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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chen H., Zhang Z., Mi R., Molokeev M. S., Liu Yu., Wang B., Mei L., Fang M., Wu X., Min X., Liu Ya.
Заглавие : Synergetic manipulation of components and multiple activator sites towards full-spectrum lighting in Eu2+-doped whitlockite phosphors for high color-rendering WLED
Колич.характеристики :9 с
Место публикации : J. Lumin. - 2024. - Vol. 275. - Ст.120795. - ISSN 00222313 (ISSN), DOI 10.1016/j.jlumin.2024.120795. - ISSN 18727883 (eISSN)
Примечания : Cited References: 47. - We acknowledge the financial support from the National Natural Science Foundation of China (Grant No. 52104272 and 52072348), the Young Elite Scientists Sponsorship Program by CAST (2024QNRC001) and the Program National Key R&D Program of China (2021YFC1910602-01)
Аннотация: Tuning the components and multiple activator sites possesses profound significances on the regulation for corresponding luminescent properties of target phosphors. However, it is still challenging to realize full-visible emission via single activator in a single phase owing to the matrix diversity and uncertainty for multi-site occupation. Herein, we developed a family of whitlockite-type solid-solution phosphors Ca8MgGa1-yLay(PO4)7: Eu2+(y = 0–1) via inducing the La3+ ions into Ca8MgGa(PO4)7:Eu2+. The local environments of Eu2+ ions and corresponding tunable photoluminescent properties, decay times and thermal stability are revealed systematically in detail. Specially, the excitation and emission spectra of Ca8MgGa1-yLay(PO4)7: Eu2+ are broadened gradually, finally towards a full-visible emission with 152 nm bandwidth spectrum for the phosphor Ca8MgLa(PO4)7: Eu2+. WLED with a high color rendering index (CRI = 95) and low color temperature (CCT = 3764 K) was fabricated based on the full-visible emission Ca8MgGa0.2La0.8(PO4)7: 0.08Eu2+ phosphors under a 365 nm chip, indicating the prominent potentials for high-color-rendering WLEDs. These results in current work provide new ideas for synergetic manipulation of components and multiple activator sites towards a full-visible emission in single-phase applied for white lighting.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Wu, Yanzheng, Li, Weiqiang, Zheng, Yifan, Xu, Yiqin, Wen, Dawei, Molokeev M. S., Pan, Zaifa
Заглавие : Apatite oxynitride phosphor (Mg,Y)5Si3(O,N)13:Ce3+,Mn2+: A single-phased host with solar-like and efficient emission
Место публикации : J. Am. Ceram. Soc. - 2023. - Vol. 106, Is. 5. - P.2985-2996. - ISSN 00027820 (ISSN), DOI 10.1111/jace.18981. - ISSN 15512916 (eISSN)
Примечания : Cited References: 35. - This work was supported by the National Natural Science Foundation of China (Project No. 10804099, 21804119), Key projects of Zhejiang Natural Science Foundation (Project No. LZ18B050002), GDAS’ Project of Science and Technology Development (Nos. 2021GDASYL-20210103069, 2021GDASYL-20210103071)
Аннотация: During pursuing high color rendering index for full-color-emitting phosphor, low quantum efficiency (QE) is usually accompanying. We intend to elevate the luminescence efficiency when realizing a solar-like spectra distribution, by constructing apatite structure oxynitride, inheriting high covalence and rigidity from oxynitride, and suitable multiple cation sites from oxyapatite compounds. Full-color-emitting apatite structure oxynitride phosphor (Mg,Y)5Si3(O,N)13:Ce3+,Mn2+ has been prepared, and the crystal sites’ occupancies of activators in this host were favorable for white emission. (Mg,Y)5Si3(O,N)13:Ce3+,Mn2+ phosphor shows whole visible light with emission wavelength ranging from 370 to 750 nm, matching the spectra of sunlight quite well. The fabricated white light-emitting diode lamp demonstrated the distinctive overall performance of QE and chromaticity properties (Ra and R9). Furthermore, correlated color temperature is tunable from cool nature to warm white. The obtained lamp possesses the feature of less blue light hazard and high saturation of red degree, compared with the commercial YAG-based lamp.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Wang, Xuejiao, Feng, Xiaowen, Molokeev M. S., Zheng, Huiling, Wang, Qiushi, Xu, Chunyan, Li, Ji-Guang
Заглавие : Modulation of Bi3+ luminescence from broadband green to broadband deep red in Lu2WO6 by Gd3+ doping and its applications in high color rendering index white LED and near-infrared LED
Место публикации : Dalton Trans. - 2023. - Vol. 52, Is. 9. - P.2619-2630. - ISSN 14779226 (ISSN), DOI 10.1039/D2DT03751C. - ISSN 14779234 (eISSN)
Примечания : Cited References: 4. - This work is supported in part by the Project of Education Department of Liaoning Province (Grant No. LQ2019014) and he Natural Science Foundation of Liaoning Province (Grant No. 2020-MS-286). The authors are thankful for the support for the 4B9A Beamline from the Beijing Synchrotron Radiation Facility (BSRF) (Project No. 2021-BEPC-PT-005290). The authors would like to thank Siqi Liu from Shiyanjia Lab (
Аннотация: Phosphors that exhibit tunable broadband emissions are highly desired in multi-functional LEDs, including pc-WLEDs and pc-NIR LEDs. In this work, broadband emissions were obtained and modulated in the unexpectedly wide spectral range of 517–609 nm for (Lu0.99−xGdxBi0.01)2WO6 phosphors by tuning the Gd3+ content (x = 0–0.99). The effects of Gd3+ doping on phase constituents, particle morphology, crystal structure, and photoluminescence were systematically investigated. Broadband green emission was obtained from Gd3+-free (Lu0.99Bi0.01)2WO6 phosphors (x = 0), whose emission intensity was enhanced by 50% with 5 at% Gd3+ (x = 0.05). The phase transition happened when x 0.50 and the broadband red-NIR emission was obtained when x = 0.75–0.99. Three luminescence centers were proved to be responsible for the broadband green emissions via crystal structure, spectral fitting and fluorescence decay analysis. A pc-WLED with a high color rendering index (Ra = 91.3), a stable emission color, and a low color temperature (3951 K) was fabricated from the (Lu0.94Gd0.05Bi0.01)2WO6 broadband green phosphor, and an LED device that simultaneously emits high color rendering index white light and NIR light was obtained with the (Gd0.99Bi0.01)2WO6 broadband red-NIR phosphor. Night vision and noninvasive imaging were also demonstrated using the latter LED device.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yan W., Wei Y., Molokeev M. S., Wang S., Li G.
