Abstract

A packaging scheme utilizing omni-directional reflective (ODR) optical coating is described to enhance the light extraction of near UV excited, phosphor-converted LEDs. A simple 1D model was developed to analyze the spectra of the extracted light measured with an integration-sphere as a function of phosphor layer concentration and thickness. Quantitative determination of the absorption coefficients at the pump and fluorescent light wavelength along with the conversion coefficient of phosphors were obtained. The reflection of the ODR film and the back reflector are also characterized. These parameters are then used for efficiency optimization of the present packaging scheme. A maximum enhancement of 40% can be expected with the materials and the configuration used in the present work.

© 2009 OSA

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  1. Y. Narukawa, M. Sano, M. Ichikawa, S. Minato, T. Sakamoto, T. Yamada, and T. Mukai, “Improvement of Luminous Efficiency in White Light Emitting Diodes by Reducing a Forward-bias Voltage,” Jpn. J. Appl. Phys. 46, Part 2, 36–40 (2007).
    [CrossRef]
  2. J. S. Kim, P. E. Jeon, J. C. Choi, H. L. Park, S. I. Mho, and G. C. Kim, “Warm-white-light emitting diode utilizing a single-phase full-color Ba3MgSi2O8:Eu2+, Mn2+ phosphor,” Appl. Phys. Lett. 84(15), 2931 (2004).
    [CrossRef]
  3. C.-H. Kuo, J.-K. Sheu, S.-J. Chang, Y.-K. Su, L.-W. Wu, J.-M. Tsai, C. H. Liu, and R. K. Wu, “n-UV+Blue/Green /Red White Light Emitting Diode Lamps,” Jpn. J. Appl. Phys. 42,(Part 1,No. 4B), 2284–2287 (2003).
    [CrossRef]
  4. J. K. Park, M. A. Lim, C. H. Kim, H. D. Park, J. T. Park, and S. Y. Choi, “White light-emitting diodes of GaN-based Sr2SiO4: Eu and the luminescent properties,” Appl. Phys. Lett. 82(5), 683 (2003).
    [CrossRef]
  5. Y.-D. Huh, J.-H. Shim, Y. Kim, and Y. R. Do, “Optical properties of three-band white light emitting diodes,” J. Electrochem. Soc. 150(2), H57 (2003).
    [CrossRef]
  6. M. H. Crawford, “LEDs for Solid-State Lighting: Performance Challenges and Recent Advances,” IEEE J Sel. Top. Quantum Electron. 15, 1026 (2009).
  7. C. C. Chang, R. Chern, C. C. Chang, C. Chu, J. Y. Chi, J. Su, I. Chan, and J. T. Wang, “Monte Carlo Simulation of Optical Properties of Phosphor-Screened Ultraviolet Light in a White Light-Emitting Device,” Jpn. J. Appl. Phys. 44(8), 6056–6061 (2005).
    [CrossRef]
  8. E.-Y. Kang, E. Wu, and D.-M. Wang, “Modeling white light-emitting diodes with phosphor layers,” Appl. Phys. Lett. 89(23), 231102 (2006).
    [CrossRef]

2009 (1)

M. H. Crawford, “LEDs for Solid-State Lighting: Performance Challenges and Recent Advances,” IEEE J Sel. Top. Quantum Electron. 15, 1026 (2009).

2006 (1)

E.-Y. Kang, E. Wu, and D.-M. Wang, “Modeling white light-emitting diodes with phosphor layers,” Appl. Phys. Lett. 89(23), 231102 (2006).
[CrossRef]

2005 (1)

C. C. Chang, R. Chern, C. C. Chang, C. Chu, J. Y. Chi, J. Su, I. Chan, and J. T. Wang, “Monte Carlo Simulation of Optical Properties of Phosphor-Screened Ultraviolet Light in a White Light-Emitting Device,” Jpn. J. Appl. Phys. 44(8), 6056–6061 (2005).
[CrossRef]

2004 (1)

J. S. Kim, P. E. Jeon, J. C. Choi, H. L. Park, S. I. Mho, and G. C. Kim, “Warm-white-light emitting diode utilizing a single-phase full-color Ba3MgSi2O8:Eu2+, Mn2+ phosphor,” Appl. Phys. Lett. 84(15), 2931 (2004).
[CrossRef]

2003 (3)

C.-H. Kuo, J.-K. Sheu, S.-J. Chang, Y.-K. Su, L.-W. Wu, J.-M. Tsai, C. H. Liu, and R. K. Wu, “n-UV+Blue/Green /Red White Light Emitting Diode Lamps,” Jpn. J. Appl. Phys. 42,(Part 1,No. 4B), 2284–2287 (2003).
[CrossRef]

J. K. Park, M. A. Lim, C. H. Kim, H. D. Park, J. T. Park, and S. Y. Choi, “White light-emitting diodes of GaN-based Sr2SiO4: Eu and the luminescent properties,” Appl. Phys. Lett. 82(5), 683 (2003).
[CrossRef]

Y.-D. Huh, J.-H. Shim, Y. Kim, and Y. R. Do, “Optical properties of three-band white light emitting diodes,” J. Electrochem. Soc. 150(2), H57 (2003).
[CrossRef]

Chan, I.

