CRYSTENGCOMM
·
2019
·Vol. 21
·期 14
·2388-2397
·
IF 3.382
Yanxi Ding,Tan Li,Xiaoyun Li,Emmanuel Acheampong Tsiwah,Chengzhen Liu,Peng Gao,Tao Zeng,Yunxia Chen,Xiujian Zhao,Yi Xie
In the present work, a novel Sn-assisted synthetic protocol is developed to control the growth and the optical performance of all-inorganic perovskite nanocrystals (NCs). We systematically elucidate the roles that the Sn4+ (i.e., SnBr4 and SnCl4) and Sn2+ (i.e., SnBr2, SnCl2 and Sn(OAc)2) species played in tuning the morphologies and optical properties of the resulting NCs in open air or under Ar atmosphere, respectively. Interestingly, the Sn4+ cations restrain the growth of the perovskite NCs along a specific plane and consequently lead to the generation of nanoplatelets (NPLs) with thicknesses of a few perovskite unit cell layers, exhibiting the quantum confinement effect. The co-existence of two populations of NCs with different thicknesses contributes to the formation of two well-defined optical absorption bands and photoluminescence (PL) emissions. The unusual disproportionation growth of the perovskite NCs was further confirmed by comparison of NCs grown in open air and under Ar atmosphere, respectively. Perovskite NCs fabricated under Ar atmosphere in the presence of either SnBr2 or SnCl2 showed a single PL emission. However, when the reactions were carried out in the open air, dual optical absorbance and PL emissions were observed. Moreover, by adjusting the input of Sn salts in the precursors, the band structure and PL properties can be precisely tuned. The present strategy can be extended to other tetravalent ions such as Ti4+. We finally employed freshly made dual-emissive CsPbBr3 perovskite NCs to fabricate a prototype white light-emitting diode (WLED) with a commercially available 365 nm GaN chip.
研究领域:
材料科学
·
纳米技术
·
光电技术
✓ 已验证
产品关联
DOI
高影响因子
Inorganic Chemistry Frontiers
·
2023
·Vol. 10
·期 14
·4230-4240
·
IF 7
Ziwang Zhang,Nan Yang,Zhuo Li,Jun Chen,Pin Chen,Yiqin Xu,Jianxin Shi,Mingmei Wu
Single-phase white light phosphors for phosphor-converted white light-emitting diodes (pc-WLEDs) have become a hot spot and attracted considerable attention. However, the unsatisfactory luminous efficiency and colour rendering index of this kind of device hinder their large-scale applications in the field of lighting. Herein, a novel multi-centre activated single-phase white light phosphor, Gd2Sr3B4O12:Ce3+,Tb3+,Sm3+, has been designed and prepared. The crystal structures of the host and the doped samples are characterized with XRD and Rietveld refinements. The band gap of the host calculated with the density functional theory is consistent with the value obtained from the UV-Vis reflection spectrum. Benefiting from the energy transfer paths of Ce3+–Tb3+, Ce3+–Sm3+ and Tb3+–Sm3+, which are quantitatively evaluated with photoluminescence spectra and decay curves, the intensities of the characteristic emission peaks of the three dopants are found to be closely interlocked and the emission colour of the phosphors can be precisely tuned by adjusting the relative ratio of the three ions. Under the excitation of near-UV light, the two phosphors of Gd2Sr3B4O12:0.03Ce3+,0.18Tb3+,0.05Sm3+ and Gd2Sr3B4O12:0.03Ce3+,0.22Tb3+,0.07Sm3+ emit white light with CIE coordinates of (0.32, 0.35) and (0.34, 0.34), and the quantum efficiencies are 46.8% and 34.9%, respectively. The temperature-dependent photoluminescence spectra of the phosphors show that the quenching temperature (T50%) is as high as 450 K. Finally, WLED devices with maximal colour rendering index of 87.5 are obtained by fabricating the two single-phase white light phosphors with 365 nm LED chips. The balanced and preferable comprehensive performances of Gd2Sr3B4O12:Ce3+,Tb3+,Sm3+ demonstrate that the as-prepared single-phase white light phosphor can be a promising candidate for fabricating near-UV chip-based WLEDs.