Заглавие : Green-emitting Bi3+-doped La2SrSc2O7 phosphor for pc-WLED lighting: Luminescent properties and energy transfer strategy
Место публикации : J. Alloys Compd. - 2022. - Vol. 908. - Ст.164621. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2022.164621
Примечания : Cited References: 63. - This work was supported by the National Natural Science Foundation of China (Grant Nos. 52072349)
Аннотация: The crystal structure, photoluminescence properties, thermal stability and corresponding mechanisms of the novel Bi3+, Eu3+-doped La2SrSc2O7 (LSS) phosphors have been measured and analyzed in details. The emission spectrum of LSS: 1.0%Bi3+ phosphor shows a novel green emission centered at 530 nm under 340 nm excitation, which is attributed to the 3P1→1S0 transition of Bi3+ ions. By designing Bi3+→Eu3+energy transfer strategy, luminescence colors of LSS: 1.0%Bi3+, yEu3+ (y = 0–5.0%) phosphors can be tuned from green to orange with increasing Eu3+ concentration, which achieve multiple emission colors in LSS host. The photoluminescence decay curves, average decay lifetimes, energy transfer efficiency and time-resolved emission spectra of LSS: 1.0%Bi3+, yEu3+ (y = 0–5.0%) phosphors prove the existence of energy transfer from Bi3+ to Eu3+. The prototype pc-WLED device with green-emitting LSS: 1.0%Bi3+ possesses high color rendering index (CRI = 96.0) and low correlated color temperature (CCT = 4306 K). These results provide clear evidences that LSS: Bi3+and LSS: 1.0%Bi3+, Eu3+ phosphors would be novel promising green-to-orange tunable phosphor candidates for pc-WLED applications.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liu Q., Dang P., Zhang G., Lian H., Li G., Molokeev M. S., Cheng Z., Lin J.
Заглавие : Broad luminescence tuning in Mn2+-doped Rb2Zn3(P2O7)2 via doping level control based on multiple synergies
Место публикации : CrystEngComm. - 2022. - Vol. 24, Is. 31. - P.5622-5629. - ISSN 14668033 (ISSN), DOI 10.1039/d2ce00719c
Примечания : Cited References: 31. - We acknowledge the financial support from the National Natural Science Foundation of China (NSFC No. 51932009, 51720105015, 51929201, 52072349, and 52172166), Projects for the Science and Technology Development Plan of Jilin Province (20210402046GH), and the Natural Science Foundation of Zhejiang Province (LR22E020004)
Аннотация: Here we constructed a series of novel non-centrosymmetric structure phosphors [Rb2Zn3(P2O7)2:Mn2+] by a high-temperature solid-state reaction. The multiband emission can be designed by Mn2+ preferentially occupying three types of crystallographic sites in Rb2Zn3(P2O7)2:Mn2+. The emission color could be continuously tuned from yellow-green to orange-red via multiple synergies among crystallographic site engineering, energy transfer, and Mn-Mn dimmers alone through the dopant concentration. These color-tunable phosphors have good thermal stability (I150 °C/I25 °C = 91%). The as-prepared pc-WLED has a low corresponding color temperature (CCT = 4820 K) and a high color rendering index (Ra = 90.4) with CIE color coordinates of (0.351, 0.358). These results show that emission-tunable Rb2Zn3(P2O7)2:xMn2+ phosphors are potential candidates for application in n-UV-based pc-WLED devices. This study offers a new insight for wide-range tuning of PL properties by using crystallographic site engineering through changing the doping level in Mn-activated phosphors.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chen J., Zou X., Li W., Zhang H., Zhang X., Molokeev M. S., Liu Y., Lei B.
