Advances in Phosphors for Light-emitting Diodes

Lin, Chun Che; Liu, Ru‐Shi

doi:10.1021/jz2002452

Cited by 1,142 publications

(645 citation statements)

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“…The highest excitation peak at 395nm corresponding to the 7 F 0 → 5 L 6 transition of Eu 3+ matches well with the emission from the near-UV LED chip, implying that the red phosphor Na 3 Eu(CO 3 ) 3 •6H 2 O has potential application in white-LED as the red component of tricolor luminescent materials. 28 As shown in Fig. 5b, the emission spectrum is composed of several distinct groups of sharp lines in the range of 500-750 nm with the most intensive line at 618 nm, which can be assigned to the 5 D 0 → 7 F j (j =0, 1, 2, 3, 4) transitions of Eu 3+ ions.…”

Section: Photoluminescence Propertiesmentioning

confidence: 87%

SYNTHESIS, CRYSTAL STRUCTURE AND PHOTOLUMINESCENCE PROPERTIES OF A NEW RARE-EARTH CARBONATE Na3Eu(CO3)(3)6H2O

Zhao

Huang

et al. 2017

J. Chil. Chem. Soc.

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A new sodium europium carbonate hydrate, Na 3 Eu(CO 3 ) 3 ·6H 2 O, has been prepared using the hydrothermal method, and its structure was determined by single crystal X-Ray diffraction analysis for the first time. It crystallizes in the polar hexagonal space group P6 3 with a = 11.382(9) Å, c = 5.989(5) Å, V = 672.06(9) Å 3 , Z = 2, Mr = 509.06, Dc = 2.516 g/cm 3 , F(000) = 492, μ(MoKα) = 4.84 mm -1 , R 1 = 0.015 and wR = 0.038. The structure features a three-dimensional（3D） framework composed of planar (CO 3 ) 2-triangles, Eu 3+ ions and Na + ions, which delimits 1D infinite chains with a hexangular star appearance along the c-axis. The IR spectrum and the self-activated photoluminescence properties were studied. Under the excitation of near UV light (395nm), it shows strong red emission at 618 nm with a lifetime of 348.7 μs. Present research indicates that Na 3 Eu(CO 3 ) 3 ·6H 2 O is a promising red phosphor for white light-emitting diodes.Keywords: hydrothermal; carbonate; X-ray diffraction; photoluminescence e-mail: iamzd1996@yahoo.com.cn; fanyunchang@hpu.edu.cn INTRODUCTIONIn the last few decades, an extensive research has been carried out for new rare earth luminescent materials, owning to their potential applications in optical information transmission, display imaging, solar photovoltaic conversion, fluorescent powder, electrical conduction, new light source and X-ray intensifying screen. 1-3 Eu 3+ ion doped material is an effective red phosphor due to its intense near UV absorption and excellent pure red emissions corresponding to the 5 D 0 → 7 F j (j = 1, 2, 3, 4) transitions of Eu 3+ . [4][5][6][7][8] In recent years, a large amount of rare earth carbonates system has been parepared, such as Na 3 Eu(CO 3 ) 3 , 9 NaLiRe(CO 3 ) 3 (Re = Eu-Er,Yb,Lu,Y), 10 Na 3 Eu(CO 3 )F 3 , 11 BaEu(CO 3 ) 2 , 12 Ba 3 Eu(CO 3 ) 2 F 3 , 13 Na 3 La(CO 3 ) 4 F: Eu 3+12 and KGd(CO 3 )F 2 : Eu 3+ . 14 However, there were few reports on their luminescence properties. 15 In order to explore a new europium carbonate that might afford red luminescent emission, we started a research using the hydrothermal method and a new alkali sodium europium carbonate hydrate Na 3 Eu(CO 3 ) 3 ·6H 2 O was successfully prepared. The crystal structure, IR spectrum and photoluminescence properties at room temperature were studied for it. EXPERIMENTAL Materials and MethodsAll of the chemicals, NaCO 3 , NaHCO 3 , Eu(NO 3 ) 3 ·6H 2 O were purchased from Shanghai Reagent Factory and were analytically pure without further purification. IR spectra were recorded on a Magna 750 FT-IR spectrometer as KBr pellets in the range of 4000−400 cm -1 . Photoluminescence (PL) properties were performed on EDINBURGHFLS980 fluorescence spectrophotometer. 2 SynthesisSingle crystal was prepared by the follow procedure: a mixture of Na 2 CO 3 (0.44 g, 4 μmol), NaHCO 3 (0.2 g, 2 μmol) and Eu(NO 3 ) 3 ·6H 2 O (0.035 g, 0.1 μmol) was dissolved in 2 ml deionized water, which was then placed in a 20 ml Teflon-lined stainless steel autoclave. The autoclave was sealed an...

