INORGANIC CHEMISTRY
·
2020
·
IF 4.825
Zhaowu Wang,Haipeng Ji,Jian Xu,Xinghui Hou,Jumpei Ueda,Setsuhisa Tanabe,Shasha Yi,Ying Zhou,Deliang Chen
A single-crystalline defect-less phosphor is desired for efficient luminescence of the therein doped optical activators. In this paper, microsized MgAl2O4:Mn4+ single-crystal phosphors with bright red luminescence were grown in molten LiCl salt at 950 °C, for application in blue LED pumped white lighting. By comparing the phosphor formation from various Mg2+- and Al3+-bearing sources, both the template-formation and the dissolution-diffusion processes were evidenced to account for the formation of the microsized MgAl2O4:Mn4+ crystallites. Using nano γ-Al2O3 as the Al3+-bearing precursor, the uniform MgAl2O4:Mn4+ microcrystallites with a {111} planes-exposed tetragonal bipyramid morphology were obtained. The photoluminescence property was studied at various temperatures, and Mg ↔ Al anti-site disorder induced luminescence broadening was discussed. The Mn4+2Eg → 4A2g transition in MgAl2O4 shows a quite short luminescence wavelength peaking at 651 nm and ultrabroadband emission extending to 850 nm. The luminescence is relatively robust against thermal effect with relatively high thermal quenching temperature of 400 K and activation energy of 0.23 eV. Employing the red-emitting MgAl2O4:Mn4+ crystallites, blue LED pumped white lighting prototypes were fabricated which simulate the solar-like spectrum and show neutral to warm white.
研究领域:
材料科学
·
光学工程
✓ 已验证
DOI
高影响因子
Optical Materials Express
·
2022
·Vol. 12
·期 3
·981-990
·
IF 3.074
Tao Long,Xiaomeng Yin,Hui Lin,Cheng Zou,Dawei Zhang,Songlin Zhuang
Cr3+ doped Ba0.75Al11O17.25 red luminescent phosphors were synthesized and densified into ceramics by spark plasma sintering. Under the 405 nm excitation, the phosphors present a narrow band emission peaked at 704 nm and the highest emission intensity when the doping concentration of Cr3+ is 3%. When the temperature reaches 205 °C, the integrated emission intensity of the red emission can still reach 88% of the counterpart at room temperature, showing good luminescence thermal stability. The thermal conductivity of the ceramics is 4.87 W/(m·K) at room temperature, which is good for heat release under high power/high brightness excitations.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
Materials
·
2018
·Vol. 11
·期 7
·1090
·
IF 2.467
Man Yan,Guanghui Liu,Jiahao Wen,Yinlong Wang
The system NaLa(MoO4)2:Eu3+/Sm3+phosphors were prepared by solid-state reaction followed by heat treatment at 450–600 °C. As shown by X-ray powder diffraction, the phosphors had a body-centered tetragonal structure, high phase purity and high crystallinity. The photoluminescence measurements carried out under excitation at 464 nm indicated the main emission at about 615 nm corresponding to the electric dipole transition5D0→7F2of Eu3+, which agreed well with the emission wavelengths of the GaN-based blue LED chips. In NaLa(MoO4)2:Eu3+/Sm3+phosphors, Sm3+can efficiently transfer excitation energy to Eu3+, which resulted in a significant improvement of the fluorescence intensity, and the fluorescence intensity of the phosphors calcined at 550 °C maximized at the doping concentrations of Eu3+and Sm3+of 15.0 and 2.0 mol %, respectively. The decay curves and CIE (Commission Internationale de L’ Eclairage) coordinates of Sm3+or/and Eu3+doped phosphors were analyzed for the investigation of the energy transfer mechanism and color variation trend. Thus, NaLa(MoO4)2:Eu3+,Sm3+can be classified as a potential red-emitting phosphor for white light-emitting diodes (WLEDs).Keywords:luminescence properties;molybdate;red-emitting phosphor;energy transfer
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
·
2020
·Vol. 49
·期 17
·5711-5721
·
IF 4.174
Haipeng Ji,Xinghui Hou,Maxim S. Molokeev,Jumpei Ueda,Setsuhisa Tanabe,Mikhail G. Brik,Zongtao Zhang,Yu Wang,Deliang Chen