C. C. Chang, R. Chern, C. C. Chang, C. Chu, J. Y. Chi, J. Su, I. Chan, and J. T. Wang, “Monte Carlo Simulation of Optical Properties of Phosphor-Screened Ultraviolet Light in a White Light-Emitting Device,” Jpn. J. Appl. Phys. 44(8), 6056–6061 (2005).
[CrossRef]

Chang, C. C.

C. C. Chang, R. Chern, C. C. Chang, C. Chu, J. Y. Chi, J. Su, I. Chan, and J. T. Wang, “Monte Carlo Simulation of Optical Properties of Phosphor-Screened Ultraviolet Light in a White Light-Emitting Device,” Jpn. J. Appl. Phys. 44(8), 6056–6061 (2005).
[CrossRef]

C. C. Chang, R. Chern, C. C. Chang, C. Chu, J. Y. Chi, J. Su, I. Chan, and J. T. Wang, “Monte Carlo Simulation of Optical Properties of Phosphor-Screened Ultraviolet Light in a White Light-Emitting Device,” Jpn. J. Appl. Phys. 44(8), 6056–6061 (2005).
[CrossRef]

Chang, S.-J.

C.-H. Kuo, J.-K. Sheu, S.-J. Chang, Y.-K. Su, L.-W. Wu, J.-M. Tsai, C. H. Liu, and R. K. Wu, “n-UV+Blue/Green /Red White Light Emitting Diode Lamps,” Jpn. J. Appl. Phys. 42,(Part 1,No. 4B), 2284–2287 (2003).
[CrossRef]

Chern, R.

C. C. Chang, R. Chern, C. C. Chang, C. Chu, J. Y. Chi, J. Su, I. Chan, and J. T. Wang, “Monte Carlo Simulation of Optical Properties of Phosphor-Screened Ultraviolet Light in a White Light-Emitting Device,” Jpn. J. Appl. Phys. 44(8), 6056–6061 (2005).
[CrossRef]

Chi, J. Y.

C. C. Chang, R. Chern, C. C. Chang, C. Chu, J. Y. Chi, J. Su, I. Chan, and J. T. Wang, “Monte Carlo Simulation of Optical Properties of Phosphor-Screened Ultraviolet Light in a White Light-Emitting Device,” Jpn. J. Appl. Phys. 44(8), 6056–6061 (2005).
[CrossRef]

Choi, J. C.

J. S. Kim, P. E. Jeon, J. C. Choi, H. L. Park, S. I. Mho, and G. C. Kim, “Warm-white-light emitting diode utilizing a single-phase full-color Ba3MgSi2O8:Eu2+, Mn2+ phosphor,” Appl. Phys. Lett. 84(15), 2931 (2004).
[CrossRef]

Choi, S. Y.

J. K. Park, M. A. Lim, C. H. Kim, H. D. Park, J. T. Park, and S. Y. Choi, “White light-emitting diodes of GaN-based Sr2SiO4: Eu and the luminescent properties,” Appl. Phys. Lett. 82(5), 683 (2003).
[CrossRef]

Chu, C.

C. C. Chang, R. Chern, C. C. Chang, C. Chu, J. Y. Chi, J. Su, I. Chan, and J. T. Wang, “Monte Carlo Simulation of Optical Properties of Phosphor-Screened Ultraviolet Light in a White Light-Emitting Device,” Jpn. J. Appl. Phys. 44(8), 6056–6061 (2005).
[CrossRef]

Crawford, M. H.

M. H. Crawford, “LEDs for Solid-State Lighting: Performance Challenges and Recent Advances,” IEEE J Sel. Top. Quantum Electron. 15, 1026 (2009).

Do, Y. R.

Y.-D. Huh, J.-H. Shim, Y. Kim, and Y. R. Do, “Optical properties of three-band white light emitting diodes,” J. Electrochem. Soc. 150(2), H57 (2003).
[CrossRef]

Huh, Y.-D.