Заглавие : Strategy to construct high thermal-stability narrow-band green-emitting Si-CDs@MAs phosphor for wide-color-gamut backlight displays
Место публикации : Adv. Opt. Mater. - 2022. - Vol. 10, Is. 21. - Ст.2200851. - ISSN 21951071 (ISSN), DOI 10.1002/adom.202200851
Примечания : Cited References: 47. - The work was supported by the Ministry of Science and Technology of China (No. G2021030022L), the Guangdong Provincial Special Fund for Modern Agriculture Industry Technology Innovation Teams (No. 2021KJ122), the National Natural Science Foundations of China (No. 52102042), the Independent Research and Development Projects of Maoming Laboratory (No. 2021ZZ004), the Key Realm R&D Program of Guangdong Province (No. 2021B0707010003), the Guangzhou Science & Technology Project (Nos. 202007020005 and 202103000059), the Guangdong Provincial Science and Technology Project (Nos. 2021A0505050006 and 2022A1515010229), and the Project of GDUPS (2018) for B.L.
Аннотация: Developing innovative narrow-band green-emitting phosphors featuring low thermal quenching and eco-friendliness for white light-emitting diode (WLED) backlights is a pivotal challenge. Benefitting from narrowband and low toxicity of green-emitting silanized carbon dots (Si-CDs), an efficient confinement and protection strategy through embedding Si-CDs in mesoporous aluminas (MAs) is proposed to construct MAs and Si-CDs composites (Si-CDs@MAs) with superior luminescence properties. Si-CDs@MAs phosphor exhibits green emission at 526 nm with narrow full width at half maximum of 51 nm, zero-thermal quenching even up to 423 K (104.1%@423 K of the emission peak intensity at 298 K), and the internal quantum efficiency of 64.46%. Compared with broad-band yellow-emitting solid-state Si-CDs (S-Si-CDs), the thermal stability, photostability, and water stability of Si-CDs@MAs phosphor are remarkably improved due to surface protection. The WLED backlight is fabricated with optimized Si-CDs@MAs phosphor, which shows high luminous efficacy of 117.43 lm W?1 and wide color gamut (107% NTSC). Furthermore, this work provides the design principles of realizing stable narrow-band solid-state fluorescence carbon dots, suggesting its great potential for wide-color-gamut display application.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Huang J., Su B., Song E., Molokeev M. S., Xia Z.
Заглавие : Ultra-broad-band-excitable Cu(I)-based organometallic halide with near-unity emission for light-emitting diode applications
Место публикации : Chem. Mater. - 2021. - Vol. 33, Is. 12. - P.4382-4389. - ISSN 08974756 (ISSN), DOI 10.1021/acs.chemmater.1c00085
Примечания : Cited References: 43. - This research was supported by the National Natural Science Foundation of China (Grant Nos. 51961145101 and 51972118), the Fundamental Research Funds for the Central Universities (D2190980), the Guangzhou Science and Technology Project (202007020005), International Cooperation Project of National Key Research and Development Program of China (2021YFE0105700), and the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01X137). The reported study was also funded by RFBR according to research project no. 19-52-80003
Аннотация: Low-dimensional hybrid metal halides demonstrate broad-band emission and high photoluminescence quantum yield (PLQY) acting as excellent candidates for a new generation of luminescent materials in lighting fields. However, most luminescent metal halides can only be excited by ultraviolet radiation, and the discovery of high-efficient emitters with broad-band excitation characteristics, especially upon efficient blue light irradiation, is a challenge. Herein, a zero-dimensional (0D) Cu(I)-based organometallic halide (18-crown-6)2Na2(H2O)3Cu4I6 (CNCI) was prepared with a green emission band centered at 536 nm and a near-unity PLQY (91.8%) upon excitation of 450 nm. Importantly, the ultrabroad excitation band covering a 300-500 nm range was observed in CNCI, and the luminescence mechanism has been discussed in detail. A white light-emitting diode (WLED) was fabricated with high luminous efficiency of 156 lm/W and a high color rendering index of 89.6. This work provides guidance for designing high-performance luminescent metal halides with suitable excitation characteristics and also promotes the application prospects of such materials in WLED fields.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhang, Qiuhong, Li, Junhao, Jiang, Wei, Lin, Litian, Ding, Jianhong, Brik, Mikhail G., Molokeev M. S., Ni, Haiyong, Wu, Mingmei
Заглавие : CaY2Al4SiO12:Ce3+,Mn2+: a single component phosphor to produce high color rendering index WLEDs with a blue chip
Место публикации : J. Mater. Chem. C. - 2021. - Vol. 9, Is. 34. - P.11292-11298. - ISSN 2050-7526, DOI 10.1039/d1tc01770e. - ISSN 2050-7534(eISSN)
Примечания : Cited References: 35. - This work has been financially supported by the National Nature Science Foundation of China (51902063, 51902354, U1801253), the Science and Technology Project of Guangdong Province (2018A050506061), the Science and Technology Project of Guangzhou City (202007020005, 202007020008) and GDAS' Project of Science and Technology Development (2020GDASYL-20200302010, 2018GDASCX-0110). M. G. Brik also thanks the support from the Chongqing Recruitment Program for 100 Overseas Innovative Talents (Grant No. 2015013), the Program for the Foreign Experts (Grant No. W2017011) and Wenfeng High-End Talents Project (Grant No. W2016-01) offered by Chongqing University of Posts and Telecommunications (CQUPT), Estonian Research Council grant PUT PRG111, European Regional Development Fund (TK141) and NCN project 2018/31/B/ST4/00924
Предметные рубрики: GARNET PHOSPHOR
ENERGY-TRANSFER
RED EMISSION
LUMINESCENCE PROPERTIES
