查找使用阿拉丁产品的科研文献

Strong f–f excitation in hafnium germanate: Near-UV LED and cathode beam–pumped red phosphor with thermal robustness

Quansheng Wu,Shanshan Ye,Xufeng Zhou,Jianyan Ding

Developing narrowband red phosphors has always been a frontier topic in the phosphor community. In this study, a novel hafnium germanate red phosphor, BaHfGe 3 O 9 :Eu 3+ , was successfully synthesized by solid-state reaction method. The phase and crystal structure of BaHfGe 3 O 9 were investigated by the Rietveld refinement of powder X-ray powder diffraction. The band structure was analyzed by density functional theory calculations. Most importantly, the luminescence behavior of phosphors under near-ultraviolet (n-UV) light and cathode rays sources was studied in detail to explore the possibility of their applications in white light-emitting diodes and field emission display. The BaHfGe 3 O 9 :Eu 3+ phosphor exhibits strong f–f excitation and excellent thermal robustness due to Eu 3+ localization in the rigid lattice and asymmetric Ba 2+ sites. Under cathode rays and n-UV light excitation, BaHfGe 3 O 9 :Eu 3+ exhibits narrowband red light emission peaked at 610 nm. Moreover, BaHfGe 3 O 9 :Eu 3+ shows excellent saturation resistance and aging resistance. The performance of the LED lamp encapsulated by the BaHfGe 3 O 9 :Eu 3+ phosphor was studied. The results show that BaHfGe 3 O 9 :Eu 3+ is a potential red phosphor for multifunctional applications.

High-performance multifunctional NIR phosphor K2NaAlF6:Mn4+,Cr3+ for pc-LED and X-ray imaging via efficient energy transfer

Juhang Liang,Xinxin Han,Hengjuan Deng,Shasha Wang,Dongxi Liu,Kui Zhang,Bingsuo Zou

The development of efficient and thermally stable near-infrared (NIR) phosphors is crucial for advancing next-generation smart NIR lighting sources, yet remains a formidable challenge. Herein, we report a high-performance K 2 NaAlF 6 :Mn 4+ ,Cr 3+ phosphor engineered via an efficient energy transfer strategy. The optimized phosphor exhibits a dominant NIR emission peak at 725 nm and achieves an exceptional energy transfer efficiency of 87.5 % from Mn 4+ to Cr 3+ . This efficient energy transfer, combined with the enhanced Cr 3+ absorption, contributes to a 91 % enhancement in NIR emission intensity and an increase in internal quantum efficiency from 74.0 % to 82.7 %. Meanwhile, the thermal stability is also significantly improved, with the co-doping sample retaining 83.4 % of its emission intensity at 425 K compared with 73.6 % for the singly Cr 3+ -doped counterpart, which is attributed to the enhanced lattice rigidity and the energy transfer process induced by Mn 4+ doping. A NIR phosphor-converted light-emitting diode (NIR pc-LED) fabricated with this phosphor and a blue chip demonstrates outstanding performance in applications of bioimaging, non-destructive testing and night vision imaging. Furthermore, its outstanding scintillation properties also enable high-resolution X-ray imaging. This work establishes a feasible design strategy for developing advanced multifunctional NIR luminescent materials that simultaneously achieve high efficiency and excellent thermal stability.

Facile synthesis of the desired red phosphor Li2Ca2Mg2Si2N6:Eu2+ for high CRI white LEDs and plant growth LED device

Xian Yang,Yu Zhang,Xuejie Zhang,Jian Chen,Haisen Huang,Dongsheng Wang,Xirong Chai,Gening Xie,Maxim S. Molokeev,Haoran Zhang,Yingliang Liu,Bingfu Lei

The red emission with suitable peak wavelength and narrow band is acutely required for high color rendering index (CRI) white LEDs without at the cost of the luminous efficacy. Herein, the Li 2 Ca 2 Mg 2 Si 2 N 6 :Eu 2+ red phosphor was prepared with facile solid-state method using Ca 3 N 2 , Mg 3 N 2 , Si 3 N 4 , Li 3 N, and Eu 2 O 3 as the safety raw materials under atmospheric pressure for the first time, which shows red emission peaking at 638 nm with full width at half maximum (FWHM) of 62 nm under blue light irradiation and becomes the desired red phosphor to realize the balance between luminous efficacy and high CRI in white LEDs. The morphology, structure, luminescence properties, thermal quenching behavior, and chromaticity stability of the Li 2 Ca 2 Mg 2 Si 2 N 6 :Eu 2+ phosphor are investigated in detail. Concentration quenching occurs when the Eu 2+ content exceeds 1.0 mol%, whereas high-temperature photoluminescent measurements show a 32% drop from the room-temperature efficiency at 423 K. In view of the excellent luminescence performances of Li 2 Ca 2 Mg 2 Si 2 N 6 :Eu 2+ phosphor, a white LEDs with CRI of 91 as a proof-of-concept experiment was fabricated by coating the title phosphor with Y 3 Al 5 O 12 :Ce 3+ on a blue LED chip. In addition, the potential application of the title phosphor in plant growth LED device was also demonstrated. All the results indicate that Li 2 Ca 2 Mg 2 Si 2 N 6 :Eu 2+ is a promising red-emitting phosphor for blue LED-based high CRI white LEDs and plant growth lighting sources.

