Journal of Materials Chemistry C
·
2019
·Vol. 7
·期 26
·7906-7914
·
IF 6.641
Jun Gao,Haomiao Zhu,Renfu Li,Decai Huang,Benlong Luo,Wenwu You,Jianxi Ke,Xiaodong Yi,Xiaoying Shang,Jin Xu,Zhonghua Deng,Li Xu,Wang Guo,Xueyuan Chen
Mn4+-Doped fluoride red phosphors with excellent moisture-resistant properties and high emission efficiency are highly desired for warm white LEDs and wide gamut liquid crystal displays. Herein, we synthesized a K2NaGaF6:Mn4+ red phosphor through a co-precipitation method at room temperature. The crystallographic structure of the K2NaGaF6 host was determined based on single crystal X-ray diffraction data for the first time. A high internal photoluminescence quantum yield of 82% was achieved for the 1.81 at% K2NaGaF6:Mn4+ sample. Through low-temperature and high-resolution spectroscopic analysis, we revealed that Mn4+ ions occupy at least four distinct sites in the K2NaGaF6 crystal. One of them is assigned to the Ga3+ site with high Oh site symmetry and the other three ones possess low non-centrosymmetric site symmetries. By employing 5.51 at% K2NaGaF6:Mn4+ as a red phosphor, a warm white LED with a low correlated color temperature of 3760 K, a high color rendering index of 92 (Ra) and a luminous efficacy of 156 lm W−1 was packaged. Aging tests at 85 °C and 85% relative humidity on the fabricated LEDs demonstrated that K2NaGaF6:Mn4+ has a better moisture-resistant property than that of the popular K2SiF6:Mn4+ phosphor. These findings demonstrate the great potential of K2NaGaF6:Mn4+ as a highly efficient red phosphor with excellent moisture-resistant performance.
研究领域:
材料科学
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光学工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Teng Zheng,Laihui Luo,Peng Du,Stefan Lis,Ulises R. Rodríguez-Mendoza,Víctor Lavín,Marcin Runowski
Remote temperature and pressure monitoring provides new and exciting chances to explore the variation of luminescence properties of compounds under extreme conditions. Herein, series of Mn 4+ -activated, double perovskite Gd 2 ZnTiO 6 phosphors were prepared to develop novel, bifunctional sensors of temperature and pressure. Upon 345 nm excitation, bright red emission originating from Mn 4+ is generated, and its intensity is affected by doping content, where the optimal intensity is achieved at 0.3 mol% of Mn 4+ doping. The determined concentration quenching mechanism is mainly governed by a dipole–dipole interaction. The internal and external quantum efficiencies of the synthesized phosphors are as high as 95.6% and 83.2%, respectively. Besides, the crystal-field strength and nephelauxetic effect are theoretically discussed to identify their impacts on the emission characteristics of Mn 4+ . Furthermore, via analysing the temperature-dependent emission bandwidth and lifetime, the thermometric properties of the resultant phosphors are explored, and the maximum relative thermal sensitivities for the Gd 2 ZnTiO 6 :Mn 4+ phosphor with optimal doping are 0.34% and 2.43% K −1 at 423 K, respectively. Additionally, the influence of pressure on the luminescence performance of the studied phosphors is investigated. When pressure increases, a significant red-shift of the emission band is observed, showing the pressure sensitivity is as high as 1.11 nm/GPa. Notably, during the compression and decompression processes, the prepared phosphors possess stable phase structure, which is confirmed by the pressure-dependent Raman spectra. These results suggest that the highly-efficient double perovskite Mn 4+ -activated Gd 2 ZnTiO 6 phosphors are promising bifunctional luminescent platforms, for both luminescence thermometry and manometry applications.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2017
·
IF 7.504
Enhai Song,Jianqing Wang,Jiahao Shi,Tingting Deng,Shi Ye,Mingying Peng,Jing Wang,Lothar Wondraczek,Qinyuan Zhang
Following pioneering work, solution-processable Mn4+-activated fluoride pigments, such as A2BF6 (A = Na, K, Rb, Cs; A2 = Ba, Zn; B = Si, Ge, Ti, Zr, Sn), have attracted considerable attention as highly promising red phosphors for warm white light-emitting diodes (W-LEDs). To date, these fluoride pigments have been synthesized via traditional chemical routes with HF solution. However, in addition to the possible dangers of hypertoxic HF, the uncontrolled precipitation of fluorides and the extensive processing steps produce large morphological variations, resulting in a wide variation in the LED performance of the resulting devices, which hampers their prospects for practical applications. Here, we demonstrate a prototype W-LED with K3AlF6:Mn4+ as the red light component