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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 *** 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 *** improvement in the performance was achieved by introducing two important modifications in the commonly used oleic acid based ***,the shell was prepared via a newly developed method characterized by a very low nucleation rate for particles of pure LiYF_(4) shell ***,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+)*** 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 *** 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

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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 *** 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 *** instance,thin two-dimensional(2D)organic-inorganic hybrid perovskite microplates usually exhibit a rather low photoluminescence quantum yield(PLQY),owning to the strong surface ***,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 *** the thickness of the 2D perovskite microplate increases,the enhancement is gradually reduced and finally *** 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 *** 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 *** 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

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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 *** 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 *** chemistry and the chemical architecture of the Ba-CDs was revealed under various spectroscopic *** 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 ***,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

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

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

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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 *** 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 *** 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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Wide emission shifts and high quantum yields of solvatochromic carbon dots with rich pyrrolic nitrogen

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Nano Research 2020年第9期13卷 2492-2499页

作者： Hua Wang Philip Haydel Ning Sui Lina Wang Yan Liang William W.Yu Departm ent of Chem istry and Physics Louisiana State UniversityShreveportLA 71115USA College of M aterials Science and Engineering Qingdao University of Science and TechnologyQingdao 266042China College of Food Science and Engineering Qilu University of Technology(Shandong A cadem y of Sciences)Jinan 250353China

Carbon dots(CDs)with solvatochromic emission colors in different solvents have attracted much attention as a new class of luminescent nanomaterial owing to their facile synthesis and low production *** this work,we prepared two kinds of CDs with solvatochromic emissions:green emission CDs(G-CDs)and multicolor emission CDs(M-CDs).G-CDs synthesized from o-phenylenediamine exhibited weak photoluminescence emission(quantum yield 2.8%-6.1%)and 39 nm solvatochromic shifts(492-531 nm).In contrast,M-CDs prepared from o-phenylenediamine and 4-aminophenol showed 87 nm solvatochromic shift range(505-592 nm)and much higher photoluminescence quantum yield(18.4%-32.5%).The two CDs exhibited different emission,absorption,and photoluminescence *** origin of solvatochromic shifts and the formation mechanism of CDs were demonstrated by analyzing the structures and compositions of two *** percentages of pyrrolic nitrogen and amino nitrogen make wider solvatochromic shifts and higher quantum *** results were well supported by density functional theory *** effective strategy to expand solvatochromic shift range and improve quantum yields could open a new window to prepare satisfied solvatochromic carbon dots.

关键词： carbon dot solvatochromism density functional theory(DFT)calculation quantum yield pyrrolic nitrogen

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SINGLET OXYGEN quantum yieldS OF PORPHYRIN-BASED PHOTOSENSITIZERS FOR PHOTODYNAMIC THERAPY

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Journal of Innovative Optical Health Sciences 2008年第1期1卷 141-149页

作者： BU-HONG LI LI-SHENG LIN HUI-YUN LIN SHU-SEN XIE Key Laboratory of OptoElectronic Science and Technology for Medicine Fujian Normal University Ministry of EducationFuzhou Fujian 350007China

The major cytotoxic agent with most current photosensitizers used in photodynamic therapy(PDT)is widely believed to be singlet oxygen(^(1)O_(2)).Determination of the ^(1)O_(2) quantum yields for porphyrin-based photosensitizers,including hematoporphyrin derivative(HiPorfin),hematoporphyrin monomethyl ether(HMME)and photocarcinorin(PsD-007)in air-saturated dimethylformamide(DMF)solutions were performed by the direct measurement of their near-infrared *** addition,^(1)O_(2) quencher sodium azide was employed to confirm the ^(1)O_(2) generation from the investigated *** maximal ^(1)O_(2) luminescence occurs at about 1280 nm with full width at half maximum of 30 *** ^(1)O_(2) quantum yields were found to be 0.61±0.03,0.60±0.02 and 0.59±0.03 for HiPorfin,HMME and PsD-007,*** results provide that these porphyrin-based photosensitizers produce ^(1)O_(2) under irradiation,which is of significance for the study of their photodynamic action in PDT.

关键词： Photodynamic therapy porphyrin singlet oxygen luminescence quantum yield

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Dependence of quantum yields on Size of Ag Nano-particle Embedded in BaO Thin Film

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Semiconductor Photonics and Technology 2002年第1期8卷 27-31页

作者： CAIWu－de YANGYi－bing 等 Dept.ofPhys YunnanNormalUniversityKunming650092CHN CollegeofArmedPoliceFrontierDefenceCommandinKunming Kunming650214CHN

Theoretical dependence of the quantum yields on the size of Agnano-particle distribution from 0.8 nm to 37 nm embedded in BaOsemiconductor is discussed. The calculation results show that theincrease in Ag nano-particle diameter leads to the increase of thequantum yield threshold and the emergence of the rough Gaussian form,the results also shown that the greater increase in Ag nano-particlediameter causes the emergence of the exact Gaussian form and makesthe peaks rise up.

关键词： quantum yield ag nano-prticles ultrafast nonlinear response

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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 *** quantum yield(QY) for Eu^(2+)doped MSAON phosphors was measured as high as 62%,indicating the excellent luminous *** 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+)***,the corresponding energy transfer efficiency,critical distance and mechanism are discussed in ***-dependent emission spectrum shows the thermal and color *** 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+) ***-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 *** 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

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Improvement of photoemission performance of a gradient-doping transmission-mode GaAs photocathode

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Chinese Physics B 2011年第11期20卷 534-540页

作者：张益军牛军赵静熊雅娟任玲常本康钱芸生 Institute of Electronic Engineering and Optoelectronic Technology Nanjing University of Science and Technology

Two types of transmission-mode GaAs photocathodes grown by molecular beam epitaxy are compared in terms of activation process and spectral response, one has a gradient-doping structure and the other has a uniform-doping structure. The experimental results show that the gradient-doping photocathode can obtain a higher photoemission capability than the uniform-doping one. As a result of the downward graded band-bending structure, the cathode performance parameters, such as the electron average diffusion length and the surface electron escape probability obtained by fitting quantum yield curves, are greater for the gradient-doping photocathode. The electron diffusion length is within a range of from 2.0 to 5.4μm for doping concentration varying from 10^19 to 10^18 cm^-3 and the electron average diffusion length of the gradient-doping photocathode achieves 3.2 μm.

关键词： transmission-mode photocathode gradient-doping Cs-O activation quantum yield

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

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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 *** 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 ***,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 *** 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 *** 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

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