Journal of Materials Chemistry C
·
2019
·Vol. 7
·期 20
·6077-6084
·
IF 6.641
Chunyan Jiang,Lihua Li,Mikhail G. Brik,Litian Lin,Mingying Peng
The poor moisture-resistant property of the commercial narrow band red-emitting K2SiF6:Mn4+ phosphor restricts its practical application in high performance warm WLEDs. Herein, we report epitaxial growth via simple ethanol-induced deposition to enhance the luminescence and moisture resistance of K2SiF6:Mn4+. Specifically, an appropriate amount of ethanol at the end of the synthesis leads to epitaxial growth of a K2SiF6:Mn4+ shell. The resultant K2SiF6:Mn4+@K2SiF6:Mn4+ presents higher photoluminescence intensity due to a high Mn4+ critical concentration in the K2SiF6:Mn4+ epitaxial shell. Furthermore, the epitaxial growth of the K2SiF6 shell on K2SiF6:Mn4+ is designed to conquer the moisture resistance. As expected, the formed K2SiF6:Mn4+@K2SiF6 retains 82% of the initial emission intensity after being immersed in water for 4 h and 90% after being exposed to high temperature and humidity (85 °C, 85%) for 10 days. By employing K2SiF6:Mn4+@K2SiF6 as a red phosphor, a packaged white LED exhibits excellent performance with a CRI of 96.5, a CCT of 2879 K and a luminous efficacy of 119.74 lm W−1. More importantly, this fabricated WLED device retains high luminous efficacy and undergoes minor chromatic coordinate changes when aged at high temperature and humidity (85 °C, 85%). Therefore, these findings not only illustrate the effect of ethanol addition on the photoluminescence intensity of Mn4+ doped phosphors in the synthesis process, but also provide a facile strategy to improve the moisture resistance of K2SiF6:Mn4+ for warm WLEDs in the future.
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高影响因子
ACS Applied Nano Materials
·
2025
·
IF 5.5
Yuhuan Tan,Yiran Yang,Shiyan Li,Zixiong Yao,Shixun Lian,Pengyan Fu,Wenli Zhou
To address issues such as uneven particle size, agglomeration, low luminescence efficiency, and poor stability in the nanosizing of Mn4+-doped fluoride red phosphors, this study combines solid solution engineering and aliovalent charge compensation to prepare high-performance K2LiB1–xB′xF6:Mn4+ (B, B′ = Al, Ga, In) nanoparticles (FNPs). Using an HF-free coprecipitation method for the synthesis of solid-solution matrices, followed by a ligand-assisted reprecipitation step that employs a small amount of HF to dissolve K2MnF6 to rapidly and uniformly incorporate Mn4+ into the matrices, and the particle size is reduced from 33.32 to 16.05 nm with improved dispersibility by adjusting the volume ratio of oleic acid (OA) to oleylamine (OAm) ligands; through the gradual solid solution of Al3+, Ga3+, and In3+, the regulatory mechanism of lattice distortion and local crystal field on luminescence is revealed, with optimal luminescence intensity achieved at specific solid-solution ratios and the emission peak blue-shifted from 636 to 632 nm. Zn2+ codoping for charge compensation enhances the luminescence intensity of the 0.9% Mn4+-doped sample by 120%, with the internal quantum efficiency (IQE) increased to 40.01%, and the fluorescence lifetime extended to 4.11 ms. The FNPs have good thermal stability (56% retention at 150 °C) and moisture resistance (85% retention after 240 h in water). Packaged white light-emitting diode (WLED) exhibits a luminous efficacy of 20.54 lm W–1, and the fluorescent ink enables red–green anticounterfeiting display under UV excitation, providing insights into applications in high-end display and lighting fields, especially micro-LED color conversion layers, WLED packaging, and anticounterfeiting/encryption inks.