via an efficient and water-processable cation-exchange green route. The prototype already shows an efficient luminous efficacy (LE) beyond 190 lm/W, along with an excellent color rendering index (Ra = 84) and a lower correlated color temperature (CCT = 3665 K). We find that the Mn4+ ions at the distorted octahedral sites in K3AlF6:Mn4+ can produce a high photoluminescence thermal and color stability, and higher quantum efficiency (QE) (internal QE (IQE) of 88% and external QE (EQE) of 50.6%.) that are in turn responsible for the realization of a high LE by the warm W-LEDs. Our findings indicate that the water-processed K3AlF6 may be a highly suitable candidate for fabricating high-performance warm W-LEDs.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Shuai Zhang,Hong Ming,Konglan Chen,Yuanjing Wang,Chuang Zhang,Yayun Zhou,Tingting Deng,Puxian Xiong
Mn 4+ -doped fluoride red-emitting materials are renowned for their distinct characteristics, including fixed emission peaks and narrow spectral emission, rendering them highly favored in photoluminescent light-emitting diodes (LEDs). However, achieving ultra-high-concentration Mn 4+ doping in fluoride phosphors is imperative to enhance quantum efficiency. Nevertheless, attaining such doping levels in metastable compound systems poses considerable challenges. In this study, we introduce an innovative reverse doping strategy, leading to the synthesis of Mn 4+ -doped cubic K 2 SiF 6 phosphor (11.38 mol %) from hexagonal K 2 MnF 6 . Remarkably, this approach significantly improves the external quantum efficiency (EQE) to 66.7 % upon 450 nm excitation. Through systematic comparisons with conventional co-precipitation and ion exchange methods, our findings unequivocally demonstrate the superior efficacy of this approach in achieving high-concentration Mn 4+ ion doping within relatively insoluble matrices. The successful application of our optimized phosphor enabled the fabrication of a red light-emitting diode (LED) that exhibits an exceptional photoelectric efficiency of 31.67 % at 350 mA, surpassing the performance of a commercial red LED chip. Furthermore, the stable red-light emission from the phosphor-converted LED (pc-LED) proves instrumental in rapid-response vascular imaging, showcasing the potential of our findings in advancing light sources for biological detection applications. This research provides valuable insights into enhancing red emission efficiency in slightly-soluble fluoride phosphors via novel synthetic strategy, unlocking possibilities for the development of highly efficient light sources in biological detection and imaging applications.
研究领域:
材料科学
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光学
·
生物医学工程
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Shengan He,Fanfan Xu,Tiantian Han,Zeqin Lu,Wei Wang,Jiaqing Peng,Fu Du,Fengli Yang,Xinyu Ye
Red-emitting phosphors composed of Mn 4+ -activated fluorides have attracted considerable interest for their applications in warm white light-emitting diodes (WLEDs). However, in addition to moisture instability, the unsatisfactory thermal stability of these phosphors limits their industrial applications. In this study, a novel red phosphor of CsMoO 2 F 3 :Mn 4+ was synthesized via simple coprecipitation. This red phosphor exhibits an orthorhombic structure with a bandgap of ~3.43 eV. The Mn 4+ ions occupy Mo 6+ sites at the centers of [MoO 2 F 4 ] 2− octahedrons. This phosphor shows narrow emission around ~633 nm excited by 450 nm blue-chip with high color purity of 99.58%. Satisfactorily, this phosphor exhibits excellent thermal stability and a strong negative-thermal-quenching. The total PL intensity of CsMoO 2 F 3 :3.88%Mn 4+ phosphor at 275 K strengthens to ~540% relative to that at 25 K, and its relative emission intensity preserves about 129.3% when the temperature rises from room temperature to 423 K (150 ℃). It also shows admirable color stability with a slight chromaticity shift ( ΔE ) of only ~ 33.9 × 10 - 3 in the temperature region from 298 to 473 K. Furthermore, a warm WLED was fabricated by the mixture of red-emitting CsMoO 2 F 3 :3.88%Mn 4+ and the yellow-emitting YAG:Ce 3+ phosphors with a blue-emitting InGaN LED chip. The device exhibits low correlated color temperature (3983 K) and high color-rendering index (Ra = 81.3). With the increasing drive current from 20 mA to 120 mA, the chromaticity coordinate variation (CCV) is only (−0.0163, 0.0202). All these results indicate that the CsMoO 2 F 3 :Mn 4+ phosphor holds tremendous potential for practical applications in high-power lighting and display with high-performance WLEDs.
