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Hybrid remote quantum dot/powder phosphor designs for display backlights

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Light(Science & Applications) 2016年第1期5卷 11-19页

作者： Sofie Abe Jonas J Joos Lisa IDJ Martin zeger hens Philippe F Smet Department of Inorganic and Physical Chemistry Ghent UniversityGentBelgium Department of Solid State Sciences LumiLabGhent UniversityGentBelgium Center for Nano and Biophotonics Ghent UniversityGentBelgium

Quantum dots are ideally suited for color conversion in light emitting diodes owing to their spectral tunability,high conversion efficiency and narrow emission *** properties are particularly important for display backlights;the highly saturated colors generated by quantum dots justify their higher production ***,we demonstrate the benefits of a hybrid remote phosphor approach that combines a green-emitting europium-doped phosphor with red-emitting CdSe/CdS core/shell quantum *** stacking geometries,including mixed and separate layers of both materials,are studied at the macroscopic and microscopic levels to identify the configuration that achieves maximum device efficiency while minimizing material *** influence of reabsorption,optical outcoupling and refractive index-matching between the layers is evaluated in detail with respect to device efficiency and *** the findings of this study,general guidelines are derived to optimize both the cost and efficiency of CdSe/CdS and other(potentially cadmium-free)quantum dot *** reabsorption of the green and/or red emission is significant compared to the absorption strength for the blue emission of the pumping light emitting diode,the hybrid remote phosphor approach becomes beneficial.

关键词： cost-efficiency lanthanide light emitting diode nanocrystal remote phosphor

Efficient,high-CRI white LEDs by combining traditional phosphors with cadmium-free InP/ZnSe red quantum dots

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Photonics Research 2022年第1期10卷 155-165页

作者： BEGA KARADZA HANNES VAN AVERMAET LEILA MINGABUDINOVA zeger hens YOURI MEURET KU Leuven Department of Electrical Engineering(ESAT)Light&Lighting LaboratoryGebroeders De Smetstraat 19000 GentBelgium Physics and Chemistry of Nanostructures and Center for Nano and Biophotonics Krijgslaan 281-S39000 GentBelgium

Quantum dots(QDs) offer an interesting alternative for traditional phosphors in on-chip light-emitting diode(LED) *** studies showed that the spectral efficiency of white LEDs with high color rendering index(CRI) values could be considerably improved by replacing red-emitting nitride phosphors with narrowband ***,the red QDs in these studies were cadmium-based,which is a restricted element in the EU and certain other *** use of InP-based QDs,the most promising Cd-free alternative,is often presented as an inferior solution because of the broader linewidth of these ***,while narrow emission lines are the key to display applications that require a large color gamut,the spectral efficiency penalty of this broader emission is limited for lighting ***,we report efficient,high-CRI white LEDs with an on-chip color converter coating based on red InP/ZnSe QDs and traditional green/yellow powder *** InP/ZnSe QDs with a quantum yield of nearly 80% and a full width at half-maximum of 45 nm,we demonstrate high spectral efficiency for white LEDs with very high CRI *** of the best experimental results in terms of both luminous efficacy and color rendering performance is a white LED with an efficacy of 132 lm/W,and color rendering indices of R_(a)≈90,R9 ≈50 for CCT ≈4000 *** experimental results are critically compared with theoretical benchmark values for white LEDs with on-chip downconversion from both phosphors and red Cd-based *** various loss mechanisms in the investigated white LEDs are quantified with an accurate simulation model,and the main impediments to an even higher efficacy are identified as the blue LED wall-plug Quantum dots(QDs) offer an interesting alternative for traditional phosphors in on-chip light-emitting diode(LED) *** studies showed that the spectral efficiency of white LEDs with high color rendering index(CRI) values could be considerably improved by re

关键词： phosphors white rendering

Localization-limited exciton oscillator strength in colloidal CdSe nanoplatelets revealed by the optically induced stark effect

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Light(Science & Applications) 2021年第6期10卷 1122-1132页

作者： Pieter Geiregat Carmelita Roda Ivo Tanghe Shalini Singh Alessio Di Giacomo Delphine Lebrun Gianluca Grimaldi Jorick Maes Dries Van Thourhout Iwan Moreels Arjan J.Houtepen zeger hens Physics and Chemistry of Nanostructures Department of ChemistryGhent UniversityGentBelgium. Center for Nano and Biophotonics Ghent UniversityGentBelgium. Photonics Research Group Ghent UniversityGentBelgium. Department of Chemical Sciences and Bernal Institute University of LimerickLimerickIreland. Center for Nanophotonics NWO-lnstitute AMOLFScience Park 1041098 XG AmsterdamThe Netherlands. Opto-Electronic Materials Section Department of Chemical EngineeringDelft UniversityDelftThe Netherlands

2D materials are considered for applications that require strong light-matter interaction because of the apparently giant oscillator strength of the exciton transitions in the absorbance ***,the effective oscillator strengths of these transitions have bee n scarcely reported,nor is there a con sistent interpretati on of the obtained ***,we analyse the transition dipole moment and the ensuing oscillator strength of the exciton transition in 2D CdSe nanoplatelets by means of the optically induced Stark effect(OSE).Intriguingly,we find that the exciton absorption line reacts to a high intensity optical field as a transition with an oscillator strength FStark that is 50 times smaller than expected based on the linear absorption *** propose that the pronounced exciton absorption line should be seen as the sum of multiple,low oscillator strength transitions,rather than a single high oscillator strength one,a feat we assign to strong exciton center-of-mass *** the quantum mechanical description of excitons,this 50-fold difference between both oscillator strengths corresponds to the ratio between the cohere nee area of the exciton's center of mass and the total area,which yields a coherence area of a mere 6.1 *** we find that the coherence area in creases with reducing temperature,we conclude that thermal effects,related to lattice vibrations,contribute to exciton *** further support of this localization model,we show that FStark is in dependent of the n anoplatelet area,correctly predicts the radiative lifetime,and lines up for strongly confined quantum dot systems.

关键词： coefficient. spectrum. oscillator

Silicon and silicon nitride photonic circuits for spectroscopic sensing on-a-chip [Invited]

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Photonics Research 2015年第5期3卷 47-59页

作者： Ananth Z.Subramanian Eva Ryckeboer Ashim Dhakal Frédéric Peyskens Aditya Malik Bart Kuyken Haolan Zhao Shibnath Pathak Alfonso Ruocco Andreas De Groote Pieter Wuytens Daan Martens Francois Leo Weiqiang Xie Utsav Deepak Dave Muhammad Muneeb Pol Van Dorpe Joris Van Campenhout Wim Bogaerts Peter Bienstman Nicolas Le Thomas Dries Van Thourhout zeger hens Gunther Roelkens Roel Baets Photonics Research Group INTEC Department Ghent University-imec Centre for Nano and Biophotonics Ghent University University of California Department of Molecular Biotechnology Ghent University imec Kapeldreef 75 Physics and Chemistry of Nanostructures Ghent University

There is a rapidly growing demand to use silicon and silicon nitride（Si3N4） integrated photonics for sensing applications, ranging from refractive index to spectroscopic sensing. By making use of advanced CMOS technology,complex miniaturized circuits can be easily realized on a large scale and at a low cost covering visible to mid-IR wavelengths. In this paper we present our recent work on the development of silicon and Si3N4-based photonic integrated circuits for various spectroscopic sensing applications. We report our findings on waveguide-based absorption, and Raman and surface enhanced Raman spectroscopy. Finally we report on-chip spectrometers and on-chip broadband light sources covering very near-IR to mid-IR wavelengths to realize fully integrated spectroscopic systems on a chip.

关键词： Invited SOI mode

Comparison of cosyntropin versus caffeine for post-dural puncture headaches:A randomized double-blind trial

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World Journal of Emergency Medicine 2012年第3期3卷 182-185页

作者： Wesley zeger Bradley Younggren Lynette Smith Department of Emergency Medicine University of Nebraska Medical CenterOmahaNE 68198USA Department of Emergency Medicine Madigan Army Medical CenterTacomaWAUSA

Cosyntropin has been reported to be effective in the treatment of post-dural puncture headaches, but there is a lack of data on its effectiveness. We compared the efficacy of cosyntropin with that of caffeine in the treatment of post-dural puncture headaches. We performed an interim analysis of a prospective, double blinded, trial of adult patients presenting to the emergency department with a post-dural puncture headache. Patients were randomized to receive either intravenous caffeine or intravenous cosyntropin. Values on a 100-mm visual analog scale （VAS） were recorded at 0, 60, and 120 minutes to assess pain. Rescue therapy was documented on the study data forms. Its effectiveness was determined by the need for this therapy. Thirty-seven patients were included and four patients were excluded from the analysis because of protocol violations or incomplete data. Analysis was based on intention-to-treat. Caffeine was 80% （95% CI 60-100%） effective and cosyntropin was 56% （95% CI 33-79%） effective in treating post-dural puncture headaches. The group＇s VAS scores at 0, 60, and 120 minutes were 80 mm, 41 mm, 31 mm for caffeine and 80 mm, 40 mm, 33 mm for cosyntropin, respectively （P=0.66）. Caffeine was not more effective than cosyntropin in treating patients with postdural puncture headaches, and there was no difference in the degree of pain relief on VAS assessment.

关键词： Cosyntropin Post-dural puncture headaches Caffeine Lumber

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小粒径再生粗骨料混凝土配合比设计试验研究

混凝土 2018年第10期 99-101页

作者：陈晓光 zeger Sierens 屈铁军李佳彬北方工业大学土木工程学院北京100144 Department of Civil Engineering KU Leuven

为推广落实再生混凝土在实际工程中的应用,在使用4～8 mm小粒径再生粗骨料的条件下,基于Bolomey理想级配曲线,通过6组试验,得出强度等级C35、坍落度180 mm再生混凝土配合比为:水泥∶水∶砂∶RCA∶SP=1∶0.6∶3.75∶1.81∶0.005,实现了... 详细信息

为推广落实再生混凝土在实际工程中的应用,在使用4～8 mm小粒径再生粗骨料的条件下,基于Bolomey理想级配曲线,通过6组试验,得出强度等级C35、坍落度180 mm再生混凝土配合比为:水泥∶水∶砂∶RCA∶SP=1∶0.6∶3.75∶1.81∶0.005,实现了再生混凝土在小截面混凝土构件上的工程应用。并通过与欧洲规范对比,修正了普通混凝土早期抗压强度模型应用于再生混凝土时的系数,即s=0.44。

关键词：再生混凝土小粒径配合比设计早期抗压强度模型

小粒径再生粗骨料对预制混凝土力学性能影响的研究

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新型建筑材料 2020年第3期47卷 1-3,48页

作者：范红波韩达光杨宇鹏尚栋周银 zeger Sierens Brecht Vandevyvere 李佳彬重庆交通大学土木工程学院重庆400074 中铁十六局第五工程公司银吴项目经理部宁夏银川751400 比利时鲁汶大学HAN&LI智慧与可持续基础设施与建筑垃圾资源化研究所比利时布鲁日8000

研究5~10 mm小粒径再生粗骨料对预制混凝土抗压强度、劈裂抗拉强度和弹性模量的影响。结果表明,抗压强度随龄期延长而提高,且主要发生在前7 d,7 d抗压强度达到其28 d抗压强度的77%;劈裂抗拉强度随龄期的延长而提高,3 d劈裂抗拉强度达到... 详细信息

研究5~10 mm小粒径再生粗骨料对预制混凝土抗压强度、劈裂抗拉强度和弹性模量的影响。结果表明,抗压强度随龄期延长而提高,且主要发生在前7 d,7 d抗压强度达到其28 d抗压强度的77%;劈裂抗拉强度随龄期的延长而提高,3 d劈裂抗拉强度达到其28 d强度的64%;弹性模量也随龄期的延长而提高,龄期为1、3、7和14 d时,弹性模量分别为其28 d弹性模量的32%、46%、62%和91%。通过与欧洲规范对比,基于试验结果,建议了劈裂抗拉强度和弹性模量的计算模型。研究结果更好的实现再生混凝土在小截面预制混凝土构件上的工程应用。

关键词：早期力学性能预制混凝土再生骨料强度发展

Mercedes-Benz首款满足SULEV法规的轻型载货车用柴油机

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汽车与新动力 2015年第6期47卷 22-26页

作者： N.WaldbüBer T.Stutte J.zeger C.Bauer 范明强

Mercedes-Benz公司2015年新型Sprinter车型是首款量产的柴油轻型载货车,满足未来LEN3-SULEV废气排放法规限值。介绍其动力总成系统、废气后处理系统,以及用于北美自由贸易协议市场的新的轻型载货车应用方案。

关键词：轻型载货车柴油机后处理燃油耗