ACS Sustainable Chemistry & Engineering
·
2022
·
IF 9.224
Jian Shen,Bin Xu,Shunwei Chen,Yuehan Jia,Jie Li,Tianlong Jiang,Zhenhua Gao,Xue Wang,Chaofeng Zhu,Hui Shi,Zifei Wang
Luminescent carbon dots (CDs) have drawn much attention in terms of photoelectronic applications, most of which are focused on single-component white-light emission. However, it still remains a significant challenge to create high-quality white-light-emitting CDs with tunable correlated color temperatures (CCTs). The theoretical calculation is initially used to predict that the enlargement of the conjugated sp2 domain induces redshift fluorescence (FL) and room temperature phosphorescence (RTP) emissions of CDs. Guided by the theoretical predictions, single-component white-light emission from CDs with high efficiency of 67.35% and tunable CCTs from 10,803 to 3376 K is realized. These CDs exhibit quadruple-model emissions with hybrid FL/RTP components at 435 nm (FL-1)/548 nm (RTP-1) and 461–522 nm (FL-2)/525–610 nm (RTP-2), which originate from a synergy between certain P bonds with aggregation-induced emission effects and different sizes of sp2 conjugated structures, respectively. Using such CDs as conversion phosphors, we prepared three white-light-emitting diodes (WLEDs) which can emit bright cool, standard, and warm white lights with color rendering indices of 81–85. Finally, highly luminescent WLEDs are also developed by dispersing these CDs in a poly(vinyl alcohol) matrix, indicating that this provides an industrial application potential.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
OPTICAL MATERIALS
·
2022
·
IF 3.754
Yun Tang,Ben Liu,Nan Yan,Xiaoqiang He,Hudie Yuan,Yalou Xin,Hongfeng Yin
Widespread application of YAG:Ce-based white light-emitting diodes (WLEDs) is being challenged due to the lack of red emission, leading to their poor color rendering index (Ra) and high correlated color temperature (CCT). Perovskite quantum dots (QDs), presenting high photoluminescence quantum yield and simple fabrication process have been recognized as promising red-emitting component for warm WLEDs. However, conventional method by mechanically mixing QDs with YAG:Ce always results in undesirable dispersion due to their huge size difference. Moreover, the two components display different sinking behavior in silicone , which would further deteriorate the color uniformity of WLED. To address these issues, in this study, red-emitting MAPbBr 3-x I x QDs-coated YAG:Ce (A-YAG@QDs) composites were successfully prepared to further fabricate WLED with compensated red emission. The chemical coordination interactions between QDs and functionalized YAG:Ce make the two components behave as a whole, which effectively avoids the dispersion and sinking-related issues. The WLED, which combined blue LED chip and A-YAG@QDs composite, exhibited warm white light with low CCT of 4474 K, high Ra of 90.1 and high value of saturated red color component R9 as 95. This study demonstrated a promising strategy to prepare QDs-coated phosphor composites for the generation of warm white light for indoor lighting application.
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
Small
·
2019
·Vol. 16
·期 1
·1905266
·
IF 10.856
Guangqi Hu,Yuqiong Sun,Jianle Zhuang,Xuejie Zhang,Haoran Zhang,Mingtao Zheng,Yong Xiao,Yeru Liang,Hanwu Dong,Hang Hu,Bingfu Lei,Chaofan Hu,Yingliang Liu
Commercial white light-emitting diodes (LEDs) have the undesirable characteristics of blue-rich emission and low color rendering index (CRI), while the constituent quantum dots (QDs) suffer from aggregation-induced fluorescence quenching and poor stability. Herein, a strategy is developed to assemble tricolor QDs into a polysiloxane matrix using a polymer-mediated hybrid approach whereby the hybrid composite exhibits a significant enhancement of aggregation-dispersed emission, outstanding photostability, high thermal stability, and outstanding fluorescence recovery. Using the as-prepared hybrid fluorescent materials, the fabricated LEDs exhibit solar spectrum-simulated emission with adjustable Commission Internationale de L'Eclairage coordinates, correlated color temperature, and a recorded CRI of 97. Furthermore, they present no ultraviolet emission and weak blue emission, thus indicating an ideal healthy and high-CRI white LED lighting source.
