junjie Tian, Zhihang Chen, Hongbin Ji, and Yun Wang. "(Sr, Ca)AlSiN3:Eu2+ Phosphor-Doped YAG:Ce3+ Transparent Ceramics as Novel Green-Light-Emitting Materials for White LEDs." Materials 16, no. 2 (January 11, 2023): 730. http://dx.doi.org/10.3390/ma16020730.

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In this work, based on Y3Al5O12:Ce3+ (YAG:Ce3+) transparent ceramic and (Sr, Ca)AlSiN3:Eu2+ phosphors, novel green-light-emitting materials were systematically studied. YAG:Ce3+ transparent ceramics with different doping-concentrations, from 0% to 1% (Sr, Ca)AlSiN3:Eu2+ phosphors, were fabricated by dry pressing and vacuum sintering. The serial phosphor ceramics had 533 nm green-light emission when excited by 460 nm blue light. The PL, PLE, and chromaticity performances were measured, indicating that more of the green-light component was emitted with the increase in doping concentration. The addition of (Sr, Ca)AlSiN3:Eu2+ phosphor increased the green-light wavelength area and improved the quantum yield (QY) of the YAG:Ce3+ ceramic matrix. The phase composition, microstructure, crystal-field structure and phosphor distribution of (Sr, Ca)AlSiN3:Eu2+ phosphor-doped YAG:Ce3+ transparent ceramics were investigated, to explore the microscopic causes of the spectral changes. Impressively, (Sr, Ca)AlSiN3:Eu2+ phosphors were distributed homogeneously, and the pinning effect of phosphor caused the suppression of grain growth. The novel materials could provide an effective strategy for full-spectrum white lighting and displaying applications in the future.

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Son, Chang Sik, Ho Jung Chang, Kang Hyun Jaekal, Young Chol Chang, and Soo Wohn Lee. "Dependence of Yellow Phosphor on Optical and Electrical Properties of the White Light Emitting Diode Chip." Materials Science Forum 510-511 (March 2006): 106–9. http://dx.doi.org/10.4028/www.scientific.net/msf.510-511.106.

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We prepared the surface mounted white light emitting diode (LED) chips by using yellow phosphors on the blue LED chip. The optical and electrical properties of prepared white LED chips were investigated. The yellow phosphor mixed with transparent epoxy was coated on the prepared LED chip. The optimum mixing conditions with epoxy and yellow phosphor is obtained at the mixing ration of epoxy: yellow phosphor = 97 : 3 wt %. The maximum luminance and light emitting efficiency are above 80,000 cd/m2 and 23.2 lm/W, respectively, at the bias voltage of 2.9 V. There was no distinct change in the luminance strength with changing of the yellow phosphor ratios. The flowing current of the white LED chip is about 30 mA at 2.9 V.

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Zhang, Xiao Qi, Li Min Dong, Xin Cheng Tang, Qin Li, and Zhi Dong Han. "Preparation and Luminescent Properties of Single White Ca₂MgSi₂O₇: Eu³⁺, Ce³⁺, Tb³⁺ Phosphor for WLED." Advanced Materials Research 989-994 (July 2014): 395–98. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.395.

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Ca2MgSi2O7: Eu3+, Ce3+, Tb3+, a single white Phosphor, was synthesized by the conventional solid-state reaction. The structure, surface morphology and luminescence properties of the prepared samples were investigated to evaluate its potentiality. XRD results confirm the orthorhombic phase of Ca2MgSi2O7: Eu3+, Ce3+, Tb3+ phosphors. The excitation spectra indicates the phosphor can be excited by 393 nm wavelength. The phosphor exhibits blue light at 467 nm, green light at 588 nm, red light at 618 nm. CIE chromaticity diagram indicates that Ca2MgSi2O7: Eu3+, Tb3+, Ce3+ exhibits white light. All properties show that the prepared phosphor is a single white phosphor suitable for near ultraviolet excitation which can be applied to new generation white LED lighting.

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9

Dutta, Dimple P., and A. K. Tyagi. "Inorganic Phosphor Materials for Solid State White Light Generation." Solid State Phenomena 155 (May 2009): 113–43. http://dx.doi.org/10.4028/www.scientific.net/ssp.155.113.

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Solid-state lighting (SSL) is emerging as a highly competent field and a possible alternative to existing lighting technologies. Development of a suitable phosphor is an important aspect of SSL. The aim of this review is to summarize status of Inorganic Phosphors towards SSL applications. Various examples have been taken from oxide, fluoride, nitride, sulfide and phosphate based host lattices. The important concepts like CIE coordinates and Color Correlated Temperature (CCT) will also be discussed. The sections encompasses of red, blue and green light emitting phosphors. The white light emitting phosphors will also be discussed in details.

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10

Chen, Hao-Long, Hung-Rung Shih, Sean Wu, and Yee-Shin Chang. "Effects of Bi3+ Ion-Doped on the Microstructure and Photoluminescence of La0.97Pr0.03VO4 Phosphor." Advances in Technology Innovation 6, no. 3 (May 19, 2021): 191–98. http://dx.doi.org/10.46604/aiti.2021.5635.

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The objective of this paper is to enhance the emission intensity of La0.97Pr0.03VO4 single-phased white light emitting phosphor. The Bi3+ ion-doped La0.97Pr0.03VO4 single-phased white light emitting phosphors are synthesized using a sol-gel method. The structure and photoluminescence properties of (La0.97-yBiy)Pr0.03VO4 (y = 0-0.05) phosphor are also examined. The XRD results show that the structure of La0.97Pr0.03VO4 phosphors with different concentrations of Bi3+ ion doping keeps the monoclinic structure. The SEM results show that the phosphor particles become smoother when the Bi3+ ion is doped. The excitation band for La0.97Pr0.03VO4 phosphor exhibits a blue shift from 320 nm to 308 nm as the Bi3+ ion contents are increased. The maximum emission intensity is achieved for a Bi3+ ion content of 0.5 mol%, which is about 30% greater than that with no Bi3+ ion doped. The CIE chromaticity coordinates are all located in the near white light region for different Bi3+ ion-doped La0.97Pr0.03VO4 phosphors.

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11

Choi, Kyoung Jae, Joung Kyu Park, Kyung Nam Kim, Chang Hae Kim, and Ho Kun Kim. "Phosphor-Conversion White Light Emitting Diode Using InGaN Near-Ultraviolet Chip." Solid State Phenomena 124-126 (June 2007): 499–502. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.499.

