An Orange-Emitting, Long-Persistent Phosphor, Ca[sub 2]Si[sub 5]N[sub 8]:Eu[sup 2+],Tm[sup 3+]

Miyamoto, Yoshinobu; Kato, Hikaru; Yuhya, Honna; Yamamoto, Hajime; Ohmi, Koutoku

doi:10.1149/1.3153114

Cited by 57 publications

(35 citation statements)

References 12 publications

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“…These materials are much more stable than the aforementioned sulfides and show a high quantum efficiency, which has led to extensive research into their use as conversion phosphors in white LEDs [11,12,[18][19][20][21][22][23][24][25][26][27][28]. Recently, orange and reddish persistent luminescence was reported in these compounds, most notably in Ca 2 Si 5 N 8 :Eu,Tm [10,13,14,18,29,30]. Key parameters for the steady-state photoluminescence and the persistent luminescence of M 2 Si 5 N 8 :Eu(,Tm) are given in Table 1. A great advantage of these Eu 2+ -doped nitride materials is their very broad excitation spectrum, extending well into the visible range.…”

Section: Introductionmentioning

confidence: 99%

Temperature and wavelength dependent trap filling in M2Si5N8:Eu (M=Ca, Sr, Ba) persistent phosphors

Smet¹,

Eeckhout²,

Bos³

et al. 2012

Journal of Luminescence

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The evaluation of persistent phosphors is often focused on the processes right after the excitation, namely on the shape of the afterglow decay curve and the duration of the afterglow, in combination with thermoluminescence glow curve analysis. In this paper we study in detail the trap filling process in europium-doped alkaline earth silicon nitrides (Ca 2 Si 5 N 8 :Eu, Sr 2 Si 5 N 8 :Eu and Ba 2 Si 5 N 8 :Eu), i.e., how the persistent luminescence can be induced. Both the temperature at which the phosphors are excited and the spectral distribution of the excitation light on the ability to store energy in the phosphors' lattices are investigated. We show that for these phosphors this storage process is thermally activated upon excitation in the lower 5d excited states of Eu 2+ , with the lowest thermal barrier for europium doped Ca 2 Si 5 N 8 . Also, the influence of co-doping with thulium on the trap filling and afterglow behavior is studied. Finally there exists a clear relation between the luminescence quenching temperature and the trap filling efficiency. The latter relation can be utilized to select new efficient 5d-4f based afterglow phosphors. 2 Center for Nano-and Biophotonics (NB-Photonics), Ghent University, Belgium.

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Section: Introductionmentioning

confidence: 99%

Temperature and wavelength dependent trap filling in M2Si5N8:Eu (M=Ca, Sr, Ba) persistent phosphors

Smet¹,

Eeckhout²,

Bos³

et al. 2012

Journal of Luminescence

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“…146,147 A limited number of red nitride phosphors have been developed, belonging to the MSi 5 N 8 (M = Ca, Sr, Ba) family as summarized in Table V. [148][149][150][151][152][153][154][155][156] The presence of inherent defects, as well as the…”

Section: Discussionmentioning

confidence: 99%

Critical Review—Narrow-Band Emission of Nitride Phosphors for Light-Emitting Diodes: Perspectives and Opportunities

Leaño

Fang

Liu

2017

ECS J. Solid State Sci. Technol.

