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LiYF_(4):Yb/LiYF_(4) and LiYF_(4):Yb,Er/LiYF_(4) core/shell nanocrystals with luminescence decay times similar to YLF laser crystals and the upconversion quantum yield of the Yb,Er doped nanocrystals

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Nano Research 2021年第3期14卷 797-806页

作者： Frederike Carl Leonie Birk Bettina Grauel Monica Pons Christian Würth Ute Resch-Genger Markus Haase Institute of Chemistry of New Materials Department Biology/ChemistryUniversity OsnabrueckBarbarastr.749076OsnabrueckGermany Division 1.2 Biophotonics Federal Institute for Materials Research and Testing(BAM)Richard-Willstaetter-Str.1112489BerlinGermany

We developed a procedure to prepare luminescent LiYF_(4):Yb/LiYF_(4) and LiYF_(4):Yb,Er/LiYF_(4) core/shell nanocrystals with a size of approximately 40 nm revealing luminescence decay times of the dopant ions that approach those of high-quality laser crystals of LiYF_(4):Yb(Yb:YLF)and LiYF_(4):Yb,Er(Yb,Er:YLF)with identical doping concentrations.As the luminescence decay times of Yb^(3+)and Er^(3+)are known to be very sensitive to the presence of quenchers,the long decay times of the core/shell nanocrystals indicate a very low number of defects in the core particles and at the core/shell interfaces.This improvement in the performance was achieved by introducing two important modifications in the commonly used oleic acid based synthesis.First,the shell was prepared via a newly developed method characterized by a very low nucleation rate for particles of pure LiYF_(4) shell material.Second,anhydrous acetates were used as precursors and additional drying steps were applied to reduce the incorporation of OH−in the crystal lattice,known to quench the emission of Yb^(3+)ions.Excitation power density(P)-dependent absolute measurements of the upconversion luminescence quantum yield(ΦUC)of LiYF_(4):Yb,Er/LiYF_(4) core/shell particles reveal a maximum value of 1.25%at P of 180 W·cm^(−2).Although lower than the values reported for NaYF4:18%Yb,2%Er core/shell nanocrystals with comparable sizes,theseΦUC values are the highest reported so far for LiYF_(4):18%Yb,2%Er/LiYF_(4) nanocrystals without additional dopants.Further improvements may nevertheless be possible by optimizing the dopant concentrations in the LiYF_(4) nanocrystals.

关键词： nanocrystal decay time luminescence LiYF_(4) quantum yield upconversion

Giant enhancement of photoluminescence quantum yield in 2D perovskite thin microplates by graphene encapsulation

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Nano Research 2021年第6期14卷 1980-1984页

作者： Wancai Li Jiaqi Ma Xue Cheng Dehui Li School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan430074China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan430074China

The optoelectronic performances of the layered materials are strongly dependent on the thickness of the samples due to the surface effect.As the size of the samples decreases to few nanometers,the surface depletion field and surface defect density are prominent arising from the large surface to volume ratio.For instance,thin two-dimensional(2D)organic-inorganic hybrid perovskite microplates usually exhibit a rather low photoluminescence quantum yield(PLQY),owning to the strong surface effect.Here,we report that the PLQY can be enhanced as large as 28 times in(iso-BA)2Pbl4(BA=C4H9NH3)2D perovskite thin microplates encapsulated by graphene,resulting in that the PLQY is more than 18%for the microplate with a thickness of 6.7 nm at 78 K.As the thickness of the 2D perovskite microplate increases,the enhancement is gradually reduced and finally vanishes.This observation is in striking contrast to that in monolayer transition metal dichalcogenides(TMDs),when the PLQY is quenched by covering a layer of graphene due to the efficient charge transfer.The enhancement of PLQY in 2D perovskites can be mainly ascribed to the reduced quantum confined Stark effect(QCSE)due to the reduced surface depletion field after covering graphene flake,resulting in the enhanced radiative recombination efficiency.Our findings provide a cost-effective approach to enhance the luminescence,which may pave the way toward high performance light emitting devices based on 2D perovskites.