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We have synthesized a Eu2+-activated Sr3MgSi2O8 blue phosphor and (Sr,Ba)2SiO4 yellow phosphor. We fabricated a phosphor-conversion white light emitting diode(LED) using an InGaN chip that emits 400 nm near-ultraviolet(n-UV) light and phosphors that emit in the blue and yellow region. When the white LED was operated at a forward-bias current of 20 mA at room temperature(RT), the color temperature(Tcp), average color rendering(Ra), operating voltage(Vf) and luminous efficacy(ηL) were estimated to be 5800K, 72.08, 3.4V, and 7.61 lm/W, respectively. The commission International de I’Eclarirage(CIE) chromaticity coordinates obtained from the measured spectra remained almost constant during the forward-baias current increase from 0.5 mA to 60 mA.

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12

Indumathi, K., S. Tamilselvan, A. Duke John David, G. Shakil Muhammed, and G. Annadurai. "Structural and Optical Properties of Dy3+ Doped with an Eulytite Type NaBaBi2(PO4)3 Phosphor for White Light Emitting Diodes." Asian Journal of Chemistry 34, no. 7 (2022): 1869–74. http://dx.doi.org/10.14233/ajchem.2022.23766.

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A series of NaBaBi(2-x)(PO4)3:xDy3+ eulytite type phosphors with varying doping concentrations were synthesized using a conventional solid-state reaction. The crystalline nature and phase formation of the phosphor were confirmed by the PXRD technique. FESEM was used to examine the surface morphology. UV-DRS measurements were used to quantify the band gap of the host and Dy3+ ion doped phosphors. The phosphors’ photoluminescence properties were thoroughly investigated. According to the excitation spectra, these phosphors show a strong absorption band in the near-ultraviolet (NUV) region, extending from 250 to 450 nm. Under the excitation of 352 nm, the peaks of the emission spectra of Dy3+ ions are located at 485 nm (blue), 575 nm (yellow) and 666 nm (red), corresponding to the magnetic dipole 4F9/2→6H15/2 transition, the electric dipole 4F9/2→6H13/2 transition and the 4F9/2→6H11/2 transition. The optimal concentration of Dy3+ doped phosphor is x = 0.075 and the major concentration quenching mechanism is accomplished by energy transfer between the nearest-neighbour ions. The critical transfer distance (Rc) is estimated to be about 19.01. The Commission International deI’Eclairage (CIE) of NaBaBi1.925(PO4)3:0.075Dy3+ phosphor was calculated to be (x = 0.341 and y = 0.374), which was very close to the “ideal white” (x = 0.33, y = 0.33). Present findings suggest that the phosphor might be a viable option for producing a white-light-emitting phosphor under NUV activation.

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Shi, Tingxing, Feng Chen, Xiyu Zhao, Jiahua Zhang, Xiao-Jun Wang, and Feng Liu. "Charging storage phosphors using a white flashlight via the upconversion approach." Applied Physics Letters 121, no. 19 (November 7, 2022): 191902. http://dx.doi.org/10.1063/5.0122858.

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As an emerging approach to charge storage phosphors, upconversion charging (UCC) is attracting increased attention owing to its fundamental and practical perspectives. Despite the potential, further development of the UCC technology is restricted by the limited types of excitation light sources. Here, we use a white flashlight as excitation to investigate the UCC performance of storage phosphors. We demonstrate, as an example, that a Y3Al2Ga3O12:Pr3+ phosphor exhibits long-lasting emissions in the ultraviolet and visible regions after intense illumination from the flashlight. Thermoluminescence investigations reveal that both excited-state absorption and energy-transfer upconversion are involved in the UCC process. Based on the luminescence performance of the white-light charged phosphor, a conceptual thermometry approach is introduced, which can remotely sense the local temperature by monitoring the afterglow intensity ratio. Considering the wide use of flashlight, such a white-light excitability and the associated glow emission may potentially revolutionize the way to utilize storage phosphors.

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Ryapolova, Yuliya V., Vasily S. Soldatkin, Kirill N. Afonin, Vasily I. Tuev, and Anatoly A. Vilisov. "Parameters Investigation of Phosphors for Solid State Lighting." Key Engineering Materials 712 (September 2016): 357–61. http://dx.doi.org/10.4028/www.scientific.net/kem.712.357.

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Five types of phosphors for LED ribbon beam elements in white LED lamps have been studied. The phosphor composition and colorimetric parameters have been researched during the experiment. It is found that the larger and more uniform the grains of the phosphor, the higher the emission efficiency. The most similar in color to the white color coordinates of the sample No. 5 phosphor having also higher brightness compared with samples No. 1 – No. 4.

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Fan, Wang, Deng, Fan, and Zhang. "High Moisture Accelerated Mechanical Behavior Degradation of Phosphor/Silicone Composites Used in White Light-Emitting Diodes." Polymers 11, no. 8 (July 31, 2019): 1277. http://dx.doi.org/10.3390/polym11081277.

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In a high-power white light emitting diode (LED) package, the phosphor/silicone composite is typically used for photometric and colorimetric conversions, ultimately producing the white light. However, the phosphor/silicone composite is always exposed under harsh environments with high temperature, high blue light irradiation and high moisture when the LED operates. Therefore, its reliability issue has become one of the critical bottlenecks to improve the lifetime of a high-power white LED package. As the curing process and mechanical behavior of phosphor/silicone composite essentially determine its reliability, this paper firstly uses an in situ viscosity monitoring approach combined with Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR) analysis to explain the curing mechanism of a phosphor/silicone composite by taking the effects of temperature and phosphor mass fraction into consideration. Then, the mechanical properties of phosphor/silicone composites aged under a long-term high moisture condition are evaluated by using the tensile test. Meanwhile, the finite element (FE) simulations, the Mori–Tanaka theoretical estimations and the microstructure analysis are applied to investigate the high moisture induced degradation mechanisms. The results show that: (1) the in situ measured isothermal viscosity curves of both pristine silicone and phosphor/silicone composites follow the Arrhenius empirical model, and high temperature and high phosphor mass fraction can increase the curing rate; (2) the hydrosilylation reaction between silicones determines the curing mechanism of phosphor/silicone composite; (3) the tensile test, FE simulation and Mori–Tanaka theoretical prediction results confirm that the Young’s modulus of phosphor/silicone composite increases by gradually adding phosphors; and (4) the Young’s modulus of phosphor/silicone composite increases after the high moisture ageing test, which can be attributed to the oxidation and cross-linking reaction of silicone and the hydrolysis of phosphor powders.

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Chen, Yi Bo, Wei Cai, Yong Qiao Liu, and Meng Lian Gong. "Ca₃Sc₂Si₃O₁₂:1%Ce³⁺, x%Ba²⁺ Green Phosphors for White Light-Emitting Diodes." Advanced Materials Research 557-559 (July 2012): 776–80. http://dx.doi.org/10.4028/www.scientific.net/amr.557-559.776.