Аннотация: A high color rendering index white light emitting diode (WLED) is generally produced by combining yellow and red mixed phosphors on a blue chip. Herein we report a single component phosphor based on CaY2Al4SiO12 (CYAS) to achieve warm white light emission with a high color rendering index (Ra), which can be up to 90.5. Ce3+, Mn2+ singly doped and co-doped CYAS phosphors have been synthesized by solid state reactions, respectively, for comparative investigations. The Rietveld X-ray diffraction (XRD) refinements show that the CYAS host crystallizes in a cubic structure with the Ia[3 with combining macron]d space group. The valence states of Ce and Mn inside the CYAS host have been confirmed by XPS and EPR. Ce3+ occupies the Ca2+/Y3+ site and generates a yellow emission band around 543 nm from its characteristic 5d–4f transition. Mn2+ occupies both the dodecahedron Ca2+/Y3+ and octahedral Al3+ sites, emitting red and deep red lights at 616 nm and 750 nm, respectively. These two emission bands are attributed to the 4T1(4G)–6A1(6S) transitions of Mn2+. Upon 460 nm light excitation, both the Ce3+ and Mn2+ characteristic emissions can be obtained, in which the emissions of Mn2+ result from the occurrence of energy transfer from Ce3+ in CYAS. All the results indicate that the prepared CYAS:Ce3+,Mn2+ could be a promising single component phosphor for blue chip WLEDs.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Шабанов, Александр Васильевич, Коршунов, Михаил Анатольевич, Буханов, Евгений Романович
Заглавие : Особенности усиления электромагнитного поля и увеличение плотности фотонных состояний в растительных фотонно-кристаллических структурах
Место публикации : Комп. оптика. - 2019. - Т. 43, № 2. - С. 231-237. - ISSN 0134-2452, DOI 10.18287/2412-6179-2019-43-2-231-237; Comput. Opt. - ISSN 2412-6179(eISSN)
Примечания : Библиогр.: 29
Предметные рубрики: BLUE IRIDESCENCE
LIGHT
COLOR
PULSE
BAND
Аннотация: Проведены расчёты с использованием метода трансфер матриц одномерных фотонных кристаллов с низким контрастом и разнопериодными асимметричными структурами. Такие структуры были найдены во многих растениях. При состыковке двух последовательно соединённых подрешёток с разными периодами отмечается увеличение амплитуды электромагнитного поля и плотности фотонных состояний внутри структуры и их изменение в зависимости от асимметрии толщин подрешёток.Calculations were performed using the transfer matrix of one-dimensional photonic crystals with low contrast and asymmetric structures of different periods. Such structures have been found in many plants. When joining two successively connected sublattices with different periods, an increase is observed in the amplitude of the electromagnetic field and the density of photon states inside the structure, and their change depends on the asymmetry of the thickness of the sublattices.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhao, Ming, Liao, Hongxu, Molokeev M. S., Zhou, Yayun, Zhang, Qinyuan, Liu, Quanlin, Xia, Zhiguo
Заглавие : Emerging ultra-narrow-band cyan-emitting phosphor for white LEDs with enhanced color rendition
Место публикации : Light: Sci. Appl. - 2019. - Vol. 8. - Ст.38. - ISSN 2047-7538, DOI 10.1038/s41377-019-0148-8
Примечания : Cited References: 31. - The present work was supported by the National Natural Science Foundations of China (Grant Nos. 51722202, 51572023 and 91622125), Natural Science Foundations of Beijing (2172036), Fundamental Research Funds for the Central Universities (FRF-TP-18-002C1), and the Guangdong Provincial Science & Technology Project (No. 2018A050506004). M.S.M. is grateful for the support from the Russian Foundation for Basic Research (Grant No. 17-52-53031).
Предметные рубрики: LUMINESCENCE PROPERTIES
TEMPERATURE
ROUTE
Аннотация: Phosphor-converted white LEDs rely on combining a blue-emitting InGaN chip with yellow and red-emitting luminescent materials. The discovery of cyan-emitting (470–500 nm) phosphors is a challenge to compensate for the spectral gap and produce full-spectrum white light. Na0.5K0.5Li3SiO4:Eu2+ (NKLSO:Eu2+) phosphor was developed with impressive properties, providing cyan emission at 486 nm with a narrow full width at half maximum (FWHM) of only 20.7 nm, and good thermal stability with an integrated emission loss of only 7% at 150 °C. The ultra-narrow-band cyan emission results from the high-symmetry cation sites, leading to almost ideal cubic coordination for UCr4C4-type compounds. NKLSO:Eu2+ phosphor allows the valley between the blue and yellow emission peaks in the white LED device to be filled, and the color-rendering index can be enhanced from 86 to 95.2, suggesting great applications in full-spectrum white LEDs.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mishra S., Yogi P., Chaudhary A., Pathak D. K., Saxena S. K., Krylov A. S., Sagdeo P. R., Kumar R.
Заглавие : Understanding perceived color through gradual spectroscopic variations in electrochromism
Коллективы : Department of Science and Technology (DST), Govt. of India; MHRD; CSIR (Govt. of India); DST under FIST scheme [SR/FST/PSI-225/2016]
Место публикации : Indian J. Phys. - 2019. - Vol. 93, Is. 7. - P.927-933. - ISSN 0973-1458, DOI 10.1007/s12648-018-1353-7. - ISSN 0974-9845(eISSN)
Примечания : Cited References: 34. - Authors acknowledge financial support from the Department of Science and Technology (DST), Govt. of India. Authors are thankful to Dr. K. V. Adarsh (IISER Bhopal) for Raman measurements. Authors thank Prof. V.D. Vankar (IIT Delhi) for useful discussions. Authors (AC and DKP) are thankful to MHRD and CSIR (Govt. of India), respectively, for providing fellowships. Support received from DST under FIST scheme (grant number: SR/FST/PSI-225/2016) is also acknowledged.
