Journal of Materials Chemistry C
·
2022
·Vol. 10
·期 40
·14971-14981
·
IF 8.067
Shuai Huang,Mengmeng Shang,Minliang Deng,Yu Yan,Peipei Dang,Jun Lin
Efficiently modulating the site occupation of activators has important implications in the design of color-tunable phosphors. In this paper, we report a series of novel Sr3Sc4O9:xEu phosphors. The activators (Eu2+) selectively occupy multiple cationic sites (Sr1–3 and Sc1–4) in the Sr3Sc4O9 matrix with the increase of doping concentration, thus achieving the modulation of emission color from deep-red to white to green. The structure-dependent luminescence mechanism is investigated in detail. The PL spectrum of the Sr3Sc4O9:0.06Eu phosphor upon blue light excitation exhibits an asymmetrically broad deep-red emission band peaking at 688 nm with a FWHM ≈ 100 nm, which clearly overlaps with the absorption curves of red-phytochrome (Pr) and far-red-phytochrome (Pfr). The photoluminescence quantum yield (PLQY) is significantly improved from 2.7% to 19.18% by adopting a double-reduction strategy. The full-visible-spectrum white emission of Sr3Sc4O9:0.01Eu is achieved when excited by UV light. A full-spectrum white LED with Ra = 86 and CCT = 5040 K was packaged with a single-component white emission Sr3Sc4O9:0.01Eu phosphor. All the results suggest the utilization potential of multifunctional Sr3Sc4O9:xEu phosphors in agricultural and full-spectrum general lighting.
研究领域:
材料科学
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光学材料
·
固态照明
·
发光与荧光粉
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LED技术
·
无机化学
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高影响因子
CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Tao Long,Zixin Wang,Yuxiao Fan,Hui Lin,Haojie Sun,Cheng Zou,Dawei Zhang,Songlin Zhuang
In this study, two kinds of composite ceramic phosphors, Ce 3+ :YAG/Al 2 O 3 and Ce 3+ :Y(Gd)AG/Al 2 O 3 were prepared via solid state reaction sintering in flowing pure oxygen at atmospheric pressure. The ceramic phosphors were packaged into chip-scale white light emitting diodes (w-LEDs), and laser assisted w-LED automobile headlight prototypes were assembled. The luminous flux output of the w-LEDs was significantly improved through additional blue diode laser excitation. Notably, the Al 2 O 3 phase is able to impart an improvement in the luminescence saturation exhibited by Ce 3+ :Y(Gd)AG, which typically reaches saturation prior to Ce 3+ :YAG.
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DALTON TRANSACTIONS
·
2022
·Vol. 51
·期 11
·4414-4422
·
IF 4.569
Zhi Wang,Xu Li,Mingyang Li,Jinxing Zhao,Zhenyang Liu,Dawei Wang,Li Guan,Fenghe Wang
With the increasing demand for new inorganic functional materials, more and more attention is paid to rare earth ion doped luminescent materials. In this work, an Eu2+ doped Ba4La6O(SiO4)6 phosphor was synthesized by the high temperature solid-phase method. In the phosphor, two Ba2+ sites could be occupied by Eu2+ cations to provide two different kinds of coordination environments, resulting in broad emitting bands in the range of 450–630 nm and ultra-wide excitation bands in the range of 250–500 nm. The presence of two different Eu2+ emitting centers is verified by measuring the photoluminescence spectra and decay curves in Ba4La6O(SiO4)6 phosphors. The temperature dependence of emission intensity and full width at half maximum of Eu2+ in the range of 293–453 K were investigated systematically. The substitution of Ba2+ by Sr2+ can adjust the crystal field; thus, the luminous intensity was improved by 2.07 times and T50 was increased from 380 K to 453 K. Due to the Sr2+ ion doping, some of the Eu3+ ions cannot be reduced and remain in the trivalent state. In addition, by integrating the as-prepared Ba1.42Sr2.5La6O(SiO4)6:Eu phosphor, commercial blue and red phosphors, and a 385 nm LED chip, a white-LED lamp was made, which realized an applicable color rendering index (Ra = 94.6). For the Ba0.42Sr3.5La6O(SiO4)6 phosphor, the emission can be shifted from yellow to green and to yellow by excitation wavelength variation from 250 to 360 and 480 nm, which proves that the phosphor is a promising candidate for anti-counterfeiting applications.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Yongfeng Liu,Qingyu Xie,Yupeng Ying,Zhaoju Gao,Xiuwen Shao,Weizhi Xia,Min Zhou,Wei Pei,Xiaosheng Tang,Yusong Tu