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Low temperature-quenching and high-efficiency Ca3Sc2Si3O12:1%Ce3+, x%Ba2+ phosphors were prepared by solid state method and the properties of these phosphors were investigated. The results showed that co-doping of Ba2+ ions can improve the photoluminescence properties and decrease temperature-quenching of Ca3Sc2Si3O12:Ce3+ phosphor obviously. High-efficiency blue-green light-emitting diode was fabricated with the prepared phosphor and an InGaN blue-emitting (~460 nm) chip. Good performance of the prepared LED indicates that Ca3Sc2Si3O12:1%Ce3+, 0.5%Ba2+ phosphor is a suitable candidate for the fabrication of high-efficiency white LEDs.

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Du, Jiang Nan, Deng Hui Xu, Zai Fa Yang, Xue Dong Gao, and Jia Yue Sun. "Preparation and Luminescence Properties of Dy³⁺ Doped Sr₃Lu(PO₄)₃ as a New Single Phase White Light Emitting Phosphor." Key Engineering Materials 727 (January 2017): 612–17. http://dx.doi.org/10.4028/www.scientific.net/kem.727.612.

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The novel white light emitting phosphors Sr3Lu(1-x)Dyx(PO4)3 (x = 0.02, 0.04, 0.06, 0.08, 0.10) were synthesized via a conventional high-temperature solid-state reaction method at 1250°C. The excitation spectrum indicated that these phosphors had a strong absorption in near UV region in the range from 260 to 460 nm. And under 350 nm excitation, the blue emission at 483nm (4F9/2→6H15/2) and yellow emission at 576 nm (4F9/2→6H13/2) were observed in the phosphors, respectively. We studied the effect of different doping concentrations of Dy3+ activator on the luminescence properties and found that the optimum doping concentration is 6 mol%. According to the Dexter’s theory, this quenching behavior is ascribed to be electric d-d interaction. Furthermore, the chromaticity coordinate (x = 0.28, y = 0.32) of Sr3Lu (PO4)3:0.06Dy3+ phosphor was very close to the “ideal white” (x = 0.33, y = 0.33) in the chromaticity diagram. Our results indicate that the Sr3Lu (PO4)3:Dy3+ phosphor can serve as a promising candidate for single-component white light emitting phosphor under near UV excitation.

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Böhnisch, David, Thomas Jansen, Rainer Pöttgen, and Thomas Jüstel. "Temperature dependent optical properties of red emitting Na3GaF6:Mn4+ as a color converter for warm white LEDs." Zeitschrift für Kristallographie - Crystalline Materials 233, no. 7 (July 26, 2018): 489–99. http://dx.doi.org/10.1515/zkri-2017-2118.

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Abstract This work presents and disentangles the temperature dependent optical properties of the red-emitting phosphor Na3GaF6:Mn4+. Moreover, crystal field and Racah parameters were investigated. It was proven that the material is suitable for the application in warm white LEDs due to its high quantum yield of about 83%, little thermal quenching of the photoluminescence up to 410 K, high lumen equivalent of about 220 lm/W, and strong absorption at 450 nm. In addition, different DFT approaches were used to investigate its band structure. The calculated data were compared to those obtained experimentally. Red phosphor spectra were calculated to evaluate the suitability of red line-emitting phosphors for the application in warm white emitting pcLEDs. Finally, warm white emitting LEDs comprising Na3GaF6:Mn4+ were constructed in order to show the potential of Na3GaF6:Mn4+ serving as a red component in phosphor blends for future warm white pcLEDs.

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Vu, Thi Hong Quan, Thi Tuyet Doan, Barsha Jain, Ravi Teja Velpula, Tung Cao Thanh Pham, Hieu Pham Trung Nguyen, and Hoang-Duy Nguyen. "Improving Color Quality of Nanowire White Light-Emitting Diodes with Mn4+ Doped Fluoride Nanosheets." Micromachines 12, no. 8 (August 15, 2021): 965. http://dx.doi.org/10.3390/mi12080965.

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A two-dimensional nanostructured fluoride red-emitting phosphor with an excellent quantum yield of ~91% is studied for cost-effective and high-color quality nanowire white light-emitting diodes (WLEDs). K2TiF6:Mn4+ phosphors are synthesized via an emulsification method using surfactants as sodium dodecyl sulphonate and oleic acid. The K2TiF6:Mn4+ phosphors in ultra-thin and nanosheet crystals are observed via scanning electron microscopy and high-resolution transmission electron microscopy. The surfactants are found to play a key role in inhibition of KTFM crystal growth process and stabilization of Mn4+ ions doping into the K2TiF6 host. The prepared phosphors exhibited intensive red emission at approximately 632 nm and excellent thermal stability in the range of 300–500 K upon 460 nm light excitation. Moreover, the K2TiF6:Mn4+ nanosheets were integrated on InGaN/AlGaN nanowire WLEDs for color quality study. The results show that the nanowire WLEDs with red-emitting phosphor exhibit unprecedentedly high color rendering index ~96.4, and correlated color temperature ~4450 K.

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Cao, Renping, Hongdong Xue, Xiaoguang Yu, Fen Xiao, Donglan Wu, and Fenxiang Zhang. "Luminescence Properties and Synthesis of SrMgAl10O17:Mn4+ Red Phosphor for White Light-Emitting Diodes." Journal of Nanoscience and Nanotechnology 16, no. 4 (April 1, 2016): 3489–93. http://dx.doi.org/10.1166/jnn.2016.11793.

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A series of Mn4+ doped SrMgAl10O17 phosphors are synthesized by a conventional solid-state reaction method in air, and their crystal structure, morphology, and fluorescence properties are investigated. The luminescence properties show clearly that SrMgAl10O17:Mn4+ phosphor can be excited by UV (200–380 nm), near UV (380–420 nm), and blue (420–480 nm) bands of LEDs chip, and emits red light in the range of 600 nm to 750 nm with satisfying CIE chromaticity coordinates (0.7207, 0.2793). The optimal doping concentration of Mn4+ ion is ∼1 mol%, and its lifetime is ∼1.15 ms. The possible luminous mechanism of Mn4+ ion is discussed by Tanabe-Sugano diagram. These experiment results indicate that Mn4+ doped SrMgAl10O17 phosphors can be a potential application as a red-emitting phosphor candidate in white LEDs.

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Chen, Jian, Hongyun Ma, and Yangai Liu. "A New Blue-Emitting Mg2Al4Si5O18:Ce3+ Phosphor for White Light Emitting Diodes." Journal of Nanoscience and Nanotechnology 16, no. 4 (April 1, 2016): 3506–10. http://dx.doi.org/10.1166/jnn.2016.11827.

