JOURNAL OF ALLOYS AND COMPOUNDS
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2025
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IF 6.3
Haifeng Zhe,Zongqi Chen,Jie Li,Yayun Zhou,Qiang Zhou,Zhengliang Wang
Modulating phase transitions in fluoride phosphors is essential for developing high-performance luminescent materials, but conventional extreme-condition methods often cause structural damage and efficiency degradation. This study proposes a thermal-pressure coupling strategy to achieve reversible Fm-3m to P6 3 mc phase transformation in K 2 SiF 6 :Mn 4+ under mild conditions. The distorted [MnF 6 ] 2- octahedra in the P6 3 mc enhance d-orbital hybridization, significantly reinforcing the zero-phonon line (ZPL). Consequently, luminescence intensity increases by 1.54-fold, external quantum efficiency (EQE) improves by 29.5%, and 90% intensity is retained at 200 °C. LED devices employing P6 3 mc phosphor sheets achieve a color rendering index (Ra) of 84.4 and luminous efficacy of 138.2 lm/W while maintaining stable Ra and correlated color temperature (CCT) across 20 - 300 mA driving currents. Notably, device temperature at 200 mA operation is reduced by 30% compared to conventional methods. This work establishes an effective approach for optimizing fluoride phosphors and advancing high-performance lighting technologies.
研究领域:
材料科学
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光学材料
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固态照明
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发光二极管
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无机荧光粉
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产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Shihang Zhang,Liying Zhang,Haipeng Ji
Mn 4+ -activated fluoride phosphors, exemplified by K 2 SiF 6 :Mn 4+ , exhibit exceptional narrow-band red emission but suffer from severe hydrolysis-driven degradation, significantly limiting their operational longevity. This study systematically investigates the stepwise degradation of K 2 SiF 6 :Mn 4+ upon water exposure, uncovering new insights into its hydrolytic behaviour. Upon immersion, the phosphor suspension undergoes a browning-clearing transition, attributed to the hydrolysis of [MnF 6 ] 2– which generates black suspended MnO 2 that temporarily darkens the solution before sedimentation. The degradation process involves two sequential stages: an initial rapid dissolution-dissociation of K 2 SiF 6 :Mn 4+ , accompanied by a sharp pH decrease, followed by relatively slower hydrolysis of [MnF 6 ] 2– and [SiF 6 ] 2– yielding crystalline MnO 2 and amorphous H 2 SiO 3 . Besides, upon reaching dissolution-ionization equilibrium, the released K + , [SiF 6 ] 2– , and [MnF 6 ] 2– ions would nucleate and precipitate, forming crystalline K 2 SiF 6 and K 2 SiF 6 :Mn 4+ particles with much smaller size compared to the original K 2 SiF 6 :Mn 4+ . Notably, this study reveals that the degradation of K 2 SiF 6 :Mn 4+ is significantly accelerated under both blue and UV light illumination, with UV light inducing faster degradation. These findings provide fundamental insights into the hydrolysis-driven degradation mechanism of Mn 4+ -activated fluoride phosphors, offering a scientific basis for developing strategies to enhance their stability and extend their service life.
研究领域:
材料科学
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化学
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DOI
高影响因子
JOURNAL OF LUMINESCENCE
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2020
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IF 3.28
Shijie Qiu,Hengwei Wei,Xiaoming Wang,Shuai Zhang,Mengmeng Wang,Yiying Wang,Ling Xu,Huan Jiao
A series of efficient red phosphors, K 2 SiF 6 :Mn 4+ (KSFM) particles with highly regular, uniform and anisotropic shapes, were successfully prepared by a two-step chemical co-precipitation method at room temperature without using surfactant and template. A morphological map for KSFM particles with five distinctive shapes was depicted by adjusting KF-HF precipitator dropping speed. Moreover, the photoluminescence , decay curves and Raman spectral dependence of the KSFM phosphors with different morphologies were investigated. Luminescence intensity of the KSFM phosphors is highly correlated with the morphology of KSFM particles, which gradually increased as the particle shapes changed from cube to octahedron . Whereas, Raman spectra and flame atomic absorption spectrophotometer results indicated that Mn 4+ concentration in a series of KSFM particles decreased gradually. Growth mechanism of particle is discussed base on reticular density and surface energy. White LED devices made of a blue GaN chip merged with yellow phosphor (YAG: Ce 3+ ) and the obtained KSFM red phosphor could produce warm white light. Drive current testing of the fabricated w-LEDs proved the KSFM phosphor in octahedron shape is more stable than that of the KSFM in cubic shape.