Blue light pumped red luminescence with broadband and high photon-energy emission is highly desired for phosphor-converted white light-emitting diodes (pc-wLEDs), to achieve a high color rendering index and high luminous efficacy. Mn4+-doped red-emitting phosphors generally exhibit sharp vibronic emissions associated with the parity- and spin-forbidden 2Eg → 4A2g transitions. In this paper, two abnormal luminescence behaviors were observed for Mn4+ in the MgAl2O4:Mn4+ spinel phosphor with a short wavelength emission band peaking at 651 nm. Firstly, the Mn4+ 2Eg → 4A2g transition exhibits ultrabroadband luminescence in MgAl2O4 and the large full-width at half-maximum (FWHM) is dependent both on the calcination temperature and on the partial substitution of Al3+ with Ga3+. Secondly, the thermal quenching behavior of the Mn4+ 2Eg → 4A2g luminescence in MgAl2O4 shows a dependence on its thermal treatment and preparation method. The Rietveld refinement and Raman results demonstrate that the variation in the FWHM of the luminescence spectra is a sum effect of structural ordering (i.e., isotropic displacement decrease of constituent atoms) and the Mg ↔ Al anti-site disorder. A model for the observed varying thermal quenching of luminescence was tentatively proposed. The intrinsic thermal quenching temperature of Mn4+ luminescence in MgAl2O4 was found to be 390–400 K using the samples prepared by the co-precipitation and molten salt methods. The present work gives a novel perspective to understand the luminescence spectra of Mn4+ 2Eg → 4A2g transition.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
Inorganic Chemistry Frontiers
·
2021
·Vol. 9
·期 9
·1879-1889
·
IF 6.569
Xiao-Kai Gong,Xiao-Song Zhang,Lan Li,Jian-Ping Xu,Ru-Kun Ding,Hao Yin,Zhao-Wei Zhang,Qian Li,Long Liu
With the addition of Na+ and Bi3+ to the lead-free double perovskite Cs2AgInCl6, high photoluminescence quantum yields (PLQYs) can be achieved, making Cs2AgInCl6 more promising; however, it is still difficult to achieve blue-light-excited narrowing emission. In this study, Cs2−xKxAg0.6Na0.4In0.8Bi0.2Cl6−xBrx was developed with K+ and Br−, realizing blue-light-excited narrowing red photoluminescence under cryogenic temperatures. The transitional non-localized donor energy level was formed by KBr addition, changing the exciton excitation and transition process. With the increase in the x value, Cs2−xKxAg0.6Na0.4In0.8Bi0.2Cl6−xBrx can be excited by blue light at 150 K and emit a narrowing red light. When 1 : 1 KBr was added, the full width at half maximum (FWHM) of Cs2−xKxAg0.6Na0.4In0.8Bi0.2Cl6−xBrx red light emission was further narrowed to only 73 nm, when excited by 467 nm blue light at 10 K. This study will stimulate further research on lead-free double perovskites in the field of display technologies.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
INORGANIC CHEMISTRY
·
2019
·
IF 4.85
Jinquan Chen,Conghua Yang,Yibo Chen,Jin He,Zhao-Qing Liu,Jing Wang,Jilin Zhang
Modulating the local environment around the emitting ions with component screening to increase the quantum yield and thermal stability is an effective and promising strategy for the design of high-performance fluorescence materials. In this work, smaller Lu3+ was introduced into the La3+ site in a Mn4+-activated LaAlO3 phosphor with the expectation of improving the luminescence properties via lattice contraction induced by cation substitution. Finally, a La1–xLuxAlO3:Mn4+ (x = 0–0.04) perovskite phosphor with a high quantum yield of 86.0% and satisfactory thermal stability was achieved, and the emission peak at 729 nm well matches with the strongest absorption peak of the Phytochrome PFR. The favorable performances could be attributed to the suppressed cell volume and superior lattice rigidity after the substitution of Lu3+. This work not only obtains a highly efficient La1–xLuxAlO3:Mn4+ (x = 0.02) phosphor, which holds great potential for application in plant-cultivation light-emitting diodes, but also provides an applicable strategy for further investigation of far-red-emitting phosphors.