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A series of blue-emitting Mg2Al4Si5O18:Ce3+ phosphors were prepared via the conventional high temperature solid-state reaction method. The phase structure, photoluminescence (PL) properties, PL thermal stability, and fluorescence decay curves of the samples were investigated for the first time. Under excitation at 365 nm, the phosphor exhibited a broad band blue emission with peak at 440 nm, which was ascribed to the 4f → 5d transition of Ce3+, and the color coordinate was (0.1602, 0.0849). When the temperature increased to 150 °C, the luminescence intensity of the Mg2Al4Si5O18:0.06Ce3+ phosphor was 55.73% of the initial value at room temperature. The activation energy ΔE was calculated to be 0.25 eV, which proved the good thermal stability of the sample. The energy transfer critical distance between Ce3+ ions in Mg2Al4Si5O18 host were also calculated. The above results indicate that the Mg2Al4Si5O18:Ce3+ is a promising candidate as a blue-emitting near ultraviolet convertible phosphor for application in white light emitting diodes (WLEDs).

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Yan, Xiao Song, Wan Wan Li, and Kang Sun. "White-Light-Emitting Phosphate Phosphors of SrZn₂(PO₄)₂: Eu²⁺, Mn²⁺ Synthesized through Combustion Process." Materials Science Forum 688 (June 2011): 344–48. http://dx.doi.org/10.4028/www.scientific.net/msf.688.344.

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The SrZn2(PO4)2: Eu2+, Mn2+ phosphors were synthesized through combustion process with varying mixture ratio of Eu2+, Mn2+. The SrZn2(PO4)2: Eu2+, Mn2+ phosphor presents three emission bands under 365nm radiation: the blue emission band of 416 nm from Eu2+ occupying the Sr2+ site, the green emission band of 538 nm and the red emission band of 630 nm from Mn2+ occupying two different Zn2+ sites. Compared with the SrZn2(PO4)2: Eu2+, Mn2+ phosphor prepared through solid state reaction, the luminous intensity of the phosphor is greatly improved through the combustion reaction. White emission light with a high color rending index of 84.7 can be obtained from the phosphor of SrZn2(PO4)2: Eu2+, Mn2+, and the emission color tone of the phosphor varies from blue, white, and finally yellow by increasing the ratio of the concentrations of Eu2+ and Mn2+.

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Nguyen Thi, Dieu An, My Hanh Nguyen Thi, and Phuc Dang Huu. "Quantum dot phosphors CaS:Ce3+ and CaS:Pb2+, Mn2+ for improvements of white light-emitting diodes optic characteristics." International Journal of Electrical and Computer Engineering (IJECE) 12, no. 5 (October 1, 2022): 4782. http://dx.doi.org/10.11591/ijece.v12i5.pp4782-4789.

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The goal of this study is to discover a new method that uses standard phosphors and quantum dots to improve the lighting qualities and heat manipulation of white light-emitting diodes (WLEDs). Despite the popularity as a good ingredient that offers good color rendering properties, quantum dots (QDs) have not been widely employed in the fabrication of WLEDs, particularly, the utilization of QDs-phosphor-mixed nanocomposite is limited. We propose a unique packaging design based on the research’s experimental findings. The layer of nanocomposites consisting of QDs and phosphors is horizontally positioned to the WLED for optimal lighting and heating efficiency. This study simulated and used four distinguishing white LEDs forms: mono-layer phosphorus, two double-layer remote phosphors featuring yellowish-red and yellowish-green organizations, and a triple-layer phosphor. In terms of color rendering and luminous outputs, the triple-layer phosphor configuration outperforms the other implementations, as per the finding.

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Ravi, Miyapuram, Ghanta Pushpa Chakrapani, Mandava Balachandrika, Pavuluri Vasudevarao, Chendela Nageswararao, Lavudia Krishna Kishore Babu, Pulipati Mallikharjuna Prasad, and Gurram Giridhar. "Photoluminescence studies on LiNa₅(PO₄)₂:Dy³⁺, Sm³⁺ phosphor." Zeitschrift für Naturforschung A 77, no. 3 (December 9, 2021): 279–90. http://dx.doi.org/10.1515/zna-2021-0153.

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Abstract This paper describes the preparation, structure and photoluminescence properties of a new class LiNa5(PO4)2:Dy3+, Sm3+-phosphor. Crystalline nature confirmed by X-ray diffraction. The phases obtained are in good agreement with the standard phase. Excitation dependence and concentration effect on luminescence features are investigated. Color purity and optical bandgap are also estimated for the LiNa5(PO4)2:Dy3+, Sm3+ phosphors. The result shows LiNa5(PO4)2:Dy3+, Sm3+-phosphor excited by 374 nm nUV light produces pure white light than others. Admixing of 4f configurations and energy transfer between dopants are identified while varying the concentration of Sm3+. The CIE coordinates for LiNa5(PO4)2:0.05Dy3+, 0.05Sm3+ (x = 0.309, y = 0.332) are positioned well in white light region and very close to pure white light. The present study on LiNa5(PO4)2:Dy3+, Sm3+-phosphor suggests that it is useful for the fabrication of white light emitting diodes.

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Xiao, Jun, Cong Wang, Xin Min, Xiaowen Wu, Yangai Liu, Zhaohui Huang, and Minghao Fang. "Multiple Energy Transfer in Luminescence-Tunable Single-Phased Phosphor NaGdTiO4: Tm3+, Dy3+, Sm3+." Nanomaterials 10, no. 7 (June 27, 2020): 1249. http://dx.doi.org/10.3390/nano10071249.

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Advances in solid-state white-light-emitting diodes (WLEDs) necessitate the urgent development of highly efficient single-phase phosphors with tunable photoluminescence properties. Herein, the Tm3+, Dy3+, and Sm3+ ions are incorporated into the orthorhombic NaGdTiO4 (NGT) phosphors, resulting in phosphors that fulfill the aforementioned requirement. The emission spectrum of Tm3+ ions overlaps well with the adsorption spectra of both Dy3+ and Sm3+ ions. Under the excitation at 358 nm, the single-phase NaGdTiO4: Tm3+, Dy3+, Sm3+ phosphor exhibits tunable emission peaks in the blue, yellow, and red regions simultaneously, resulting in an intense white-light emission. The coexisting energy transfer behaviors from Tm3+ to Dy3+ and Sm3+ ions and the energy transfer from Dy3+ to Sm3+ ions are demonstrated to be responsible for this phenomenon. The phosphors with multiple energy transfers enable the development of single-phase white-light-emitting phosphors for phosphor-converted WLEDs.

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Nguyen, Thi Kim Chi, Duy Hung Nguyen, Tan Vinh Le, Thanh Vu Tran, Chi Nguyen Vo, and Thi Kim Trung Pham. "Luminescence properties of Mn4+-doped CaAl2O4as a red emitting phosphor for white LEDs." Ministry of Science and Technology, Vietnam 63, no. 3 (September 21, 2021): 3–7. http://dx.doi.org/10.31276/vjste.63(3).03-07.