研究领域:
材料科学
·
光电技术
·
照明技术
✓ 已验证
产品关联
DOI
高影响因子
Materials Today Communications
·
2024
·
IF 3.7
Feng Hong,Long Li,Maoyu Xu,Haiqing Su,Yunkai Dong,Jingjing Zhang,Dechuan Yu,Hai Lin
Mn 4+ -doped fluoride phosphors have important application value in the background light and WLED lighting fields. Therefore, the synthesis of efficient and stable Mn 4+ -doped red phosphor is of great application value. In this study, a series of red-emitting K 2 NaAl 1- y Ga y F 6 : x Mn 4+ ( y = 0, 0.2, 0.4, 0.6, 0.8 and 1) ( x = 0.01, 0.03, 0.05, 0.07 and 0.09) solid solution phosphors are successfully synthesized by simple coprecipitation method. The synthesis strategy of simple crystal structure optimization is proposed to realize simultaneously the crystal field optimization, luminescence enhancement and thermal stability of red phosphor. The calculation and theoretical analysis of crystal field strength are used to prove that solid solution matrix K 2 NaAl 0.4 Ga 0.6 F 6 is the most ideal matrix material. X-ray powder diffraction, energy-dispersive X-ray spectrometer and scanning electron microscope are employed to determine the crystal structure, composition and morphology of all samples. Optical properties are characterized using excitation spectra, emission spectra and fluorescence lifetime curves. Moreover, the CIE coordinates of red-light show that the phosphor has low correlated color temperature and excellent color purity. Intriguingly, the as-prepared K 2 NaAl 0.4 Ga 0.6 F 6 :Mn 4+ phosphor possesses admirable thermal quenching behavior and color stability at high temperature. At a temperature of 423 K, the photoluminescence intensity can be maintained at 52 % of the original intensity (298 K). The activation energy, the chromaticity shift and chromaticity coordinate variation are also systematically calculated. More importantly, A high-performance warm WLED with low correlated color temperature (CCT = 3982 K) and high color rendering index (R a = 93.7) is achieved by using K 2 NaAl 0.4 Ga 0.6 F 6 :Mn 4+ as a red-emitting material. These results demonstrate that K 2 NaAl 0.4 Ga 0.6 F 6 :Mn 4+ red phosphor provides a novel choice for the warm WLED required for indoor lighting.
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
OPTICAL MATERIALS
·
2025
·
IF 4.2
Liang Dong,Ziying Wang,Sihan Yang,Qi Zhu,Ji-Guang Li,Xuejiao Wang
Phosphor-converted white light-emitting diode (pc-WLED) is crucial for solid-state lighting, but the color rendering index of commercial pc-WLED needs to be improved. In this study, a series of silicates KSrScSi 2 O 7 : x Ce 3+ ( x= 0-10at%) were synthesized. Under the 365 nm near-ultraviolet excitation, the silicate emits a high-quality broadband cyan-blue light (385-550 nm) covering the cyan gap. The emission intensity reaches its maximum at approximately 450 nm and the emission peak is slightly shifted with varying Ce 3+ concentration, which is because Ce 3+ doping changes the crystal field around the luminescence center. The prepared phosphors showed promising properties for application in high-color rendering lighting. The crystal structure analysis via X-ray diffraction and Rietveld refinement and Gaussian fitting of the PL spectra indicated that Ce 3+ occupies the Sr 2+ and K + positions in the monoclinic host lattice. The optimal Ce 3+ content is 3at% and concentration quenching is attributed to the non-radiative energy transfer between the nearest-neighboring Ce 3+ ions. The temperature-dependent luminescence showed that the T 50 is 394 K for the KSrScSi 2 O 7 : x Ce 3+ materials. The thermal quenching is attributed to increased lattice vibrations and enhanced non-radiative transitions at elevated temperatures. The performance of the pc-WLED device fabricated with KSrScSi 2 O 7 : 3at%Ce 3+ was studied, and the device showed a high-color rendering index (Ra=93.8) and exceptional stability during operation.
