Abstract

For a systematic approach to improve the reliability and the white light quality of phosphor converted light-emitting diodes (LEDs) it is imperative to gain a better understanding of the individual parameters that affect color temperature constancy and maintenance. By means of a combined optical and thermal simulation procedure, in this contribution we give a comprehensive discussion on the impact of different current driving schemes on the thermal load of the color conversion elements (CCEs) of phosphor converted LEDs. We show that on the one hand a decreasing duty cycle under pulse width modulation driving conditions may cause a notable temperature variation and on the other hand also effects due to the non-linearity between the blue radiant flux and the current have to be considered for the thermal load of the CCEs.

© 2013 OSA

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    [CrossRef]
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    [CrossRef]
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    [CrossRef] [PubMed]
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    [CrossRef]
  10. Z.-Y. Liu, C. Li, B.-H. Yu, Y.-H. Wang, H.-B. Niu, “Uniform white emission of WLEDs realized by multilayer phosphor with pyramidal shape and inversed concentration distribution,” IEEE Photon. Technol. Lett. 24(17), 1558–1560 (2012).
    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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2012 (6)

Z.-Y. Liu, C. Li, B.-H. Yu, Y.-H. Wang, H.-B. Niu, “Uniform white emission of WLEDs realized by multilayer phosphor with pyramidal shape and inversed concentration distribution,” IEEE Photon. Technol. Lett. 24(17), 1558–1560 (2012).
[CrossRef]

Z.-Y. Liu, C. Li, B.-H. Yu, Y.-H. Wang, H.-B. Niu, “Effects of YAG:Ce phosphor particle size on luminous flux and angular color uniformity of phosphor-converted white LEDs,” J. Disp. Technol. 8(6), 329–335 (2012).
[CrossRef]

C. Sommer, P. Hartmann, P. Pachler, H. Hoschopf, F. P. Wenzl, “White light quality of phosphor converted light-emitting diodes: A phosphor materials perspective of view,” J. Alloy. Comp. 520, 146–152 (2012).
[CrossRef]

K. H. Loo, Y. M. Lai, S.-C. Tan, C. K. Tse, “On the color stability of phosphor-converted white LEDs under DC, PWM, and bilevel drive,” IEEE Trans. Power Electron. 27(2), 974–984 (2012).
[CrossRef]

H. Zheng, X. Luo, R. Hu, B. Cao, X. Fu, Y. Wang, S. Liu, “Conformal phosphor coating using capillary microchannel for controlling color deviation of phosphor-converted white light-emitting diodes,” Opt. Express 20(5), 5092–5098 (2012).
[CrossRef] [PubMed]

C.-C. Sun, C.-Y. Chen, C.-C. Chen, C.-Y. Chiu, Y.-N. Peng, Y.-H. Wang, T.-H. Yang, T.-Y. Chung, C.-Y. Chung, “High uniformity in angular correlated-color-temperature distribution of white LEDs from 2800K to 6500K,” Opt. Express 20(6), 6622–6630 (2012).
[CrossRef] [PubMed]

2011 (3)

C. Sommer, F. Reil, J. R. Krenn, P. Hartmann, P. Pachler, H. Hoschopf, F. P. Wenzl, “The impact of light scattering on the radiant flux of phosphor-converted high power white light-emitting diodes,” J. Lightwave Technol. 29(15), 2285–2291 (2011).
[CrossRef]

Y. Shuai, Y. He, N. T. Tran, F. G. Shi, “Angular CCT uniformity of phosphor converted white LEDs: Effects of phosphor materials and packaging structures,” IEEE Photon. Technol. Lett. 23(3), 137–139 (2011).
[CrossRef]

B. Yan, N. T. Tran, J.-P. You, F. G. Shi, “Can junction temperature alone characterize thermal performance of white LED emitters?” IEEE Photon. Technol. Lett. 23(9), 555–557 (2011).
[CrossRef]

2010 (1)

2009 (2)

K. H. Loo, W.-K. Lun, S.-C. Tan, Y. M. Lai, C. K. Tse, “On driving techniques for LEDs: Toward a generalized methodology,” IEEE Trans. Power Electron. 24(12), 2967–2976 (2009).
[CrossRef]

C. Geuzaine, J.-F. Remacle, “Gmsh: A 3-D finite element mesh generator with built-in pre- and post-processing facilities,” Int. J. Numer. Methods Eng. 79(11), 1309–1331 (2009).
[CrossRef]