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A series of Mn4+-activated CaAl2O4 (CAO) compounds were synthesized by co-precipitation to seek a candidate for a red-emitting phosphor to be employed in a white LED. The crystal structure, morphology, and fluorescence properties of the as-obtained phosphors were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL). The deep red luminescence of Mn4+ in CaAl2O4 is reported and discussed. The excitation spectrum exhibited broadband emission between 260 and 550 nm with three peaks dominating at 320 nm due to the transition of 4A24T1. Theemission spectra between 600 to 720 nm displays an overwhelming emission peak at 654 nm owing to the 2E4A2 transition of Mn4+ ion.This research demonstrates the great promise of CaAl2O4:Mn4+ as a commercial red phosphor in warm white LEDs and opens up new avenues for the exploration of novel non-rare-earth red-emitting phosphors.

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Xi, Cui Sheng, Shi Kao Shi, Hui Li Gong, and Ji Zhou. "Preparation and Luminescent Properties of Na₅Eu(MoO₄)_4-x(PO₄)_x Red Phosphors for White Light-Emitting Diodes Application." Materials Science Forum 654-656 (June 2010): 2025–28. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.2025.

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(PO4)3- -doped red phosphors, Na5Eu(MoO4)4-x(PO4)x (x ≤ 0.10), were prepared by the conventional solid-state reaction method, and their luminescent properties were studied. Under the excitation of near-UV 395 nm, the phosphors show intense red emission. In particular, the relative emission intensity of Na5Eu(MoO4)3.96(PO4)0.04 sample reaches about 5.0 times in comparison with that of the commercial red phosphor Y2O2S:Eu3+. The phosphor could be suitable for the application of white light-emitting diodes.

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Kousaka, Shinichiro, Kenji Toda, Tadashi Ishigaki, Kazuyoshi Uematsu, and Mineo Sato. "Development of New Red Phosphor Na₃YSi₂O₇:Eu³⁺ for a White LED." Key Engineering Materials 421-422 (December 2009): 360–63. http://dx.doi.org/10.4028/www.scientific.net/kem.421-422.360.

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New red phosphors Na3YSi2O7:Eu3+ was prepared by a conventional solid-state reaction. This silicate phosphor can be efficiently excited by near UV light, yielding an intense red emission. Under the excitation of near UV light, the emission intensity is higher than that of a commercial red phosphor Y2O2S:Eu3+.

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Zhang, Xiangting, Dan Zhang, Dongxiao Kan, Tong Wu, Yanhua Song, Keyan Zheng, Ye Sheng, Zhan Shi, and Haifeng Zou. "Crystal structure, luminescence properties and application performance of color tuning Y2Mg2Al2Si2O12:Ce3+,Mn2+ phosphors for warm white light-emitting diodes." Materials Advances 1, no. 7 (2020): 2261–70. http://dx.doi.org/10.1039/d0ma00556h.

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Sun, Jia Yue, Liu Han, Qiu Mei Di, and Qi Guang Xu. "Synthesis and Luminescence Properties of Na₃YSi₂O₇:Sm³⁺, Eu³⁺ Phosphor." Applied Mechanics and Materials 633-634 (September 2014): 306–9. http://dx.doi.org/10.4028/www.scientific.net/amm.633-634.306.

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Novel Na3YSi2O7: Sm3+, Eu3+phosphors for white light-emitting diodes were prepared by high-temperature solid-state reaction. The photoluminescence excitation and emission spectra, energy transfer from Eu2+to Tb3+are investigated in detail. The current research suggests that Na3YSi2O7: Sm3+, Eu3+phosphor is a potential candidate for application in Phosphor-converted LEDs.

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Jung, Jae-Yong. "Luminescent Color-Adjustable Europium and Terbium Co-Doped Strontium Molybdate Phosphors Synthesized at Room Temperature Applied to Flexible Composite for LED Filter." Crystals 12, no. 4 (April 15, 2022): 552. http://dx.doi.org/10.3390/cryst12040552.

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In this study, terbium and europium rare-earth ions were single-doped and co-doped to synthesized SoMoO4 phosphor at room temperature. The samples prepared synthesized crystalline SrMoO4 powder by the co-precipitation. Samples had a tetragonal structure in XRD analysis and d(112) spacing was changed by rare-earth doping. As the amount of rare earth added increased, a secondary phase appeared, and the structure changed. The synthesized SrMoO4:Tb3+ phosphors showed a green light emission at 544 nm under 287 nm, SrMoO4:Eu3+ phosphors showed a red light emission at 613 nm under 290 nm, and SrMoO4:[Eu3+]/[Tb3+] phosphor showed a yellow-white light emission at 544 and 613 nm when excited at 287 nm. The synthesized phosphor exhibited a change in green and red luminescence intensity based on the amount of Eu3+ doped and showed strong red luminescence as the Eu3+ doping increased. To use the SrMoO4:[Eu3+]/[Tb3+] phosphor with these characteristics in an LED color filter, a flexible composite prepared by mixing with PDMS showed green, red, and yellow-white emission under a UV-lamp.

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Liu, Xin, Xinglu Qian, Peng Zheng, Xiaopu Chen, Yagang Feng, Yun Shi, Jun Zou, Rongjun Xie, and Jiang Li. "Composition and structure design of three-layered composite phosphors for high color rendering chip-on-board light-emitting diode devices." Journal of Advanced Ceramics 10, no. 4 (June 26, 2021): 729–40. http://dx.doi.org/10.1007/s40145-021-0467-0.

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AbstractA three-layered phosphor structure was designed and prepared by the spin coating of BaSi2N2O2:Eu (cyan-emitting) and (Sr,Ca)AlSiN3:Eu (red-emitting) phosphor films on the yellow-emitting Y3Al5O12:Ce (YAG:Ce) phosphor ceramic synthesized by the solid-state reaction under vacuum sintering. In order to achieve high color rendering lighting, the influence of the composition and structure of the three-layered phosphors on the optical, thermal, and electrical properties of the chip-on-board (COB) packaged white-light-emitting diodes (WLEDs) was studied systematically. The WLED with the structure of “red+cyan+yellow” (R+C+Y) three-layered phosphor generated neutral white light and had a luminous efficacy of 75 lm/W, the fidelity index (Rf) of 93, the gamut index (Rg) of 97, and the correlated color temperature (CCT) of 3852 K. Under the excitation of laser diode (LD), the layer-structured phosphor yielded the white light with a luminous efficacy of 120 lm/W, color rendering index (CRI) of 90, and CCT of 5988 K. The result indicates that the three-layered phosphor structure is a promising candidate to achieve high color rendering and high luminous efficacy lighting.

