Emerging cool white light emission from Dy<sup>3+</sup> doped single phase alkaline earth niobate phosphors for indoor lighting applications

Vishwakarma, Anand Kumar; Jha, Kaushal; Jayasimhadri, M.; Bathula, Sivaiah; Gahtori, Bhasker; Haranath, D.

doi:10.1039/c5dt02436f

Cited by 178 publications

(52 citation statements)

References 54 publications

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“…The nonradiative energy transfer and concentration quenching may take place due to resonance energy transfer (RET) and cross relaxation (CR) channels among neighboring Dy 3+ ions. Considering the energy match rule, the possible resonant energy transfer and three cross relaxation channels (CR1, CR2, CR3) are as follows:

RET : (^{4} {normalF}_{9 / 2} +^{6} {normalH}_{15 / 2} \to^{6} {normalH}_{15 / 2} +^{4} {normalF}_{9 / 2})

CR 1 : (^{4} {normalF}_{9 / 2} +^{6} {normalH}_{15 / 2} \to^{6} {normalF}_{11 / 2},^{6} {normalH}_{9 / 2} +^{6} {normalF}_{3 / 2})

…”

Section: Resultsmentioning

confidence: 99%

“…Presently, the commercial approach comprises of blue emitting InGaN chip with yellow emitting (YAG: Ce 3+ ) phosphor . However, this approach has disadvantages such as halo effect, low color rendering index (CRI) index R a ≤65) and high correlated color temperature (CCT) due to the lack of red color . Another approach has been widely investigated, which is based on the ultraviolet/near‐ultraviolet (UV/n‐UV) chip with the combination of red, green, and blue (RGB) phosphors .…”

Section: Introductionmentioning

confidence: 99%

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White light emitting thermally stable bismuth phosphate phosphor Ca₃Bi(PO₄)₃:Dy³⁺ for solid‐state lighting applications

Sahu

Jayasimhadri

2019

J Am Ceram Soc

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White light emitting dysprosium‐doped Ca3Bi(PO4)3 phosphor was successfully synthesized via co‐precipitation method for the first time and the structural, vibrational, morphological, and luminescent properties have been investigated for solid‐state lighting applications. X‐ray diffraction (XRD) and structural refinement studies reveal that the synthesized phosphors consist of single phase with cubic structure. The field emission scanning electron microscopy (FE‐SEM) images reveal that the as‐synthesized phosphor has micron size particle with an irregular shape. Under near‐ultraviolet (n‐UV) and blue excitation, the phosphor exhibits white light emission via a combination of blue (~484 nm) and yellow (~575 nm) emission bands. The optimized concentration of Dy3+ ions is 6.0 mol % after which the concentration quenching takes place. The process of energy transfer between Dy3+ ions is due to dipole‐dipole interaction, which was confirmed by applying Dexter's theory. The CIE chromaticity coordinates for the optimized phosphor were (0.329, 0.377), and they lie in the white light region. The emission intensity remains to be 83.41% at 373 K to that of at room temperature, which indicates good thermal stability. The above mentioned results demonstrate that Ca3Bi(PO4)3 is a potential phosphor for solid‐state lighting applications.

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RET : (^{4} {normalF}_{9 / 2} +^{6} {normalH}_{15 / 2} \to^{6} {normalH}_{15 / 2} +^{4} {normalF}_{9 / 2})

CR 1 : (^{4} {normalF}_{9 / 2} +^{6} {normalH}_{15 / 2} \to^{6} {normalF}_{11 / 2},^{6} {normalH}_{9 / 2} +^{6} {normalF}_{3 / 2})

…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

White light emitting thermally stable bismuth phosphate phosphor Ca₃Bi(PO₄)₃:Dy³⁺ for solid‐state lighting applications

Sahu

Jayasimhadri

2019

J Am Ceram Soc

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“…However, this strategy has a number of disadvantages, such as high correlated color temperature (CCT > 4500 K) and low color rendering (CRI) index (R a < 75)[13, 14]. An alternative strategy to generate white light is to coat near UV emitting LEDs with a mixture of high efficiency red, green and blue emitting phosphors which produces excellent CRI values and better color stability[15, 16]. However, it suffers from poor efficiency due to the large Stokes shift between emission and excitation of the near UV excitable phosphor.…”

Section: Introductionmentioning

confidence: 99%

Development of a Blue Emitting Calcium-Aluminate Phosphor

Kim

2016

PLoS ONE

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We report methodological advances that enhance the phosphorescence efficiency of a blue-emitting calcium aluminate phosphor (CaAl2O4: Eu2+, Nd3+). The investigation of long-persistence blue-emitting phosphors is highly desirable due to their promising applications, such as white LEDs; however, the development of highly efficient blue-emitting phosphors is still challenging. Here, we have quantitatively characterized the phosphorescence properties of the blue-emitting phosphor CaAl2O4:Eu2+, Nd3+ with various compositions and directly related these properties to the quality of its luminescence. We optimized the composition of the activator Eu2+ and the co-activator Nd3+, the doping conditions with alkaline earth metals, alkali metals, and Si to create crystallographic distortions and, finally, the flux conditions to find the best parameters for bright and persistent blue-emitting phosphors. Our research has identified several doping compositions with good to excellent performance, with which we have demonstrated bright and persistent phosphors with afterglow characteristics superior to those of conventional phosphors.