2008 (2)

Z. Liu, S. Liu, K. Wang, X. Luo, “Optical analysis of color distribution in white LEDs with various packaging methods,” IEEE Photon. Technol. Lett. 20(24), 2027–2029 (2008).
[CrossRef]

N. T. Tran, F. G. Shi, “Studies of phosphor concentration and thickness for phosphor-based white light-emitting-diodes,” J. Lightwave Technol. 26(21), 3556–3559 (2008).
[CrossRef]

2007 (1)

M. R. Krames, O. B. Shchekin, R. Mueller-Mach, G. O. Mueller, L. Zhou, G. Harbers, M. G. Craford, “Status and future of high-power light-emitting diodes for solid-state lighting,” J. Disp. Technol. 3(2), 160–175 (2007).
[CrossRef]

2006 (1)

E. F. Schubert, J. K. Kim, H. Luo, J. Q. Xi, “Solid-state lighting – a benevolent technology,” Rep. Prog. Phys. 69(12), 3069–3099 (2006).
[CrossRef]

2005 (1)

M. Dyble, N. Narendran, A. Bierman, T. Klein, “Impact of dimming white LEDs: Chromaticity shifts due to different dimming methods,” Proc. SPIE 5941, 59411H, 59411H-9 (2005).
[CrossRef]

2004 (1)

N. Narendran, L. Deng, R. M. Pysar, Y. Gu, H. Yu, “Performance characteristics of high-power light-emitting diodes,” Proc. SPIE 5187, 267–275 (2004).
[CrossRef]

Bierman, A.

M. Dyble, N. Narendran, A. Bierman, T. Klein, “Impact of dimming white LEDs: Chromaticity shifts due to different dimming methods,” Proc. SPIE 5941, 59411H, 59411H-9 (2005).
[CrossRef]

Cao, B.

Chen, C.-C.

Chen, C.-Y.

Chen, F.

Chiu, C.-Y.

Chung, C.-Y.

Chung, T.-Y.

Craford, M. G.

M. R. Krames, O. B. Shchekin, R. Mueller-Mach, G. O. Mueller, L. Zhou, G. Harbers, M. G. Craford, “Status and future of high-power light-emitting diodes for solid-state lighting,” J. Disp. Technol. 3(2), 160–175 (2007).
[CrossRef]

Deng, L.

N. Narendran, L. Deng, R. M. Pysar, Y. Gu, H. Yu, “Performance characteristics of high-power light-emitting diodes,” Proc. SPIE 5187, 267–275 (2004).
[CrossRef]

Dyble, M.

M. Dyble, N. Narendran, A. Bierman, T. Klein, “Impact of dimming white LEDs: Chromaticity shifts due to different dimming methods,” Proc. SPIE 5941, 59411H, 59411H-9 (2005).
[CrossRef]

Fu, X.

Geuzaine, C.

C. Geuzaine, J.-F. Remacle, “Gmsh: A 3-D finite element mesh generator with built-in pre- and post-processing facilities,” Int. J. Numer. Methods Eng. 79(11), 1309–1331 (2009).
[CrossRef]

Gu, Y.

N. Narendran, L. Deng, R. M. Pysar, Y. Gu, H. Yu, “Performance characteristics of high-power light-emitting diodes,” Proc. SPIE 5187, 267–275 (2004).
[CrossRef]

Harbers, G.

M. R. Krames, O. B. Shchekin, R. Mueller-Mach, G. O. Mueller, L. Zhou, G. Harbers, M. G. Craford, “Status and future of high-power light-emitting diodes for solid-state lighting,” J. Disp. Technol. 3(2), 160–175 (2007).
[CrossRef]

Hartmann, P.

C. Sommer, P. Hartmann, P. Pachler, H. Hoschopf, F. P. Wenzl, “White light quality of phosphor converted light-emitting diodes: A phosphor materials perspective of view,” J. Alloy. Comp. 520, 146–152 (2012).
[CrossRef]

C. Sommer, F. Reil, J. R. Krenn, P. Hartmann, P. Pachler, H. Hoschopf, F. P. Wenzl, “The impact of light scattering on the radiant flux of phosphor-converted high power white light-emitting diodes,” J. Lightwave Technol. 29(15), 2285–2291 (2011).
[CrossRef]

He, Y.

