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Temperature effects on photoluminescence of YAG:Ce^(3+) phosphor and performance in white light-emitting diodes

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Journal of Rare Earths 2008年第3期26卷 446-449页

作者：张艳芳李岚张晓松奚群 Institute of Material Physics Tianjin University of Technology Key Laboratory of Display Materials and Photoelectric Devices Ministry of Education The Tianjin Key Laboratory for Optoelectronic Materials and Devices

The well crystalline YAG：Ce^3＋ phosphor was synthesized by sold-state method, and the temperature dependence of excitation and emission spectra of YAG：Ce^3＋ phosphor were investigated in the temperature range from room temperature to 573 K. With temperature increasing, it was noted that the emission intensity of as-repared phosphors decreased considerably more rapidly when pumped by 460 nm than by 340 nm. The temperature-intensity curves under different excitation wavelengths were obtained using an Arrhenius function, and the corresponding activation energies were also obtained respectively. Thus, the experimental phenomenon was discussed in terms of nonradiative decay rate. The effects of as-prepared phosphors on the performance of the white LED with changing temperature were also studied.

关键词： white light-emitting diodes YAG： Ce^3＋ activation energy nonradiative decay rate rare earths

Samarium doping improves luminescence efficiency of Cs_(3)Bi_(2)Br_(g)perovskite quantum dots enabling efficient white light-emitting diodes

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Journal of Rare Earths 2021年第4期39卷 374-379页

作者： Yongsheng Zhu Jinyang Zhu Haizhen Song Jinshu Huang Zhiwen Lu Gencai Pan College of Physics and Electronic Engineering Nanyang Normal UniversityNanyang 473061China State Centre for International Cooperation on Designer Low-carbon&Environmental Materials School of Materials Science and EngineeringZhengzhou University Zhengzhou 450001ChinaSchool of Physics and ElectronicsHenan UniversityKaifeng 475004China

Considering the toxicity problem of lead-based perovskite quantum dots(PQDs),the lead-free Cs_(3)Bi_(2)Br_(g)PQDs has been recognized as one of the promising candidates.However,the low photoluminescence quantum yields(PLQYs)hinder its practical application in optoelectronic devices.Here,w e successfully prepared Sm^(3+)ions doped Cs_(3)Bi_(2)Br_(g)PQDs with effective white light-emission by modified ligandassisted recrystallization method.The realization of white light-emission is attributed to the broadband blue emission of excitons and the red emission(^(4)G_(5/2)-^(6)HJ(J=5/2,7/2,9/2))of Sm^(3+)ions for Sm^(3+)ions doped Cs_(3)Bi_(2)Br_(g)PQDs.More importantly,compared with the undoped Cs_(3)Bi_(2)Br_(g)PQDs,the PLQYs of Sm^(3+)ions doped Cs_(3)Bi_(2)Br_(g)PQDs are improved from 10.9%to 20.8%,and the anti-water stability is also obviously improved.Finally,the Sm^(3+)ions doped PQDs based white light-emitting diodes(LEDs)with luminous efficiency of 12.6 lm/W were explored,which indicates that there is a potential prospect of lead-free PQDs in white light lighting application.

关键词： Lead-free perovskite quantum dots Photoluminescence quantum yields Energy transfer white light-emitting diodes Rare earths

Highly efficient emission and high-CRI warm white light-emitting diodes from ligand-modified CsPbBr_(3) quantum dots

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Opto-Electronic Advances 2022年第1期5卷 35-48页

作者： Dongdong Yan Shuangyi Zhao Yubo Zhang Huaxin Wang Zhigang Zang Key Laboratory of Optoelectronic Technology&Systems(Ministry of Education) Chongqing UniversityChongqing 400044China Department of Physics Southern University of Science and TechnologyShenzhen 518055China

All-inorganic CsPbBr_(3) perovskite quantum dots(QDs)have received great attention in white light emission because of their outstanding properties.However,their practical application is hindered by poor stability.Herein,we propose a simple strategy to synthesize excellent stability and efficient emission of CsPbBr_(3) QDs by using 2-hexyldecanoic acid(DA)as a ligand to replace the regular oleic acid(OA)ligand.Thanks to the strong binding energy between DA ligand and QDs,the modified QDs not only show a high photoluminescence quantum yield(PLQY)of 96%but also exhibit high stability against ethanol and water.Thereby warm white light-emitting diodes(WLEDs)are constructed by combining lig-and modified CsPbBr_(3) QDs with red AgInZnS QDs on blue emitting InGaN chips,exhibiting a color rendering index of 93,a power efficiency of 64.8 lm/W,a CIE coordinate of(0.44,0.42)and correlated color temperature value of 3018 K.In ad-dition,WLEDs based on ligand modified CsPbBr_(3) QDs also exhibit better thermal performance than that of WLEDs based on the regular CsPbBr_(3) QDs.The combination of improved efficiency and better thermal stability with high color quality indicates that the modified CsPbBr_(3) QDs are ideal for WLEDs application.

