JOURNAL OF MATERIALS SCIENCE
·
2024
·Vol. 59
·期 47
·21882-21894
·
IF 3.5
Hu Hao,Zhao Xia,Mao Xiang,Dong Yongrun,Li Wen,Xue Jinkun,Li Zequan,Gao Wei
White light-emitting diodes (WLEDs), as strong contenders for future solid-state light sources, hold significant promise in solid-state lighting due to their high efficiency, low power consumption, self-emission, and versatility. Carbon dots (CDs), a novel type of carbon nanomaterials, exhibit excellent luminescence properties. However, their intricate structure and unclear fluorescence mechanism hinder long-wavelength modulation, and solid-state aggregation leads to luminescence quenching, limiting their application in optoelectronic devices. This study focuses on the preparation of CDs with dual yellow–green emission peaks via a hydrothermal method using sodium lignosulfonate as a carbon source. The mechanism behind the dual emission is elucidated by analyzing the morphology and chemical composition of the CDs. Specifically, the green light originates from surface-related states due to N doping, while the yellow light results from the carbon-core state at higher hydrothermal temperatures. By incorporating these CDs into transparent wood, a material capable of emitting white light under blue light excitation is achieved. This transparent wood was successfully applied in the fabrication of WLEDs, providing valuable insights into CDs modulation and their utilization for white light solid-state lighting 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
ADVANCED FUNCTIONAL MATERIALS
·
2024
·
IF 18.5
Yupeng Liu,Bingzhe Wang,Yunsen Zhang,Jia Guo,Xiaoyi Wu,Defang Ouyang,Shi Chen,Yeqing Chen,Shuangpeng Wang,Guichuan Xing,Zikang Tang,Songnan Qu
Carbon dots (CDs) are a burgeoning star of luminescent carbon-based nanomaterials with emerging interest for various applications. Luminescence from the sp 2 -conjugated domains in the carbon cores is considered to be the intrinsic bandgap emission of CDs, whereas the relationship between them remains poorly understood. Simultaneously, the solvent relaxation of water molecules will quench the fluorescence of CDs, thus, obtaining strong luminescence from CDs aqueous solutions remains a great challenge. Herein, a facile one-step spatial-confined cross-condensation method that uses a heat-induced self-foaming process in ambient pressure has been developed to synthesize highly luminescent CDs with unprecedented photoluminescence quantum yield (PLQY) over 97.2% in water. The unique precursor-derived cross-arranged perylene skeleton in the cores hinders π–π stacking, while the hydrophobicity of the conjugated units mitigates solvent relaxation by water molecules, resulting in near-unity PLQY in aqueous solutions, enabling this to demonstrate the first optically pumped green lasing emission in the CDs aqueous solution. Moreover, a biomaterial-based white light emitting diode is fabricated using the CDs-stained silks as a fluorescence conversion cover to realize a high luminous efficiency of 60.7 lm W −1 with CIE color coordinate of (0.33, 0.35).
研究领域:
材料科学
·
光学工程
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
Inorganic Chemistry Frontiers
·
2021
·Vol. 8
·期 23
·5113-5123
·
IF 6.569
Runtian Kang,Hang Chen,Ruijie Ji,Haoyang Wang,Takatoshi Seto,Yuhua Wang
It is of great significance for white light-emitting diodes (wLEDs) to explore new, efficient and stable inorganic phosphors excited by wideband near-ultraviolet (n-UV) light. A new type of efficient emission-tunable Ce3+/Mn2+ doped Ca2YHf2Al3O12 (CYHAO) garnet phosphor which can be excited by n-UV light is studied in this work. Due to the effective energy transfer (ET) from Ce3+ to Mn2+ in CYHAO, CYHAO:0.09Ce3+,xMn2+ phosphors have a wide excitation band in the 370–470 nm region with a peak at 410 nm. Under excitation at 410 nm, all the samples show tunable color emission and match with the near UV chip. Through the decay time, it is determined that the energy transfer efficiency is as high as 88.83%. The calculated activation energy is about 0.217 eV, indicating the relatively good thermal stability. The cathodoluminescence (CL) properties show that the phosphor has a high saturation current and saturation voltage. A single component white LED is fabricated by using the CYHAO:0.09Ce3+,0.3Mn2+ phosphor and a 400 nm n-UV chip. It is worth noting that the detailed study of the energy transfer mechanism, thermal quenching mechanism and CL mechanism has reference value for the development of new co-doped phosphors.