Y. Shuai, Y. He, N. T. Tran, F. G. Shi, “Angular CCT uniformity of phosphor converted white LEDs: Effects of phosphor materials and packaging structures,” IEEE Photon. Technol. Lett. 23(3), 137–139 (2011).
[CrossRef]

Hoschopf, H.

C. Sommer, P. Hartmann, P. Pachler, H. Hoschopf, F. P. Wenzl, “White light quality of phosphor converted light-emitting diodes: A phosphor materials perspective of view,” J. Alloy. Comp. 520, 146–152 (2012).
[CrossRef]

C. Sommer, F. Reil, J. R. Krenn, P. Hartmann, P. Pachler, H. Hoschopf, F. P. Wenzl, “The impact of light scattering on the radiant flux of phosphor-converted high power white light-emitting diodes,” J. Lightwave Technol. 29(15), 2285–2291 (2011).
[CrossRef]

Hu, R.

Kim, J. K.

E. F. Schubert, J. K. Kim, H. Luo, J. Q. Xi, “Solid-state lighting – a benevolent technology,” Rep. Prog. Phys. 69(12), 3069–3099 (2006).
[CrossRef]

Klein, T.

M. Dyble, N. Narendran, A. Bierman, T. Klein, “Impact of dimming white LEDs: Chromaticity shifts due to different dimming methods,” Proc. SPIE 5941, 59411H, 59411H-9 (2005).
[CrossRef]

Krames, M. R.

M. R. Krames, O. B. Shchekin, R. Mueller-Mach, G. O. Mueller, L. Zhou, G. Harbers, M. G. Craford, “Status and future of high-power light-emitting diodes for solid-state lighting,” J. Disp. Technol. 3(2), 160–175 (2007).
[CrossRef]

Krenn, J. R.

Lai, Y. M.

K. H. Loo, Y. M. Lai, S.-C. Tan, C. K. Tse, “On the color stability of phosphor-converted white LEDs under DC, PWM, and bilevel drive,” IEEE Trans. Power Electron. 27(2), 974–984 (2012).
[CrossRef]

K. H. Loo, W.-K. Lun, S.-C. Tan, Y. M. Lai, C. K. Tse, “On driving techniques for LEDs: Toward a generalized methodology,” IEEE Trans. Power Electron. 24(12), 2967–2976 (2009).
[CrossRef]

Li, C.

Z.-Y. Liu, C. Li, B.-H. Yu, Y.-H. Wang, H.-B. Niu, “Uniform white emission of WLEDs realized by multilayer phosphor with pyramidal shape and inversed concentration distribution,” IEEE Photon. Technol. Lett. 24(17), 1558–1560 (2012).
[CrossRef]

Z.-Y. Liu, C. Li, B.-H. Yu, Y.-H. Wang, H.-B. Niu, “Effects of YAG:Ce phosphor particle size on luminous flux and angular color uniformity of phosphor-converted white LEDs,” J. Disp. Technol. 8(6), 329–335 (2012).
[CrossRef]

Liu, S.

Liu, Z.

K. Wang, D. Wu, F. Chen, Z. Liu, X. Luo, S. Liu, “Angular color uniformity enhancement of white light emitting diodes integrated with freeform lenses,” Opt. Lett. 35(11), 1860–1862 (2010).
[CrossRef] [PubMed]

Z. Liu, S. Liu, K. Wang, X. Luo, “Optical analysis of color distribution in white LEDs with various packaging methods,” IEEE Photon. Technol. Lett. 20(24), 2027–2029 (2008).
[CrossRef]

Liu, Z.-Y.

Z.-Y. Liu, C. Li, B.-H. Yu, Y.-H. Wang, H.-B. Niu, “Effects of YAG:Ce phosphor particle size on luminous flux and angular color uniformity of phosphor-converted white LEDs,” J. Disp. Technol. 8(6), 329–335 (2012).
[CrossRef]

Z.-Y. Liu, C. Li, B.-H. Yu, Y.-H. Wang, H.-B. Niu, “Uniform white emission of WLEDs realized by multilayer phosphor with pyramidal shape and inversed concentration distribution,” IEEE Photon. Technol. Lett. 24(17), 1558–1560 (2012).
[CrossRef]

Loo, K. H.