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Searching for narrow-band red-emitting and thermally stable phosphors is the ultimate strategy toward enhanced performance of phosphor converted light emitting diodes (pc-LED). The red emission is assured by the nitride host because of its relatively more covalent character than oxides and sulfides; however, the narrow emission is attributed to crystallographic, morphological, and electronic considerations. The symmetric coordination site ensures equal ligand effect in all direction fits well with the configuration of Eu 2+ f orbitals in the excited state, as observed in cuboid nitrides. Further, thermal stability is ascribed not only to suitable bandgap but more specifically, a relatively distant location of the lowest 5d level from the bottom of the conduction band (CB) that consequently entails high energy to quench excited electrons by exciting them further up to the CB. Modes toward the development of new nitride hosts with potentially narrow-band emission have been identified. A viewpoint on light-emitting diode (LED), backlighting, and laser lighting, which remains the most economically-rewarding phosphors application, is presented. Other exciting frontiers, such as agricultural illumination and persistent luminescence, maximize nitride systems that have other properties other than the stringent narrow-band red emission and excellent thermal stability required for the desired improvement of the mainstream LED application. is a Critical Review in Electrochemical and Solid State Science and Technology (CRES 3 T). This article was reviewed by Anant Setlur (setlur@ge.com) and Jing Wang (ceswj@mail.sysu.edu.cn). This paper is part of the JSS Focus Issue on Visible and Infrared Phosphor Research and Applications.The discovery, development, and commercialization of phosphors are expected to satisfactorily fare with the benchmark set for phosphor converted-LEDs. First, the excitation wavelength of the phoshpors must be compatible with the blue LED pump, thereby emitting the desired colors and consequently generating white light. Second, the quantum efficiency should be high. Third, phosphor must have a high absorption rate in the LED range, which technically narrows the choices to those that are excitable through 4f → 5d, d → d, np → nd, and ns → np transitions. Fourth, it must have high thermal quenching temperature. Fifth, the inherent stability against moisture and continuous irradiation ensures the durability and longevity of the device. Sixth, a rational design must be presented for the synthesis conditions from the selection of starting materials, synthesis strategy, and costs to allow the smooth cross-over to eventual industrial-scale production. 1,2Tuning the phosphor photoluminescence requires a tunable phosphor and a set of strategies to introduce changes in intensity, emission wavelength, and full width at half-maximum (fwhm). Moreover, the following are of paramount consideration in tuning the phosphor photoluminescence. First, a clear understanding of crystal and local structures and the investigati...

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“…The afterglow duration increases to 2500s upon appropriate codoping with thulium [27]. The addition of thulium introduces new traps, which are observed in the thermoluminescence glow curves around 220K (which is of no use for afterglow at room temperature) and 350 to 375K [30,32]. Next to these glow peaks, a very shallow intrinsic trap is found in all Ca 2 Si 5 N 8 :Eu,RE phosphors, with release at 110K in thermoluminescence [30,32].…”

Section: Eumentioning

confidence: 99%

“…The red phosphors should preferably have a relatively narrow emission band and a peak wavelength not higher than 625nm, otherwise the human eye is not sensitive enough for the emitted light and the efficiency of the LED is compromised [46]. [30,32]. The afterglow duration of Ca 2 Si 5 N 8 :Eu without co-dopants was found to be only 150s, taking 0.32 mcd/m² as threshold.…”

Section: Eumentioning

confidence: 99%

“…The addition of thulium introduces new traps, which are observed in the thermoluminescence glow curves around 220K (which is of no use for afterglow at room temperature) and 350 to 375K [30,32]. Next to these glow peaks, a very shallow intrinsic trap is found in all Ca 2 Si 5 N 8 :Eu,RE phosphors, with release at 110K in thermoluminescence [30,32]. The addition of Dy or Nd to Ca 2 Si 5 N 8 :Eu does introduce additional traps, but these are too shallow to play a role at room temperature [30,32].…”

Section: Eumentioning

confidence: 99%

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Persistent luminescence in nitride and oxynitride phosphors: A review

et al. 2014

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The research field of persistent luminescence has experienced a strong growth in the past two decades, with a steady development of new materials and applications. Here we give an overview of the recent progress in a specific class of host materials, namely oxynitride and nitride persistent phosphors. These are interesting hosts to explore because of their unique characteristics, such as chemical stability and tunability of the emission over the entire visible range upon doping with divalent europium. To yield persistent luminescence however, codopants have to be added or the synthesis conditions have to be adjusted. Specific materials, such as Ca 2 Si 5 N 8 :Eu,Tm and BaSi 2 O 2 N 2 :Eu, are highlighted and their properties are put into the context of emerging applications such as in vivo imaging and pressure sensing via mechanoluminescence. Finally, directions for future research are given.

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An Orange-Emitting, Long-Persistent Phosphor, Ca[sub 2]Si[sub 5]N[sub 8]:Eu[sup 2+],Tm[sup 3+]

Cited by 57 publications

References 12 publications

Temperature and wavelength dependent trap filling in M2Si5N8:Eu (M=Ca, Sr, Ba) persistent phosphors

Temperature and wavelength dependent trap filling in M2Si5N8:Eu (M=Ca, Sr, Ba) persistent phosphors

Critical Review—Narrow-Band Emission of Nitride Phosphors for Light-Emitting Diodes: Perspectives and Opportunities

Persistent luminescence in nitride and oxynitride phosphors: A review

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