Y.-D. Huh, J.-H. Shim, Y. Kim, and Y. R. Do, “Optical properties of three-band white light emitting diodes,” J. Electrochem. Soc. 150(2), H57 (2003).
[CrossRef]

Jeon, P. E.

J. S. Kim, P. E. Jeon, J. C. Choi, H. L. Park, S. I. Mho, and G. C. Kim, “Warm-white-light emitting diode utilizing a single-phase full-color Ba3MgSi2O8:Eu2+, Mn2+ phosphor,” Appl. Phys. Lett. 84(15), 2931 (2004).
[CrossRef]

Kang, E.-Y.

E.-Y. Kang, E. Wu, and D.-M. Wang, “Modeling white light-emitting diodes with phosphor layers,” Appl. Phys. Lett. 89(23), 231102 (2006).
[CrossRef]

Kim, C. H.

J. K. Park, M. A. Lim, C. H. Kim, H. D. Park, J. T. Park, and S. Y. Choi, “White light-emitting diodes of GaN-based Sr2SiO4: Eu and the luminescent properties,” Appl. Phys. Lett. 82(5), 683 (2003).
[CrossRef]

Kim, G. C.

J. S. Kim, P. E. Jeon, J. C. Choi, H. L. Park, S. I. Mho, and G. C. Kim, “Warm-white-light emitting diode utilizing a single-phase full-color Ba3MgSi2O8:Eu2+, Mn2+ phosphor,” Appl. Phys. Lett. 84(15), 2931 (2004).
[CrossRef]

Kim, J. S.

J. S. Kim, P. E. Jeon, J. C. Choi, H. L. Park, S. I. Mho, and G. C. Kim, “Warm-white-light emitting diode utilizing a single-phase full-color Ba3MgSi2O8:Eu2+, Mn2+ phosphor,” Appl. Phys. Lett. 84(15), 2931 (2004).
[CrossRef]

Kim, Y.

Y.-D. Huh, J.-H. Shim, Y. Kim, and Y. R. Do, “Optical properties of three-band white light emitting diodes,” J. Electrochem. Soc. 150(2), H57 (2003).
[CrossRef]

Kuo, C.-H.

C.-H. Kuo, J.-K. Sheu, S.-J. Chang, Y.-K. Su, L.-W. Wu, J.-M. Tsai, C. H. Liu, and R. K. Wu, “n-UV+Blue/Green /Red White Light Emitting Diode Lamps,” Jpn. J. Appl. Phys. 42,(Part 1,No. 4B), 2284–2287 (2003).
[CrossRef]

Lim, M. A.

J. K. Park, M. A. Lim, C. H. Kim, H. D. Park, J. T. Park, and S. Y. Choi, “White light-emitting diodes of GaN-based Sr2SiO4: Eu and the luminescent properties,” Appl. Phys. Lett. 82(5), 683 (2003).
[CrossRef]

Liu, C. H.

C.-H. Kuo, J.-K. Sheu, S.-J. Chang, Y.-K. Su, L.-W. Wu, J.-M. Tsai, C. H. Liu, and R. K. Wu, “n-UV+Blue/Green /Red White Light Emitting Diode Lamps,” Jpn. J. Appl. Phys. 42,(Part 1,No. 4B), 2284–2287 (2003).
[CrossRef]

Mho, S. I.

J. S. Kim, P. E. Jeon, J. C. Choi, H. L. Park, S. I. Mho, and G. C. Kim, “Warm-white-light emitting diode utilizing a single-phase full-color Ba3MgSi2O8:Eu2+, Mn2+ phosphor,” Appl. Phys. Lett. 84(15), 2931 (2004).
[CrossRef]

Park, H. D.

J. K. Park, M. A. Lim, C. H. Kim, H. D. Park, J. T. Park, and S. Y. Choi, “White light-emitting diodes of GaN-based Sr2SiO4: Eu and the luminescent properties,” Appl. Phys. Lett. 82(5), 683 (2003).
[CrossRef]

Park, H. L.

J. S. Kim, P. E. Jeon, J. C. Choi, H. L. Park, S. I. Mho, and G. C. Kim, “Warm-white-light emitting diode utilizing a single-phase full-color Ba3MgSi2O8:Eu2+, Mn2+ phosphor,” Appl. Phys. Lett. 84(15), 2931 (2004).
[CrossRef]

Park, J. K.

J. K. Park, M. A. Lim, C. H. Kim, H. D. Park, J. T. Park, and S. Y. Choi, “White light-emitting diodes of GaN-based Sr2SiO4: Eu and the luminescent properties,” Appl. Phys. Lett. 82(5), 683 (2003).
[CrossRef]

Park, J. T.