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Sarda, Narendra G., Hiroshi Fujigaki, Yuma Ogita, Andrew Chan, Kei-Ichiro Murai, Geoffrey I. N. Waterhouse, and Toshihiro Moriga. "Photoluminescence Properties of (Ba_1-(x+y)Sr_xEu_y)₂Si₆O₁₂N₂ Phosphors for White LED Applications." Journal of Nano Research 36 (November 2015): 1–7. http://dx.doi.org/10.4028/www.scientific.net/jnanor.36.1.

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(Ba1-(x+y)SrxEuy)2Si6O12N2 oxynitride phosphors were successfully synthesized by the solid-state reaction method at 1200°C under a H2(5%) + N2(95%) atmosphere. The Sr2+ content (x) was varied in the range 0-0.6 and the Eu2+ content varied in the range 0.05-0.25, with the Si/(Ba+Sr+Eu) ratio fixed at 3. Results showed that the emission characteristics of (Ba1-(x+y)SrxEuy)2Si6O12N2 phosphors under UV or blue-light excitation was strongly dependent on the chemical composition. The phosphor (Ba0.95Eu0.05) Si6O12N2 showed an intense green emission peak at 520 nm, whilst the phosphor (Ba0.45Sr0.5Eu0.05)Si6O12N2 had a weaker emission maximum at 548 nm. Ba2+ substitution with Sr2+ decreased the lattice volume of the (Ba1-(x+y)SrxEuy)2Si6O12N2 phosphors and was responsible for the red-shift in the emission peak. Optimization of the Eu2+ concentration at a fixed Sr2+ content of 0.2 identified the phosphor (Ba0.65Sr0.2Eu0.15)2Si6O12N2 as a potential alternative to YAG:Ce yellow phosphors for white LED applications.

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Deng, Taoli, and Qiuyun Zhang. "Optimization of LaPO4:Bi3+ Single-Phased White-Emitting Phosphor Luminescence Properties by Li+/Na+ Doping." International Journal of Optics 2019 (March 3, 2019): 1–6. http://dx.doi.org/10.1155/2019/4530978.

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LaPO4:Bi3+ single-phased white-emitting phosphors doped with both Li+/Na+ ions were successfully prepared by a conventional solid-state reaction technique. Microstructures were analyzed by both X-ray diffraction and high-resolution scanning electron microscopy experiments. Under the excitation of 335 nm, the La0.97PO4:Bi3+0.03 phosphor showed four emission bands with maxima at 460 nm, 487 nm (blue), 530 nm (yellow), and 637 nm (red); these can be successfully combined to form pure white light in a single host lattice only by simple activator Bi3+ ion. It was found that changing the concentration of dopant (Li+, Na+ ions) did not produce a change in shape or location of the emission peaks, but the value of the emission intensity increased; this was particularly evident in the red emission, which could optimize the white light emitting performance of the phosphors. When the Na+ doping concentration was 0.02, the CIE chromaticity coordinate of phosphor La0.95PO4:Bi3+0.03, Na+0.02 was (0.3008, 0.3203), close to that of the standard white light.

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Jargus, Vitasek, Nedoma, Vasinek, and Martinek. "Effect of Selected Luminescent Layers on CCT, CRI, and Response Times." Materials 12, no. 13 (June 28, 2019): 2095. http://dx.doi.org/10.3390/ma12132095.

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Phosphors have been used as wavelength converters in illumination for many years. When it is excited with blue light, the frequently used yttrium aluminium garnet doped with cerium (YAG:Ce) phosphor converts a part of blue light to a wideband yellow light, resulting in the generated light having a white color. By combining an appropriate concentration of the YAG:Ce phosphor and blue excitant light, white light of a desired correlated color temperature (CCT) can be obtained. However, this type of illumination has a lower color rendering index value (CRI). In an attempt to improve the CRI value, we mixed the YAG:Ce phosphor with europium-doped calcium sulfide phosphor (CaS:Eu), which resulted in a considerably increased CRI value. This article examines an experiment with luminescent layers consisting of a mixture of selected phosphors and polydimethylsiloxane (PDMS). Different thicknesses in these layers were achieved by changing the speed of rotation during their accumulation onto laboratory glass using the method of spin coating. The spectral characteristics of these luminescent layers as they were excited with blue light emitting diode (LED) and laser diode (LD) were then determined. A suitable combination of the YAG:Ce phosphor with a phosphor containing europium, as it was excited with a blue LED, yielded a source of white light with a CRI value of greater than 85. The response time in the tested luminescent layers to a rectangular excitant impulse (generated by a signal generator and transmitted by LD) was also measured in order to examine their potential use in visible light communications (VLC).

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Tu, Huan, Guoying Zhao, Jingshan Hou, Yufeng Liu, Yan Zhou, Ganghua Zhang, Hong-Tao Sun, Ji-Guang Li, and Yongzheng Fang. "A garnet-structured (Y, Ca)₃(Al, Mg)₂(Al, Si)₃O₁₂:Ce³⁺ phosphor-in-glass engineering for use in high color rendering white LEDs." AIP Advances 12, no. 5 (May 1, 2022): 055113. http://dx.doi.org/10.1063/5.0084578.

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White light emitting diodes (LEDs) suffer from two most common drawbacks: the deficiency of the red component and the poor thermal stability of silicone. Ce3+-doped garnet phosphors with tailor-made luminescence properties can be achieved by variations in {A}, {B}, and {C} cation sites. Herein, a simultaneous ion co-substitution design strategy has been adopted to synthesize a series of (Y, Ca)3(Al, Mg)2(Al, Si)3O12 garnet phosphors and corresponding phosphor-in-glass (PiG) films. The co-substitution is finely restricted to the assigned sites. The emission peak is shifted from 529 to 565 nm, which is beneficial to obtain low color temperatures and high color rendering using a single phosphor for white LEDs. By employing the as-synthesized phosphor, the corresponding PiG films were fabricated by the low temperature co-sintering technology using the SiO2–B2O3–ZnO–Na2O glass system characterized with excellent thermal stability and moisture resistance. The morphological and elemental analyses demonstrated that the as-made phosphor powders were uniformly distributed in the glass host without any interfacial reactions. Finally, modular white LEDs with a high color rendering (Ra = 82.7) is achieved through the as-synthesized PiG film on an InGaN blue chip. This study may open up a facile approach to obtain high quality luminescence based on the mono-luminescence center, avoiding excitation energy wastage and low quantum efficiency aroused by multi-luminescence centers or color compensation phosphors in glass.