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 LUMINESCENCE
·
2021
·
IF 3.599
Liqin Yao,Shengan He,Wendong Nie,Lei Fu,Zhijian Liao,Wenting Cai,Ruixiang Wang,Jiaqing Peng,Xinyu Ye
Mn 4+ -activated (oxy)fluoride-based red phosphors have received extensive attention. In this work, a phase transformation from K 2 NbF 7 to K 3 HF 2 NbOF 5 was successfully achieved by stoichiometric control during coprecipitation process, resulting in a novel red phosphor K 3 HF 2 NbOF 5 :Mn 4+ with narrow-band emission. A systematic study was carried out on its crystal structure and luminescent properties. By introducing O ions into the local coordinated structure, the emission intensity of K 3 HF 2 NbOF 5 :Mn 4+ phosphors is 2.15 times as high as that of K 2 NbF 7 :Mn 4+ with a photoluminescence internal quantum yield (IQE) of 73.28% and absorption efficiency (AE) of 49.68%, which could be attributed to the layered structure of the oxyfluoride host. High quenching concentration of 8.39 mol% and short decay lifetime of 4.19 ms are realized. Based on K 3 HF 2 NbOF 5 :Mn 4+ and commercial YAG:Ce 3+ , a white light-emitting diode (WLED) for solid state lighting was fabricated, which has low CCT of 3802 K, high Ra of 86.3 and high luminous efficiency (LE) of 126.23 lm/W. Moreover, by employing commercial β-sialon:Eu 2+ and K 3 HF 2 NbOF 5 :8.39%Mn 4+ , another WLED with high LE of 95.78 lm/W and wide color gamut of 108.6% National Television Standard Committee (NTSC) standard for backlight lighting was packaged, indicating a great potential of K 3 HF 2 NbOF 5 :Mn 4+ as a red component in the application of backlight lighting.
研究领域:
材料科学
·
光学工程
✓ 已验证
DOI
高影响因子
DALTON TRANSACTIONS
·
2021
·Vol. 51
·期 2
·608-617
·
IF 4.39
Tingting Deng,Shuai Zhang,Rongfu Zhou,Ting Yu,Ming Wu,Xueliang Zhang,Konglan Chen,Yayun Zhou
Non-equivalent or non-octahedral substitution is a crucial strategy to gain Mn4+-doped fluoride red phosphors with a short fluorescence lifetime, whereas the impact of their structural defects on the photoluminescence (PL) properties remains unrevealed. Here, a non-equivalently doped RbSbF6:Mn4+ (RSFM) with a high quantum efficiency of 88% and a thermal stability of 121% at 425 K is newly reported to probe the defect-related PL behavior. Formation energy calculations imply that an interstitial defect was formed to balance the charge and stabilize the crystal structure. Concentration-dependent decay studies reveal that Mn4+ emission is quenched mainly by energy transfer to a neighboring defect . The large ionic radius of Sb5+ and defect leading to a premature optimal doping (0.11 mol%) is demonstrated by the refined contrast of the crystal structure and substitution mode among various Mn4+-doped prototypes. A couple of medium 4T2 state energies and the energy difference between the Mn4+ level with the valence band maximum enable its superior thermal stability. A higher defect concentration slightly aggravates this thermal quenching. Using the RSFM red phosphor in a white light-emitting diode offers a wide-color-gamut of 121% NTSC for backlight displays. This work would provide a new perspective to understand the defect effect on the PL behavior of special Mn4+ asymmetrically doped fluorides.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Applied Materials & Interfaces
·
2018
·
IF 8.097
Hong Ming,Shuifu Liu,Lili Liu,Jiaqing Peng,Junxiang Fu,Fu Du,Xinyu Ye