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
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2018
·Vol. 29
·期 12
·10453-10460
·
IF 2.324
Yuan Rongrong,Liu Jianming,Xiang Weidong,Liang Xiaojuan
Various luminescent carbon materials are artificially synthesized and as admirable fluorescent materials because of the increased research of carbon nanodots (CDs). Herein, a novel solvent-dependent red CDs (rCDs) is introduced through solvothermal method. The as-prepared rCDs remain benzene structure and possess abundant surface function groups that endow them well solubility in various solvents. Furthermore, multicolor luminescence are observed when rCDs are dissolved in different solvents, and the emission wavelength of these materials can be well-tuned from 475 to 624 nm, which presents intensity solvent-dependent properties. Red luminescence carbon phosphors are successfully synthesized by mix rCDs with silica powder. Finally, warm white light emitting diodes (WLEDs) are constructed using rCDs powder with Ce 3+ : YAG single crystal and blue GaN chips. The results demonstrate that the rCDs can act as red component to modify the correlated color temperature (CCT) and the color rendering index (CRI) of 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 THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Cong Wei,Cen Shao,Pengfei Sang,Chunming Zhou,Jian Kang,Baolin Jiang,Rongyu Xu,Wieslaw Strek,Hao Chen,Le Zhang
The shortage of red-light emission in Ce 3+ :Y 3 Al 5 O 12 (Ce:YAG) luminescent ceramics is a bottleneck problem to realize the key applications of ceramics based white light-emitting diode (LED) and laser diode (LD) devices. However, the energy band-gap engineering for Ce 3+ ion via host substitution or red-emission ions co-doping always leads to its decrease of luminescence efficiency (LE), while a spectrum overlay strategy would be simple and effective. In this study, multilayer composite structure Ce:YAG/Cr:YAG transparent ceramics (TCs) with high color rendering index (CRI) were fabricated by tape casting and vacuum sintering. An organic tape casting protocol with low toxicity and environmental protection was developed and the amounts of dispersants, binders, and plasticizers were systematically optimized to produce good quality tapes with no defects. The transmittance of ceramic reached 78% at 800 nm. By using a 455 nm blue chip, the CRI of the Ce:YAG/Cr:YAG TCs based LED device was increased from 26.7 to 77.5, and the LE was decreased from 181.5 to 10.4 lm/W. Additionally, the optimized LE and CRI for LD device were 130.2 lm/W and 78.1, respectively. Therefore, this research displays that the design and implementation of ceramic functional layer to achieve the essential enhancement of CRI in TC based white lighting is a promising method through the tape casting forming technology.
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
MATERIALS RESEARCH BULLETIN
·
2021
·
IF 4.641
Yanzhen Yin,Zhen Wang,Maochen Zhu,Yue Zhang,Jianhong Li,Chao Dou,Shijia Sun,Bing Teng,Yang Che,Degao Zhong
A single-phased warm white phosphor of α-Sr 2 V 1.98 P 0.02 O 7 : 0.5 % Eu 3+ with low correlated color temperature (CCT) and high color rendering index (CRI) was synthesized by high temperature solid phase method. By changing the ratio of PO 4 3− /VO 4 3− , the emission intensity of VO 4 3− and the energy transfer efficiency of VO 4 3− →Eu 3+ can be effectively tuned, and the full-spectrum warm white light emission of phosphors in the range of 400−700 nm can be realized. Moreover, the temperature-dependent emission spectra and thermal quenching properties were investigated in detail. On this basis, the WLED prototype devices were packaged with the synthesized phosphors α-Sr 2 V 1.98 P 0.02 O 7 : 0.5 % Eu 3+ and 365 nm near-ultraviolet (NUV) chips and high-quality warm white light emission with CCT = 3188 K and CRI Ra = 93.5 were achieved. These findings provide new insights into exploring single-phased white phosphors for NUV-pumped warm w-LEDs with high CRI property and low CCT value.