Предметные рубрики: 3 REDOX FORMS
TUNGSTEN-OXIDE
RAMAN-SPECTRA
VIOLOGEN
SALTS
Аннотация: A bias-dependent in situ Raman scattering and UV–Vis absorption spectroscopic change has been correlated with the corresponding color change of an electrochromic device in an attempt to explain how to understand the relationship between actual perceived color and its absorption/transmittance spectra. For this, the bias across an electrochromic device was increased gradually, rather than abruptly turning ON and OFF, to see subtle variations in Raman and absorption spectra due to bias. Raman scattering establishes that viologen changes its oxidation state reversibly between two redox species (EV2+ to EV+•) as a result of bias-induced dynamic redox process. A gradual variation in Raman and absorption spectra, which shows maximum absorption corresponding to the yellow light, accompanies similar variation in color change of the device as visible by naked eye. These spectroscopic results are correlated with the perceived blue color, in the reflected light, by the eye to understand the actual reason behind this. Maximum absorption of yellow light by the device resulting in blue appearance has been explained using the concept of additive and subtractive primary colors.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Hu T., Molokeev M. S., Xia Z., Zhang Q.
Заглавие : Aliovalent substitution toward reinforced structural rigidity in Ce3+-doped garnet phosphors featuring improved performance
Место публикации : J. Mater. Chem. C. - 2019. - Vol. 7, Is. 46. - P.14594-14600. - ISSN 20507534 (ISSN), DOI 10.1039/c9tc05354a
Примечания : Cited References: 38. - This work was supported by the National Natural Science Foundation of China (No. 51722202 and 51972118), the Guangdong Provincial Science & Technology Project (2018A050506004) and the Fundamental Research Funds for the Central Universities (D2190980).
Аннотация: Highly efficient phosphors with thermal stability and color-tunable emission are required for the fabrication of phosphor-converted white light-emitting diodes (pc-WLEDs). Currently developed engineering strategies are generally successful in photoluminescence tuning but, unfortunately, suffer severe deterioration in emission intensity/efficiency and/or thermal stability. Herein, an efficient aliovalent substitution strategy toward reinforced structural rigidity is proposed and demonstrated experimentally. By incorporating Be2+ ion into the garnet-type Lu2SrAl4SiO12:Ce3+ phosphor, the phosphor shows enhanced internal/external quantum efficiency, from 79.2%/26.7% to 84.5%/32.9%, photoluminescence tuning from green (peaking at ∼512 nm) to yellow (peaking at ∼552 nm), and zero thermal quenching, even up to 200 °C. The Be2+ substitution at the Al2/Si2 site enables stable and rigid local surroundings around the Ce3+ activator, which is responsible for the unprecedented performance. In addition, high-quality warm WLED devices with a luminous efficiency of 158.1 lm W-1, correlated color temperature of 3858 K and high color rendering index of 81.7, are obtained by combining Lu2SrAl4SiO12:Ce3+,Be2+ as the yellow emitter, CaAlSiN3:Eu2+ as the red emitter and a blue-emitting InGaN chip. These findings highlight a new strategy for performance optimization of LED phosphors by selecting rigid covalent compounds with further reinforced structural rigidity via aliovalent substitution.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liao H., Zhao M., Zhou Y., Molokeev M. S., Liu Q., Zhang Q., Xia Z.
Заглавие : Polyhedron Transformation toward Stable Narrow-Band Green Phosphors for Wide-Color-Gamut Liquid Crystal Display
Место публикации : Adv. Funct. Mater. - 2019. - Vol. 29, Is. 30. - Ст.1901988. - ISSN 1616301X (ISSN) , DOI 10.1002/adfm.201901988
Примечания : Cited References: 34. - The present work was supported by the National Natural Science Foundations of China (Grant Nos. 51722202, 91622125, and 51572023), Natural Science Foundations of Beijing (2172036), Fundamental Research Funds for the Central Universities (FRF‐TP‐18‐002C1), and the Guangdong Provincial Science & Technology Project (No. 2018A050506004).
Аннотация: A robust and stable narrow-band green emitter is recognized as a key enabler for wide-color-gamut liquid crystal display (LCD) backlights. Herein, an emerging rare earth silicate phosphor, RbNa(Li3SiO4)2:Eu2+ (RN:Eu2+) with exceptional optical properties and excellent thermal stability, is reported. The resulting RN:Eu2+ phosphor presents a narrow green emission band centered at 523 nm with a full width at half maximum of 41 nm and excellent thermal stability (102%@425 K of the integrated emission intensity at 300 K). RN:Eu2+ also shows a high quantum efficiency, an improved chemical stability, and a reduced Stokes shift owing to the modified local environment, in which [NaO8] cubes replace [LiO4] squares in RbLi(Li3SiO4)2:Eu2+ via polyhedron transformation. White light-emitting diode (wLED) devices with a wide color gamut (113% National Television System Committee (NTSC)) and high luminous efficacy (111.08 lm W−1) are obtained by combining RN:Eu2+ as the green emitter, K2SiF6:Mn4+ as the red emitter, and blue-emitting InGaN chips. Using these wLEDs as backlights, a prototype 20.5 in. LCD screen is fabricated, demonstrating the bright future of stable RN:Eu2+ for wide-color-gamut LCD backlight application.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Deng J., Zhang H., Zhang X., Molokeev M. S., Qiu J., Liu Y., Lei B., Ma L., Wang X.