All-inorganic perovskite quantum dots (PeQDs) hold immense potential for use in light-emitting diodes (LEDs) due to their excellent optoelectronic properties. However, the scalable synthesis and poor stability have severely hindered their application. Here, we solved both the two issues with “one stone”, namely a bipolar ligand 3-(N,N-dimethyloctadecylammonio) propane sulfonate (ASC18). ASC18 contains a positively charged quaternary ammonium group and a negatively charged sulfonic group, which enables for long-term reaction and gram-level synthesis of PeQDs with outstanding morphology, crystallinity, and optical properties. Density functional theory calculations and experimental studies show that these merits arise from the inhibition of Ostwald ripening by ASC18 due to their simultaneous interaction with undercoordinated Br – and Pb 2+ via a bidentate binding mode. Furthermore, ASC18 capped PeQDs present significantly improved stabilities against air, UV irradiation, heat, and polar solvent. Finally, both electroluminescent LEDs and down-conversion white LEDs fabricated with our PeQDs show significant operational stability. This presents a trustworthy avenue to obtain high-quality PeQDs for their practical applications.
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INORGANIC CHEMISTRY COMMUNICATIONS
·
2024
·
IF 4.4
Houteng Zhao,Yilian Ran,Xiya Miao,Siyu Cheng,Dongze Li,Yufeng Du,Xiang Liu,Ruijin Yu
A series of novel phosphors, doping Eu 3+ and Na + ions in the Sr 3 MgNb 2 O 9 (SMNO) crystal lattice (SMNO: x Eu 3+ , x Na + , x = 0.5–30 mol%), was successfully synthesized through high-temperature solid-state reaction. X-ray diffraction (XRD) analysis and Rietveld refinement confirmed the successful synthesis of SMNO:Eu 3+ , Na + . The phosphor belongs to the hexagonal crystal system and the P 3 ¯ m 1 (No.164) space group. The bandgap energy of SMNO was calculated with Materials Studio and measured with the use of diffuse reflectance spectroscopy. The excitation spectrum of SMNO:Eu 3+ , Na + displays multiple narrow absorption peaks in the violet-blue region as well as a charge transfer band (CTB) near 300 nm, exhibiting the highest peak at 394 nm. Four distinct characteristic peaks are observed in the emission spectrum of SMNO:Eu 3+ , Na + . Notably, the peak at 601 nm shows the highest emission intensity due to the radiative transition from 5 D 0 → 7 F 2 . By varying doping concentrations, it was determined that an optimal concentration of 5 mol%Eu 3+ resulted in phosphors, with high color purity exceeding 99 %. Concentration quenching is attributed to the nearest neighbor ions interaction. Furthermore, SMNO:Eu 3+ , Na + exhibited good stability in 300–480 K, with luminescent intensity remaining 68.6 % at 420 K and 54.4 % at 480 K compared to room temperature (300 K). The internal quantum efficiency (IQE) of SMNO:5%Eu 3+ , 5 %Na + is 65.0 %. Both red and white light-emitting diodes (LEDs) were prepared using SMNO:Eu 3+ , Na + . The chromaticity coordinates of w-LED were measured as (0.357, 0.376), correlating to a correlated color temperature (CCT) of 4685 K and exhibiting a good color rendering index (CRI, R a = 88). Additionally, the latent fingerprint (LFP) development demonstrated clear visualization of Levels I-III characteristic structures of fingerprints when utilizing SMNO:Eu 3+ , Na + . These findings suggest promising applications for SMNO:Eu 3+ , Na + in w-LED lighting and LFP development.