K. H. Loo, Y. M. Lai, S.-C. Tan, C. K. Tse, “On the color stability of phosphor-converted white LEDs under DC, PWM, and bilevel drive,” IEEE Trans. Power Electron. 27(2), 974–984 (2012).
[CrossRef]

K. H. Loo, W.-K. Lun, S.-C. Tan, Y. M. Lai, C. K. Tse, “On driving techniques for LEDs: Toward a generalized methodology,” IEEE Trans. Power Electron. 24(12), 2967–2976 (2009).
[CrossRef]

Lun, W.-K.

K. H. Loo, W.-K. Lun, S.-C. Tan, Y. M. Lai, C. K. Tse, “On driving techniques for LEDs: Toward a generalized methodology,” IEEE Trans. Power Electron. 24(12), 2967–2976 (2009).
[CrossRef]

Luo, H.

E. F. Schubert, J. K. Kim, H. Luo, J. Q. Xi, “Solid-state lighting – a benevolent technology,” Rep. Prog. Phys. 69(12), 3069–3099 (2006).
[CrossRef]

Luo, X.

Mueller, G. O.

M. R. Krames, O. B. Shchekin, R. Mueller-Mach, G. O. Mueller, L. Zhou, G. Harbers, M. G. Craford, “Status and future of high-power light-emitting diodes for solid-state lighting,” J. Disp. Technol. 3(2), 160–175 (2007).
[CrossRef]

Mueller-Mach, R.

M. R. Krames, O. B. Shchekin, R. Mueller-Mach, G. O. Mueller, L. Zhou, G. Harbers, M. G. Craford, “Status and future of high-power light-emitting diodes for solid-state lighting,” J. Disp. Technol. 3(2), 160–175 (2007).
[CrossRef]

Narendran, N.

M. Dyble, N. Narendran, A. Bierman, T. Klein, “Impact of dimming white LEDs: Chromaticity shifts due to different dimming methods,” Proc. SPIE 5941, 59411H, 59411H-9 (2005).
[CrossRef]

N. Narendran, L. Deng, R. M. Pysar, Y. Gu, H. Yu, “Performance characteristics of high-power light-emitting diodes,” Proc. SPIE 5187, 267–275 (2004).
[CrossRef]

Niu, H.-B.

Z.-Y. Liu, C. Li, B.-H. Yu, Y.-H. Wang, H.-B. Niu, “Uniform white emission of WLEDs realized by multilayer phosphor with pyramidal shape and inversed concentration distribution,” IEEE Photon. Technol. Lett. 24(17), 1558–1560 (2012).
[CrossRef]

Z.-Y. Liu, C. Li, B.-H. Yu, Y.-H. Wang, H.-B. Niu, “Effects of YAG:Ce phosphor particle size on luminous flux and angular color uniformity of phosphor-converted white LEDs,” J. Disp. Technol. 8(6), 329–335 (2012).
[CrossRef]

Pachler, P.

C. Sommer, P. Hartmann, P. Pachler, H. Hoschopf, F. P. Wenzl, “White light quality of phosphor converted light-emitting diodes: A phosphor materials perspective of view,” J. Alloy. Comp. 520, 146–152 (2012).
[CrossRef]

C. Sommer, F. Reil, J. R. Krenn, P. Hartmann, P. Pachler, H. Hoschopf, F. P. Wenzl, “The impact of light scattering on the radiant flux of phosphor-converted high power white light-emitting diodes,” J. Lightwave Technol. 29(15), 2285–2291 (2011).
[CrossRef]

Peng, Y.-N.

Pysar, R. M.

N. Narendran, L. Deng, R. M. Pysar, Y. Gu, H. Yu, “Performance characteristics of high-power light-emitting diodes,” Proc. SPIE 5187, 267–275 (2004).
[CrossRef]

Reil, F.

Remacle, J.-F.

C. Geuzaine, J.-F. Remacle, “Gmsh: A 3-D finite element mesh generator with built-in pre- and post-processing facilities,” Int. J. Numer. Methods Eng. 79(11), 1309–1331 (2009).
[CrossRef]

Schubert, E. F.

E. F. Schubert, J. K. Kim, H. Luo, J. Q. Xi, “Solid-state lighting – a benevolent technology,” Rep. Prog. Phys. 69(12), 3069–3099 (2006).
[CrossRef]

Shchekin, O. B.