A new generation of red phosphors of complex fluoride matrices activated with Mn4+ has gained a broad interest in getting high color quality and low color temperature of solid-state white light-emitting diodes (WLEDs). However, besides their instability toward moisture, the extremely irregular and nonuniform morphologies of these phosphors have limited their practical industry applications. In the present study, a novel type of K3ScF6:Mn4+ red phosphor with highly regular, uniform, and high color purity was obtained successfully through a facile coprecipitation route under mild conditions. The crystal structure was identified with aids of the powder X-ray diffraction, Rietveld refinement, and density functional theory calculations. The prototype crystallizes in the space group Fm3m with a cubic structure, and the lattice parameters are fitted well to be a = b = c = 8.4859(8) Å and V = 611.074(2) Å3. The Mn4+ ions occupy Sc3+ sites and locate at the centers of the distorted ScF6 octahedrons. A wide band gap of approximately 6.15 eV can provide sufficient space to accommodate impurity energy levels. Unlike most other Mn4+ ion-activated fluoride phosphors, the as-prepared K3ScF6:Mn4+ phosphors demonstrate highly uniform and regular morphologies with shapes transforming from cube to octahedron with increasing Mn4+ ion concentration. Under blue light excitation, the as-prepared K3ScF6:Mn4+ sample exhibits intense sharp-line red fluorescence (the strongest peak located at 631 nm) with high color purity. An excellent recovery in luminescence upon heating and cooling processes implies high stability of K3ScF6:Mn4+. Furthermore, a warm WLED fabricated with blue GaN chips merged with the mixture of K3ScF6:Mn4+ and the well-known commercial YAG:Ce3+ yellow phosphors exhibits wonderful color quality with lower correlated color temperature (3250 K) and higher color-rendering index (Ra = 86.4). These results suggest that the K3ScF6:Mn4+ phosphor possesses stupendous potentiality for practical applications.
研究领域:
材料科学
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光学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Advanced Ceramics
·
2020
·Vol. 10
·期 1
·88-97
·
IF 2.889
Wang Zixin,Lin Hui,Zhang Dawei,Shen Yiming,Li Yang,Hong Ruijin,Tao Chunxian,Han Zhaoxia,Chen Lei,Zhou Shengming
In this study, deep-red emitting Mg 2 TiO 4 :Mn 4+ phosphor ceramics were synthesized by the high temperature solid-state reaction method. The ceramics can be excited by the 465 nm blue light and had a narrow emission with a full width at half maximum (FWMH) value of 31 nm. The peak wavelength was located at 658 nm, which matched the demanded wavelength for photosynthesis. The crystal field strength ( D q ) and the Racah parameters ( B and C ) were estimated by the Tanabe-Sugano diagram. The thermal conductivity of the Mg 2 Ti( 0.999 )O 4 :0.001Mn 4+ ceramic was 7.535 W/(m·K) at room temperature, which was one order of magnitude higher than that of the traditional packaging method using the silicone gel. A set of phosphor converted LEDs were fabricated by mounting the phosphor ceramics onto the 460 nm blue LED chips and the CIE coordinates can move from the blue region to the purple light region with the thickness of the ceramic increasing. These results indicated that the Mg 2 TiO 4 :Mn 4+ phosphor ceramic was suitable for plant lighting when combined with a blue LED chip.