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 Express
·
2017
·Vol. 7
·期 9
·3065-3076
·
IF 2.591
Wanlu Zhang,Wu Yang,Ping Zhong,Shiliang Mei,Guilin Zhang,Guoping Chen,Guoxing He,Ruiqian Guo
The spectral optimization for maximizing limited luminous efficacy (LLE) of correlated color temperature (CCT) tunable white light-emitting diodes (LEDs) with two, three and four color perovskite quantum dots (QDs) excited by a blue chip was investigated under the constraint of designated ultrahigh color rendering index (CRI) and color quality scale (CQS). The results show that high quality white lights with CRIs of 96-97, CQSs of 95-96, and LLEs of 243-225 lm/W at CCTs of 2700 K to 6500 K could be realized by the QDs-converted white LEDs (QD-WLEDs) using a blue chip and different combinations of perovskite quantum dots. The luminous efficacies of QD-WLEDs are expected to reach 114 to 122 lm/W at CCTs of 2700 K to 6500 K, if the radiant efficiency of a blue chip is 60% and the real PLQY values of perovskite QDs are 75%. These results demonstrate that perovskite QD-based LEDs are expected to be promising in next generation display and lighting technologies.
研究领域:
光学工程
·
材料科学
·
照明技术
✓ 已验证
产品关联
DOI
高影响因子
OPTICS EXPRESS
·
2023
·Vol. 31
·期 15
·24914-24925
·
IF 3.8
Zitong Liu,Le Zhang,Le Zhang,Le Zhang,Le Zhang,Jian Kang,Jian Kang,Tianyuan Zhou,Tianyuan Zhou,Shiwei Chen,Shiwei Chen,Peng Yang,Bingheng Sun,Yang Li,Hao Chen,Hao Chen,Hao Chen
Ceramic phosphors are widely considered the next-generation phosphor material for white LED/LD lighting, and a wide spectrum is a key factor in improving the CRI of lighting sources. In this paper, a novel, to our knowledge, barcode-structured YAG:Ce/YAG:Ce,Mn ceramic phosphor was designed and fabricated. The lighting sources with the CRI value of 73.5 and 68.9 were obtained under the excitation of blue LEDs and blue LDs, respectively. Simultaneously, thanks to the effective supplementary emission from a red LD, the CRI of the ceramic-based lighting source reached 81.8 under blue LD excitation. Specifically, the microstructure and luminescent property of ceramic phosphors with different thicknesses and ion doping concentrations were systematically studied. Besides, by changing the blue power from 0.52 W to 2.60 W, the CCT of the laser lighting source with the encapsulation of optimized YAG:Ce/YAG:Ce,Mn ceramic phosphors ranged from 3928 K to 5895 K, while the CRI always maintained above 80. The above results indicate that barcode-structured Ce:YAG/Ce,MnYAG ceramic phosphor is a candidate to achieve a high CRI and ican be applied to various lighting occasions.
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
·
2022
·
IF 5.532
Fan Guo,Rui Yuan,Yun-Ling Yang,Jing-Tai Zhao,Hui Lin,Zhi-Jun Zhang
Phosphor-in-glass (PiG) is one of the most important spectral converters to overcome thermal effect in high-power white light-emitting diodes (LEDs). The Al 2 O 3 –SiO 2 –B 2 O 3 –ZnO–Na 2 O–Li 2 O glass was designed and sintered with Y 3 Al 5 O 12 :Ce 3+ (YAG: Ce) phosphors at the low temperature of 650 °C to obtain YAG: Ce-PiG. The optimized YAG: Ce-PiG shows the white light of the luminous efficiency (LE), correlated color temperature (CCT) and chromaticity coordinate (CIE) of 177.5 lm/W, 6410 K and (0.31,0.34), respectively. The white LEDs (WLED) were fabricated by coupling the YAG: Ce-PiG with a blue light emitting chip, and the correlation between the luminescence properties , the thickness of PiG and the ratio of phosphors was investigated. More importantly, the WLEDs of a maximum luminous efficiency can reach up to 199.5 lm/W with the thickness of 0.35 mm. In addition, a structure with vacuum packaging technique based on the WLEDs lighting combined with sapphire as substrate was fabricated, which can effectively reduce the heat accumulation during the working process of WLEDs. Compared with normal non-vacuum packaging, the working temperature of WLEDs was reduced by about 35%, from 359.2 to 232.2 °C, with the novel vacuum packaging technique under 30W high-power chip and the luminous performance can still be maintained at 94.7%. In a word, the prepared YAG: Ce-PiG exhibits a great potential for application in high-power solid-state WLEDs.