M. R. Krames, O. B. Shchekin, R. Mueller-Mach, G. O. Mueller, L. Zhou, G. Harbers, M. G. Craford, “Status and future of high-power light-emitting diodes for solid-state lighting,” J. Disp. Technol. 3(2), 160–175 (2007).
[CrossRef]

Shi, F. G.

Y. Shuai, Y. He, N. T. Tran, F. G. Shi, “Angular CCT uniformity of phosphor converted white LEDs: Effects of phosphor materials and packaging structures,” IEEE Photon. Technol. Lett. 23(3), 137–139 (2011).
[CrossRef]

B. Yan, N. T. Tran, J.-P. You, F. G. Shi, “Can junction temperature alone characterize thermal performance of white LED emitters?” IEEE Photon. Technol. Lett. 23(9), 555–557 (2011).
[CrossRef]

N. T. Tran, F. G. Shi, “Studies of phosphor concentration and thickness for phosphor-based white light-emitting-diodes,” J. Lightwave Technol. 26(21), 3556–3559 (2008).
[CrossRef]

Shuai, Y.

Y. Shuai, Y. He, N. T. Tran, F. G. Shi, “Angular CCT uniformity of phosphor converted white LEDs: Effects of phosphor materials and packaging structures,” IEEE Photon. Technol. Lett. 23(3), 137–139 (2011).
[CrossRef]

Sommer, C.

C. Sommer, P. Hartmann, P. Pachler, H. Hoschopf, F. P. Wenzl, “White light quality of phosphor converted light-emitting diodes: A phosphor materials perspective of view,” J. Alloy. Comp. 520, 146–152 (2012).
[CrossRef]

C. Sommer, F. Reil, J. R. Krenn, P. Hartmann, P. Pachler, H. Hoschopf, F. P. Wenzl, “The impact of light scattering on the radiant flux of phosphor-converted high power white light-emitting diodes,” J. Lightwave Technol. 29(15), 2285–2291 (2011).
[CrossRef]

Sun, C.-C.

Tan, S.-C.

K. H. Loo, Y. M. Lai, S.-C. Tan, C. K. Tse, “On the color stability of phosphor-converted white LEDs under DC, PWM, and bilevel drive,” IEEE Trans. Power Electron. 27(2), 974–984 (2012).
[CrossRef]

K. H. Loo, W.-K. Lun, S.-C. Tan, Y. M. Lai, C. K. Tse, “On driving techniques for LEDs: Toward a generalized methodology,” IEEE Trans. Power Electron. 24(12), 2967–2976 (2009).
[CrossRef]

Tran, N. T.

Y. Shuai, Y. He, N. T. Tran, F. G. Shi, “Angular CCT uniformity of phosphor converted white LEDs: Effects of phosphor materials and packaging structures,” IEEE Photon. Technol. Lett. 23(3), 137–139 (2011).
[CrossRef]

B. Yan, N. T. Tran, J.-P. You, F. G. Shi, “Can junction temperature alone characterize thermal performance of white LED emitters?” IEEE Photon. Technol. Lett. 23(9), 555–557 (2011).
[CrossRef]

N. T. Tran, F. G. Shi, “Studies of phosphor concentration and thickness for phosphor-based white light-emitting-diodes,” J. Lightwave Technol. 26(21), 3556–3559 (2008).
[CrossRef]

Tse, C. K.

K. H. Loo, Y. M. Lai, S.-C. Tan, C. K. Tse, “On the color stability of phosphor-converted white LEDs under DC, PWM, and bilevel drive,” IEEE Trans. Power Electron. 27(2), 974–984 (2012).
[CrossRef]

K. H. Loo, W.-K. Lun, S.-C. Tan, Y. M. Lai, C. K. Tse, “On driving techniques for LEDs: Toward a generalized methodology,” IEEE Trans. Power Electron. 24(12), 2967–2976 (2009).
[CrossRef]

Wang, K.

K. Wang, D. Wu, F. Chen, Z. Liu, X. Luo, S. Liu, “Angular color uniformity enhancement of white light emitting diodes integrated with freeform lenses,” Opt. Lett. 35(11), 1860–1862 (2010).
[CrossRef] [PubMed]

Z. Liu, S. Liu, K. Wang, X. Luo, “Optical analysis of color distribution in white LEDs with various packaging methods,” IEEE Photon. Technol. Lett. 20(24), 2027–2029 (2008).
[CrossRef]

Wang, Y.