研究领域:
材料科学
·
光学工程
✓ 已验证
DOI
高影响因子
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
2020
·Vol. 126
·期 4
·1-7
·
IF 1.81
Cao Renping,Shao Wenhua,Zhao Yanshu,Chen Ting,Ao Hui,Guo Siling,Liu Pan,Fan Ting
CaTi 4 (PO 4 ) 6 : x Eu 3+ phosphors are successfully synthesized under air condition by high-temperature solid-state method. The crystal structure, morphology, energy spectrum, atomic percentage, elemental mapping, and luminescence properties are investigated, respectively. Monitored at 594 nm, the excitation spectral bands of CaTi 4 (PO 4 ) 6 :Eu 3+ phosphor in the range of 210–550 nm are assigned to the O 2− –Eu 3+ charge transfer band (CTB) and the 7 F 0 → 5 H 3 , 5 L 7 , 5 L 6 , 5 D 1 , 5 D 2 , 5 D 3 , and 5 D 4 transitions of Eu 3+ ion. With excitation at 394 nm, CaTi 4 (PO 4 ) 6 :Eu 3+ phosphor emits orange-red light with the chromaticity coordinates (0.548, 452), and the emission spectral bands in the region from 575 to 720 nm are attributed to the 5 D 0 → 7 F 1 , 7 F 2 , 7 F 3 , and 7 F 4 transitions of Eu 3+ ion. The optimal doping concentration of Eu 3+ ion is ~ 8 mol%. The lifetime of CaTi 4 (PO 4 ) 6 :Eu 3+ phosphors decreases from 1.87 to 0.97 ms with increasing Eu 3+ concentrations from 1 to 10 mol%. CaTi 4 (PO 4 ) 6 :Eu 3+ phosphor has a good thermal stability. The experimental results indicate that CaTi 4 (PO 4 ) 6 :Eu 3+ phosphor has an application prospect in white light-emitting diodes (LEDs) based on the near ultraviolet (~ 394 nm) LED chip.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2019
·Vol. 102
·期 10
·5910-5918
·
IF 3.094
Renping Cao,Xinyan Lv,Yaqin Ran,Longxiang Xu,Ting Chen,Siling Guo,Hui Ao,Xiaoguang Yu
Li 5 La 3 Ta 2 O 12 :Mn 4+ (LLTO:Mn 4+ ) phosphors are prepared in air via high-temperature solid-state method and investigated for their crystal structures and luminescence properties. LLTO:Mn 4+ phosphor under excitation at 314 nm shows deep-red emission peaking at 714 nm due to the 2 E→ 4 A 2 transition of Mn 4+ ion. The excitation bands in the range 220 - 570 nm are attributed to the Mn 4+ - O 2- charge-transfer band and the 4 A 2g → 4 T 1g , 2 T 2g , and 4 T 2g transitions of Mn 4+ , respectively. The optimal Mn 4+ ion concentration is ~0.4 mol%. The concentration quenching mechanism in LLTO:Mn 4+ phosphor is electric dipole-dipole interaction. The luminous mechanism and temperature quenching phenomenon are explained by the Tanabe-Sugano energy level diagram and the configurational coordinate diagram of Mn 4+ in the octahedron, respectively. The experimental results indicate that LLTO:Mn 4+ phosphor has a potential application prospect as candidate of deep-red component in light-emitting diode (LED) lighting.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
CHEMOSPHERE
·
2021
·
IF 7.086
Guo-Qiang Li,Zheng-Yang Huo,Qian-Yuan Wu,Zhuo Chen,Yin-Hu Wu,Yun Lu,Hong-Ying Hu
Recently, ultraviolet light-emitting diodes (UV-LEDs) and chlorine combined system has been employed as an emerging advanced oxidation process . However, UV-LEDs were commonly considered as monochromatic UV sources. In this study, the obvious quantum yields of chlorine photolysis under 265 nm and 280 nm LEDs irradiations were investigated with treating LEDs as polychromatic UV sources. Particularly, Φ obs-poly of HOCl and OCl⁻ for 265 nm LED were found to be 1.50 and 0.70 mol E −1 , respectively, whereas Φ obs-poly of HOCl and OCl⁻ for 280 nm LED were 1.28 and 0.64 mol E −1 , respectively. It was identified that Φ obs-poly were 5.66–14.63 % lower than Φ obs-mono . This suggests that obvious quantum yield using peak emission wavelength would overestimate the true quantum yield. The production of radical species in LED UV/chlorine systems were determined by the degradation of BA , and illustrated by a mathematical model. Different trends were observed for 265 nm and 280 nm LED UV/chlorine systems as pH increased from 5.0 to 10.0. As pH increased, the formation of OH continuously decreased in both 265 nm and 280 nm LED systems. The formation of Cl increased at neutral pH and more Cl and OH were formed due to the higher molar absorbance coefficient at 280 nm. The chlorine dose-dependent effects on radical productions at pH of 5.0, 7.5 and 10.0 were also assessed. At pH of 5.0, OH was the main radical product and had linear correlation with chlorine dose. At pH of 7.5, the productions of OH and Cl showed similar profiles that increased rapidly at low chlorine dosage and then slowed down.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Advanced Optical Materials