研究领域:
材料科学
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光学
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DOI
高影响因子
ACS Applied Materials & Interfaces
·
2024
·
IF 8.3
Yufan Wei,Qianxing Huang,Shijie Yu,Qiyue Shao,Jianqing Jiang
The K2SiF6:Mn4+ (KSFM) phosphor featuring efficient ultranarrow red emissions is an outstanding candidate for white light-emitting diode (WLED) applications. However, poor moisture resistance seriously affects its application performance. In this study, a two-step surface reconstruction strategy is proposed to dramatically enhance the moisture resistance of commercially available KSFM phosphors, involving treatment with H2NbF7 and subsequent hydrothermal treatment. The modified KSFM phosphor exhibits a high internal quantum efficiency (IQE) of 98.9% after the two-step surface treatment. Meanwhile, nearly 100% of the initial emission intensity is retained for the modified KSFM phosphor even after aging in high temperature (85 °C) and high relative humidity (85% RH) environments for 6 days, in sharp contrast to only 18.6% retention for the original KSFM phosphor. The relative emission intensity of the modified KSFM remains at 98.9% even after being immersed in water for 6 h. Additionally, the phosphor-converted LED fabricated with the modified KSFM phosphor demonstrated excellent long-term stability, retaining up to 97.9% of initial luminous efficacy after aging under 85 °C and 85% RH conditions for 500 h. The moisture-resistance mechanism is elucidated on the basis of spectroscopic analysis as well as structural and compositional characterization of the phosphor surface layer, which can be attributed to the formation of a robust Mn4+-rare shell with high crystalline quality following this two-step surface treatment. The findings contribute to the performance improvements of KSFM phosphors for industrial applications.
研究领域:
材料科学
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光学工程
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产品关联
DOI
PubMed
高影响因子
MATERIALS RESEARCH BULLETIN
·
2023
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IF 5.4
Xixiang Pan,Di Wu,Songbin Liu,Qiang Zhou,Biqing Song,Lu Wen,Li Luo,Jie Wang,Xinyu Ye
Recently, Mn 4+ doped fluoride phosphors have been considered as ideal candidate materials employed in white light-emitting diodes (WLEDs). However, the extremely serious performance deterioration in a wet environment has affected their practical commercial applications. Herein, we developed a novel thiourea loading strategy for greatly improving the moisture resistance of typical K 2 SiF 6 : Mn 4+ (KSF) red phosphors through treated by thiourea ethanol solution evaporation. The luminescent properties and moisture resistance have been discussed in detail, and the underlying moisture resistance mechanism was further proposed. The results show that the moisture resistance of KSF phosphor treated by thiourea significantly increased approximately sevenfold than that of untreated counterpart, exhibiting a potential application in the WLEDs backlight with high gamut display. These works brings up a promising alternative strategy for enhancing moisture resistance and provides a deeper understanding on the performance degradation mechanism for a variety of Mn 4+ doped fluoride phosphors system.
研究领域:
材料科学
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光学工程
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产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2020
·Vol. 103
·期 12
·6901-6912
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IF 3.502
Qiyun Wu,Chenxing Liao,Jinquan Pan,Xinyu Ye,Weixiong You,Libin Xia
It has been one of the hot issues to prepare the red-emitting Mn 4+ -doped fluoride phosphors with highly efficient and waterproofness for warm white-light-emitting diodes (WLEDs) by the green and environmentally friendly method. Herein, we design a novel green molten salt route to synthesize K 2 SiF 6 :Mn 4+ red powder using molten NH 4 HF 2 salt instead of HF liquor as the reaction medium. The results show that KMnO 4 and MnF 2 could produce Mn 4+ in NH 4 HF 2 molten salt through a reduction reaction, and the resulting Mn 4+ -doped K 2 SiF 6 exhibited a bright red emission peaked at 632 nm under blue light excitation. The luminescence intensity of the as-obtained product after immersing into water for 24 hours maintain nearly 100% of that before soaking and emission peak shape remains unchanged. The thermal stability of the sample was evaluated by temperature-dependent luminescence spectral intensity during heating and cooling. Furthermore, a warm white-light-emitting diodes (WLEDs) with an excellent color rendering index (Ra = 87.1), lower correlated color temperature (CCT = 3536K), and high luminous efficacy (116.99 lm·W −1 ) was fabricated based on blue chip and K 2 SiF 6 :Mn 4+ and commercial yellow phosphor (Y 3 Al 5 O 12 :Ce 3+ ).