Wang, Y.-H.

C.-C. Sun, C.-Y. Chen, C.-C. Chen, C.-Y. Chiu, Y.-N. Peng, Y.-H. Wang, T.-H. Yang, T.-Y. Chung, C.-Y. Chung, “High uniformity in angular correlated-color-temperature distribution of white LEDs from 2800K to 6500K,” Opt. Express 20(6), 6622–6630 (2012).
[CrossRef] [PubMed]

Z.-Y. Liu, C. Li, B.-H. Yu, Y.-H. Wang, H.-B. Niu, “Effects of YAG:Ce phosphor particle size on luminous flux and angular color uniformity of phosphor-converted white LEDs,” J. Disp. Technol. 8(6), 329–335 (2012).
[CrossRef]

Z.-Y. Liu, C. Li, B.-H. Yu, Y.-H. Wang, H.-B. Niu, “Uniform white emission of WLEDs realized by multilayer phosphor with pyramidal shape and inversed concentration distribution,” IEEE Photon. Technol. Lett. 24(17), 1558–1560 (2012).
[CrossRef]

Wenzl, F. P.

C. Sommer, P. Hartmann, P. Pachler, H. Hoschopf, F. P. Wenzl, “White light quality of phosphor converted light-emitting diodes: A phosphor materials perspective of view,” J. Alloy. Comp. 520, 146–152 (2012).
[CrossRef]

C. Sommer, F. Reil, J. R. Krenn, P. Hartmann, P. Pachler, H. Hoschopf, F. P. Wenzl, “The impact of light scattering on the radiant flux of phosphor-converted high power white light-emitting diodes,” J. Lightwave Technol. 29(15), 2285–2291 (2011).
[CrossRef]

Wu, D.

Xi, J. Q.

E. F. Schubert, J. K. Kim, H. Luo, J. Q. Xi, “Solid-state lighting – a benevolent technology,” Rep. Prog. Phys. 69(12), 3069–3099 (2006).
[CrossRef]

Yan, B.

B. Yan, N. T. Tran, J.-P. You, F. G. Shi, “Can junction temperature alone characterize thermal performance of white LED emitters?” IEEE Photon. Technol. Lett. 23(9), 555–557 (2011).
[CrossRef]

Yang, T.-H.

You, J.-P.

B. Yan, N. T. Tran, J.-P. You, F. G. Shi, “Can junction temperature alone characterize thermal performance of white LED emitters?” IEEE Photon. Technol. Lett. 23(9), 555–557 (2011).
[CrossRef]

Yu, B.-H.

Z.-Y. Liu, C. Li, B.-H. Yu, Y.-H. Wang, H.-B. Niu, “Uniform white emission of WLEDs realized by multilayer phosphor with pyramidal shape and inversed concentration distribution,” IEEE Photon. Technol. Lett. 24(17), 1558–1560 (2012).
[CrossRef]

Z.-Y. Liu, C. Li, B.-H. Yu, Y.-H. Wang, H.-B. Niu, “Effects of YAG:Ce phosphor particle size on luminous flux and angular color uniformity of phosphor-converted white LEDs,” J. Disp. Technol. 8(6), 329–335 (2012).
[CrossRef]

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N. Narendran, L. Deng, R. M. Pysar, Y. Gu, H. Yu, “Performance characteristics of high-power light-emitting diodes,” Proc. SPIE 5187, 267–275 (2004).
[CrossRef]

Zheng, H.

Zhou, L.

M. R. Krames, O. B. Shchekin, R. Mueller-Mach, G. O. Mueller, L. Zhou, G. Harbers, M. G. Craford, “Status and future of high-power light-emitting diodes for solid-state lighting,” J. Disp. Technol. 3(2), 160–175 (2007).
[CrossRef]

IEEE Photon. Technol. Lett. (4)

Y. Shuai, Y. He, N. T. Tran, F. G. Shi, “Angular CCT uniformity of phosphor converted white LEDs: Effects of phosphor materials and packaging structures,” IEEE Photon. Technol. Lett. 23(3), 137–139 (2011).
[CrossRef]

