Effects of packaging structure on optical performances of phosphor converted light emitting diodes

Abstract

Effects of tilt angles of reflective cup structure and phosphor surface geometries on light extraction efficiency and angular color uniformity (ACU) of phosphor converted light emitting diodes (pcLED) are investigated by Monte Carlo ray-tracing simulations. It is found that tilt angles of reflective cup and phosphor surface geometries affect the light extraction efficiency and the ACU distinctly. When the tilt angle varied from 60° to 15°, the light extraction efficiency of LED can achieve the improvements of 13.87%, 18.25% and 14.79% respectively, when the phosphor surface geometry is concave, flat and convex, respectively. It is also found the variety law of phosphor concentrations with the change of tilt angles and phosphor surface geometries to maintain a fixed correlated color temperature (CCT).

Keywords

phosphor / packaging structure / reflective cup / light emitting diodes (LEDs)

References

[1] Liu S, Luo X B. LED Packaging for Lighting Applications: Design, Manufacturing, and Testing. New York: John Wiley Press, 2011

[2] Yu R Y, Jin S Z, Cen S Y, Liang P. Effect of the phosphor geometry on the luminous flux of phosphor-converted light-emitting diodes. IEEE Photonics Technology Letters, 2010, 22(23): 1765–1767

[3] Lin Y C, You J P, Tran N T, He Y Z, Shi F G.Packaging of phosphor based high power white LEDs: Effects of phosphor concentration and packaging configuration. Journal of Electronic Packaging, 2011, 133(1): 011009–011014

[4] Shuai Y, He Y, Tran N T, Shi F G. Angular CCT uniformity of phosphor converted white LEDs: Effects of phosphor materials and packaging structures. IEEE Photonics Technology Letters, 2011, 23(3): 137–139

[5] Masui H, Nakamura S, Denbaars S P. Effects of phosphor application geometry on white light-emitting diodes. Japanese Journal of Applied Physics, 2006, 45(34): L910–L912

[6] Liu Z Y, Liu S, Wang K, Luo X B. Studies on optical consistency of white LEDs affected by phosphor thickness and concentration using optical simulation. IEEE Transactions on Components and Packaging Technologies, 2010, 33(4): 680–687

[7] Wang K, Wu D, Chen F, Liu Z Y, Luo X B, Liu S. Angular color uniformity enhancement of white light-emitting diodes integrated with freeform lenses. Optics Letters, 2010, 35(11): 1860–1862

[8] Lee T X, Gao K F, Chien W T, Sun C C. Light extraction analysis for GaN-based LEDs with pyramid array. Optics Letters, 2007, 15: 6670–6675

[9] Liu Z Y, Wang K, Luo X B, Liu S. Precise optical modeling of blue light-emitting diodes by Monte Carlo ray-tracing. Optics Express, 2010, 18(9): 9398–9412

[10] Liu Z Y, Liu S, Wang K, Luo X B. Optical analysis of color distribution in white LEDs with various packaging methods. IEEE Photonics Technology Letters, 2008, 20(24): 2027–2029

[11] Liu Z Y, Liu S, Wang K, Luo X B. Measurement and numerical studies of optical properties of YAG:Ce phosphor for white light-emitting diode packaging. Applied Optics, 2010, 49(2): 247–257

[12] Hu R, Luo X B, Liu S. Study on the optical properties of conformal coating light-emitting diodes by Monte Carlo simulation. IEEE Photonics Technology Letters, 2011, 23(22): 1673–1675

Acknowledgements

The authors would like to acknowledge the financial support in part from the Major State Basic Research Development Program of the Ministry of Science and Technology of China (No. 2011CB013105), and in part by the National Natural Science Foundation of China (Grant No. 2011AA03A109).

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg