Abstract

We report an investigation of the optical performance of a conformal-shaped phosphor coating fabricated using pulsed spray techniques on horizontal LED chips. Both the nitride and YAG:Ce phosphor mixed configuration and the multilayer configuration were studied. Also, 3535-packaged LED devices with the two typical phosphor configurations were prepared and analyzed. The results revealed that the LED devices with multilayer phosphor configurations emitted an average of 5.6% more radiant flux than those with mixed phosphor configurations. However, such LED devices presented an interesting reversed tendency in the luminosity measurements, which were 0.3 lm and 6 lm lower at 10 mA and 350 mA, respectively. Finally, the color rendering index (CRI) and correlated color temperature (CCT) homogeneity of the LED devices were further analyzed. A twofold reduction in CCT variation was observed compared with the conventional phosphor coating methods. It was found that the mixed phosphor LED devices demonstrated outstanding angular CCT distributions for viewing angles ranging from -80° to 0°, and a CCT variation of only 45 K was detected, while the multilayer phosphor coating had higher color rendering capabilities, reaching a CRI<sub>general</sub> value as high as 85.6. A promising guideline found through this work is that the pulse-sprayed conformal phosphor configuration would particularly be able to improve the light quality of LED devices by a significant amount: the mixed phosphor configuration achieves excellent CCT homogeneity, and the multilayer phosphor configuration reveals a novel concept for fabricating a low-CCT and high-CRI LED device with less nitride phosphor. The findings of our research should provide valuable insight to LED industries.

© 2012 IEEE

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2012 (7)

R. Farrell, E. Young, F. Wu, S. DenBaars, J. Speck, "Materials and growth issues for high-performance nonpolar and semipolar light-emitting devices," Semicond. Sci. Technol. 27, 024001 (2012).

D. A. Browne, E. C. Young, J. R. Lang, C. A. Hurni, J. S. Speck, "Indium and impurity incorporation in InGaN films on polar, nonpolar, and semipolar GaN orientations grown by ammonia molecular beam epitaxy," J. Vacuum Sci. Technol. A 30, 041513-041513-8 (2012).

P. S. Hsu, "444.9 nm semipolar (112) laser diode grown on an intentionally stress relaxed InGaN waveguiding layer," Appl. Phys. Lett. 100, 021104 (2012).

Y. Zhang, L. Wu, M. Ji, B. Wand, Y. Kong, J. Xu, "Structure and photoluminescence properties of KSr4(BO3)3:Eu3+ red-emitting phosphor," Opt. Mater. Express 2, 92-102 (2012).

H. Li, "Tunable photoluminescence properties of Eu (II)-and Sm (III)-coactivated Ca9Y(PO4)7 and energy transfer between Eu (II) and Sm (III)," Opt. Mater. Express 2, 443-451 (2012).

P. F. Smet, K. Van den Eeckhout, A. J. J. Bos, E. van der Kolk, P. Dorenbos, "Temperature and wavelength dependent trap filling in M2Si5N8: Eu (M=Ca, Sr, Ba) persistent phosphors," J. Lumin. 132, 682-689 (2012).

H. Zheng, "Conformal phosphor coating using capillary microchannel for controlling color deviation of phosphor-converted white light-emitting diodes," Opt. Express 20, 5092-5098 (2012).

2011 (13)

L. Chen, C. I. Chu, R. S. Liu, "Improvement of emission efficiency and color rendering of high-power LED by controlling size of phosphor particles and utilization of different phosphors," Microelectron. Reliab. (2011).

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, 555-557 (2011).

A. I. Zhmakin, "Enhancement of light extraction from light emitting diodes," Phys. Rep. 498, 189-241 (2011).

P. F. Smet, A. B. Parmentier, D. Poelman, "Selecting conversion phosphors for white light-emitting diodes," J. Electrochem. Soc. 158, R37 (2011).

C. Sommer, "The impact of light scattering on the radiant flux of phosphor-converted high power white light-emitting diodes," J. Lightw. Technol. 29, 2285-2291 (2011).

H. C. Kuo, "Patterned structure of remote phosphor for phosphor-converted white LEDs," Opt. Express 19, A930-A936 (2011).

S. E. Brinkley, "Robust thermal performance of Sr2Si5N8:Eu2+: An efficient red emitting phosphor for light emitting diode based white lighting," Appl. Phys. Lett. 99, 241106-241106-3 (2011).

H. Zhao, G. Liu, J. Zhang, J. D. Poplawsky, V. Dierolf, N. Tansu, "Approaches for high internal quantum efficiency green InGaN light-emitting diodes with large overlap quantum wells," Opt. Express 19, A991-A1007 (2011).