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Rao, Haibo, Caineng Li, Qi Zhang, Chunyu Zhou, Wei Zhang, Kun Zhang, Da Zhou, Qiaolin Lei, and Xuemei Wang. "Cymbal-shaped phosphor structure for phosphor-converted white LEDs." Optics Express 23, no. 15 (July 15, 2015): A949. http://dx.doi.org/10.1364/oe.23.00a949.

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Lin, Ming-Te, Shang-Ping Ying, Ming-Yao Lin, Kuang-Yu Tai, Sheng-Chieh Tai, Chih-Hsuan Liu, Jyh-Chen Chen, and Ching-Cherng Sun. "Ring Remote Phosphor Structure for Phosphor-Converted White LEDs." IEEE Photonics Technology Letters 22, no. 8 (April 2010): 574–76. http://dx.doi.org/10.1109/lpt.2010.2043088.

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Ying, Shang-Ping, Han-Kuei Fu, and Huang-Zong Tu. "Curved remote phosphor structure for phosphor-converted white LEDs." Applied Optics 53, no. 29 (August 29, 2014): H160. http://dx.doi.org/10.1364/ao.53.00h160.

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Bui, Thuc Minh, Nguyen Thi Phuong Loan, Phan Xuan Le, Nguyen Doan Quoc Anh, Anh Tuan Le, and Le Van Tho. "Enhancing the CRI and lumen output for the 6600 K WLED with convex-dual-layer remote phosphor geometry by applying red-emitting MGSR3SI2O8:EU2+,MN2+ phosphor." International Journal of Electrical and Computer Engineering (IJECE) 10, no. 4 (August 1, 2020): 3501. http://dx.doi.org/10.11591/ijece.v10i4.pp3501-3507.

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The traditional white LED product established with a single chip and a single phosphor results in a low color rendering index (CRI). The upgrade of LED package is comprised of two chips and one phosphor material and gives the higher CRI while keeping high luminous efficiency. Based on previous findings, the research paper performs the application of the two chips and two phosphors to enhance the color tunability of LEDs with different amounts and intensities of the two employed phosphors. Additionally, a color design model is built to serve the purpose of bettering the color fine-tuning of the white-light LED module. The maximum value of the difference between the measured CIE 1931 color coordinates and that of the simulated model is approximately 0.0063 around the 6600 K correlated color temperature (CCT). From the results, this study offers a quick approach to achieve the color fine tuning of a white-light LED module with a high CRI and luminous efficiency.

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Liem Bui, Van, and Phan Xuan Le. "The impacts of green Cs2ZnSi5O12:Eu2+ phosphor for white light emitting diode." Indonesian Journal of Electrical Engineering and Computer Science 27, no. 3 (September 1, 2022): 1270. http://dx.doi.org/10.11591/ijeecs.v27.i3.pp1270-1275.

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We created the green-light phosphor Cs2ZnSi5O12 (CZSO) with Eu2+ replacement for the practical use of ultraviolet white illumination through the solid-state technique. The phosphor displays many different forms and crystallizes in the space group Pbca along with Pa , with formation resembling CsAlSi2O6, the leucite in cube form. We utilized the X-ray powder diffraction as well as the spectroscopic knowledge to validate that the crystal formation in the phosphor CZSO:Eu2+ belongs to the space group Pa . CZSO can generate wide green emission with a wavelength of 504 nm when excited by ultraviolet. We enveloped the blend using the translucent silicone resin and the red-light phosphor Sr2Si5N8:Eu2+ as well as excited it using an ultraviolet light emitting diode (LED) device with a wavelength of 370 nm to generate white illumination that yields remarkable chromatic output. The generation of illumination utilizing the phosphor CZSO benefits from the wide green emission, which does not require the integration of the three phosphors that are critical to the ultraviolet pumping. Such benefit will allow the model of the apparatus to become simpler and simultaneously create a desirable ultraviolet white illumination. When the augmentation the emission efficacy as well as the heat consistency for the phosphor CZSO is realized, we can easily incorporate the ultraviolet LED devices to create better white illumination.

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Kang, Fengwen, Mingying Peng, Xiaobao Yang, Guoping Dong, Guochao Nie, Weijiang Liang, Shanhui Xu, and Jianrong Qiu. "Broadly tuning Bi3+ emission via crystal field modulation in solid solution compounds (Y,Lu,Sc)VO4:Bi for ultraviolet converted white LEDs." J. Mater. Chem. C 2, no. 30 (2014): 6068–76. http://dx.doi.org/10.1039/c4tc00238e.

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For phosphor-converted white LEDs based on UV chips, it is essential to search high efficient phosphors that better feature with broadly tunable emission and particularly have no or less excitation in visible ranges.

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Huang, Xiaoyong. "Red phosphor converts white LEDs." Nature Photonics 8, no. 10 (October 2014): 748–49. http://dx.doi.org/10.1038/nphoton.2014.221.

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Fartode, S. A., Vijay Singh, and S. J. Dhoble. "Photoluminescence and Thermoluminescence Properties of Eu²⁺ and Ce³⁺Activated BaAlSi₅O₂N₇ Phosphors." Defect and Diffusion Forum 361 (January 2015): 177–93. http://dx.doi.org/10.4028/www.scientific.net/ddf.361.177.

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Ce3+ and Eu2+ activated BaAlSi5O2N7 phosphors have been prepared by the modified three step solid state diffusion method. Prepared phosphors are characterized by XRD, SEM, photoluminescence and thermoluminescence techniques. Upon excitation at 234nm, Ce3+ activated BaAlSi5O2N7 phosphor shows strong emission at 360nm. Upon excitation at 348nm, Eu2+ activated BaAlSi5O2N7 phosphor shows strong emission at 469nm in the blue region of the optical spectrum. After quenching at higher temperature and upon excitation at 363nm, BaAlSi5O2N7:Eu2+ phosphor shows broad band at 516nm in the green region of the optical spectrum. The trap parameters are studied using glow curve deconvolution. It was found that the obtained samples may be suitable for near UV excited white light emitting diodes.

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Liu, Qingbo, Yufeng Liu, Fu Yang, Bing Han, Hao Feng, and Quanmao Yu. "A novel orange-red phosphor Ca3B2O6:Sm3+, A+(A = Li, Na, K) for white light emitting diodes." Functional Materials Letters 07, no. 03 (June 2014): 1450033. http://dx.doi.org/10.1142/s1793604714500337.