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“…Generally speaking, the leading commercial strategy of generating WLED is by combining a blue InGaN LED chip with the yellow phosphors (Y 3 Al 5 O 12 :Ce 3+ ), which was packed on the chip surface using epoxy resin or silicone. However, the WLED device based on this phosphor suffers a poor color‐rendering index (CRI, Ra < 80) and a high correlated color temperature (CCT ≈ 7750 K) caused by the lack of red spectral components, which limits the further expansion of the LED applications . Current lighting technology based on the combination of UV LED chips with red, green, and blue phosphors can improve these problems to some extent .…”

Section: Introductionmentioning

confidence: 99%

“…However, the WLED device based on this phosphor suffers a poor color-rendering index (CRI, Ra < 80) and a high correlated color temperature (CCT % 7750 K) caused by the lack of red spectral components, which limits the further expansion of the LED applications. 5,6 Current lighting technology based on the combination of UV LED chips with red, green, and blue phosphors can improve these problems to some extent. 7 However, the mixture of different emission bands of multiple phosphors may lower the luminous efficiency by reason of color reabsorption.…”

Section: Introductionmentioning

confidence: 99%

New single‐component multicolor emission Na_1−xAl_1+2xSi_1−2xO4:xBi³⁺/Eu³⁺ phosphors via energy transfer

Song

et al. 2018

J Am Ceram Soc

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A series of emission‐tunable Na1−xAl1+2xSi1−2xO4:xBi3+/Eu3+ phosphors were synthesized via high temperature solid‐state reaction method. The luminescence properties, energy transfer from Bi3+ to Eu3+ ions, color tuning, thermal stability and quantum efficiency were systematically investigated. Especially, in the host, a certain amount of Si4+ were replaced by Al3+ in order to remedy the charge compensating defect, so that, the emission intensity had been improved. The results of Rietveld refinements, the analysis of SEM mapping and the fourier transform infrared (FT‐IR) indicated that this charge balance strategy was an effective method. Meanwhile, the energy transfer from Bi3+ to Eu3+ can be inferred and confirmed and the mechanisms were demonstrated to quadrupole–quadrupole interaction. The emission hue can be tuned from blue to pink, and finally to orange red light by properly varying the ratio of Bi3+ and Eu3+. Importantly, when the temperature was raised to 150°C, the integrated emission intensity was 71.20% of the initial value for NAS:1%Bi3+,2%Eu3+ samples indicating that these phosphors had excellent thermal stability and stable color (no emission shift). All these properties indicate that the developed phosphors may be potentially used as single‐component color‐tunable‐emitting phosphors for UV light‐emitting diodes.

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Emerging cool white light emission from Dy³⁺ doped single phase alkaline earth niobate phosphors for indoor lighting applications

Cited by 178 publications

References 54 publications

White light emitting thermally stable bismuth phosphate phosphor Ca₃Bi(PO₄)₃:Dy³⁺ for solid‐state lighting applications

White light emitting thermally stable bismuth phosphate phosphor Ca₃Bi(PO₄)₃:Dy³⁺ for solid‐state lighting applications

Development of a Blue Emitting Calcium-Aluminate Phosphor

New single‐component multicolor emission Na_1−xAl_1+2xSi_1−2xO4:xBi³⁺/Eu³⁺ phosphors via energy transfer

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Emerging cool white light emission from Dy3+ doped single phase alkaline earth niobate phosphors for indoor lighting applications

Cited by 178 publications

References 54 publications

White light emitting thermally stable bismuth phosphate phosphor Ca3Bi(PO4)3:Dy3+ for solid‐state lighting applications

White light emitting thermally stable bismuth phosphate phosphor Ca3Bi(PO4)3:Dy3+ for solid‐state lighting applications

Development of a Blue Emitting Calcium-Aluminate Phosphor

New single‐component multicolor emission Na1−xAl1+2xSi1−2xO4:xBi3+/Eu3+ phosphors via energy transfer

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Emerging cool white light emission from Dy³⁺ doped single phase alkaline earth niobate phosphors for indoor lighting applications

White light emitting thermally stable bismuth phosphate phosphor Ca₃Bi(PO₄)₃:Dy³⁺ for solid‐state lighting applications

White light emitting thermally stable bismuth phosphate phosphor Ca₃Bi(PO₄)₃:Dy³⁺ for solid‐state lighting applications

New single‐component multicolor emission Na_1−xAl_1+2xSi_1−2xO4:xBi³⁺/Eu³⁺ phosphors via energy transfer