Заглавие : Enhanced luminescence performance of CaO:Ce3+,Li+,F- phosphor and its phosphor-in-glass based high-power warm LED properties
Место публикации : J. Mater. Chem. C. - 2018. - Vol. 6, Is. 15. - P.4077-4086. - ISSN 20507534 (ISSN), DOI 10.1039/c8tc00813b
Примечания : Cited References: 44. - The present study was supported by the National Natural Science Foundation of China (Grant No. 21671070), the Project for Construction of High-level University in Guangdong Province, the Teamwork Projects funded by the Guangdong Natural Science Foundation (Grant No. S2013030012842), the Guangzhou Science & Technology Project (No. 201704030086) and the Open Project Fund from Key Laboratory of Advanced of Materials of Yunnan Province (No. 2018KF01).
Ключевые слова (''Своб.индексиров.''): correlated color temperature--critical concentration--doping concentration--enhanced luminescence--high color rendering index--high power white led--high temperature solid-state reaction--thermal and chemical stabilities
Аннотация: To obtain white light-emitted diodes (wLEDs) with a low correlated color temperature (CCT) and a high color rendering index (CRI), red-emission is indispensable in their emission spectra. Herein, CaO:Ce3+,Li+,F- yellow phosphors with more red spectral component have been prepared via a high temperature solid-state reaction. As compared to the F- undoped samples, CaO:Ce3+,Li+,F- phosphor have lower critical doping concentration of Ce3+ and show stronger luminescence. At the critical concentration, a quantum efficiency of 66.4% and enhanced thermal and chemical stability were obtained in CaO:Ce3+,Li+,F-. Furthermore, a CaO:Ce3+,Li+,F--based phosphor-in-glass (PiG) using the red-emitting glass system with the composition of SiO2-Na2CO3-Al2O3-CaO:Eu3+ as the host material was constructed and used for high-power white LED applications. Such PiG samples with different phosphor doping concentrations can satisfy various light color demands and display higher reliability than the CaO:Ce3+,Li+,F- phosphor. An optimal PiG-based wLED exhibits color coordinates of (0.3769, 0.3386), a CCT of 3774 K, a CRI of 82.5 and a LE of 73.1 when the mass ratio of phosphor to glass matrix was 7:50 in PiG. Moreover, such PiG-based wLED also showed acceptable color stability under different drive currents. All the above results demonstrate that CaO:Ce3+,Li+,F- can be expected to be a potential alternative yellow phosphor for blue light excited PiG based warm wLEDs, particularly for high-power devices.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liao, Hongxu, Zhao, Ming, Molokeev M. S., Liu, Quanlin, Xia, Zhiguo
Заглавие : Learning from a mineral structure toward an ultra-narrow-band blue-emitting silicate phosphor RbNa3(Li3SiO4)4:Eu2+
Место публикации : Angew. Chem. - Int. Edit. - 2018. - Vol. 57, Is. 36. - P.11728-11731. - ISSN 1433-7851, DOI 10.1002/anie.201807087. - ISSN 1521-3773(eISSN)
Примечания : Cited References: 22. - This work was supported by the National Natural Science Foundations of China (Grant Nos. 51722202, 91622125 and 51572023), and Natural Science Foundations of Beijing (2172036), and M.S.M. acknowledges support of the Russian Foundation for Basic Research (17-52-53031).
Предметные рубрики: RED PHOSPHORS
COLOR-GAMUT
LUMINESCENCE
Ключевые слова (''Своб.индексиров.''): luminescence--minerals--phosphors--rigid structure--silicates
Аннотация: Learning from natural mineral structures is an efficient way to develop potential host lattices for applications in phosphor converted (pc)LEDs. A narrow‐band blue‐emitting silicate phosphor, RbNa3(Li3SiO4)4:Eu2+ (RNLSO:Eu2+), was derived from the UCr4C4‐type mineral model. The broad excitation spectrum (320–440 nm) indicates this phosphor can be well matched with the near ultraviolet (n‐UV) LED chip. Owing to the UCr4C4‐type highly condensed and rigid framework, RNLSO:Eu2+ exhibits an extremely small Stokes shift and an unprecedented ultra‐narrow (full‐width at half‐maximum, FWHM=22.4 nm) blue emission band (λem=471 nm) as well as excellent thermal stability (96 %@150 °C of the initial integrated intensity at 25 °C). The color gamut of the as‐fabricated (pc)LEDs is 75 % NTSC for the application in liquid crystal displays from the prototype design of an n‐UV LED chip and the narrow‐band RNLSO:Eu2+ (blue), β‐SiAlON:Eu2+ (green), and K2SiF6:Mn4+ (red) components as RGB emitters.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chen M., Xia Z., Molokeev M. S., Lin C. C., Su C., Chuang Y. -C., Liu Q.