研究领域:
材料科学
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光学工程
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DOI
高影响因子
ACS Applied Nano Materials
·
2025
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IF 5.5
Yun Tang,Miao Wang,Yalou Xin,Xiaohu Ren,Hudie Yuan,Nan Yan
Perovskite quantum dots (PQDs) and K2SiF6:Mn4+ (KSF) phosphor, renowned for high color purity, are prime candidates for emitters in white light-emitting diodes (WLEDs) for wide color gamut displays. To enhance the luminous efficacy (LE) and working stability of PQDs and KSF-integrated WLEDs, intricate fabrication processes, involving multiple post-treatments of PQDs and their blending with KSF, are often necessitated, inevitably compromising the production efficiency of the device. Herein, we develop a facile in situ synthesis approach that not only effectively passivates surface defects in PQDs and enhances their stability but also simplifies the fabrication process of PQDs and KSF-integrated WLEDs. Specifically, the silica-coated PQDs/KSF (PQDs/KSF@SiO2) composite is synthesized via the in situ growth of MAPbBr3 on an ethanol-treated KSF surface followed by SiO2 encapsulation. The Pb–F coordination and SiO2 encapsulation enable high luminescence intensity and simultaneously enhanced photothermal stability of PQDs. Eventually, the WLED based on PQDs/KSF@SiO2 achieves a high LE of 83.11 lm·W–1 alongside a wide color gamut of 122.6% NTSC standard. Remarkably, the device exhibits excellent working stability, preserving its high LE virtually unaltered after 4 h of continuous operation. This work provides a facile approach to yield WLEDs with superior LE, wide color gamut, and exceptional working stability, positioning them ideally for practical display applications.
研究领域:
材料科学
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光学工程
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显示技术
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产品关联
DOI
高影响因子
Advanced Optical Materials
·
2020
·Vol. 8
·期 23
·2000976
·
IF 8.286
Yayun Zhou,Changkai Yu,Enhai Song,Yuanjing Wang,Hong Ming,Zhiguo Xia,Qinyuan Zhang
Narrow-band red-emitting fluoride phosphors play a crucial role in lighting and backlight displays, whereas the stability issue is a major challenge. Here, highly stable K 2 SiF 6 :Mn 4+ (KSFM) single crystal phosphors with tunable sizes (20–1000 µ m) are grown by a facile saturated crystallization method. The small specific surface area together with the unique Mn 4+ -rare interface layer in KSFM single crystals enables the simultaneous fulfillment of high external quantum efficiency, excellent moisture, improved thermal quenching, and dissipation for high-power and laser-driven lighting applications. As a prototype, a warm white laser diode device with a high luminous flux of 202.7 lm and correlated color temperature of 3277 K, as well as a color rendering index of 87.9 is presented. This work provides new insights into the development of highly efficient and stable materials for advanced lighting applications.
研究领域:
材料科学
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光学工程
·
发光材料
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产品关联
DOI
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.
研究领域:
材料科学
·
光学工程
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产品关联
DOI
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.
研究领域:
材料科学
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光学工程
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产品关联
DOI
高影响因子
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.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2026
·
IF 6.3
Mingxin Zhang,Xiaoliang Dong,Dan Yue,Liying Zhang,Haipeng Ji
Large K 2 SiF 6 :Mn 4+ crystals that emit red light surpass conventional micro-powders in both hydrolytic stability and quantum efficiency. However, preparation of K 2 SiF 6 :Mn 4+ crystals to > 1 mm while stabilizing Mn 4+ valence has remained elusive. Herein, seed-assisted crystallization under a controlled cooling ramp from 25°C to –40°C was used which suppresses hydrolysis-driven reduction of [MnF 6 ] 2– and yields K 2 SiF 6 :Mn 4+ crystals with near-unit quantum yield and unprecedented dimensions up to 3 mm—a 200 % size increase over the current record. After 5 h in water the crystals (>2 mm) retain 80.7 % of their initial emission intensity,outperforming sub-millimeter counterparts (58.9 %) and micro-sized powders (3.6 %). The single-crystal like nature enables superior internal/external quantum efficiencies of 97 %/82 % and preserves 82 % of the room-temperature intensity at 500 K. Warm-white LEDs built with these phosphor crystals deliver a high luminous efficacy of 157.3 lm/W and an R 9 value of 79. This work demonstrates that crystal-growth engineering can unlock hydrolysis-resistant fluoride phosphors for high-power optoelectronics.
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DOI
高影响因子
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