Z.-Y. Liu, C. Li, B.-H. Yu, Y.-H. Wang, H.-B. Niu, “Uniform white emission of WLEDs realized by multilayer phosphor with pyramidal shape and inversed concentration distribution,” IEEE Photon. Technol. Lett. 24(17), 1558–1560 (2012).
[CrossRef]

B. Yan, N. T. Tran, J.-P. You, F. G. Shi, “Can junction temperature alone characterize thermal performance of white LED emitters?” IEEE Photon. Technol. Lett. 23(9), 555–557 (2011).
[CrossRef]

Z. Liu, S. Liu, K. Wang, X. Luo, “Optical analysis of color distribution in white LEDs with various packaging methods,” IEEE Photon. Technol. Lett. 20(24), 2027–2029 (2008).
[CrossRef]

IEEE Trans. Power Electron. (2)

K. H. Loo, W.-K. Lun, S.-C. Tan, Y. M. Lai, C. K. Tse, “On driving techniques for LEDs: Toward a generalized methodology,” IEEE Trans. Power Electron. 24(12), 2967–2976 (2009).
[CrossRef]

K. H. Loo, Y. M. Lai, S.-C. Tan, C. K. Tse, “On the color stability of phosphor-converted white LEDs under DC, PWM, and bilevel drive,” IEEE Trans. Power Electron. 27(2), 974–984 (2012).
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Int. J. Numer. Methods Eng. (1)

C. Geuzaine, J.-F. Remacle, “Gmsh: A 3-D finite element mesh generator with built-in pre- and post-processing facilities,” Int. J. Numer. Methods Eng. 79(11), 1309–1331 (2009).
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J. Alloy. Comp. (1)

C. Sommer, P. Hartmann, P. Pachler, H. Hoschopf, F. P. Wenzl, “White light quality of phosphor converted light-emitting diodes: A phosphor materials perspective of view,” J. Alloy. Comp. 520, 146–152 (2012).
[CrossRef]

J. Disp. Technol. (2)

Z.-Y. Liu, C. Li, B.-H. Yu, Y.-H. Wang, H.-B. Niu, “Effects of YAG:Ce phosphor particle size on luminous flux and angular color uniformity of phosphor-converted white LEDs,” J. Disp. Technol. 8(6), 329–335 (2012).
[CrossRef]

M. R. Krames, O. B. Shchekin, R. Mueller-Mach, G. O. Mueller, L. Zhou, G. Harbers, M. G. Craford, “Status and future of high-power light-emitting diodes for solid-state lighting,” J. Disp. Technol. 3(2), 160–175 (2007).
[CrossRef]

J. Lightwave Technol. (2)

Opt. Express (2)

Opt. Lett. (1)

Proc. SPIE (2)

N. Narendran, L. Deng, R. M. Pysar, Y. Gu, H. Yu, “Performance characteristics of high-power light-emitting diodes,” Proc. SPIE 5187, 267–275 (2004).
[CrossRef]

M. Dyble, N. Narendran, A. Bierman, T. Klein, “Impact of dimming white LEDs: Chromaticity shifts due to different dimming methods,” Proc. SPIE 5941, 59411H, 59411H-9 (2005).
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Rep. Prog. Phys. (1)

E. F. Schubert, J. K. Kim, H. Luo, J. Q. Xi, “Solid-state lighting – a benevolent technology,” Rep. Prog. Phys. 69(12), 3069–3099 (2006).
[CrossRef]

Other (7)

M. Arik, S. Weaver, C. Becker, M. Hsing, and A. Srivastava, “Effects of localized heat generations due to the color conversion in phosphor particles and layers of high brightness Light Emitting Diodes,” Proc. ASME/IEEE Int. Electronic Packaging Technical Conf. and Exhibition (InterPACK’03), Maui, HI, Jul. 6–11, (2003).
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P. Krivic, F. P. Wenzl, C. Sommer, G. Langer, P. Pachler, H. Hoschopf, P. Fulmek, and J. Nicolics, “Investigation of thermal properties of power LED illumination assemblies,” Proc. 35th Intern. Spring Seminar on Electron. Technol. (ISSE), 76 – 83 (2012).
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F. P. Wenzl, C. Sommer, P. Hartmann, P. Pachler, H. Hoschopf, G. Langer, P. Fulmek, J. Nicolics, White light quality of phosphor converted LEDs from a phosphor materials perspective of view: an evaluation based on combined thermal and optical simulations, Proc. of SPIE 8484, 848403 (2012)

Y. Gu, N. Narendran, T. Dong, and H. Wu, “Spectral and luminous efficacy change of high-power LEDs under different dimming methods,” Proc. of SPIE 6337, 63370J (2006).