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
Zhihui Wang,Yingnan Dong,Zhongxiang Shi,Jing Wang,Xu Sun,Chuheng Guan,Qingyun Yan
In order to explore the potential application of rare earth doped luminescent materials in illumination display, (K 1- x Na x ) 0.94 Al 11 O 17 : 0.06Eu 2+ (KNAO: Eu 2+ )(0.0 ≤ x ≤ 1.0) phosphors with tunable spectrum were synthesized by high temperature solid-state reaction. Through X-ray diffraction(XRD), Scanning electron microscope(SEM), Energy dispersive X-ray spectroscopy(EDS), X-ray photoelectron spectroscopy(XPS) and other characterization means, it is confirmed that Na + can enter the matrix lattice by substituting K + ions, and cause unit cell shrinkage. Spectral analysis indicates that with the increase of Na + content, the emission peak of Eu 2+ redshifts from 443 nm to 490 nm, and the FWHM broadens from 41.1 nm to 94.7 nm, thus realizing continuous controllable tuning from blue light to cyan light, and effectively compensation for the "cyan light defect" in the luminescence spectrum. Theoretical calculation reveals that this phenomenon is due to the enhancement of crystal field splitting energy by Na + substitution and the centroid shift caused by the decrease of anion polarizability. Thermal stability studies show that the fully substituted sample exhibits near-zero thermal quenching (99.33 %@423 K), and its thermal quenching activation energy (0.483 eV) is significantly higher than that of the unsubstituted sample (0.270 eV). WLED devices were fabricated by packaging the optimized components (K 0 Na 1 ) 0.94 Al 11 O 17 : 0.06Eu 2+ , Ca 9 KMn(PO 4 ) 7 : 0.03Eu 2+ , and KAl 11 O 17 : 0.04Mn 2+ with 365 nm chip. The color rendering index was 73.5, the correlated color temperature was 4308 K, and excellent color stability was shown in the range of 50–700 mA forward bias current. Compared with commercial WLED, this material has strong luminous continuity in cyan band and significantly improved color restoration ability, which provides a new candidate material for developing full-spectrum lighting devices with high color rendering.
✓ 已验证
产品关联
DOI
高影响因子
Materials Today Advances
·
2024
·
IF 8.1
Reziwanguli Yantake,Aierken Sidike,Wang Qingling,Zhou Shihang
Among the green-cyan phosphors widely used in white LEDs, the full width at half maximum, thermal stability and quantum efficiency are key performance indicators. This kind of phosphor should have stable peak shape and peak position when working at different temperatures. It should simultaneously exhibit ultrawideband emission, which is conducive to the realization of two-color white light and simplification of the preparation process of white LED devices. In this paper, a series of KAlSiO 4 :Eu 2+ , Mn 2+ luminescent materials were synthesized by a high-temperature recalcination strategy. Phase analysis and refinement results showed that the samples were effectively synthesized. After the first calcination, a bright green powder was obtained. The main emission peak was at 514 nm, and the FWHM was 30 nm. After recalcination, the color of the light emission from the representative samples changed from green to cyan-green, which was very close to white light, under near-UV irradiation. The emission range was wide, including blue and green light, and the full width at half maximum could reach 150 nm. After recalcination, the emission intensity of the representative samples increased by 3.4 times, and the quantum efficiency reached 90 % under near-UV excitation. The emission intensity at 150 °C was 82 % of that at room temperature. The Raman spectra showed that recalcination had a good effect on the lattice symmetry of the samples and promoted their luminescence intensity. The experimental value of the optical bandgap of the matrix was 5.6 eV, whereas the DFT-calculated bandgap was 4.8 eV, indicating good thermal stability. The chromaticity shift of the sample at high temperatures was very small, indicating good chromaticity stability. A commercial broadband red powder and representative samples after refiring were combined with 365 nm near-UV chips. The color rendering index of the white LED devices exhibited under different driving currents was greater than 90, indicating that the refiring strategy successfully improved the luminous performance of the representative samples. KAlSiO 4 :Eu 2+ , Mn 2+ phosphors were verified to have good application prospects in the field of white LED lighting. This work provides a new idea and technology for calcination and color control of luminescent phosphors.