研究领域:
材料科学
·
光学
·
法医学
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2026
·
IF 4.8
Samra Jabeen,Ying Lin,Hongyu Chen,Shulei Li,Shu-Wei Chen,Yanwei ji,Xiang Liu,Jie Chu,Ruijin Yu
A simple, scalable, and solvent-free route for producing solid-state emissive carbon dots (CDs) with visible-light excitation remains challenging, particularly for dual applications in latent fingerprint (LFP) detection and white light emitting diodes (LEDs). Herein, we report a microwave-assisted, solvent-free synthesis of yellow-emitting carbon dots (Y-CDs) using phloroglucinol and boric acid as precursors. The obtained Y-CDs exhibit uniform morphology (2.63 nm), strong solid-state yellow fluorescence with optimal excitation at 520 nm, and an absolute photoluminescence quantum yield of 22.5%. The material demonstrates excellent photostability, thermal degradation, and long-term storage stability. Owing to these properties, the Y-CDs enable high-contrast latent fingerprint visualization with clear Level III ridge features across multiple substrates with negligible background interference. Moreover, the Y-CDs were successfully integrated in white and monochromatic LED fabrication. A WLED was achieved by integrating Y-CDs with a 456 nm blue chip, yielding Commission Internationale de l'Éclairage (CIE) coordinates (0.329, 0.321) close to the ideal white point.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Zihan Zhao,Xiuping Wu,Yanjie Zhang,Jiaheng Zhao,Bing Li,Hao Song,Desheng Li
As an all-inorganic solid state lighting material, phosphor-in-glass (PiG) receives much attention in high-power white lighting. However, poor heat-dissipation performance and low color rendering index (Ra) caused by low doping concentration of phosphor limit its application in white laser diodes (wLDs). Herein, phosphor-in-glass films on sapphire (PiFS) with heat-conducting properties and high Ra were newly synthesized via screen printing technology, which is highly desired for high-power wLEDs/wLDs. The interfacial corrosion product of CaWO 4 between nitride phosphor (CaAlSiN 3 :Eu 2+ ) and borosilicate glass (BS-glass) was found and investigated in detail firstly to determine the sintering temperature . Laminated structure of PiFS with red layer inside and green layer outside was intentionally designed to effectively avoid “reabsorption” effect between the red and green emitting phosphors. Compared with the opposite laminated structure, the PiFS exhibited the higher luminance efficiency (LE) and better optical properties (Ra = 85, CCT = 5362, CIE = (0.3348, 0.3156)) in wLDs. Notably, the adjustable optical characteristics can be achieved by changing the concentration of phosphor, the number of printing layers and the driving current for the application of PiFS in wLED and wLDs. High quality white light in wLED with CIE coordinates (0.3679, 0.3648) was also acquired and showed the excellent color rendering property (Ra = 90.8) and low color correlated temperature (CCT = 4280 K). Further, the working temperature of PiFS stabilized at 47 °C when applied in wLDs (1 W), which greatly prevented the phenomenon of “thermal quenching” for the phosphors caused by high temperature under high power LDs. Thus, high Ra PiFS prepared by this strategy has better heat dissipation and optical properties than PiG, indicating a prospective application in high-power white LEDs/LDs.