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A novel orange-red phosphor Ca 3 B 2 O 6: Sm 3+, A+( A = Li , Na , K ) has been synthesized by solid-state reaction at 950°C. The phase purity and photoluminescence (PL) behavior of the phosphor are studied in detail using the powder X-ray diffraction (XRD) technique and PL measurements. Ca 3 B 2 O 6: Sm 3+ phosphor can be efficiently excited by near ultraviolet (n-UV) and blue light, and the emission spectrum consists of four emission peaks at 563, 599, 646 and 709 nm, generating bright orange-red light. When a cation A+ is introduced into Ca 3 B 2 O 6: Sm 3+ as charge compensator, the emission intensity of Ca 3 B 2 O 6: Sm 3+ is evidently enhanced, but the PL spectral profile is unchanged. The integral intensity of the emission spectrum of Ca 2.96 Sm 0.02 Na 0.02 B 2 O 6 excited at 401 nm is about 1.2 times than that of Y 2 O 2 S : Eu 3+ commercial red phosphor. The CIE chromaticity coordinates of Ca 2.96 Sm 0.02 Na 0.02 B 2 O 6 phosphor were (0.608, 0.365), which are close to that of the commercial red phosphors Y 2 O 3: Eu 3+ (0.655, 0.345), Y 2 O 2 S : Eu 3+ (0.622, 0.351) and Sr 2 Si 5 N 8: Eu 2+ (0.620, 0.370).

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Nguyen, Doan Quoc Anh, Xuan Le Phan, and Hsiao-Yi Lee. "Enhanced Luminous Flux of White Led using Flat Dual-layer Remote Phosphor Configuration." Journal of Advanced Engineering and Computation 3, no. 2 (June 30, 2019): 425. http://dx.doi.org/10.25073/jaec.201932.222.

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The luminous flux of two different dual-remote phosphor structures concluding flat dual-remote phosphor (FDRP) and concave dual-remote phosphor (CDRP) is compared in this paper. The outcomes demonstrate that the FDRP structure is more lucrative than the CDRP structure. The article additionally clears up that in CDRP structure, the distance between two phosphor layers (d1) and the distance between the phosphor layer with the LED surface (d2) enormously affect the optical properties. Moreover, the difference in d1 and d2 causes a dramatic variance in the scattering and absorption properties of the remote phosphor layer and hence hugely affects WLEDs' illumination ability and chromatic uniformity. In order to limit these problems, the correlated color temperature of WLEDs, which is essentially a gauge of how the chromaticity observed when a "black body" radiator is warmed to a foreordained temperature, should be balanced out at 8500K when d1 and d2 vary, requiring a suitable modification of the YAG:Ce3+ phosphor's concentration. When d1 = d2 = 0, the scattering and assimilation in the remote phosphor layer become lowermost, prompting the most reduced viability in both shading quality and iridescent transition, which is confirmed dependent on the unearthly impacts created when these two separations are not same. Then again, when d1 and d2 get bigger, so does the dispersing surface, and the mixing of the blue beams with yellow beams swings to be increasingly homogeneous. This gives the insignificant different white light yet can't achieve any enhancement for luminous flux. According to the researched results, the luminous flux reaches a peak at 1020 lm when d1 = 0.08 mm or d2 = 0.63 mm whereas the chromatic inhomogeneity hits the lowest point when d1 = 0.64 mm or d2 = 1.35 mm.This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

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Zhao, Yin Sheng, Hai Long Yang, Jing Wang, Jia Song Zhong, Wei Dong Xiang, and Yong Jun Dong. "Mn³⁺ Ion Co-Doped in Y₃Al₅O₁₂Ce³⁺ Phosphor to Enhance the Red Spectral Emission." Advanced Materials Research 284-286 (July 2011): 2259–62. http://dx.doi.org/10.4028/www.scientific.net/amr.284-286.2259.

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Mn3+ ions doped in YAG:Ce phosphors as a co-activator and host lattice element by co-precipitation method, which have enlarged the emission spectral of pure YAG:Ce phosphor in the emission spectral, caused by 5T2-5E and 5T2-1T2 transition. Respectively, the manganese co-doped yttrium aluminum garnet doped cerium blended with YAG:Ce phosphor would show an improved white light emission.

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Sun, Zhihong, Aaqib Khurshid, Muhammad Sohail, Weidong Qiu, Derong Cao, and Shi-Jian Su. "Encapsulation of Dyes in Luminescent Metal-Organic Frameworks for White Light Emitting Diodes." Nanomaterials 11, no. 10 (October 18, 2021): 2761. http://dx.doi.org/10.3390/nano11102761.

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The development of white light emitting diodes (WLEDs) holds great promise for replacing traditional lighting devices due to high efficiency, low energy consumption and long lifetime. Metal-organic frameworks (MOFs) with a wide range of luminescent behaviors are ideal candidates to produce white light emission in the phosphor-converted WLEDs. Encapsulation of emissive organic dyes is a simple way to obtain luminescent MOFs. In this review, we summarize the recent progress on the design and constructions of dye encapsulated luminescent MOFs phosphors. Different strategies are highlighted where white light emitting phosphors were obtained by combining fluorescent dyes with metal ions and linkers.

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Sharma, Suchinder K., Jan Beyer, Richard Gloaguen, and Johannes Heitmann. "Comparing the optical properties and thermal stability of green (TbPO4), yellow (DyPO4), and red (PrPO4) emitting single crystal samples." Physical Chemistry Chemical Physics 22, no. 18 (2020): 10247–55. http://dx.doi.org/10.1039/d0cp01561j.

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Zhang, Xing Hua, Zun Ming Lu, Fan Bin Meng, Long Hu, Xue Wen Xu, Jing Lin, and Cheng Chun Tang. "The Structure and Photoluminescence Properties of Ca₃Si₂O₇: Eu²⁺Phosphor." Advanced Materials Research 509 (April 2012): 192–96. http://dx.doi.org/10.4028/www.scientific.net/amr.509.192.

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Abstract:

A series of yellow-emitting phosphors based on a silicate host matrix, Ca3-xSi2O7: xEu2+, were prepared by solid-state reaction method. The structure and photoluminescent properties of the phosphors were investigated. The XRD results show that the Eu2+ substitution of Ca2+ does not change the structure of Ca3Si2O7 host. The SEM images display that phosphors aggregate obviously and the shape of the phosphor particle is irregular. The EDX results reveal that the phosphors consist of Ca, Si, O, and Eu elements. The Ca3-xSi2O7: xEu2+ phosphors can be excited at wavelength of 300-490 nm, which is suitable for the emission band of near ultraviolet or blue light-emitting-diode (LED) chips. The phosphors exhibit a broad emission region from 520 to 650 nm and the emission peak centered at 568 nm. The phosphor for has the strongest excitation and emission intensity, and the energy transfer style between Eu2+ ions is quadrupole-quadrupole interaction for higher concentration Eu2+ doped Ca3Si2O7 phosphor. The Ca3-xSi2O7: xEu2+ phosphors can be used as candidates for white LEDs.

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Journal articles on the topic 'White Phosphor'

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