·
2019
·Vol. 7
·期 23
·1901098
·
IF 7.125
Shunran Li,Qingsong Hu,Jiajun Luo,Tong Jin,Jing Liu,Jinghui Li,Zhifang Tan,Yibo Han,Zhi Zheng,Tianyou Zhai,Haisheng Song,Liang Gao,Guangda Niu,Jiang Tang
Low dimensional halide perovskites with self-trapped excitons (STEs) emission have emerged as promising white light phosphors because of their ultrabroadband emission covering the entire visible spectrum from 400 to 800 nm. Such a broad emission from a single material can overcome emission color change and self-absorption problems within multiple phosphors. However, the color rendering index (CRI) and correlated color temperature (CCT) as two essential parameters of white light quality can hardly be modulated in these perovskite materials. Here, rare earth ion Ho 3+ is introduced into Cs 2 (Na,Ag)InCl 6 for the first time, utilizing the hydrothermal method. Besides the strong warm white STEs emission, the as-synthesized materials exhibit effective characteristic emission of Ho 3+ in the visible region. Further, the mechanism of associated emission is explored and the existence of energy transfer from STEs to rare earth is first confirmed. A white light-emitting diode (LED) prototype is also fabricated by employing the Ho 3+ doped Cs 2 (Na,Ag)InCl 6 as the color conversion material on a commercial 365 nm GaN LED chip, achieving an improved CRI from 70.3 to 75.4 compared to the pure Cs 2 (Na,Ag)InCl 6 . This result suggests a promising way to achieve high quality single phase all-inorganic white phosphors and this mechanism has enormous potentials in other optoelectronic applications.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
AICHE JOURNAL
·
2016
·Vol. 62
·期 8
·2614-2621
·
IF 2.98
Luting Ling,Wei Wang,Cai-Feng Wang,Su Chen
The intrinsic low quantum yield (QY) of type II core shell quantum dots (QDs) composes the limitation for these heterostructured nanomaterials to be used in practical application. Herein, magnetic hyperthermia method is employed to intensify reaction process and facilely synthesize CdTe/CdSe heterostructured QDs with improved optical performance for the first time. The QY of the type II QDs is increased to 49% by further growing an inert ZnO layer. The type I interface between CdSe and ZnO helps confine electrons to the inner structure of the QDs, thus improving the QY. The successful preparation and performance enhancement of the CdTe/CdSe type II QDs via magnetic hyperthermia method demonstrate the great potential of this method for the preparation of other materials. Besides, the red-emission QDs are used as conversion materials in white light emitting diodes to reveal their promising application in practical illumination. © 2016 American Institute of Chemical Engineers AIChE J , 62: 2614–2621, 2016
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Jianming Liu,Shengnan Liu,Ya Chen,Qiliang Zhao,Yajuan Zhao,Weidong Xiang,Xiaojuan Liang,Baodong Ren
Since being synthesized, CsPbX 3 (X = Cl, Br or I) quantum dots (QDs) have gained increased interest due to their superior performances in photovoltaic applications. Herein, Sm 3+ -doped CsPbBr 3 nanocrystallines (NCs) were successfully prepared in zinc borosilicate sodium (ZnO–B 2 O 3 –SiO 2 –Na 2 CO 3 , ZBSN) glass, and the as-prepared glass exhibited a strong red emission, which was attributed to the effects of the energy level transitions in Sm 3+ . Importantly, white light-emitting diodes (W-LEDs) were prepared by combining the glass with a blue InGaN chip, eliminating the need for a red phosphor to provide the red light, and white light was generated with a high colour rendering index (CRI: 82.6), a low correlated colour temperature (CCT: 4455 K) and colour coordinates in the white light region (0.3547, 0.3234). The glasses show excellent stability at 85 °C and 85% RH. Therefore, the Sm 3+ -doped CsPbBr 3 NCs glass can be used as a colour converter for application in lighting engineering.