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Materials Today Chemistry
·
2021
·
IF 8.301
Zongjie Zhang,Balaji Devakumar,Shaoying Wang,Liangling Sun,Nan Ma,Wei Li,Xiaoyong Huang
White light-emitting diodes (LEDs) with high color rendering index (CRI) and low correlated color temperature (CCT) are desirable for next-generation solid-state lighting. In this work, we demonstrated an efficient near-UV-excited cyan-emitting phosphor based on Ce 3+ -doped Ca 2 LuHf 2 Al 3 O 12 (CLHAO) garnet , which could be used to cover the cyan gap for fabricating high-CRI warm-white LEDs. We found that the CLHAO:Ce 3+ samples exhibited a broad excitation band in the 300–450 nm wavelength range peaking at 400 nm, and upon 400 nm excitation they showed broad cyan emission bands in the 420–600 nm spectral region with peak positions ranging from 477 to 493 nm. The optimal CLHAO:0.02Ce 3+ sample had CIE color coordinates of (0.160, 0.255), and its internal and external quantum efficiencies were measured to be 84.3% and 60.8%, respectively. Impressively, the luminescence intensity of CLHAO:0.02Ce 3+ sample at 423 K still remained at 62% of the initial value at 303 K, and the chromaticity shift was calculated to be as low as 1.7 × 10 −2 , revealing its high thermal stability and color stability at a higher temperature. Finally, a warm-white LED device (CCT = 3,194 K) was fabricated by combining CLHAO:0.02Ce 3+ cyan phosphors with commercial blue/green/red tricolor phosphors, showing bright white-light emission with a high CRI of 89.4, which was superior to that of another warm-white LED device (CRI = 83.2) fabricated without CLHAO:0.02Ce 3+ cyan phosphors. These outstanding luminescence properties of CLHAO:Ce 3+ cyan phosphors illustrated that they offer a new feasible approach for the production of high-CRI warm-white LEDs toward high-color-quality solid-state lighting.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2021
·
IF 8.128
Nan Ma,Wei Li,Balaji Devakumar,Zongjie Zhang,Xiaoyong Huang
White light-emitting diodes (LEDs) are widely used in lighting and display devices, and the exploration of phosphors with excellent luminescence performance and good stability is the key to the development of white LEDs. In this work, we reported novel near-UV-excited green-emitting Ca 2 LuHf 2 (AlO 4 ) 3 :Ce 3+ ,Tb 3+ garnet phosphors with efficient Ce 3+ → Tb 3+ energy transfer. The CLHA:Ce 3+ ,Tb 3+ green phosphors were successfully synthesized by a high-temperature solid-state method, and the phosphors were characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, elemental mapping, photoluminescence excitation and photoluminescence spectra, the Commission International de I’Eclairage (CIE) chromaticity coordinates, quantum efficiency and temperature-dependent emission spectra. Due to the spin-allowed 4f → 5d transition of Ce 3+ ions, the CLHA:Ce 3+ ,Tb 3+ phosphors exhibited a strong broad excitation band in the 300–470 nm near-ultraviolet (near-UV) range. Under 408 nm excitation, the CLHA:Ce 3+ ,Tb 3+ phosphors showed strong green light with emission center at 543 nm. The mechanism of energy transfer from Ce 3+ to Tb 3+ ions was attributed to quadruple-quadruple interaction. Impressively, the internal quantum efficiency and external quantum efficiency of the optimal CLHA:0.02Ce 3+ ,0.5Tb 3+ green phosphors were measured to be 77.1% and 55.8%, respectively. Finally, using the CLHA:0.02Ce 3+ ,0.5Tb 3+ phosphors as green-emitting color converter, a near-UV-pumped white LED device was fabricated, and under 80 mA driving current the LED device demonstrated bright warm-white light with high color rendering index (93.7), low correlated color temperature (3574 K), CIE chromaticity coordinates (0.3922, 0.3633), and high luminous efficacy (29.35 lm/W).