Заглавие : Probing Eu2+ luminescence from different crystallographic sites in Ca10M(PO4)7:Eu2+ (M = Li, Na, and K) with β-Ca3(PO4)2-type structure
Место публикации : Chem. Mater.: American Chemical Society, 2017. - Vol. 29, Is. 17. - P.7563-7570. - ISSN 08974756 (ISSN), DOI 10.1021/acs.chemmater.7b02724
Примечания : Cited References: 34. - The present work was supported by the National Natural Science Foundation of China (Grants 51722202, 91622125, and 51572023), Natural Science Foundations of Beijing (2172036), and Fundamental Research Funds for the Central Universities (FRF-TP-16-002A3). C.C.L. and C.C.S. acknowledge the financial support from the Ministry of Science and Technology of Taiwan (Contract No. MOST 104-2113-M-027-007-MY3), and M. Molokeev acknowledges support of the Russian Foundation for Basic Research (17-52-53031).
Ключевые слова (''Своб.индексиров.''): calcium--doping (additives)--excited states--light emission--lithium--luminescence--phosphors--photoluminescence--positive ions--rietveld refinement--single crystals--color tuning--crystallographic sites--different distributions--emission bands--local environments--long wavelength bands--luminescent centers--power diffraction data--europium
Аннотация: Eu2+ local environments in various crystallographic sites enable the different distributions of the emission and excitation energies and then realize the photoluminescence tuning of the Eu2+ doped solid state phosphors. Herein we report the Eu2+-doped Ca10M(PO4)7 (M = Li, Na, and K) phosphors with β-Ca3(PO4)2-type structure, in which there are five cation crystallographic sites, and the phosphors show a color tuning from bluish-violet to blue and yellow with the variation of M ions. The difference in decay rate monitored at selected wavelengths is related to multiple luminescent centers in Ca10M(PO4)7:Eu2+, and the occupied rates of Eu2+ in Ca(1), Ca(2), Ca(3), Na(4), and Ca(5) sites from Rietveld refinements using synchrotron power diffraction data confirm that Eu2+ enters into four cation sites except for Ca(5). Since the average bond lengths d(Ca-O) remain invariable in the Ca10M(PO4)7:Eu2+, the drastic changes of bond lengths d(M-O) and Eu2+ emission depending on the variation from Li to Na and K can provide insight into the distribution of Eu2+ ions. It is found that the emission band at 410 nm is ascribed to the occupation of Eu2+ in the Ca(1), Ca(2), and Ca(3) sites with similar local environments, while the long-wavelength band (466 or 511 nm) is attributed to Eu2+ at the M(4) site (M = Na and K). We show that the crystal-site engineering approach discussed herein can be applied to probe the luminescence of the dopants and provide a new method for photoluminescence tuning.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhang Y., Liu H., Mei L., Molokeev M. S., Wang Y., Huang Z.
Заглавие : Structure and color-tunable luminescence properties of Ce3+ and Tb3+-activated Mg2La8(SiO4)6O2 phosphors based on energy transfer behavior
Место публикации : J. Solid State Chem. - 2017. - Vol. 255. - P.36-41. - ISSN 00224596 (ISSN), DOI 10.1016/j.jssc.2017.07.026
Примечания : Cited References: 45. - This present work was supported by the National Natural Science Foundations of China (Grant no. 41172053), the Fundamental Research Funds for the Central Universities (Grant nos. 2652016083 and 2652016037), and Science and Technology Innovation Fund of the China University of Geosciences (Beijing).
Ключевые слова (''Своб.индексиров.''): crystal structure--luminescence properties--phosphors--apatite structure
Аннотация: A series of novel luminescent emission-tunable phosphors Mg2La8(SiO4)6O2:Ce3+,Tb3+ (MLS:Ce3+,Tb3+) have been prepared by a solid-state reaction. The phase formation was firstly confirmed through X-ray diffraction technique and refined by the Rietveld method. The MLS:Ce3+,Tb3+ phosphors, which crystallized in apatite-type hexagonal phase, exhibited a broad excitation band ranging from 200 to 400 nm and several emission bands centered at 426 nm and 551 nm. Energy transfer from Ce3+ to Tb3+ ions via a dipole-dipole mechanism occurred in the as-synthesized phosphors upon ultraviolet (UV) excitation. The energy transfer efficiency increases with increasing doping content of Tb3+ ions, which was confirmed by the luminescence spectra and fluorescence decay curves of corresponding ions simultaneously. The energy transfer critical distance was calculated and evaluated by both the concentration quenching and spectral overlap methods. The chromaticity of emission-tunable phosphors was also characterized by the Commission International de l'eclairage (CIE) chromaticity indexes, and the color tone can be tuned from blue (0.179, 0.122) to green (0.267, 0.408) by controlling the ratio of Ce3+/Tb3+. © 2017 Elsevier Inc.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhao M., Xia Z., Molokeev M. S., Ning L., Liu Q.
Заглавие : Temperature and Eu2+-doping induced phase selection in NaAlSiO4 polymorphs and the controlled yellow/blue emission
Место публикации : Chem. Mater.: American Chemical Society, 2017. - Vol. 29, Is. 15. - P.6552-6559. - ISSN 08974756 (ISSN), DOI 10.1021/acs.chemmater.7b02548
Примечания : Cited References: 48. - The present work was supported by the National Natural Science Foundation of China (Grants 91622125 and 51572023 and 11574003), Natural Science Foundations of Beijing (2172036), and Fundamental Research Funds for the Central Universities (FRF-TP-16-002A3). L.N. acknowledges the support from the Special and Excellent Research Fund of Anhui Normal University.