The composition engineering of red-emitting Eu3+-doped Ca10.5(PO4)7-type solid solution phosphors and application in LED

Jindi Wang,Shuai Huang,Yu Yan,Mengmeng Shang

In this work, using Ca 10.5 (PO 4 ) 7 as the structural model, a number of Eu 3+ -doped [Ca 9 Na 3x Y 1-x (PO 4 ) 7 (CNYP-I, 0 ≤ x ≤ 1/2) ← Ca 10.5 (PO 4 ) 7 → Ca 9+y Na 3/2-y/2 Y (1-y)/2 (PO 4 ) 7 (CNYP-II, 0 ≤ y ≤ 1)] phosphors were designed and synthesized through the heterovalent substitution of Y 3+ and Na + to Ca 2+ . The substitution mechanism, composition structure, luminescence performance, and thermal stability of Eu 3+ -doped CNYP-I (0 ≤ x ≤ 1/2) as well as the solid solutions of CNYP-II (0 ≤ y ≤ 1), were discussed in detail. The morphology and element composition of CNYP-I (0 ≤ x ≤ 1/2) and CNYP-II (0 ≤ y ≤ 1) solid solutions were analyzed by SEM and EDS. The PL spectra of the specimens were containing the predominant red peak of emission at 612 nm caused via the transition of 5 D 0 - 7 F 2 , indicating that Eu 3+ occupies the low-symmetry center. Moreover, the site symmetry Eu 3+ occupied changed with the x/y value. The luminous intensity of Eu 3+ -doped CNYP-I (0 ≤ x ≤ 1/2) and CNYP-II (0 ≤ y ≤ 1) phosphors at 150°C maintained about 60% of room temperature. The representative compound CNYP-I (x = 1/3) was used as the red phosphor to prepare a near-UV based white LEDs along with Ra of 80.9 and CCT of 4100 K.

Surfactin-methylene blue complex under LED illumination for antibacterial photodynamic therapy: Enhanced methylene blue transcellular accumulation assisted by surfactin

Juan Zhao,Lixian Xu,Hao Zhang,Yuhong Zhuo,Yanan Weng,Shuang Li,Dinghua Yu

Recently, increased attention has been focused on antibacterial photodynamic therapy (APDT) to treat multidrug-resistant bacterial infection due to the antibiotic abuse. Methylene blue has been used as a kind of efficient and cheap commercial photosensitizer in APDT. However, due to high hydrophilicity, methylene blue is not able to be transcellular intaken and accumulated efficiently. To promote accumulation and APDT efficiency of methylene blue, lipopeptide surfactin-methylene blue complex has been prepared through electrostatic interaction. The complex under LED irradiation was found to effectively reduce 5.0 Log 10 CFU and 7.6 Log 10 CFU for P. aeruginosa and S. aureus , respectively. The bacterial reduction efficiency is slightly higher than free methylene blue. The photosensitizers accumulation and APDT targeting protein have been characterized by fluorescence spectroscopy, fluorescence microscopy and protein electrophoresis techniques. These results demonstrated that more surfactin-methylene blue complex could be accumulated more into the cell, and inactivate bacteria through destroying intracellular protein under LED illumination. In comparison, free methylene blue under light could inactivate bacteria through destroying membrane protein and lipid structures. These results would provide valuable insight for developing advanced clinical medicine and designing photo-drug for photodynamic therapy.