研究领域:
材料科学
·
植物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
DALTON TRANSACTIONS
·
2023
·
IF 4
Bowen Wang,Changshuai Gong,Xuyan Xue,Meiting Li,Qi Zhu,Xuejiao Wang,Ji-Guang Li
A series of CaGdAlO4-type layered perovskite phosphors showing deep red luminescence (λem = 711 nm, λex = 338 nm) were synthesized via a solid-state reaction. A comprehensive analysis performed via photoluminescence, X-ray photoelectron spectroscopy, thermoluminescence, and fluorescence decay revealed that the deep red luminescence is related to oxygen defects and particularly oxygen interstitials. The defect-related luminescence was effectively regulated through partial substitution of multi-cationic sites (the Ca2+ site with Mg2+, Sr2+, and Ba2+; the Gd3+ site with La3+, Y3+, and Lu3+) and full substitution of Gd3+ with Y3+. Remarkably, a 383.3% stronger luminescence was obtained through partial substitution with Lu3+, and the quantum yield of luminescence reached 28.74%, which is higher than those values of most previously reported self-luminescent systems. A pc-LED device was fabricated using this phosphor, and the device was shown to have potential application in indoor plant cultivation.
研究领域:
材料科学
·
光学工程
·
农业科学
✓ 已验证
DOI
PubMed
高影响因子
Journal of Materials Chemistry C
·
2024
·
IF 5.7
Chenyang Li,Yimin Zhou,Fei Tang,Yizhuo Chen,Kangzhen Tian,Bo Zhao,Shijie Xu
Far-red (FR) emission (>700 nm) with high efficiency and excellent thermal stability is in great demand for solid-state lighting applications in health illumination. However, currently used FR materials often face challenges such as complex synthesis, low efficiency, and thermal instability. In this study, we present a highly efficient and thermally stable far-red phosphor, Mn4+-activated La1−xCaxAlO3−yFy, with a dominant emission wavelength of 731 nm. Based on this, an ultrathin phosphor–glass composite (PGC), with a FR luminescence quantum yield of 68.2%, is prepared using a tape-casting process combined with a low-temperature cofiring technique. The impact of ionic substitution on the crystal structure and luminescence properties is examined to establish the optimal doping conditions. Interestingly, we observed that the prepared PGC exhibits temperature-dependent luminescence distinct from that of FR phosphor. The luminescence lifetime for the PGC is measured to be nearly 3.576 ms, representing a 28.4% decrease compared to that of the pure phosphor. Ultimately, light-emitting diodes (LEDs) are fabricated by combining the PGC with a violet chip, and their electroluminescence (EL) properties are strongly dependent on the configuration of the PGC composite. This research offers a straightforward and versatile method for producing ultrathin far-red PGCs that hold promise for diverse photonic 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
JOURNAL OF LUMINESCENCE
·
2020
·
IF 3.28
Wei Li,Nan Ma,Qi Sun,Shaoying Wang,Zongjie Zhang,Balaji Devakumar,Xiaoyong Huang
Novel efficient Ba 2 YTaO 6 :Mn 4+ (BYT:Mn 4+ ) far-red emitting double-perovskite phosphors for plant cultivation LEDs were reported in this article. These phosphors were successfully synthesized via a traditional high-temperature solid-state reaction method, and their crystal structure, luminescence properties, fluorescence decay lifetimes, Commission Internationale de l'Eclairage (CIE) chromaticity coordinates, internal quantum efficiency, and thermal stability have been systematically investigated. XRD Rietveld refinement demonstrated that the BYT:Mn 4+ compound crystallized into cubic crystal system with Fm 3 ‾ m space group, and the lattice parameter were a = b = c = 8.445 (7) Å, α = β = γ = 90°, and V = 602.231 (10) Å 3 . Interestingly, the obtained samples showed an intense far-red emission band centered at 690 nm under excitation of 360 nm, which matched well with the absorption band of phytochrome P FR. In BYT:Mn 4+ phosphors, the Mn 4+ ions occupied the TaO 6 octahedron by replacing the Ta 5+ site, and the optimal doping concentration of Mn 4+ ions was determined to be 0.4 mol%. The CIE chromaticity coordinates and internal quantum efficiency of BYT:0.4%Mn 4+ phosphors were (0.7283, 0.2717) and 41.5%, respectively. In addition, when the temperature reached at 423 K, the emission intensity of BYT:0.4%Mn 4+ phosphors remained 37% of that at 303 K. Therefore, all of these investigations demonstrated that BYT:Mn 4+ phosphors could be used as potential far-red emitting phosphors for plants cultivation LEDs.