关键词： two-dimensional perovskite photoluminescence quantum yield quantum confinement surface depletion field

Barium charge transferred doped carbon dots with ultra-high quantum yield photoluminescence of 99.6% and applications

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Chinese Chemical Letters 2021年第2期32卷 861-865页

作者： Yao Liu Jianfei Wei Xiang Yan Ming Zhao Chaozhong Guo Quan Xu Chongqing Key Laboratory of Materials Surface&Interface Science College of Materials Science and EngineeringChongqing University of Arts and SciencesChongqing 402160China School of Materials Designing and Engineering Beijing Institute of Fashion TechnologyBeijing 100029China School of Materials Science and Engineering Boise UniversityBaise 533000China State Key Laboratory of Heavy Oil Processing Beijing Key Laboratory of Biogas Upgrading UtilizationChina University of Petroleum-BeijingBeijing 102249China

Long-emission carbon dots(CDs) is triggering immense enthusiasm on account of their intrinsic merits of high chemical stability and excellent optical properties.In this study,a facile and rapid approach was developed for the preparation of barium-doped carbon dots(Ba-CDs) with yellow fluo rescence emission and high quantum yields.Surface chemistry and the chemical architecture of the Ba-CDs was revealed under various spectroscopic methods.This work provides more insights into the effects of charge transfer caused by Ba heteroatoms,which is considered as the most challenging step in the investigation on luminescence mechanism.Remarkably,the prepared Ba-CDs were successfully applied as fluorescent probes in the detection of trace water in organic solvents(ethanol,isopropanol,acetone,tetrahydrofuran).Comparing with traditional fluorescent probes for water detection in organic solvents,Ba-CDs detection provides a more sensitive,much faster and more economical approach.

关键词： Ba-doped Carbon dots quantum yield Charge transfer Fluorescent sensors

Determination of singlet oxygen quantum yield of HiPorfin using Singlet Oxygen Sensor Green

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Determination of singlet oxygen quantum yield of HiPorfin us...

Enhanced luminescence efficiency and thermal stability via introduction of non-rare earth Bi^(3+)in Gd_5Si_(2)BO_(13):Eu^(3+)

2010亚洲光电子会议保健和生物医学光学分会场

作者： Huiyun Lin Yi Shen Defu Chen Lisheng Lin Buhong Li Shusen Xie Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education Fujian Provincial Key Laboratory for Photonics Technology Fujian Normal University Fuzhou Fujian China 350007

Singlet oxygen （1 O 2） is widely considered to be the predominant cytotoxic agent for photodynamic therapy （PDT）,and the 1 O 2 quantum yield is a key characteristic for the newly developed photosensitizers.In this study,1 O 2 generation from the HiPorfin is monitored indirectly by using the fluorescence probe Singlet Oxygen Sensor Green （SOSG）.The good linear relationship between the concentration of HiPorfin and the initial reaction rate of SOSG is observed,and the 1 O 2 quantum yield of HiPorfin is determined to be 0.124 ± 0.001,as compared to the standard reference of Rose Bengal.The results suggest that SOSG can be useful for 1 O 2 quantum yield determination for the potential photosensitizers in PDT.

关键词： Photodynamic therapy Singlet oxygen quantum yield HiPorfin Singlet Oxygen Sensor Green Fluorescence Initial reaction rate

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Journal of Rare Earths 2023年第7期41卷 989-996,I0001页

作者： Yukun Liu Yangai Liu Haojun Yu Chenguang Yang Cian Xie Jian Chen Beijing Key Laboratory of Material Utilization of Nonmetallic Minerals and Solid Wastes National Laboratory of Mineral MaterialsSchool of Materials Sciences and TechnologyChina University of GeosciencesBeijing 100083China Office of Scientific Research Peking UniversityBeijing 100871China

A series of Gd_5Si_(2)BO_(13):Eu^(3+)and non-rare earth Bi^(3+)ions doped Gd_5Si_(2)BO_(13):Eu^(3+)phosphors was successfully synthesized via high-temperature solid-state method,and the as-obtained phosphors were studied on their phase structures,luminescence characteristics,thermal stability and luminescence lifetime.Transient fluorescence spectroscopy data show that the addition of Bi^(3+)can obviously enhance the emission intensity of Eu^(3+)in the near-ultraviolet band owing to energy transfer from Bi^(3+)to Eu^(3+).Besides,the addition of Bi^(3+)can improve the thermal stability of a single-doped phosphor Gd_5Si_(2)BO_(13):0.35Eu^(3+)from 70.33%to 87.45%at 150℃and the quantum yield from 58.80%to 78.61%at room temperature.Finally,Gd_5Si_(2)BO_(13):Eu^(3+),Bi^(3+)was used to encapsulate white light-emitting diodes(WLEDs)with green((Ba,Sr)_(2)SiO_(4):Eu^(2+))and blue(BaMgAI_(10)O_(17):Eu^(2+))commercial phosphors.The color rendering index of WLEDs was calculated to be larger than 90,and the color temperature was estimated to be 4300-4500 K,which demonstrate that Gd_5Si_(2)BO_(13):Eu^(3+),Bi^(3+)can be regarded as a red phosphor with great potential application.This paper can provide a new insight into design of high-efficiency phosphors by introducing non-rare earth Bi^(3+)ions via energy transfer from Bi^(3+)to Eu^(3+).

关键词： Red phosphors Gd_5Si_(2)BO_(13):Eu^(3+) Bi^(3+) Energy transfer Thermal stability quantum yield WLED

Organoboron luminophores with extremely strong dual-phase emissions

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Chinese Chemical Letters 2023年第3期34卷 274-278页

作者： Qingsong Liu Man Zhang Ye Fu Shen Shen Liangliang Zhu Department of Macromolecular Science State Key Laboratory of Molecular Engineering of PolymersFudan UniversityShanghai 200438China

Developing efficient dual-phase emission emitters upon organoboron luminophores remains a formidable challenge due to the ubiquitous self-absorption and deleterious π-π interactions from aromatic structure.Here, a new family of benzothiazole-enolate-based organoboron luminophores(HN1-4) with effective dual-phase emission was constructed. HN4 showed almost the highest quantum yield(QY) among this type of compound so far. The three-ring-fused rigid skeleton and moderate intramolecular charge transfer(ICT) effect ensured that HN4 could give rise to extremely strong emission in any solution(QY up to 99%). X-ray crystallographic analysis showed that the twisted core structure constructed by the boronic coordination of two penta-fluorobenzene of HN4 was responsible for intense emission in the solid state(QY up to 68%). Besides, HN4 exhibited a unique response to mechanical force accompanied by a reversible change of the QY. We believe that this strategy provides beneficial inspiration and methodology to design materials with high emissive quantum yield that can be used in a variety of luminescent events.

关键词： Organoboron Dual-phase emission quantum yield Rigid-twisted core Mechanical force

PSI-driven cyclic electron fl ow partially alleviates the peroxidation of red alga Gelidium amansii(Gelidiaceae)caused by temporary high temperature

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Journal of Oceanology and Limnology 2022年第1期40卷 206-215页

作者： Yongfu LI Jianguo LIU Litao ZHANG CAS and Shandong Province Key Laboratory of Experimental Marine Biology Center for Ocean Mega-ScienceInstitute of OceanologyChinese Academy of SciencesQingdao 266071China Marine Biology and Biotechnology Laboratory Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China

PSI-driven cyclic electron fl ow(CEF-I)helps higher plants avoid severe heat damage.Gelidium amansii,a red seaweed used in the production of agar,inhabits subtidal rocks but can be found in the intertidal zone.The biological role of CEF-I is still unclear in this organism.Wild G.amansii was exposed to 30℃heat stress for 12 h with continuous lighting.The results showed that treatment at 30℃gradually decreased maximal PSII photochemical effi ciency(F_(v)/F_(m)),linear electron transfer rate,and activity of photosynthetic reaction center.Both the maximal photochemical effi ciency under light(F_(v)'/F_(m)')and maximum quantum yield of light-adapted PSII(Φ_(PSII))were maintained at a relatively stable level during the initial 6 h and then signifi cantly decreased at 12 h.The up-regulated CEF-I helps to enhance proton gradient transfer across thylakoid membrane to protect oxygen-evolving complex against heat damage.Following the addition of a CEF-I inhibitor to plants,the F_(v)/F m greatly decreased,suggesting that the CEF-I alleviates degree of photoinhibition caused by strong light.The results of measurement of antioxidant enzymes,including superoxide dismutase(SOD),ascorbate peroxidase(APX)and catalase(CAT),and the contents of H_(2)O_(2)and malonaldehyde(MDA)provided additional evidence that CEF-I plays a protective role to a certain extent for G.amansii to manage stress at 30℃.Therefore,it can be concluded that CEF-I enables G.amansii to survive in intertidal zones by protecting it from the heat damage caused by high temperature stress.

关键词： cyclic electron fl ow Gelidium amansii heat stress chlorophyll fl uorescence quantum yield natural distribution

Highly fluorescence Ta_(4)C_(3) MXene quantum dots as fluorescent nanoprobe for heavy ion detection and stress monitoring of fluorescent hydrogels

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Chinese Chemical Letters 2022年第4期33卷 1850-1854页

作者： Shouzhen Li Junfei Ma Xuelin Zhao Peide Zhu Meng Xu Yingchun Niu Dixian Luo Quan Xu State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development National Energy Shale Oil Research and Development CenterChina University of Petroleum(Beijing)Beijing 102249China Department of Musculoskeletal Tumor Senior Department of Orthopedicsthe Fourth Medical Center of PLA General HospitalBeijing 100142China Department of Laboratory Medicine Huazhong University of Science and Technology Union Shenzhen Hospital(Nanshan Hospital)Shenzhen 518000China

Compared with other transition metal Mxene derived quantum dots(MQD_(S)),Ta-based Mxene quantum dots have good functionality,but Ta-based Mxene quantum dots and their applications have not been studied so far.In this paper,we report for the first time the synthesis of high fluorescence quantum yield(QY) N-doped Ta_(4)C_(3) quantum dots(N-MQDs) using Ta_(4)C_(3) quantum dots in acid reflux damaged Ta_(4)C_(3) nanosheets as precursors and ethylenediamine as nitrogen source.The prepared N-MQDs have excellent blue photoluminescence(PL) properties,particle size is only 2.60 nm,QY is up to 23.4%,and good stability.In addition,it has been reported that N-MQDs can be used as fluorescent probe for detection of Fe;and remote force sensing analysis In liquid ion sensing,N-MQDS shows a unique selective quenching of Fe;with a detection limit as low as 2 μmol/L,and has great potential as a fast and super-sensitive fluorescent probe for the detection of heavy ion.More importantly,in solid mechanics sensing,the introduction of N-MQDs into self-healing hydrogels can be developed into a fluorescent hydrogel that can be used for accurate remote force measurement and applied in the field of mechanical sensing analysis.Therefore,Ta-based N-MQDs show excellent potential in the field of fluorescence sensing,which provides a door for multi-dimensional sensing of new materials in the future.

关键词： MXene quantum dots Fluorescent probe Fluorescent hydrogel Hydrothermal method quantum yield

Emission tunable of Mg_(0.695)Si_(0.695)Al_(1.39)O_(3.65)N_(0.35):Eu^(2+),Mn^(2+) oxynitride phosphors via energy transfer for WLEDs

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Journal of Rare Earths 2021年第6期39卷 643-650,I0002页

作者： Yijun Yu Yi Chen Liang Chen Yuyu Shen Xiao Liu Degang Deng Shiqing Xu College of Optical and Electronic Technology China Jiliang UniversityHangzhou 310018China Institute of Optoelectronic Materials and Devices China Jiliang UniversityHangzhou 310018China

A series of Eu^(2+)doped and Eu^(2+)/Mn^(2+) co-doped Mg_(0.695)Si_(0.695)Al_(1.39)O_(3.65)N_(0.35)(MSAON) phosphors were synthesized by solid-state reaction at a lower temperature of 1500℃.The crystal morphology and structure of MSAON host were characterized by SEM,TEM and XRD.The quantum yield(QY) for Eu^(2+)doped MSAON phosphors was measured as high as 62%,indicating the excellent luminous efficiency.For the Eu^(2+)/Mn^(2+)co-doped MSAON phosphor,the photoluminescence spectrum and delay curves reveal the efficient energy transfer(ET) process from Eu^(2+)to Mn^(2+)ions.Meanwhile,the corresponding energy transfer efficiency,critical distance and mechanism are discussed in detail.Temperature-dependent emission spectrum shows the thermal and color stabilities.The emission color of MSAON:Eu^(2+),Mn^(2+)phosphors could be tuned from blue through white to red via varying the concentration of Mn^(2+) ions.White-light-emitting diodes(WLEDs) were successfully fabricated by encapsulating the phosphors in nUV LED(365 nm) devices obtaining white light with color rendering index(CRI) as high as 87.7.The results reveal that the MSAON:Eu^(2+),Mn^(2+)phosphors could have potential application in the field of n-UV WLEDs.

关键词： Mg_(0.695)Si_(0.695)Al_(1.39)O_(3.65)N_(0.35):Eu^(2+) Mn^(2+) Emission tunable quantum yield Photoluminescence Energy transfer Rare earths