A novel phosphor for glareless white light-emitting diodes

Daicho, Hisayoshi; Iwasaki, Takeshi; Enomoto, Kiminori; Sasaki, Yasutaka; Maeno, Yuzo; Shinomiya, Yu; Aoyagi, Shinobu; Nishibori, Eiji; Sakata, Makoto; Sawa, Hiroshi; Matsuishi, Satoru; Hosono, Hideo

doi:10.1038/ncomms2138

Cited by 328 publications

(163 citation statements)

References 43 publications

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“…[1][2][3][4] Among these applications, white light emitting diodes (WLEDs) have been regarded as the next generation illumination tools due to their energy saving ability, environmental friendliness, and high efficiency merits over the traditional incandescent and uorescent lamps. 5,6 Since WLEDs fabricated with three (blue, green, red) LEDs need complicated technology and high expense, 6,7 the main approach to obtain WLEDs is the combination of blue or ultra violet LED with down converting phosphors, known as phosphor-converted WLEDs.…”

Section: Introductionmentioning

confidence: 99%

Structure and photoluminescence properties of novel Ca₂NaSiO₄F:Re (Re = Eu²⁺, Ce³⁺, Tb³⁺) phosphors with energy transfer for white emitting LEDs

et al. 2014

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A series of Eu 2+ and Ce 3+ /Tb 3+ doped Ca 2 NaSiO 4 F (CNSOF) phosphors have been synthesized and their structure and photoluminescence properties have been investigated in detail. Rietveld structure refinement indicates that the phosphors crystalized in an orthorhombic system with a space group of Pnma (no. 62) and there are two kinds of cation sites for the doped ions to occupy in forming emission centers. The CNSOF:Eu 2+ and CNSOF:Ce 3+ phosphors both have broad excitation bands, which match well with the commercial UV LED chips. The CNSOF:Eu 2+ phosphor can have intense green emission with a maximum at 530 nm under irradiation at 380 nm, while the CNSOF:Ce 3+ sample can emit intense blue light, peaking at 470 nm with excitation at 365 nm. By codoping the Tb 3+ and Ce 3+ ions into an CNSOF host and varying their relative ratio, tunable blue-green colors are obtained due to efficient energy transfer from the Ce 3+ to Tb 3+ ions. Moreover, energy transfer mechanisms for the Eu 2+ ions in CNSOF:Eu 2+ and Ce 3+ / Tb 3+ in CNSOF:Ce 3+ ,Tb 3+ have been studied systematically. Our investigation indicates that CNSOF:Eu 2+ and CNSOF:Ce 3+ ,Tb 3+ may be potential green and blue-green phosphors for UV WLEDs, respectively.

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Section: Introductionmentioning

confidence: 99%

Structure and photoluminescence properties of novel Ca₂NaSiO₄F:Re (Re = Eu²⁺, Ce³⁺, Tb³⁺) phosphors with energy transfer for white emitting LEDs

et al. 2014

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“…Plants grow better under red LEDs compared to those grown under daylight fluorescent (white) lamps because red light is close to the maximum absorbance for chlorophyll. 16,17 In this regard, searching for a new red phosphor is one of the big challenges in the field of luminescent materials particularly when a red-emitting phosphor is preferred in some occasions with high color purity.The basic requirements of potential red phosphor for a blue chip scheme are (1) it should have significant absorption in blue; 18,19 (2) it must have high quantum efficiency of the red emission; 20 (3) it must be capable of retaining its luminescent characteristics over long periods at 150°C. 21 Recently, nonrare earth-based eco-friendly phosphors, Mn 4+ -doped crystalline host materials, which can be synthesized under milder conditions, have received great interest.…”

mentioning

confidence: 99%

A Novel Efficient Mn⁴⁺ Activated Ca₁₄Al₁₀Zn₆O₃₅ Phosphor: Application in Red-Emitting and White LEDs

et al. 2014

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A new, highly efficient deep red-emitting phosphor Ca14Al10Zn6O35:Mn(4+) was developed as a component of solid-state white light-emitting diodes (LEDs). The structural and optical characterization of the phosphor is described. The phosphor exhibits strong emission in the range of 650-700 nm when excited by 460 nm excitation, with a quantum efficiency approaching 50%. Concentration dependence of Mn(4+) luminescence in Ca14Al10Zn6O35:Mn(4+) is investigated. Attempts to understand the thermal stability on the basis of the thermal quenching characteristics of Ca14Al10Zn6O35:Mn(4+) is presented. The results suggest that phosphors deriving from Ca14Al10Zn6O35:Mn(4+) have potential application for white LEDs. In addition, influence of cation substitution on the luminescence intensity of these phosphors is elucidated.