J. Zhang, N. Tansu, "Improvement in spontaneous emission rates for InGaN quantum wells on ternary InGaN substrate for light-emitting diodes," J. Appl. Phys. 110, 113110-113110-5 (2011).

H. Zhao, J. Zhang, G. Liu, N. Tansu, "Surface plasmon dispersion engineering via double-metallic Au/Ag layers for III-nitride based light-emitting diodes," Appl. Phys. Lett. 98, 151115-151115-3 (2011).

X. H. Li, R. Song, Y. K. Ee, P. Kumnorkeaw, J. F. Gilchrist, N. Tansu, "Light extraction efficiency and radiation patterns of III-nitride light-emitting diodes with colloidal microlens arrays with various aspect ratios," IEEE Photon. J. 3, 489-499 (2011).

E. Rangel, E. Matioli, Y. S. Choi, C. Weisbuch, J. S. Speck, E. L. Hu, "Directionality control through selective excitation of low-order guided modes in thin-film InGaN photonic crystal light-emitting diodes," Appl. Phys. Lett. 98, 081104-081104-3 (2011).

Y. Li, "Defect-reduced green GaInN/GaN light-emitting diode on nanopatterned sapphire," Appl. Phys. Lett. 98, 151102-151102-3 (2011).

2010 (5)

H. Zhao, G. Liu, R. A. Arif, N. Tansu, "Current injection efficiency induced efficiency-droop in InGaN quantum well light-emitting diodes," Solid-State Electron. 54, 1119-1124 (2010).

Z. Y. Liu, S. Liu, K. Wang, X.-B. Luo, "Studies on optical consistency of white LEDs affected by phosphor thickness and concentration using optical simulation," IEEE Trans. Compon. Packag. Technol. 33, 680-687 (2010).

C. Sommer, "The impact of inhomogeneities in the phosphor distribution on the device performance of phosphor-converted high-power white LED light sources," J. Lightw. Technol. 28, 3226-3232 (2010).

J. P. You, N. T. Tran, F. G. Shi, "Light extraction enhanced white light-emitting diodes with multi-layered phosphor configuration," Opt. Express 18, 5055-5060 (2010).

H. T. Huang, C. C. Tsai, Y. P. Huang, "Conformal phosphor coating using pulsed spray to reduce color deviation of white LEDs," Opt. Express 18, A201-A206 (2010).

2009 (10)

Z. Liu, S. Liu, K. Wang, X. Luo, "Optical analysis of phosphor's location for high-power light-emitting diodes," IEEE Trans. Device Mater. Rel. 9, 65-73 (2009).

B. Hou, H. Rao, J. Li, "Methods of increasing luminous efficiency of phosphor-converted LED realized by conformal phosphor coating," J. Display Technol. 5, 57-60 (2009).

C. Sommer, "A detailed study on the requirements for angular homogeneity of phosphor converted high power white LED light sources," Opt. Mater. 31, 837-848 (2009).

C. C. Tsai, "Investigation of Ce: YAG doping effect on thermal aging for high-power phosphor-converted white-light-emitting diodes," IEEE Trans. Device Mater. Rel. 9, 367-371 (2009).

S. C. Huang, "Particle size effect on the packaging performance of YAG: Ce phosphors in white LEDs," Int. J. Appl. Ceram. Technol. 6, 465-469 (2009).

C. Sommer, "The effect of the phosphor particle sizes on the angular homogeneity of phosphor-converted high-power white LED light sources," IEEE J. Sel. Topics Quantum Electron. 15, 1181-1188 (2009).

J. P. You, F. G. Shi, "Effect of phosphor particle size on luminous efficacy of phosphor-converted white LED," J. Lightw. Technol. 27, 5145-5150 (2009).

Y. K. Ee, J. M. Biser, W. Cao, H. M. Chan, R. P. Vinci, N. Tansu, "Metalorganic vapor phase epitaxy of III-nitride light-emitting diodes on nanopatterned AGOG sapphire substrate by abbreviated growth mode," IEEE J. Sel. Topics Quantum Electron. 15, 1066-1072 (2009).

S. Pimputkar, J. S. Speck, S. P. DenBaars, S. Nakamura, "Prospects for LED lighting," Nat. Photon. 3, 180-182 (2009).

Y. K. Ee, P. Kumnorkaew, R. A. Arif, H. Tong, J. F. Gilchrist, N. Tansu, "Light extraction efficiency enhancement of InGaN quantum wells light-emitting diodes with polydimethylsiloxane concave microstructures," Opt. Express 17, 13747-13757 (2009).