J. K. Park, M. A. Lim, C. H. Kim, H. D. Park, J. T. Park, and S. Y. Choi, “White light-emitting diodes of GaN-based Sr2SiO4: Eu and the luminescent properties,” Appl. Phys. Lett. 82(5), 683 (2003).
[CrossRef]

Sheu, J.-K.

C.-H. Kuo, J.-K. Sheu, S.-J. Chang, Y.-K. Su, L.-W. Wu, J.-M. Tsai, C. H. Liu, and R. K. Wu, “n-UV+Blue/Green /Red White Light Emitting Diode Lamps,” Jpn. J. Appl. Phys. 42,(Part 1,No. 4B), 2284–2287 (2003).
[CrossRef]

Shim, J.-H.

Y.-D. Huh, J.-H. Shim, Y. Kim, and Y. R. Do, “Optical properties of three-band white light emitting diodes,” J. Electrochem. Soc. 150(2), H57 (2003).
[CrossRef]

Su, J.

C. C. Chang, R. Chern, C. C. Chang, C. Chu, J. Y. Chi, J. Su, I. Chan, and J. T. Wang, “Monte Carlo Simulation of Optical Properties of Phosphor-Screened Ultraviolet Light in a White Light-Emitting Device,” Jpn. J. Appl. Phys. 44(8), 6056–6061 (2005).
[CrossRef]

Su, Y.-K.

C.-H. Kuo, J.-K. Sheu, S.-J. Chang, Y.-K. Su, L.-W. Wu, J.-M. Tsai, C. H. Liu, and R. K. Wu, “n-UV+Blue/Green /Red White Light Emitting Diode Lamps,” Jpn. J. Appl. Phys. 42,(Part 1,No. 4B), 2284–2287 (2003).
[CrossRef]

Tsai, J.-M.

C.-H. Kuo, J.-K. Sheu, S.-J. Chang, Y.-K. Su, L.-W. Wu, J.-M. Tsai, C. H. Liu, and R. K. Wu, “n-UV+Blue/Green /Red White Light Emitting Diode Lamps,” Jpn. J. Appl. Phys. 42,(Part 1,No. 4B), 2284–2287 (2003).
[CrossRef]

Wang, D.-M.

E.-Y. Kang, E. Wu, and D.-M. Wang, “Modeling white light-emitting diodes with phosphor layers,” Appl. Phys. Lett. 89(23), 231102 (2006).
[CrossRef]

Wang, J. T.

C. C. Chang, R. Chern, C. C. Chang, C. Chu, J. Y. Chi, J. Su, I. Chan, and J. T. Wang, “Monte Carlo Simulation of Optical Properties of Phosphor-Screened Ultraviolet Light in a White Light-Emitting Device,” Jpn. J. Appl. Phys. 44(8), 6056–6061 (2005).
[CrossRef]

Wu, E.

E.-Y. Kang, E. Wu, and D.-M. Wang, “Modeling white light-emitting diodes with phosphor layers,” Appl. Phys. Lett. 89(23), 231102 (2006).
[CrossRef]

Wu, L.-W.

C.-H. Kuo, J.-K. Sheu, S.-J. Chang, Y.-K. Su, L.-W. Wu, J.-M. Tsai, C. H. Liu, and R. K. Wu, “n-UV+Blue/Green /Red White Light Emitting Diode Lamps,” Jpn. J. Appl. Phys. 42,(Part 1,No. 4B), 2284–2287 (2003).
[CrossRef]

Wu, R. K.

C.-H. Kuo, J.-K. Sheu, S.-J. Chang, Y.-K. Su, L.-W. Wu, J.-M. Tsai, C. H. Liu, and R. K. Wu, “n-UV+Blue/Green /Red White Light Emitting Diode Lamps,” Jpn. J. Appl. Phys. 42,(Part 1,No. 4B), 2284–2287 (2003).
[CrossRef]

Appl. Phys. Lett. (3)

J. S. Kim, P. E. Jeon, J. C. Choi, H. L. Park, S. I. Mho, and G. C. Kim, “Warm-white-light emitting diode utilizing a single-phase full-color Ba3MgSi2O8:Eu2+, Mn2+ phosphor,” Appl. Phys. Lett. 84(15), 2931 (2004).
[CrossRef]

J. K. Park, M. A. Lim, C. H. Kim, H. D. Park, J. T. Park, and S. Y. Choi, “White light-emitting diodes of GaN-based Sr2SiO4: Eu and the luminescent properties,” Appl. Phys. Lett. 82(5), 683 (2003).
[CrossRef]

E.-Y. Kang, E. Wu, and D.-M. Wang, “Modeling white light-emitting diodes with phosphor layers,” Appl. Phys. Lett. 89(23), 231102 (2006).
[CrossRef]

IEEE J Sel. Top. Quantum Electron. (1)

M. H. Crawford, “LEDs for Solid-State Lighting: Performance Challenges and Recent Advances,” IEEE J Sel. Top. Quantum Electron. 15, 1026 (2009).

