Increasing light extraction efficiency is an important task when it comes to manufacturing a powerful white light emitting diode with high luminous flux per watt. In this paper the fabrication of a pyramid-shaped 3-dimensional phosphor coating is reported. It is represented by a phosphor cover, shaped into an array of pyramid like formations. It is proposed that such a structure can improve the light extraction efficiency and the color distribution characteristics of any phosphor-converted white LED. The luminous flux and luminous efficacy are being studied as a function of the forward current across the die. It was found out that with this kind of technique it was possible to achieve an 8% - 14% increase in the efficacy of the pc-LED. This increase of light output power is being attributed to the reduction of the phenomena of total internal reflection (TIR) inside the packaging module.
References
[1]
Gorrotxategi, P., Consonni, M. and Gasse, A. (2015) Optical Efficiency Characterization of LED Phosphors Using a Double Integrating Sphere System. Journal of Solid State Lighting, 2, 1-14. https://doi.org/10.1186/s40539-014-0020-7
[2]
Steigerwald, D.A., Bhat, J.C., Collins, D., Fletcher, R.M., Holcomb, M.O., Ludowise, M.J., Martin, P.S. and Rudaz, S.L. (2002) Illumination with Solid State Lighting Technology. Journal of Selected Topics Quantum Electron, 8, 310-320. https://doi.org/10.1109/2944.999186
[3]
Zheng, Y. and Stough, M. (2008) White LED with High Package Extraction Efficiency. Osram Sylvania Product Inc. Central Research and Service Laboratory, Wilmington. https://doi.org/10.2172/963890
[4]
Narendran, N. (2005) Improved Performance White LED. Fifth International Conference on Solid State Lighting, San Diego, 31 July 2000, 45-50. https://doi.org/10.1117/12.625921
[5]
Narendran, N., Gu, Y., Freyssinier-Nova, J.P. and Zhu, Y. (2005) Extracting Phosphor-Scattered Photons to Improve White LED EFFIciency. Physica Status Solidi(a), 202, 60-62. https://doi.org/10.1002/pssa.200510015
[6]
Lin, M., Ying, S.P., Lin, M.Y., Tai, K.Y., Tai, S.C., Liu, C.H., Chen, J.C. and Sun, C.C. (2010) Ring Remote Phosphor Structure for Phosphor-Converted White LEDs. IEEE Photonics Technology Letters, 22, 574-576. https://doi.org/10.1109/LPT.2010.2043088
[7]
Chen, D., Xiang, W., Liang, X., Zhong, J., Yu, H., Ding, M., Lu, H. and Ji, Z. (2015) Advances in Transparent Glass—Ceramic Phosphors for White Light-Emitting Diodes—A Review. Journal of the European Ceramic Society, 35, 859-869. https://doi.org/10.1016/j.jeurceramsoc.2014.10.002
[8]
Nishiura, S., Tanabe, S., Fujioka, K. and Fujimoto, Y. (2011) Properties of Transparent Ce:YAG Ceramic Phosphors for White LED. Optical Materials, 33, 688-691. https://doi.org/10.1016/j.optmat.2010.06.005
[9]
Chao, W.-H., Wu, R.-J. and Wu, T.-B. (2010) Structural and Luminescent Properties of YAG:Ce Thin Film Phosphor. Journal of Alloys and Compounds, 506, 98-102. https://doi.org/10.1016/j.jallcom.2010.04.136
[10]
Nyman, M., Shea-Rohwer, L.E., Martin, J.E. and Provencio, P. (2009) Nano-YAG:Ce Mechanisms of Growth and Epoxy-Encapsulation. Chemistry of Materials, 21, 1536-1542. https://doi.org/10.1021/cm803137h
[11]
Sun, C.C., Chang, Y., Yang, T.H., Chung, T.Y., Chen, C.C., Lee, T., Li, D., Lu, C., Ting, Z.Y., Glorieux, B., Chen, Y.C., Lai, K.Y. and Liu, C.Y. (2014) Packaging Efficiency in Phosphor-Converted White LEDs and Its Impact to the Limit of Luminous Efficacy. Journal of Solid State Lighting, 1, 1-17. https://doi.org/10.1186/s40539-014-0019-0
[12]
Choi, H.S. and Moon, C.H. (2016) Improvement of the Light Extraction Effi-ciency of LED Package Using Double-Layered Encapsulant with Curved Interface. Journal of Nanoelectronics and Optoelectronics, 11, 170-174(5).
[13]
Shin, M.H., Hong, H.G., Kim, H.J. and Kim, Y.J. (2014) Enhancement of Optical Extraction Efficiency in White LED Package with Quantum Dot Phosphors and Air-Gap Structure. Applied Physics Express, 7, No. 052101. https://doi.org/10.7567/apex.7.052101
[14]
Shin, J.H., Choi, H.J., Han, K.S., Ra, S., Choi, K.W. and Lee, H. (2013) Effect of Anti-Reflective Nano-Patterns on LED Package. Current Applied Physics, 13, 93-97. https://doi.org/10.1016/j.cap.2013.01.014