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高影响因子
Advanced Photonics Research
·
2021
·Vol. 3
·期 2
·2100146
·
IF 0
Shuaichen Si,Lin Huang,Xuejie Zhang,Jing Wang
Laser diodes (LDs) are expected to be the next-generation high luminance sources because of the unobvious “efficiency droop” phenomenon under high power. To achieve high-quality white lighting, red emission is essential for white lighting devices. K 2 SiF 6 :Mn 4+ (KSFM) is a highly suitable red phosphor for its strong broadband excitation in the UV and blue region and intense red emission at 631 nm. In addition, the ultranarrow emission makes it suitable for wide gamut displays. Herein, a stable and easily prepared red color converter, KSFM based phosphor-in-glass films on a coated sapphire substrate (CSA) is developed, which exhibits a high thermal conductivity of 32.02 W m −1 K −1 . Compared with the KSFM phosphor, this KSFM–CSA composite shows an overall increase in thermal quenching and irradiation resistance abilities. A wide color gamut covering 128% of the National Television Standards Committee (NTSC) standard white LD (WLD) is fabricated by coupling a green-emitting CsPbBr 3 embedded glass plate and red-emitting KSFM–CSA with blue LDs. Furthermore, a high-quality WLD with a luminous flux (520 lm), luminous efficiency (93.0 lm W −1 ), and color rendering index (CRI, 81.4) is achieved. With its excellent properties, the KSFM–CSA has great potential in high-power laser lighting and display.
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INORGANIC CHEMISTRY
·
2017
·
IF 4.857
Hongzhou Lian,Qingming Huang,Yeqing Chen,Kai Li,Sisi Liang,Mengmeng Shang,Manman Liu,Jun Lin
Narrow band red-emitting A2GeF6:Mn4+ (A = Na, K, Rb, Cs) phosphors were prepared through a two-step precipitation–cation exchange route using a K2MnF6 precursor as the Mn4+ source. The phase purity, morphology, and constituent were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectric spectroscopy (XPS), and electron paramagnetic resonance (EPR) examination. Optical properties were investigated by photoluminescence spectra (PL and PLE) and high-resolution PL. A temperature-dependent PL examination was performed to investigate the electron–phonon coupling emission mechanism of Mn4+ in these alkali fluorogermanates. The PL data show that both ordered distribution and appropriate distance between Mn4+ ions are propitious for enhancement of the emission intensity. A resonance emission enhancement (REE) mechanism has been proposed to explain the intensity increment among these products. These phosphors present bright red emission under blue light (467 nm) illumination, among which Cs2GeF6:0.03Mn4+ exhibits the most excellent optical properties with a quantum yield (QY) of 93%. A WLED (white light-emitting diode) fabricated with blend of commercial YAG:Ce3+ and this phosphor emits intense warm white light with low color temperature (CCT = 3385 K) and high color rendering index (Ra = 90.5), implying its potential application as red phosphor in WLEDs.
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PubMed
高影响因子
ACS Sustainable Chemistry & Engineering
·
2025
·
IF 7.3
Jun Zhang,Lanyu Luo,Jiankun Wang,Xinlan Xu,Tiantian Peng,Boyu Liu,Lingying Jiang,Meng Jin,Weimin Wu,Laizheng Luo,Huan Yi,Shi-Yu Lu
Optimizing the electronic configuration presents a promising approach to enhance intrinsic activity and minimize noble metal use in direct methanol fuel cells (DMFCs). Metal–support interactions, commonly employed to induce interfacial charge redistribution, play a crucial role in this optimization. This study successfully synthesized a Pd/O-OMS-2 electrocatalyst characterized by Pd–O–Mn interfacial chemical bonds and Mn3+/Mn4+ redox couples, serving as a stable bifunctional catalyst for both the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). Unlike the mixed Pd–O/Mn bonds in Pd/O/Mn-OMS-2, the Pd–O–Mn bonds in Pd/O-OMS-2 not only enhance metal–support interactions and promote uniform dispersion of Pd nanoparticles but also facilitate electron transfer and the conversion between Mn3+ and Mn4+. These structural and compositional advantages endow the Pd/O-OMS-2 catalyst with superior ORR and MOR performance. The catalyst achieves a higher half-wave potential (E1/2) of 0.901 V, a mass activity of 0.937 A mgPd–1, and enhanced methanol permeability, outperforming Pd/O/Mn-OMS-2, Pd/OMS-2 and commercial Pd/C catalysts. Moreover, in an alkaline electrolyte, the Pd/O-OMS-2 catalyst follows a typical four-electron reaction pathway for ORR (O2 to H2O) and promotes faster reaction kinetics and charge transfer rates. In terms of durability, the Pd/O-OMS-2 catalyst exhibits minimal E1/2 decay (8 mV) and retains its structural integrity even after 10,000 cyclic voltammetry (CV) cycles. Additionally, it demonstrates the highest mass activity and stability during the MOR process. The exceptional ORR/MOR performance can be attributed to the synergistic effect of strong metal–support interactions, high Pd nanoparticle dispersion, and increased Mn3+ active species. The construction of interfacial chemical bonds offers a prospective strategy to optimize electronic configurations and develop advanced bifunctional electrocatalysts for ORR and MOR.