研究领域:
材料科学
·
光电技术
·
农业工程
✓ 已验证
产品关联
DOI
高影响因子
DALTON TRANSACTIONS
·
2017
·Vol. 46
·期 40
·13835-13844
·
IF 4.029
Luqing Xi,Yuexiao Pan,Mengmeng Zhu,Hongzhou Lian,Jun Lin
A novel red phosphor, NaHF2:Mn4+ (NHF:Mn), was obtained via substituting Na+ located at the center of the octahedron coordinated with six F− ions with Mn4+ in the host lattice of NHF. The phase purity and the exact composition of the obtained NHF:Mn were confirmed by X-ray powder diffraction (XRD), Rietveld refinement, energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and infrared (IR) spectroscopy, respectively. The luminescence intensity of NHF:Mn was enhanced by optimizing the synthetic conditions. A series of warm white light-emitting diodes (WLEDs) with a color rendering index (CRI) higher than 88.0 and correlated color temperatures (CCT) between 3146 and 5172 K were obtained by encapsulating the as-prepared red phosphor NHF:Mn with the yellow one Y3Al5O12:Ce3+ (YAG:Ce) on blue chips. The advantage of the synthetic strategy to obtain NHF:Mn can be extended to develop novel Mn4+ doped red phosphors via substituting for central ions with unequal electric charge in the centers of octahedra.
研究领域:
材料科学
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光学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Omega
·
2019
·
IF 2.584
Qi Sun,Shaoying Wang,Balaji Devakumar,Liangling Sun,Jia Liang,Xiaoyong Huang
In this article, a series of novel Mn4+-doped Ba2GdTaO6 (BGT) red-emitting phosphors were successfully synthesized via a high-temperature solid-state method. The crystal structure, morphology, and luminescent performance of the samples were investigated in detail with X-ray diffraction, field emission scanning electron microscopy, photoluminescence (PL) spectra, decay curves, and internal quantum efficiency (IQE). Excited at 358 nm, these samples showed an intense deep-red emission band peaking at 688 nm in the wavelength region of 620–800 nm. The excitation spectra of these samples monitored at 688 nm exhibited two broad excitation bands from 250 to 600 nm with peaks at 358 and 469 nm. The systematic investigation of the concentration-dependent PL properties of BGT:Mn4+ phosphors revealed that the deep-red emission intensity reached the maximum when the Mn4+ doping concentration was 0.6 mol %. The critical distance (Rc) between Mn4+ ions for concentration quenching was 36.57 Å, and the major mechanism of energy transfer among Mn4+ activators in BGT:Mn4+ was dipole–dipole interaction. The decay lifetimes decreased from 0.285 to 0.248 ms with the increasing Mn4+ doping concentration from 0.2 to 1.2 mol %. The Commission Internationale de l’Éclairage coordinates of the optimal BGT:0.6%Mn4+ sample were (0.7294, 0.2706). The values of the IQE for all BGT:Mn4+ samples were measured, and the highest value could reach up to 62%. The above results revealed that these high-efficiency BGT:Mn4+ deep-red-emitting phosphors had promising potential for application in indoor plant growth lighting.
研究领域:
材料科学
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光学
·
农业科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
DALTON TRANSACTIONS
·
2020
·Vol. 49
·期 38
·13226-13232
·
IF 4.174
Yajun Jia,Yuexiao Pan,Jiawen Zhu,Xi'an Chen,Aiyin Wang,Hongzhou Lian,Jun Lin
Red emitting phosphors of Mn4+ doped fluorides are in high demand because the high color purities of phosphors make them potentially useful white light-emitting diodes (WLEDs) as backlights of electronic devices. We herein report an efficient red emitting phosphor KRbGeF6 : Mn4+ (KRGF : Mn) that was prepared by an in situ one-pot ion-exchange method at room temperature without organic solvents or HF. Homogenous mixtures of the starting materials with a stoichiometric KRGF : Mn ratio were partly dissolved in various acid solutions, and [MnF6]2− and [GeF6]2− successively underwent ion exchange under stirring. More importantly, in situ recrystallization of KRGF : Mn occurred simultaneously in solution with water as a solvent. Evidently, the formation of stable KRGF : Mn crystals propels the processes of dissolution and ion exchange. We also investigated the effect of inorganic acids on the resultant phases and photoluminescence properties of KRGF : Mn. The red phosphor KRGF : Mn prepared in HCl solution shows the highest luminescence intensity with an yield of 80%.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）