2008 (2)

W. Wang, J. Tang, S. T. V. Hsu, J. Wang, B. P. Sullivan, "Energy transfer and enriched emission spectrum in Cr and Ce co-doped Y3Al512 yellow phosphors," Chem. Phys. Lett. 457, 103-105 (2008).

N. T. Tran, F. G. Shi, "Studies of phosphor concentration and thickness for phosphor-based white light-emitting-diodes," J. Lightw. Technol. 26, 3556-3559 (2008).

2007 (4)

R. J. Xie, N. Hirosaki, "Silicon-based oxynitride and nitride phosphors for white LEDs—A review," Sci. Tech. Adv. Mater. 8, 588-600 (2007).

M. R. Krames, "Status and future of high-power light-emitting diodes for solid-state lighting," J. Display Technol. 3, 160-175 (2007).

J. Brodrick, "Next-generation lighting initiative at the U.S. Department of Energy: Catalyzing science into the marketplace," J. Display Technol. 3, 91-97 (2007).

M. P. Liao, "DC current-induced rollover of illumination efficiency of GaN-Based power LEDs," IEEE Photon. Technol. Lett. 19, 2000-2002 (2007).

2006 (3)

H. Luo, "Trapped whispering-gallery optical modes in white light-emitting diode lamps with remote phosphor," Appl. Phys. Lett. 89, 041125 (2006).

Y. Q. Li, "Luminescence properties of red-emitting M2Si5N8:Eu2+ (M=Ca, Sr, Ba) LED conversion phosphors," J. Alloys Compd. 417, 273-279 (2006).

E. F. Schubert, J. K. Kim, H. Luo, J.-Q. Xi, "Solid-state lighting—A benevolent technology," Rep. Prog. Phys. 69, 3069 (2006).

2005 (2)

E. F. Schubert, J. K. Kim, "Solid-state light sources getting smart," Science 308, 1274 (2005).

H. Luo, J. K. Kim, E. F. Schubert, J. Cho, C. Sone, Y. Park, "Analysis of high-power packages for phosphor-based white-light-emitting diodes," Appl. Phys. Lett. 86, 243505 (2005).

2002 (3)

F. Steranka, "High power LEDs—Technology status and market applications," Phys. Status Solidi A 194, 380-388 (2002).

M. R. Krames, "High-power III-nitride emitters for solid-state lighting," Phys. Status Solidi A 192, 237-245 (2002).

D. A. Steigerwald, "Illumination with solid state lighting technology," IEEE J. Sel. Topics Quantum Electron. 8, 310-320 (2002).

1995 (1)

T. Schlieper, W. Schnick, "Nitrido-silicate. I. hochtemperatur-synthese und kristallstruktur von Ca2Si5N8," Z. Anorg. Allg. Chem. 621, 1037-1041 (1995).

Appl. Phys. Lett. (7)

P. S. Hsu, "444.9 nm semipolar (112) laser diode grown on an intentionally stress relaxed InGaN waveguiding layer," Appl. Phys. Lett. 100, 021104 (2012).

H. Zhao, J. Zhang, G. Liu, N. Tansu, "Surface plasmon dispersion engineering via double-metallic Au/Ag layers for III-nitride based light-emitting diodes," Appl. Phys. Lett. 98, 151115-151115-3 (2011).

Y. Li, "Defect-reduced green GaInN/GaN light-emitting diode on nanopatterned sapphire," Appl. Phys. Lett. 98, 151102-151102-3 (2011).

E. Rangel, E. Matioli, Y. S. Choi, C. Weisbuch, J. S. Speck, E. L. Hu, "Directionality control through selective excitation of low-order guided modes in thin-film InGaN photonic crystal light-emitting diodes," Appl. Phys. Lett. 98, 081104-081104-3 (2011).

S. E. Brinkley, "Robust thermal performance of Sr2Si5N8:Eu2+: An efficient red emitting phosphor for light emitting diode based white lighting," Appl. Phys. Lett. 99, 241106-241106-3 (2011).

H. Luo, J. K. Kim, E. F. Schubert, J. Cho, C. Sone, Y. Park, "Analysis of high-power packages for phosphor-based white-light-emitting diodes," Appl. Phys. Lett. 86, 243505 (2005).

H. Luo, "Trapped whispering-gallery optical modes in white light-emitting diode lamps with remote phosphor," Appl. Phys. Lett. 89, 041125 (2006).

Chem. Phys. Lett. (1)

W. Wang, J. Tang, S. T. V. Hsu, J. Wang, B. P. Sullivan, "Energy transfer and enriched emission spectrum in Cr and Ce co-doped Y3Al512 yellow phosphors," Chem. Phys. Lett. 457, 103-105 (2008).