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
·
2019
·
IF 3.45
Xinwei Li,Hualan Xu,Xianming Xia,Feiyan Xie,Shengliang Zhong,Dekang Xu
Sc 2 W 3 O 12 is an important host matrix for rare-earth doped luminescence. However, the conventional method to prepare the material is solid-state reaction, which results into coarse and irregular morphologies. In this work, Eu 3+ doped Sc 2 W 3 O 12 phosphors with high crystallinity and pure phase were successfully synthesized via one-step hydrothermal method . It was found that the crystalline phase changed from Sc 2 W 3 O 12 phase to Na 4 Sc 2 (WO 4 ) 5 phase when the molar ratio between Sc(NO 3 ) 3 and Na 2 WO 4 decreased. The temperature-dependent X-ray diffraction analysis was performed to prove the negative thermal expansion property of Sc 2 W 3 O 12 . A systematic study on the effect of reaction time, temperature and Eu 3+ doping concentration was explored. It was also found that the as-prepared samples displayed tunable emission colors, ranging from blueish white to orange red. Particularly, the white light emission with the chromaticity coordinate of (0.3395, 0.3289) can be realized in Sc 2 W 3 O 12 : 5% Eu 3+ . What's more, the photoluminescence properties of the samples were investigated under different ambient temperatures between 97 and 280 K. The result clearly showed energy transfer between Eu 3+ and WO 4 2− . The above results suggested that Sc 2 W 3 O 12 :Eu 3+ can be excellent candidate for solid-state lasing, panel display and WLEDs.
研究领域:
材料科学
·
光电
·
发光材料
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2015
·
IF 2.605
Renping Cao,Qingqiang Xiong,Wenjie Luo,Donglan Wu,Xiao Fen,Xiaoguang Yu
A series of SrAl [4−(4 x )/3] O 7 : x Mn 4+ (0≤ x ≤1.4 mol%) and Sr (1−0.06/2) Al [4−(4×0.008)/3] O 7 :0.008Mn 4+ ,0.06R + (R + =Li + , Na + , and K + ) phosphors are synthesized by a conventional solid-state reaction method in air. The PLE bands peaking at~325, 395, and 470 nm and the strongest PL band peaking at~660 nm are assigned to the 4 A 2 → 4 T 1 transition of Mn 4+ ion and O 2− –Mn 4+ change transfer band, 4 A 2 → 2 T 1 , 4 A 2 → 4 T 2 , and 2 E → 4 A 2 transitions, respectively. The optimum Mn 4+ doping concentration is about 0.8 mol%. Li + , Na + , and K + ions used as charge compensator can improve observably the PL intensity of SrAl 4 O 7 :Mn 4+ phosphor with excitation 325 nm. The fluorescence lifetimes of SrAl [4−(4×0.008)/3] O 7 :0.008Mn 4+ and Sr [1−0.06/2] Al [4−(4×0.008)/3] O 7 :0.008Mn 4+ ,0.06 R + (R + =Li + , Na + , and K + ) are 0.958, 0.97, 1.113 and 0.965 ms, respectively. The luminous mechanism is explained by schematic energy level diagram of Mn 4+ ion. These experiment results indicate that SrAl 4 O 7 :Mn 4+ ,R + (R + =Li + , Na + , and K + ) phosphors can be used as red emitting phosphor candidate for white LEDs based on a UV (~325 nm) and near UV (~395 nm) bands of LEDs chip.
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
·
2016
·
IF 3.014
Zheng-Bin Tang,Cai-Li Xu,Xun-Rong Wei,Xin-Guo Zhang,Yi-Bo Chen
Developing high brightness, high color purity and thermal stable red phosphors has gained an increasing attention for enhancing the performance of white light emitting diodes (w-LEDs). Herein, a series of red-emitting KBaY 1−x Eu x Si 2 O 7 (0 < x < 1) solid-solution phosphors were designed and fabricated. The phosphors can be excited by 394 nm near-UV light and emit red light peaking at 612 nm due to the 5 D 0 → 7 F 2 transition of Eu 3+ . The increasing proportion of Eu 3+ in the solid-solution system can improve the photoluminescence intensity and thermal stability of the phosphors continuously until the Eu 3+ concentration comes to 100%, while no deformation of the crystal structure has been brought. The as-prepared KBaEuSi 2 O 7 phosphor shows excellent thermal photoluminescence stability, its emission integrated intensity can still maintain ∼90% of the initial value at room temperature when heating to 180 °C. The CIE coordinates (0.652, 0.348) of KBaEuSi 2 O 7 phosphor are very close to the NTSC (National television system committee) standard red chromaticity (0.67, 0.33), and the color shift at high temperature is very slight. The KBaEuSi 2 O 7 phosphor can be regarded as a promising red luminescence candidate for w-LEDs.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）