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
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Guangtao Lu,Yichao Wang,Kailin Ma,Xizhi Chen,Wanying Geng,Tianshuo Liu,Sai Xu,Jinsu Zhang,Baojiu Chen
The research of narrow band green emitter with excellent luminescent property is regarded as a very significant innovation direction for light-emitting diodes (LED) backlights in liquid crystal displays (LCDs). Herein, a high-efficiency near-ultraviolet (n-UV) excitation Mn 2+ doped green phosphor NaGa 11 O 17 : Mn 2+ phosphor is obtained based on the strong charge transfer absorption located in the n-UV region. The optimal sample exhibits a high color purity green light emission(≈89.7%) centered at 505 nm with a full width at half maximum (FWHM) around 29 nm. The absorption efficiency (AE), internal quantum efficiency (IQE) and external quantum efficiency (EQE) of optimal sample are 69.8%, 80.4% and 56.1%, respectively. In addition, the doping of Al 3+ significantly improves the thermal stability (26.9%–80.1% at 150 °C) by enhancing the electron recombination process. Using NGO: Mn 2+ and commercial β-sialon:Eu 2+ dual green phosphors as green component fabricated with BAM: Eu 2+ , KSF: Mn 4+ and 310 nm LED chips shows a wide color gamut of 125% NTSC. These findings suggest that our material may find use in LED backlights for liquid crystal displays and provide a meaningful reference for the development of new narrowband emitters.
研究领域:
材料科学
·
光学工程
·
显示技术
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry C
·
2017
·Vol. 5
·期 11
·2910-2918
·
IF 5.256
T. T. Deng,E. H. Song,J. Sun,L. Y. Wang,Y. Deng,S. Ye,J. Wang,Q. Y. Zhang
Herein, a new red phosphor Na3GaF6:Mn4+ has been designed and synthesized by a facile two-step co-precipitation method at room temperature. Single crystal X-ray diffraction analysis reveals that the fluoride Na3GaF6 crystallizes in the P2(1)/n space group with a = 5.4760 Å, b = 5.6862 Å, c = 7.9009 Å, β = 90.309°, and z = 2. Upon blue or UV light excitation, the obtained phosphor Na3GaF6:Mn4+ emits intense and pure red fluorescence. The effects of raw materials, doping concentration and environmental temperature on its luminescence properties and crystal structure have been investigated and discussed in detail. Such a newly synthesized red phosphor shows excellent anti-thermal quenching behavior (∼118.8% of emission intensity at 150 °C relative to 25 °C) and good color stability upon blue light (∼467 nm) excitation. By using the Na3GaF6:Mn4+ phosphor as a red light component, a high-power stable warm white light-emitting diode (WLED, Ra = 81, CCT = 2966 K, luminous efficacy = 56.73 lm W−1) was fabricated, further evidencing the potential of the as-synthesized Na3GaF6:Mn4+ phosphor for white LED applications.
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
DALTON TRANSACTIONS
·
2021
·Vol. 51
·期 2
·645-654
·
IF 4.39
Qinghong Meng,Guoying Zhao,Qi Zhu,Xiaodong Li,Xudong Sun,Ji-Guang Li
Synergistic doping of the metastable Gd3Al5O12:Ce garnet with a Ca2+/Hf4+ pair and Sc3+ to form Gd2.97−xCaxHfxScyAl3O12:0.03Ce (x = 0.5–2.0, y = 0.0–1.5, x + y = 2.0) solid solution was conducted for the structural stabilization and photoluminescence manipulation. The site selection of Ca2+/Hf4+/Sc3+ dopants and the effects of doping on the crystal structure, local coordination, band structure and Ce3+ luminescence were revealed in detail with the results of XRD, Rietveld refinement, TEM, and UV-Vis/photoluminescence spectroscopy. A decrease in Ca2+/Hf4+ and an increase in the Sc3+ content were observed to shrink the lattice, widen the bandgap of the garnet host, red-shift the excitation/emission wavelength, broaden the emission band and shorten the fluorescence lifetime of Ce3+. The spectral changes were rationalized by considering the local coordination and crystal field splitting of the Ce3+ 5d energy level. Application of typical Gd0.97Ca2Hf2Al3O12:0.03Ce (x = 2.0, y = 0) cyan and Gd2.47Ca0.5Hf0.5Sc1.5Al3O12:0.03Ce (x = 0.5, y = 1.5) greenish-yellow phosphors in w-WLED lighting produced low correlated color temperatures of ∼3842 and 3514 K, high color rendering indices of ∼88 and 93 and favorable luminous efficacies of ∼32.9 and 14.7 lm/W under the excitation of 395 nm n-UV and 450 nm blue LED chips, respectively.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