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Section: Photoluminescence Propertiesmentioning

confidence: 87%

SYNTHESIS, CRYSTAL STRUCTURE AND PHOTOLUMINESCENCE PROPERTIES OF A NEW RARE-EARTH CARBONATE Na3Eu(CO3)(3)6H2O

Zhao

Huang

et al. 2017

J. Chil. Chem. Soc.

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“…For the latter reason, many investigations focus on improving the technology based on blue-LEDs, notably with the specific aim of lowering their CCT as well as increasing their CRI. Strategies to improve these properties include for example the addition of highly efficient red components made of InP quantum dots [6]. A compilation of luminescence data for various inorganic phosphors used in pcWLED devices is shown in Table 1.…”

Section: Phosphor Converted White Light Emitting Diodesmentioning

confidence: 99%

“…It is intended to be complementary to the many excellent review articles that have appeared in the literature (e.g., [4][5][6][7][8][9][10][11][12][13], to cite only a few).…”

Section: Introductionmentioning

confidence: 99%

Inorganic Phosphor Materials for Lighting

2016

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This chapter addresses the development of inorganic phosphor materials capable of converting the near UV or blue radiation emitted by a light emitting diode to visible radiation that can be suitably combined to yield white light. These materials are at the core of the new generation of solid-state lighting devices that are emerging as a crucial clean and energy saving technology. The chapter introduces the problem of white light generation using inorganic phosphors and the structureproperty relationships in the broad class of phosphor materials, normally containing lanthanide or transition metal ions as dopants. Radiative and non-radiative relaxation mechanisms are briefly described. Phosphors emitting light of different colors (yellow, blue, green, and red) are described and reviewed, classifying them in different chemical families of the host (silicates, phosphates, aluminates, borates, and non-oxide hosts). This research field has grown rapidly and is still growing, but the discovery of new phosphor materials with optimized properties (in terms of emission efficiency, chemical and thermal stability, color, purity, and cost of fabrication) would still be of the utmost importance.

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“…In order to improve the color rendering properties, multiple phosphors with different emission spectra are used [11][12][13]. For instance, a portion of red or orange phosphors are used to mix with yellow phosphor to increase the output in the red region [14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Numerical Prediction and Experimental Validation of Multiple Phosphor White LED Spectrum

Lee

Guo

et al. 2016

Transactions of The Japan Institute of Electronics Packaging

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Abstract-Conventional phosphor converted white light LEDs utilize yellow phosphor to convert the blue light emitted from the chip to yellow light. Although this can generate white light with various correlated color temperatures (CCT), the color rendering properties are generally poor as the spectrum of the LEDs, as compared with the reference light source, is not broad enough. The red light output is low in particular. This limitation is caused by the emission spectrum of yellow phosphor. To improve the color rendering properties, multiple phosphors with different emission spectra should be used. For instance, a certain amount of red or orange phosphors may be used to mix with yellow phosphor to increase the output in the red region. In this paper, a numerical model is proposed to predict the emission spectra of LEDs with multiple phosphors. The excitation and emission spectra of various phosphors are measured and input to the model. The mixing ratio and reabsorption between phosphors have also been taken into consideration. White light LEDs with multiple phosphors are fabricated. The spectra are measured and compared with the modeling results. It is found that the proposed model can estimate the emission spectra of LEDs with multiple phosphors with a high degree of accuracy.

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Advances in Phosphors for Light-emitting Diodes

Cited by 1,142 publications

References 28 publications

SYNTHESIS, CRYSTAL STRUCTURE AND PHOTOLUMINESCENCE PROPERTIES OF A NEW RARE-EARTH CARBONATE Na3Eu(CO3)(3)6H2O

SYNTHESIS, CRYSTAL STRUCTURE AND PHOTOLUMINESCENCE PROPERTIES OF A NEW RARE-EARTH CARBONATE Na3Eu(CO3)(3)6H2O

Inorganic Phosphor Materials for Lighting

Numerical Prediction and Experimental Validation of Multiple Phosphor White LED Spectrum

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