R. Enigl, “Verfahren zur Messung der Wärmeübertragung durch freie Konvektion an elektronischen Bauelementen,” Masters Thesis, AEM-ISAS, University of Technology Vienna, (2000).

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Figures (7)

Fig. 1
Fig. 1

Top, left side: The model of the LED assembly consists of a blue emitting LED die with a square-shaped CCE placed on top of it. The sketches refer to an LED with a thick phosphor layer (CCE having a height h of 400 μm, a width b of 1040 µm and a concentration of the phosphor particles in the silicone matrix of 10 vol. %) and an LED with a thin phosphor layer (CCE with a height h of 200 μm, a width b of 1040 µm and a concentration of the phosphor particles in the silicone matrix of 16 vol. %). Right side: Sketch of the different operational conditions: PWM with duty cycles of 25% and 50%). Bottom, left side: 3D sketch of the model for the LED with a thick phosphor layer. The CCE (0 µm to 400 µm) is placed on top of the silicon substrate (0 µm to −100 µm) of the LED die. The printed circuit board consists of an aluminum substrate with a height of 1500 µm (below −260 µm) and a dielectric layer (−180 µm to −260 µm) as well as a copper layer on top of it. Latter and the adhesive layer range from −100 µm to −180 µm. Right side: Temperature distribution as determined for one exemplary operational condition superposed on the 3D model.

Fig. 2
Fig. 2

Top, left side: Line scans for the steady state temperature profiles along the vertical directions of the LED package with a thick phosphor layer assuming that the assembly is mounted on a cooler with a constant temperature of 300 K and that the quantum efficiency of the phosphor is 100%. The LED assembly is operated at currents which vary from 350 mA to 700 mA and 1000 mA. Right side: same as in the left side for the LED package with the thin phosphor layer. Bottom: Comparison of the thermal load of the CCEs of the LEDs with the thick and the thin phosphor layers for the three different currents investigated.

Fig. 3
Fig. 3

Top images: Thermal response of the LED with a thick phosphor layer on a power-on step (1000 mA, top left) and a power-off step (top right) for different positions within the LED package. Bottom images: Same as for the top images but for the LED with the thin phosphor layer.

Fig. 4
Fig. 4

Left side: Thermal response of the LED package with the thick phosphor layer operated under PWM conditions (1000 mA, duty cycle 50% at 100 Hz) for three different positions within the LED package. Also shown is the thermal response under DC conditions for IF/2, PE/2, PB/2 and a combination of PE/2 and PB/2, (PE/2@PB/2). Right side: Thermal response of the LED package shown in the left side on a larger time scale. In addition, the thermal response within (z = 100 μm) and on the top of the CCE (z = 400 μm) is added in this image.

Fig. 5
Fig. 5

Left side: Thermal response of the LED package with a thick phosphor layer operated under PWM operation conditions (1000 mA, duty cycle 50% at 100 Hz) at a position of z = 100 μm within the CCE. Also shown is the thermal response under DC conditions for IF/2, PE/2, PB/2 and a combination of PE/2 and PB/2, (PE/2@PB/2). Right side: Same as in the left side but at a position of z = 400 μm on the top of the CCE.

Fig. 6
Fig. 6

Left side: Thermal response of the LED with a thick phosphor layer operated under PWM conditions (1000 mA, duty cycle 25% at 100 Hz) at a position of z = 100 μm within the CCE. Also shown is the thermal response under DC drive current for IF/2, PE/2, PB/2 and a combination of PE/2 and PB/2, (PE/2@PB/2). Right side: Same as in the left side but at a position of z = 400 μm on the top of the CCE.

Fig. 7
Fig. 7

Left side: Thermal response of the LED with a thin phosphor layer operated under PWM conditions (1000 mA, duty cycle 25% at 100 Hz) at a position of z = 100 μm within the CCE. Also shown is the thermal response under DC drive current for IF/2, PE/2, PB/2 and a combination of PE/2 and PB/2, (PE/2@PB/2). Right side: Same as in the left side but at a position of z = 200 μm on the top of the CCE.

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