Ключевые слова (''Своб.индексиров.''): chemical modification--coordination reactions--europium--light emitting diodes--photoluminescence--functional properties--high color rendering index--local coordination structures--near ultraviolet excitations--structural transformation--synthesis temperatures--temperature dependent--white light emitting diodes--density functional theory
Аннотация: The union of temperature-dependent phase transition and relating structural transformation via modification of chemical compositions is of fundamental importance for the discovery of new materials or their functional properties optimization. Herein, the synthesis temperature and Eu2+-doping content induced phase selection and variations of the local structures in nepheline, low-carnegieite and high-carnegieite types of NaAlSiO4 polymorphs were studied in detail. The luminescence of Eu2+ in low-carnegieite and nepheline phases shows blue (460 nm) and yellow (540 nm) broad-band emissions, respectively, under near-ultraviolet excitation. The photoluminescence evolution can be triggered by the different synthesis temperatures in relation to the Eu2+-doping concentration, as corroborated by density functional theory calculations on the local coordination structures and corresponding mechanical stabilities in terms of the Debye temperature. The fabricated white light-emitting diode device with high color rendering index demonstrates that the multicolor phosphors from one system provides a new gateway for the photoluminescence tuning. © 2017 American Chemical Society.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ma, Bin, Guo Q. F., Molokeev M. S., Lv, Zhenfei, Yao, Jun, Mei, Lefu, Huang, Zhaohui
Заглавие : Crystal structure and luminescence properties of green-emitting Sr1−xAl12O19:xEu2+ phosphors
Место публикации : Ceram. Int.: Elsevier Science, 2016. - Vol. 42, Is. 5. - P.5995-5999. - ISSN 0272-8842, DOI 10.1016/j.ceramint.2015.12.149. - ISSN 1873-3956(eISSN)
Примечания : Cited References: 30. - This work was supported by the National Natural Science Foundation of China (Grant nos. 51032007 and 51372232) and the Fundamental Research Funds for the Central Universities (Grant no. 2652015024).
Предметные рубрики: COLOR-TUNABLE PHOSPHOR
ENERGY-TRANSFER
Dy3+ PHOSPHORS
NEAR-UV
Eu2+
DIODES
PHASE
STATE
Ce3+
Ключевые слова (''Своб.индексиров.''): crystal structure--magnetoplumbite--phosphor
Аннотация: In this paper, a series of novel luminescent Sr1−xAl12O19:xEu2+ phosphors were synthesized by a high temperature solid-state reaction. The phase structure, photoluminescence (PL) properties, as well as the decay curves were investigated. The quenching concentration of Eu2+ in SrAl12O19 was about 0.15 (mol). Upon excitation at 378 nm, the composition-optimized Sr0.85Al12O19:0.15Eu2+ exhibited strong broad-band green emission at 530 nm with the CIE chromaticity (0.2917, 0.5736). The results indicate that Sr1−xAl12O19:xEu2+ phosphors have potential applications as green-emitting phosphors for UV-pumped white-light LEDs.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Xia Y., Chen J., Liu Y.-G., Molokeev M. S., Guan M., Huang Z., Fang M.
Заглавие : Crystal structure evolution and luminescence properties of color tunable solid solution phosphors Ca2+xLa8-x(SiO4)6-x(PO4)xO2:Eu2+
Место публикации : Dalton Trans.: Royal Society of Chemistry, 2016. - Vol. 45, Is. 3. - P.1007-1015. - ISSN 14779226 (ISSN), DOI 10.1039/c5dt03786g
Примечания : Cited References: 42. - This work was sponsored by National Natural Science Foundation of China (Grant No. 51472223), the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-12-0951) and the Fundamental Research Funds for the Central Universities (Grant No. 2652015020).
Предметные рубрики: LIGHT-EMITTING-DIODES
WHITE-LIGHT
ENERGY-TRANSFER
SILICATE GLASS
SINGLE-PHASE
EU2+
LEDS
PHOTOLUMINESCENCE
EMISSION
UV
Аннотация: A series of apatite solid solution phosphors Ca2+xLa8-x(SiO4)6-x(PO4)xO2:Eu2+ (x = 0,2,4,6) were synthesized by a conventional higherature solid-state reaction. The phase purity was examined using XRD, XPS and XRF. The crystal structure information, such as the concentration, cell parameters and occupation rate, was analyzed using a Rietveld refinement, demonstrating that the Eu2+ activated the Ca2La8(SiO4)6O2 and Ca8La2(PO4)6O2 to form continuous solid solution phosphors. Different behaviors of luminescence evolution in response to structural variation were verified among the series of phosphors. Two kinds of Eu2+ ion sites were proved using low temperature PL spectra (8k) and room temperature decay curves. The substitution of large La3+ ions by small Ca2+ ions induced a decreased crystal field splitting of the Eu2+ ions, which caused an increase in emission energy from the 5d excited state to the 4f ground state and a resultant blue-shift from 508 nm to 460 nm. Therefore, with the crystal structure evolution, the emitted color of the series of phosphors could be tuned from green to blue by adjusting the ratio of Ca/La. © 2016 The Royal Society of Chemistry.
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