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高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2020
·
IF 4.65
Yuan Zhong,Yue Zhou,Cheng Zhou,Hongxi Chen,Zhi Zhou,M.G. Brik,Mao Xia
Greenhouse plant cultivation (GPC) has attracted great attention in recent years, and the search for novel high efficiency far-red emitting phosphor is a crucial task. With this aim in view, in the present paper Ca 14 Al 10 Zn 6 O 35 :Mn 4+ (CAZO:Mn 4+ ) was investigated as a prototype phosphor. By simply incorporating excessive amount of Al, CA 10.25 ZO:Mn 4+ can meet two criteria simultaneously: it has relatively high quantum efficiency (QE) and good thermal stability, which tackle the goal of “killing two birds with one stone”. The internal QE (IQE) could further enhance from 83.9% to 90.0% due to the increased occupancy capability of Mn 4+ in [AlO 6 ] octahedron, which is evidenced by solid-state 27 Al nuclear magnetic resonance (NMR) and energy dispersive spectra (EDS) measurements. In addition, the Mn 4+ concentration-dependent excitation and emission spectra also demonstrate that the optimal doping concentration of Mn 4+ in CA 10.25 ZO host increases from 0.15 to 0.17 mol. Moreover, compared with CA 9.85 ZO:0.15Mn 4+ , the thermal stability of CA 10.25 ZO:0.15Mn 4+ improves from 55% to 58% at 150 °C and 38%–45% at 200 °C, respectively. The as-fabricated plant growth LED devices shows better potential to be applied in GPC. This design strategy shown here provides an alternative pathway to further improve the luminescence properties of phosphors.
研究领域:
材料科学
·
光学工程
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高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2019
·Vol. 103
·期 2
·1018-1026
·
IF 3.094
Xuefang Luo,Ziyang Hou,Tianliang Zhou,Rong-Jun Xie
Mn 4+ -activated fluoride red-emitting narrow-band phosphors have been successfully used in wide color-gamut white LEDs for liquid crystal display (LCD) backlights. However, highly concentrated and toxic HF is usually used in their synthesis, causing environment and safety issues. In this work, we proposed a HF-free green method, that is, using NH 4 F/HCl instead of HF, to synthesize a series of A 2 X F 6 :Mn 4+ ( A = K, Na, Rb, Cs; X = Si, Ge, Ti) phosphors. The microstructure, photoluminescence (PL) properties, thermal quenching, and applications of the synthesized phosphors were investigated. Using the proposed approach, the phosphors generally showed a pure phase, a particle size ranging from 5 to 45 μm, and some characteristic sharp emission lines of Mn 4+ in the red spectral range. The internal quantum efficiency was varied in a broad range of 69%-94% under the 460 nm excitation, depending on the composition of the fluoride host. Among these compositions, K 2 X F 6 :Mn 4+ ( X = Ge and Ti) phosphors even had a similar external quantum efficiency (>60%) with commercial ones. By combining K 2 GeF 6 :Mn 4+ (narrow-band red) and β -sialon:Eu 2+ (narrow-band green) with a blue LED, a white light-emitting diode (wLED) backlight with a color gamut of 87.7% National Television System Committee Standard, color temperature of 8423 K, and a luminous efficacy of 110.8 lm/W was demonstrated. These results indicate that the synthetic method proposed in this work is universal for preparing highly efficient fluoride phosphors used in wLEDs.