J. Electrochem. Soc. (1)

Y.-D. Huh, J.-H. Shim, Y. Kim, and Y. R. Do, “Optical properties of three-band white light emitting diodes,” J. Electrochem. Soc. 150(2), H57 (2003).
[CrossRef]

Jpn. J. Appl. Phys. (2)

C.-H. Kuo, J.-K. Sheu, S.-J. Chang, Y.-K. Su, L.-W. Wu, J.-M. Tsai, C. H. Liu, and R. K. Wu, “n-UV+Blue/Green /Red White Light Emitting Diode Lamps,” Jpn. J. Appl. Phys. 42,(Part 1,No. 4B), 2284–2287 (2003).
[CrossRef]

C. C. Chang, R. Chern, C. C. Chang, C. Chu, J. Y. Chi, J. Su, I. Chan, and J. T. Wang, “Monte Carlo Simulation of Optical Properties of Phosphor-Screened Ultraviolet Light in a White Light-Emitting Device,” Jpn. J. Appl. Phys. 44(8), 6056–6061 (2005).
[CrossRef]

Other (1)

Y. Narukawa, M. Sano, M. Ichikawa, S. Minato, T. Sakamoto, T. Yamada, and T. Mukai, “Improvement of Luminous Efficiency in White Light Emitting Diodes by Reducing a Forward-bias Voltage,” Jpn. J. Appl. Phys. 46, Part 2, 36–40 (2007).
[CrossRef]

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Figures (5)

Fig. 1
Fig. 1

The transmission spectra of the ODR film for the p-polarisation (a) and s-polarisation(b) at various incident angles used in the present work; (c) the schematics of the sample holds used for the present work; (d) the emission spectra for the UV excited LED with (dashed line)and without (solid) the ODR film. P1 (P2 ) is the integrated intensity for the area shorter (longer) than 430nm.

Fig. 2
Fig. 2

(a) Schematics showing the parameters used in the 1D model. (b) Transmitted UV power vs. thickness and the phosphors concentration measured with an integration sphere. The corresponding concentrations are 1,3, 5, 10, 15, and 20wt% from the top line to the bottom.

Fig. 3
Fig. 3

Measured visible light output with and without ODRs and with and without the back reflectors. (1) and (2) are measured with the back reflector but with and without the ODR films. (3) and (4) are measured without the back reflector with and without the ODR film. The lines are the curve fitting to the experimental results according the present calculation. Parts (a) through (f) are for 1, 3, 5, 10, 15, and 20 wt % phosphors, respectively.

Fig. 4
Fig. 4

(a)The absorption(α1 and α2 ) and conversion coefficients (β) determined from the measured data; (b) reflectivity parameters (r1 and r2 ) due to the ODR films and the back reflectors.

Fig. 5
Fig. 5

The equal power contours based on the model and the material constants shown in Fig. 4 with the reflection coefficients are r1 = 1.0 and r2 = 2.0. The unit for the contour is mW. Part (a) corresponds to the case without ODR; Part (b) corresponds to the case with ODR. The thick red line in (b) is the contour with the maximum power value of the part (a). It represents the region of enhancement by ODR. The x’s in (a) and (b) mark the location of the maxima. The inset in (b) is a magnified view of the region shown in the dashed box.

Equations (8)

Equations on this page are rendered with MathJax. Learn more.

dP 1 + /dz  = - α 1 P 1 +
dP 1 - /dz  =    α 1 P 1 -
dP 2 + /dz  = - α 2 P 2 + + β P 1 + /2 + β P 1 - /2
dP 2 - /dz  =   α 2 P 2  - - β P 1 + /2- β P 1 - /2
P 1 + (z) = A 1 + exp(- α 1 z )
P 1 - (z) =  A 1 - exp( α 1 z)
P 2 + (z) = A 2 + exp(- α 2 z ) + B 2 + exp(- α 1 z + C 2 + exp( α 1 z )
P 2 (z) = A 2 1 exp( α 2 z ) + B 2 exp(- α 1 z + C 2 exp( α 1 z )

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