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“…There is also a special class of Eu 2+ -activated phosphors that exhibit the characteristics of both normal 4 f 6 5 d →4 f 7 transitions (e.g., large transition probabilities for emission and excitation) and anomalous luminescence (e.g., very large bandwidth and Stokes shift of emission)101112131415. Based on the relationship between the luminescence and host crystalline structure in this special class of Eu 2+ -activated phosphors, Poort et al attributed this type of emission to 4 f 6 5 d →4 f 7 transitions and suggested that the linear chain structure of large cations in the lattice (depending on the values of lattice parameters) contributed to this special luminescence10.…”

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confidence: 99%

New localized/delocalized emitting state of Eu2+ in orange-emitting hexagonal EuAl2O4

Liu

Meltzer

et al. 2014

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Eu2+-activated phosphors are being widely used in illuminations and displays. Some of these phosphors feature an extremely broad and red-shifted Eu2+ emission band; however, convincing explanation of this phenomenon is lacking. Here we report a new localized/delocalized emitting state of Eu2+ ions in a new hexagonal EuAl2O4 phosphor whose Eu2+ luminescence exhibits a very large bandwidth and an extremely large Stokes shift. At 77 K, two luminescent sites responsible for 550 nm and 645 nm broadband emissions are recognized, while at room temperature only the 645 nm emission band emits. The 645 nm emission exhibits a typical radiative lifetime of 1.27 μs and an unusually large Stokes shift of 0.92 eV. We identify the 645 nm emission as originating from a new type of emitting state whose composition is predominantly that of localized 4f65d character but which also contains a complementary component with delocalized conduction-band-like character. This investigation provides new insights into a unique type of Eu2+ luminescence in solids whose emission exhibits both a very large bandwidth and an extremely large Stokes shift.

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A novel phosphor for glareless white light-emitting diodes

Cited by 328 publications

References 43 publications

Structure and photoluminescence properties of novel Ca₂NaSiO₄F:Re (Re = Eu²⁺, Ce³⁺, Tb³⁺) phosphors with energy transfer for white emitting LEDs

Structure and photoluminescence properties of novel Ca₂NaSiO₄F:Re (Re = Eu²⁺, Ce³⁺, Tb³⁺) phosphors with energy transfer for white emitting LEDs

A Novel Efficient Mn⁴⁺ Activated Ca₁₄Al₁₀Zn₆O₃₅ Phosphor: Application in Red-Emitting and White LEDs

New localized/delocalized emitting state of Eu2+ in orange-emitting hexagonal EuAl2O4

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A novel phosphor for glareless white light-emitting diodes

Cited by 328 publications

References 43 publications

Structure and photoluminescence properties of novel Ca2NaSiO4F:Re (Re = Eu2+, Ce3+, Tb3+) phosphors with energy transfer for white emitting LEDs

Structure and photoluminescence properties of novel Ca2NaSiO4F:Re (Re = Eu2+, Ce3+, Tb3+) phosphors with energy transfer for white emitting LEDs

A Novel Efficient Mn4+ Activated Ca14Al10Zn6O35 Phosphor: Application in Red-Emitting and White LEDs

New localized/delocalized emitting state of Eu2+ in orange-emitting hexagonal EuAl2O4

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Structure and photoluminescence properties of novel Ca₂NaSiO₄F:Re (Re = Eu²⁺, Ce³⁺, Tb³⁺) phosphors with energy transfer for white emitting LEDs

Structure and photoluminescence properties of novel Ca₂NaSiO₄F:Re (Re = Eu²⁺, Ce³⁺, Tb³⁺) phosphors with energy transfer for white emitting LEDs

A Novel Efficient Mn⁴⁺ Activated Ca₁₄Al₁₀Zn₆O₃₅ Phosphor: Application in Red-Emitting and White LEDs