研究领域:
光学
·
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
OPTICS COMMUNICATIONS
·
2018
·
IF 1.887
Wu Yang,Wanlu Zhang,Guilin Zhang,Jiatao Zhu,Guoxing He,Ruiqian Guo
We reported two types of tunable white LEDs (WLEDs) based on high quality the single emissive InP/ZnS quantum dots (QDs) and the dual emissive Ag:InP/ZnS QDs via myristic acid (MA) passivation and Ag doping. The WLEDs with three color InP/ZnS QDs could realize color rendering indices (CRIs) of 97–98, color quality scales (CQSs) of 94–98, and limited luminous efficacies (LLEs) of 238–246 lm/W at correlated color temperatures (CCTs) of 2700 K to 6500 K, and the WLEDs with dual emissive Ag:InP/ZnS and red emissive InP/ZnS QDs could realize CRIs of 90–93, CQSs of 90–93, and LLEs of 223–242 lm/W at CCTs of 2700 K to 4000 K. Finally, their luminous efficacies were estimated.
研究领域:
材料科学
·
光学工程
·
半导体技术
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Tuan Lin,Hexin Chen,Shuxing Li,Le Wang,Fan Huang,Rong-Jun Xie
Laser-driven white lighting sources promise super-high brightness, good directionality and high efficiency, but are usually suffering from low color rendering index (Ra), high correlated color temperature (CCT) and poor light uniformity. To solve these problems, we designed bi-color phosphor-in-glass (PiG) films containing broadband green and red phosphors, and introduced Al 2 O 3 particles as scattering centers into the PiG films. The addition of Al 2 O 3 effectively increases the Ra value from 83 to 93, and greatly improves the angular uniformity in Ra and CCT with C v (Ra) decreasing from 14.96% to 0.16% and C v (CCT) decreasing from 45.87% to 1.5%. The coefficient of variation (C v ) is used to evaluate the light uniformity, and the smaller the value, the better the uniformity. The color temperatures can be tuned in a wide range of 2500 ∼ 6300 K by controlling the content of Al 2 O 3 or the ratios of phosphor-to-glass in the films as well as their thicknesses, while high Ra values of > 90 are maintained. A prototype laser-driven white light with excellent color qualities (Ra = 95, Rf = 95, Rg = 104, R9 = 99, R15 = 98) and a high luminous efficacy of 102 lm/W was demonstrated for stage spotlights by optimizing the composition and structure of the bi-color PiG films. This work highlights the roles of secondary phase in heat dissipation and light scattering, and provides ideas to design PiG color converter films for use in super-high color quality laser lighting.
研究领域:
光学材料
·
光源技术
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry C
·
2020
·Vol. 8
·期 23
·7734-7740
·
IF 7.059
Yanyi Huang,Hao Lin,Jing Qiu,Zhongtao Luo,Zhiqiang Yao,Libo Liu,Huanbin Liu,Xiaosheng Tang,Xiaoxiao Fu
Solid-state white light-emitting diodes (WLEDs) based on carbon dots (CDs) have attracted broad attention due to their high brightness and environmental friendliness. However, the poor performance, including low efficiency and weak emission of red-emitting CDs, further hinder their application in WLED devices. Herein, we constructed one outstanding WLED device by combining carbon dots (blue emission and green emission) and Ag–In–Zn–S (AIZS) nanoparticles with red emission. Moreover, by adjusting the volume ratio of the three materials, the WLED showed a maximum color rendering index (CRI) of 97 and maintained a CRI value above 90 as the correlated color temperature (CCT) was tuned from 3387 to 8018 K. Meanwhile, the as-fabricated WLED devices showed excellent color rendering stability during the adjustment of working voltages from 3.0 V to 3.5 V. This work may provide one new avenue for the development of low-cost, environmentally friendly and high-performance CD phosphor-based WLEDs.
研究领域:
材料科学
·
光学工程
·
环境科学
✓ 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）