DALTON TRANSACTIONS
·
2022
·Vol. 51
·期 8
·3159-3169
·
IF 4.569
Qinghong Meng,Guoying Zhao,Qi Zhu,Xudong Sun,Ji-Guang Li
Doping Gd2LuAl5O12:Ce with a Ca2+/Si4+ pair produced a series of Gd1.97−xLuCaxAl5−xSixO12:0.03Ce (x = 0.0–1.2) garnet new phosphors, and remarkable regulation of the crystal structure and Ce3+ luminescence was achieved. Rietveld refinement and spectral analysis revealed that greater incorporation of Ca2+/Si4+ led to a higher lattice rigidity by cell contraction, a narrower bandgap, a longer average bond length/less distortion of the [CeO8] dodecahedron and decreased centroid shift/crystal field splitting of the Ce3+ 5d energy level. A blue-shifted 4f–5d1 transition, a narrower emission band, improved thermal stability of luminescence and a shorter fluorescence lifetime were observed with increasing Ca2+/Si4+ content. Applying the yellowish-green-emitting Gd0.77LuCa1.2Al3.8Si1.2O12:0.03Ce optimal phosphor (x = 1.2), together with a commercial CaAlSiN3:Eu red phosphor, in 450 nm-excited LED lighting produced a low CCT of ∼3625 K and a high CRI/R9 of ∼95.2/94.8, indicating that the phosphor has application potential in high-performance w-WLED.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
DALTON TRANSACTIONS
·
2022
·Vol. 51
·期 24
·9445-9453
·
IF 4.569
Yifei Zhao,Fangrui Cheng,Shuai Zhang,Ruirui Yang,Man Li,Hong Ming,Shi Ye
The instability of all-inorganic perovskite nanocrystals (NCs) remains a major challenge to their practical applications in displays and lighting. In order to improve their environmental resistance, highly luminescent CsPbBr3 NC embedded Cs4PbBr6 microcrystals (MCs) have been fabricated by an anti-solvent reprecipitation method with the assistance of 1-alkyl-3-methyl-imidazolium bromides. The heterostructure of the MCs is investigated in detail, and their formation mechanism is discussed in terms of the dissolution–precipitation equilibria and the total energy of variously scaled nanoparticles via density functional theory (DFT) calculations. Although the imidazolium ligands are not directly capping with the inner CsPbBr3 NCs, they are important to the formation of these MCs. The MCs exhibit better thermal resistance compared to conventional CsPbBr3 NCs prepared by the hot-injection method. Additionally, a prototype white light-emitting diode (WLED) was fabricated to demonstrate its practical application prospects. Thanks to the narrow emission bands and enhanced stability of the MCs, the WLED shows greater performance compared to bare perovskite NCs, indicating its great potential as a green phosphor in lighting and display applications.
研究领域:
材料科学
·
光电技术
·
纳米技术
·
光子学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2024
·
IF 4.3
Fengli Xu,Ruoyu Dong,Junchao Cui,Yufei Zhang,Weijie Ren,Kai Song,Shuai Meng,Rui Zhang,Kun Li,Jingjing Bai,Zhenxing Qin
Regulation of the fluorescence through crystalizing from the matrix in the Carbon dots (CDs)-based solid-state materials has been verified to be one of the effective methods, yet there are not only challenges in preparing such materials efficiently, but also insufficient insight into their regulation mechanisms. Here, a one-pot solvothermal route to synthesize a series of CDs-based composites with crystalline matrix is reported. These crystals exhibited multicolor fluorescence with the feature of multi-peaks emissions with increasing temperatures from 140 ℃ to 220 ℃, in which the orange emitting O-CDs@PA and the yellow emitting Y-CDs@PA crystals obtained the FLQYs of 22% and 68% respectively due to relatively stable crystalline structures. After comparative analysis to both crystals in detail, the core and the groups associated with them on the interface between CDs and matrix were adjusted in size and species during structural transformation of the crystal matrix, which changes radically the energy band structures to influence fluorescent emitting of both crystals ultimately. In addition, the reasons resulting in higher FLQY for Y-CDs@PA were provided leveraging the schematic illustration presumed based on the PL properties of both crystals. Because of the optimal optical performances, these fluorescent materials promised to fabricate WLED devices and obtained a number of photometric parameters endowed these WLED devices with the feature of warm-white light.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）