One-pot synthesis of dispersible thermally stable organic downconversion materials under DBU catalyzation for high performance hybrid-LED lamps

Junjie He,Shixing Yang,Kai Zheng,Youming Zhang,Jun Song,Junle Qu

The lighting market has been dominated by light emitting diodes (LEDs), which not only need Ga for wafer production, but also consume abundant non-sustainable rare-earth elements such as Y, Ce and Eu. Hybrid-LED technology using organic downconversion materials (ODMs) is a promising candidate technology to save the rare-earth elemental resources. However, it is still a challenge to fabricate hybrid-LED devices with a high color rendering index (CRI), lumen efficiency and long lifetime at the same time. Herein, highly dispersible perylene diimides are synthesized in short routes and dispersed into a polymer matrix at high temperature to produce low cost light ODMs. Cold to warm white LED lamps with a CRI up to 92 can be fabricated with the ODMs. In particular, a warm white lamp with the same high CRI and efficiency up to 82 lm W−1 is obtained. It is comparable to all inorganic warm white LEDs with such a high CRI. By applying our OMDs, an approach for highly efficient yellow LED lamps, which can improve efficiency by 66% to 153 lm W−1 compared with the present method, is illustrated. More importantly, incorporating a remote phosphor configuration (RPC) effectively improves the lifetime of ODMs superior to 2870 h, extrapolated to 6000 h maintaining 70% of the original fluorescence efficiency after continuous operation in an ambient environment. This approach could be a quite simple protocol paving the way for the practical application of hybrid-LED lamps.

A novel KSrScSi2O7:xCr silicate phosphor, luminescence/chromaticity, and applications in NIR pc-LED and stable green ceramic pigments

Sihan Yang,Xuyan Xue,Feng Jiang,Liang Dong,Qi Zhu,Xuejiao Wang,Ji-Guang Li

The emission wavelength of current near-infrared phosphors activated by Cr 3+ is generally smaller than 900 nm in near-infrared (NIR) I region, and it is extremely challenging and is of great practical significance to realize emission towards NIR-II region. In this study, a novel Cr 3+ excited KSrScSi 2 O 7 silicate broad-band phosphor was prepared using the traditional solid-state method. Cr 3+ resides in a weak crystal field in the KSrScSi 2 O 7 lattice and exhibits broad-band near-infrared emission at 984 nm, longer than those of most Cr 3+ activated phosphors, under 493 nm blue light excitation. This is due to the strong charge polarization caused by the unique local coordination environment of the silicate matrix, which leads to a reduction in the crystal field splitting energy of the [ScO 6 ] octahedron where Cr 3+ is located and the downward shift of the 4 T 2 energy level. The optimal doping concentration of Cr 3+ is found to be 2 mol%, and the quenching mechanism is dipole-dipole interaction. Compared to the phosphors with similar emission wavelengths ( λ em > 900 nm), KSrScSi 2 O 7 :Cr 3+ demonstrates outstanding advantages in various aspects of luminescent performance. The fabricated phosphor-converted light-emitting diode (pc-LED) is shown to have the potential for night vision and non-invasive imaging. Novel application of KSrScSi 2 O 7 : x Cr 3+ as stable green ceramic pigments is also explored. The KSrScSi 2 O 7 : x Cr 3+ powders show a bright yellowish green appearance, and the KSrScSi 2 O 7 :0.02Cr 3+ typical composition has chromaticity values of L* = 82.73, a* = –8.53, b* = 7.97. Remarkably, the glazing samples using KSrScSi 2 O 7 : x Cr 3+ as pigments well retain the bright color after 1200 °C sintering in different atmospheres. Therefore, multi-functional applications of KSrScSi 2 O 7 : x Cr 3+ for near-infrared spectroscopy and as ceramic pigments are achieved in this work.

A Compact UV-LED-Induced Fluorescence With Short Metal Capillary and Low Light Leakage: Application to Noninvasive Glucose Detection

Weicheng Cai,Zhaolin Li,Hui Huang,Xuejing Li,Jian Zhao,Pengbo Liu,Yajun Wu,Mingchang Liu,Jian Wang

Orange LED and cell fluorescence imaging of Mn2+ doped CsPbCl3 water-soluble nanocrystals with improved stability and optimized luminescence

Ting Fan,Jian-tao Lü,Wen-qiang Deng,Jun-xian Mai,Jie Liang,Ting-ting Deng,Wen Fan,Qin-song Zhou,Qi-feng Lin

Water-soluble Mn 2+ doped CsPbCl 3 nanocrystals coating by 6-aminocaproic acid (ACA) ligand were prepared by a simple ligand assisted reprecipitation method at room temperature. The CsPbCl 3 :Mn 2+ /ACA nanocrystals were almost cubic phase and had mean size of about 10 nm. Due to the coating and passivation of ACA, the CsPbCl 3 :Mn 2+ /ACA nanocrystals retained the initial fluorescence intensity of 20% after being dispersed in deionized water for 20 days. The orange LED device based on CsPbCl 3 :Mn 2+ /ACA nanocrystals were prepared with excellent luminescence properties. In the cytotoxicity test, even if the MCF-7 cells were cultured for 24 h at the concentration of CsPbCl 3 :Mn 2+ /ACA nanocrystals as high as 160 μg·ml −1 , the cell survival rate was still 70%. Confocal fluorescent cell imaging results showed that the nanocrystals had remarkable fluorescent cell imaging effect even after 24 h. The synthesized CsPbCl 3 :Mn 2+ /ACA nanocrystals have nice water solubility, good water stability, low cytotoxicity and highly luminescence properties, and have great application potential in the field of orange LED and fluorescent probes .