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高影响因子
NANOTECHNOLOGY
·
2021
·Vol. 32
·期 39
·395703
·
IF 3.874
Zhihua Li,Xin Ding,Bing Yu,Yu Min,Bin He,Youqing Shen,Hailin Cong
Near-infrared (NIR) emission materials can be widely applied in various fields, such as food detection, imaging, treatment, electronic products. With the trend of miniaturization of equipment, smaller materials are needed. In this work, we successfully synthesized a series of M2Ga2GeO7:N3+ (M = Ca, Ba, Sr; N = Cr, Nd, Er) samples and then focused on the study of Nd3+ doped Sr2Ga2GeO7 (SGGO). A series of SGGO:xNd3+ sub-micron phosphors were prepared via a microwave-assisted sol–gel process combined with subsequent calcination at 750 ℃, and the structural information and luminescent properties were systematically studied. SGGO is a representative tetragonal crystal and belonging to the space group of P4¯21m (113). The Nd3+ ions occupy eight-coordinated Sr2+ sites in the crystal lattice. From SEM analysis, the average particle size distribution is 219.7 ± 41.4 nm. The sub-micron phosphors have rich excitation spectra ranging from 350 nm to 850 nm and can produce multiband NIR emissions of 1331, 1056, and 905 nm when excited by ultraviolet and NIR light. The maximum emission intensity was obtained by optimizing the doping ratio of Nd3+ ions. A commercial chip was then utilized to fabricate light-emitting diodes (LEDs) to verify its application potential in NIR-II mini-LEDs. Compared with blue light LEDs, the as-prepared LEDs had good imaging penetration depth and could be clearly observed under 10 mm of chicken breast coverage. The maximum imaging penetration depth can be 33 mm.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Xuemei Yao,Yatuan Ma,Xiya Miao,Shulei Li,Yufeng Du,Yun Cheng,Yue Yang,Xianchao Du,Huajuan Deng,Huiling Geng,Ruijin Yu
The propensity of carbon dots (CDs) to undergo significant self-quenching in the solid state, whether due to excessive resonance energy transfer or direct molecule collision, has significantly limited their application in light-emitting diodes (LEDs). However, incorporating electron-deficient boron atoms, guanidine functional groups, and boron hydroxyl groups proves advantageous in forming a hydrogen bond structure network. This network effectively suppresses the self-quenching phenomenon observed in solid CDs, thereby enhancing their potential for use in LEDs. Therefore, on this basis, a series of multicolor tunable solid-state fluorescent CDs were obtained, and their formation mechanism was discussed. The structure and morphology of the prepared series of multicolor tunable CDs were also characterized. The photoluminescence quantum yield (PLQY) of B-CD, Y-CD, and R-CD is 34.3 %, 23.7 %, and 20.5 %, respectively. The prepared series of CDs were used to successfully package the red, blue, and yellow monochromatic LEDs. By adjusting the ratio of CDs of different colors, a single matrix white-LEDs (w-LEDs), two primary colors w-LEDs, and the full-carbon-based w-LED of three primary colors are also obtained. The correlated color temperature of the above three w-LEDs is 7277, 3957, and 5040 K, the Color Rendering Index is 88, 91, and 92, and color coordinates are (0.302, 0.319), (0.376, 0.355), and (0.344, 0.354), respectively. It is demonstrated that CDs are a promising material in the solid-state lighting field.
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Applied Materials Today
·
2024
·
IF 7.2
Huajiang Hu,Jiurong Li,Xiao Gong
Due to their unique fluorescence properties and wide range of applications, carbon dots (CDs) have emerged as a prominent research subject. Acid reagents have traditionally been regarded as versatile means to facilitate the carbonization and polymerization of CDs, resulting in increased carbonization and polymerization levels, which in turn cause a redshift in the luminescence of CDs. However, there has been limited investigation into the impact of excess acid reagents on CDs luminescence. In this study, we discovered that the addition of excess acid reagent, in the presence of oxygen-containing functional groups, does not enhance the graphitization of CDs, but rather, it has the opposite effect. Excess acid reagents prevent CDs polymerization and reduce the content of graphite-N in the CDs. Simultaneously, excess acid reagent leads to an increase in oxygen-containing functional groups on the surface of the CDs, resulting in a blueshift in luminescence. Building upon these findings, we have devised a synthesis scheme for full-color CDs that cover nearly the entire visible light spectrum. Furthermore, leveraging the diverse color range, we have also employed these CDs for anti-counterfeiting encryption and LEDs applications.
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