IEEE J. Sel. Topics Quantum Electron. (3)

Y. K. Ee, J. M. Biser, W. Cao, H. M. Chan, R. P. Vinci, N. Tansu, "Metalorganic vapor phase epitaxy of III-nitride light-emitting diodes on nanopatterned AGOG sapphire substrate by abbreviated growth mode," IEEE J. Sel. Topics Quantum Electron. 15, 1066-1072 (2009).

C. Sommer, "The effect of the phosphor particle sizes on the angular homogeneity of phosphor-converted high-power white LED light sources," IEEE J. Sel. Topics Quantum Electron. 15, 1181-1188 (2009).

D. A. Steigerwald, "Illumination with solid state lighting technology," IEEE J. Sel. Topics Quantum Electron. 8, 310-320 (2002).

IEEE Photon. J. (1)

X. H. Li, R. Song, Y. K. Ee, P. Kumnorkeaw, J. F. Gilchrist, N. Tansu, "Light extraction efficiency and radiation patterns of III-nitride light-emitting diodes with colloidal microlens arrays with various aspect ratios," IEEE Photon. J. 3, 489-499 (2011).

IEEE Photon. Technol. Lett. (2)

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, 555-557 (2011).

M. P. Liao, "DC current-induced rollover of illumination efficiency of GaN-Based power LEDs," IEEE Photon. Technol. Lett. 19, 2000-2002 (2007).

IEEE Trans. Compon. Packag. Technol. (1)

Z. Y. Liu, S. Liu, K. Wang, X.-B. Luo, "Studies on optical consistency of white LEDs affected by phosphor thickness and concentration using optical simulation," IEEE Trans. Compon. Packag. Technol. 33, 680-687 (2010).

IEEE Trans. Device Mater. Rel. (2)

C. C. Tsai, "Investigation of Ce: YAG doping effect on thermal aging for high-power phosphor-converted white-light-emitting diodes," IEEE Trans. Device Mater. Rel. 9, 367-371 (2009).

Z. Liu, S. Liu, K. Wang, X. Luo, "Optical analysis of phosphor's location for high-power light-emitting diodes," IEEE Trans. Device Mater. Rel. 9, 65-73 (2009).

Int. J. Appl. Ceram. Technol. (1)

S. C. Huang, "Particle size effect on the packaging performance of YAG: Ce phosphors in white LEDs," Int. J. Appl. Ceram. Technol. 6, 465-469 (2009).

J. Alloys Compd. (1)

Y. Q. Li, "Luminescence properties of red-emitting M2Si5N8:Eu2+ (M=Ca, Sr, Ba) LED conversion phosphors," J. Alloys Compd. 417, 273-279 (2006).

J. Appl. Phys. (1)

J. Zhang, N. Tansu, "Improvement in spontaneous emission rates for InGaN quantum wells on ternary InGaN substrate for light-emitting diodes," J. Appl. Phys. 110, 113110-113110-5 (2011).

J. Display Technol. (3)

J. Electrochem. Soc. (1)

P. F. Smet, A. B. Parmentier, D. Poelman, "Selecting conversion phosphors for white light-emitting diodes," J. Electrochem. Soc. 158, R37 (2011).

J. Lightw. Technol. (4)

J. P. You, F. G. Shi, "Effect of phosphor particle size on luminous efficacy of phosphor-converted white LED," J. Lightw. Technol. 27, 5145-5150 (2009).

C. Sommer, "The impact of light scattering on the radiant flux of phosphor-converted high power white light-emitting diodes," J. Lightw. Technol. 29, 2285-2291 (2011).

N. T. Tran, F. G. Shi, "Studies of phosphor concentration and thickness for phosphor-based white light-emitting-diodes," J. Lightw. Technol. 26, 3556-3559 (2008).

C. Sommer, "The impact of inhomogeneities in the phosphor distribution on the device performance of phosphor-converted high-power white LED light sources," J. Lightw. Technol. 28, 3226-3232 (2010).

J. Lumin. (1)

P. F. Smet, K. Van den Eeckhout, A. J. J. Bos, E. van der Kolk, P. Dorenbos, "Temperature and wavelength dependent trap filling in M2Si5N8: Eu (M=Ca, Sr, Ba) persistent phosphors," J. Lumin. 132, 682-689 (2012).

J. Vacuum Sci. Technol. A (1)

D. A. Browne, E. C. Young, J. R. Lang, C. A. Hurni, J. S. Speck, "Indium and impurity incorporation in InGaN films on polar, nonpolar, and semipolar GaN orientations grown by ammonia molecular beam epitaxy," J. Vacuum Sci. Technol. A 30, 041513-041513-8 (2012).

Microelectron. Reliab. (1)

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Nat. Photon. (1)

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