Improving photoluminescent water-stability of CsPbBr3 perovskite nanocrystals via constructing nanocrystals/polymer composites with hydrophobic surfaces for LED applications

Pengyu Su,Yuehao Huang,Yadong Li,Chenguo Hu,Wenbing Shi

With quick development of optoelectronic devices, lead halide perovskite nanocrystals (PNCs) have been extensively researched due to their excellent optoelectronic and luminescent properties. However, the water-induced low stability seriously restricts their applications. In this study, CsPbBr 3 PNCs/polymer composite films are prepared based on even dispersion of PNCs and ultraviolet (UV)-induced chemical crosslinking of methyl methacrylate (MMA) monomers and vinyl silicone oil (VT-PDMS) oligomers . The optimized polymer/PNCs composite film exhibits high photoluminescence quantum yield (PLQY) of 82% comparable to common PNCs, as well as high surface hydrophobicity . This film shows high photoluminescence (PL) intensity (90% of original value) after air aging for 60 days. Its high surface hydrophobicity is attributed to use of VT-PDMS oligomers bearing Si element with low surface energy. Light-emitting-diode (LED) device is constructed employing this optimized composite film, and its color coordinates (0.343, 0.334) is rather close to that of standard white light. Specifically, high PL and surface hydrophobic properties of specimens are simultaneously achieved. The importance of this work can lie in a mild rapid preparation of hydrophobic CsPbBr 3 PNCs/polymer nanocomposites with stable white-light emission for commercial LED devices.

Ce:YScAG phosphor-converted transparent ceramics with high thermal saturation and weak concentration quenching for LED and LD white lighting

Yukun Li,Zhaohua Luo,Yongfu Liu,Zehua Liu,Svenja Hanson,Hui Lin,Pan Hu,Peng Sun,Jun Jiang

In the high-power white light LEDs/LDs area, obtaining phosphor-converted materials with high thermal stability and high luminous emittance with proper blue/yellow light ratio has been the main challenge in recent years. In this study, a group of (Ce x Y 1-x ) 3 (Sc y Al 1-y ) 5 O 12 transparent ceramics with high optical quality were proposed to rise to that challenge. Their spectra were regulated by incorporating Sc 3+ , showing blue shifted emission bands (peak position from 554 nm–538 nm), blue shifted excitation bands (462–445 nm) and narrowed full width at half maxima (120–112 nm). Significantly, the prepared Ce:YScAG transparent ceramics (TC) exhibited decent thermal quenching performance with the photoluminescence intensity at 150 °C maintaining 88.7% of its original value at room temperature. The Sc incorporation impacted the atoms’ occupation and distance, crystal field splitting and energy band structure . Under remote LD excitation mode, the luminous efficiency of the prepared Ce:YScAG TC can achieve 164.8 lm/W. And even if the Ce 3+ doping reaches 2.0 at%, the LE can still maintain 117.8 lm/W, exhibiting decent concentration quenching characteristic. Consequently, Ce:YScAG TCs have great potential as promising phosphor-converted materials in future high-power LED and LD white lighting.

A full visible LED enabled by a broadband yellow emission nepheline phosphor derived from a europium doped SOD zeolite

Xinzhe Zhou,Tiezhen Ren,Jian Yin,Xiurong Zhang,Peng Li,Huanrong Li

Developing a broadband yellow emission phosphor that covers green to orange light regions is an effective way to achieve high-quality solid-state lighting. A broadband yellow phosphor with excellent thermal stability was obtained by heating a europium-doped SOD zeolite under a reducing atmosphere. Under UV excitation, the phosphor exhibits a broad emission band (FWHM = 120 nm) and high thermal stability (80% intensity at 423 K). Prototype white LEDs using this broadband yellow-emit phosphor, a blue-emit phosphor (NaMgBO3:Ce3+), and a red-emit phosphor (Sr2Si5N8:Eu2+) show excellent color quality (CRI = 93, R10 = 88) and a low correlated color temperature (CCT = 4219 K), outperforming most of the tricolor phosphor-converted NUV-LEDs. This work highlights the great potential of lanthanide-doped zeolites in developing promising phosphors for high quality lighting.