研究领域:
材料科学
·
植物生物学
·
光电技术
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Min Lu,Jie Guo,Siqi Sun,Po Lu,Xiaoyu Zhang,Zhifeng Shi,William W. Yu,Yu Zhang
All-inorganic CsPbX 3 (X = Cl, Br, I) quantum dots (QDs) are promising materials for light-emitting diodes (LEDs), but the long insulating ligands such as oleic acid (OA) and oleylamine (OLA) on the QD surface limit the device performances. They reduce the electrical conductivity of QDs, while their loss deteriorates the photoluminescence and stability. To overcome these issues, octylphosphonic acid (OPA) with a shorter carbon chain was added in the synthesis of perovskite QDs to partially replace OA ligands. Owing to the strong interaction between OPA and Pb atoms, the undercoordinated Pb atoms on the surface of CsPbI 3 QDs can be effectively passivated by OPA, leading to improved fluorescence quantum efficiency (close to unity) and solution stability. Furthermore, the electrical conductivity of QD films was also enhanced from 5.3 × 10 −4 to 1.1 × 10 −3 S/m by using shorter chain OPA ligands. Finally, highly efficient red perovskite QD LEDs with peak external quantum efficiency (EQE) of 12.6% and maximum luminance of 10171 cd m −2 were achieved in a top-emitting device structure, a nearly 3-fold enhancement in luminance compared with pristine CsPbI 3 QDs based LEDs.
研究领域:
材料科学
·
光电技术
✓ 已验证
产品关联
DOI
高影响因子
Nanoscale
·
2020
·Vol. 12
·期 14
·7712-7719
·
IF 6.895
Yongsheng Zhu,Jun Zhao,Gang Yang,Xiumei Xu,Gencai Pan
Lead halide perovskite nanocrystals (PNCs) have very recently emerged as promising emitters for their superior optoelectronic properties. However, the defects in perovskite itself make it susceptible to the external environment and internal ion migration, resulting in low photoluminescence quantum yield (PLQY) and poor device efficiency. Herein, we developed a method to reduce the surface defects of PNCs by introducing ammonium acetate in the synthesis of CsPbI3 PNCs. The addition of ammonium acetate can effectively eliminate undesired surface metallic lead cations and dangling bonds, resulting in an enhanced PLQY and stability. The passivated PNCs have an overall up-shift energy level, demonstrating better hole injection efficiency. As a result, the red light-emitting diodes (LEDs) fabricated with the passivated CsPbI3 PNCs achieved an optimal EQE of 10.6% and a maximum brightness of 981 cd m−2, which are 3.1 and 2.4 times that of unpassivated PNCs based devices, respectively.
研究领域:
材料科学
·
光电技术
✓ 已验证
DOI
高影响因子
Nanoscale
·
2022
·Vol. 14
·期 43
·16156-16169
·
IF 8.307
Yang Wang,Shuai Zhou,Fuyao Sun,Po Hu,Wei Zhong,Jiajun Fu
NaErF4 is the most extensively studied host for self-sensitized upconversion (UC), and Yb3+ is the most commonly used energy absorber. It has been reported that the red luminescence of Er3+ can be enhanced by introducing Yb3+ into the NaErF4 host lattice, where Yb3+ ions serve as trapping centers to confine the excitation energy. Also, it has been pointed out that the Yb3+ doping in the shell of NaErF4-hosted core–shell nanocrystals can further improve the red emission intensity. Conversely, it can be argued that the Yb3+ doping in the shell always results in the luminescence quenching of the NaErF4 core. These imply that the impact of Yb3+ on NaErF4-based host-sensitized UC is rather complicated and must be probed deeply. In this study, we thoroughly discussed the effect of Yb3+ located in the core/shell on the NaErF4-based host sensitization UC and afforded the related mechanism interpretations. In the NaErF4 core nanocrystals, the green-dominated UCL presented an enhancement on increasing the concentration of the Yb3+ dopant owing to the promoted energy harvesting for luminescence. Furthermore, the emission properties of NaErF4:10%Yb shelled with diverse inert layers were also investigated, and the intensity difference of these core-inert shell nanoparticles could be explained by the lattice mismatch and shell thickness. In NaErF4:10%Yb@NaYF4:Yb with variable Yb3+ doping in the shell, the red-dominated UCL was generally weakened with more Yb3+ localized in the shell, which was ascribed to the competition of energy pooling and energy dissipation of Yb3+ in the outer layer. Therefore, Yb3+ ions wield a two-sided influence (termed a “double-edged sword”) on the UC emissions of the Er3+ host. Additionally, we demonstrated the application potential of such UCNPs in water sensing and high-level anti-counterfeiting. This work offers an in-depth insight into the UC mechanism of Yb3+-doped NaErF4 nanocrystals and inspires the engineering of novel luminescent materials with distinguished properties.
研究领域:
材料科学
·
纳米技术
·
光学
·
化学
✓ 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）