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高影响因子
JOURNAL OF LUMINESCENCE
·
2022
·
IF 4.171
Yi Zhang,Cuiping Zhou,Qifeng Zhang,Pengfei Yin,Xiyuan Sun,Kaiming Wang,Jian Wang,Xing Feng
In this paper, a synthesized material change from perovskite-layer-structured La 2 Ti 2 O 7 to perovskite type LaTiO 3 induced by Li 2 CO 3 addition was observed. The [TiO 6 ] octahedral site symmetry and particle uniformity showed an obvious variation with the change from La 2 Ti 2 O 7 to LaTiO 3 . A broadband far-red emission from 670 to 780 nm emerged when Mn 4+ , Li + ions were co-doped. Furthermore, (Mn 4+ , Li + ) co-doped LaTiO 3 phosphor can be effectively excited by near-UV and blue lights, which is suitable for combining with commercial InGaN LED chips. The LaTiO 3 :0.4%Mn 4+ , 150%Li + phosphor exhibited a high quantum efficiency of 71.1% and a good thermal stability with emission intensity retained 65% at 423 K. Finally, a LED device was fabricated with the LaTiO 3 :0.4%Mn 4+ , 150%Li + phosphor, which matches well with the absorption of photochrome of P FR and shows a good potential for use in agricultural cultivation fields.
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高影响因子
Journal of Materials Chemistry C
·
2018
·Vol. 7
·期 2
·247-255
·
IF 5.976
Chunyan Jiang,Mikhail G. Brik,Alok M. Srivastava,Lihua Li,Mingying Peng
Mn4+ doped fluoride phosphors have attracted tremendous attention in the solid-state lighting field due to the outstanding feature of efficient narrow band red emission. However, poor resistance against moisture-induced luminescence quenching is a recognized obstacle for realizing their wider commercial use. Herein, we design and fabricate a highly stable red phosphor based on previously unnoticed Rb2SnF6:Mn4+, which, estimated by the single crystal X-ray diffraction data, crystallizes in the trigonal space group Pm1 with the lattice parameters a = b = 6.0323(12) Å, c = 4.7880(8) Å, and V = 150.89(7) Å3. The Rb2SnF6:Mn4+ as expected exhibits highly efficient red emission upon excitation by UV and blue light. Significantly, the poor water resistance is conquered by constructing a protective deactivated layer with surface reduction of Mn4+. A treatment solution with appropriate reducing ability is emphasized to obtain Rb2SnF6:Mn4+ with simultaneous high brightness and water resistance. The results show that the low concentration of H2C2O4 solution treated Rb2SnF6:Mn4+ preserves a bright red-emitting color analogous to its initial color and >95% of its initial emission intensity when immersing in water at room temperature (RT) and in boiling water for 3 h. Lastly, by employing H2C2O4 treated Rb2SnF6:Mn4+ as a red phosphor, a high quality WLED with a CRI of 90, CCT of 3936 K and luminous efficacy of 106.24 lm W−1 is fabricated. This work not only experimentally fabricates a new efficient and stable Rb2SnF6:Mn4+ phosphor that can be used for high performance warm WLEDs but also provides a deep insight into how to well address moisture-induced Mn4+ luminescence quenching through appropriate reduction of Mn4+, opening up new opportunities for future solid-state lighting purposes.
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高影响因子
Journal of Materials Chemistry C
·
2024
·
IF 5.7
Wenrui Zhang,Yayun Zhou,Ce Shi,Jiajun Ren,Liying Zhang,Haipeng Ji
Mn4+-activated fluoride phosphors are some of the crucial red-emitting phosphors for white lighting systems driven by light-emitting diodes (LEDs). In this study, we successfully synthesized high-quality K2Si1−xF6:xMn4+ (nominal x = 0.03–0.70, measured x of 0.22%–33.3%) crystals, measuring approximately 1 mm in size, through a new cooling-induced crystallization method. These crystals exhibit narrow line-type photoluminescence emission bands and exceptional optical properties, including a high absorption efficiency of up to 92.9% and an external quantum efficiency of up to 78.5%, which are among the record values for Mn4+-doped fluoride phosphors. Furthermore, they exhibit a notably elevated luminescence thermal quenching temperature (T1/2) exceeding 500 K. A comprehensive investigation into the phase transformation, zero-phonon line tuning, and fluorescence decay behavior as a function of increasing Mn concentrations was also conducted. Practical applications were demonstrated through the fabrication of warm white LEDs, integrating a blue LED with a garnet yellow phosphor and the as-synthesized K2Si1−xF6:xMn4+ (measured x of 2.94%) crystals as the red component. The white LEDs exhibit an impressive luminous efficacy of 192.1 lm W−1, a color rendering index of Ra = 87.5 and R9 = 62 under a 20 mA driving current. Our study highlights the outstanding properties of Mn4+-doped fluoride crystals with bulk size rather than conventional powdery form and the potential of the cooling-induced crystallization method for cultivating the crystals.
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高影响因子
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