关键词： CsPbBr_(3)quantum dots ligand modification stability efficiency white light-emitting diodes

Rare-earth single atom based luminescent composite nanomaterials:Tunable full-color single phosphor and applications in WLEDs

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Nano Research 2022年第4期15卷 3594-3605页

作者： Shan Bao Haiyue Yu Guoyang Gao Hongyang Zhu Dingsheng Wang Peifen Zhu Guofeng Wang Key Laboratory of Functional Inorganic Material Chemistry Ministry of EducationSchool of Chemistry and Materials ScienceHeilongjiang UniversityHarbin 150080China School of Physics and Electronic Engineering Linyi UniversityLinyi 276005China Department of Chemistry Tsinghua UniversityBeijing 100084China Department of Physics and Engineering Physics The University of TulsaTulsaOK 74104USA

High-quality single-component white phosphors are instrumental in realizing high-efficiency devices.Rare earth fluorides and carbon quantum dots have great potential in the white light-emitting diode(WLED)field due to their unique advantages.Here,Rare-earth single atom based NaGdF4:Tb^(3+)/Eu^(3+)@C:N/Eu^(3+)single phosphor with tunable full-color luminescence was reported.The results of density functional theory(DFT)calculation and experimental characterization show that C atoms cannot be replaced by Eu^(3+),but C atoms are more favorable for anchoring Eu^(3+)single atoms.The DFT was employed to optimize the structures of the C:N/Eu^(3+)and NaGdF4:Tb^(3+)/Eu^(3+),and calculate the work function,optical properties,and charge density difference.The obtained tunable full-color single phosphor can emit stable light from blue to red or even white.The constructed WLED devices also have stable and excellent color performance,that is,a color rendering index of up to 95 and a lower color temperature,and it has broad application possibilities in WLEDs.

关键词： single atoms luminescence single phosphor white light-emitting diodes

A single-phase full-color phosphor Sr_(2)Ca_(2)La(PO_(4))_(3)O:Eu^(2+),Tb^(3+),Mn^(2+):Photoluminescence and energy transfer

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Journal of Rare Earths 2022年第4期40卷 541-550,I0002页

作者： Ju Cheng Xintian Bian Zhangyin Zhai Maryam Sardar Jian Lu School of Physics and Electronic Electrical Engineering Huaiyin Normal UniversityHuai'an 223001China School of Science Nanjing University of Science and TechnologyNanjing 210094China

A single-phase full-color emitting phosphor Sr_(2)Ca_(2)La(PO_(4))_(3)O:Eu^(2+),Tb^(3+),Mn^(2+) was synthesized by the high temperature solid-state method.The phase formation,luminescence properties,thermal stability,and energy transfer from Eu^(2+)to Tb^(3+) and Eu^(2+)to Mn^(2+) in Sr_(2)Ca_(2)La(PO_(4))_(3)O were investigated in details.Tunable emission color from blue to blueish green or orange can be observed under 365 nm near-ultraviolet excitation based on the energy transfer from Eu^(2+) to Tb^(3+)or Mn^(2+) ions by varying the ratio of Eu^(2+)/Tb^(3+)or Eu^(2+)/Mn^(2+) ions.white light was obtained with chromaticity coordinates of(0.3558,0.3500)in the Sr_(2)Ca_(2)La(PO_(4))_(3)O:0.04Eu^(2+),0.08Tb^(3+),0.40Mn^(2+) phosphor,suggesting their potential applications in white light emitting diodes.

关键词： Phosphors Energy transfer Photoluminescence properties white light-emitting diodes Rare earths

Preparation and photoluminescence properties of Dy^(3+)-doped Ba_3Lu(PO_4)_3 phosphors

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Journal of Rare Earths 2015年第12期33卷 1251-1255页

作者：杨在发孙宇梅徐齐光孙家跃 School of Science Beijing Technology and Business University

Ba3Lu（PO4）3：Dy3＋ phosphors were successfully synthesized by conventional solid state reaction and its photoluminescence properties were investigated by X-ray diffraction （XRD）, photoluminescence spectra and diffuse reflectance spectra, respectively. Results showed that the phosphor could be excited by the ultraviolet visible light in the region from 320 to 460 nm, and it showed two dominant emission bands peaking at 484 nm （blue light） and 575 nm （yellow light） which originated from the transitions of 4F9/2--6H15/2 and 4F9/2----6rH13/2 of Dy3＋, respectively. According to Dexter＇s theory, the concentration quenching mechanism occurred via the electric dipole-dipole interaction. The lifetime values of Dy3＋ ions at different concentrations （x-0.01, 0.03, 0.05, 0.08 and 0.10） were determined to be about 0.8556, 0.7595, 0.6864, 0.6059 and 0.5456 ms.

关键词： luminescence white light-emitting diodes Ba3Lu（PO4）3：Dy3＋ phosphors rare earths

Self-adaptive phosphor coating technology for wafer-level scale chip packaging

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Journal of Semiconductors 2013年第5期34卷 96-99页

作者：周琳淞饶海波王伟万贤龙廖骏源王雪梅周炟雷巧林 School of Opto-Electronic Information University of Electronic Science and Technology of China

A new self-adaptive phosphor coating technology has been successfully developed, which adopted a slurry method combined with a self-exposure process. A phosphor suspension in the water-soluble photoresist was applied and exposed to LED blue light itself and developed to form a conformal phosphor coating with self- adaptability to the angular distribution of intensity of blue light and better-performing spatial color uniformity. The self-adaptive phosphor coating technology had been successfully adopted in the wafer surface to realize a wafer- level scale phosphor conformal coating. The first-stage experiments show satisfying results and give an adequate demonstration of the flexibility of self-adaptive coating technology on application of WLSCP.

关键词： white light-emitting diodes self-adaptive conformal coating wafer level encapsulation technology multi-chip packaging