ImprovedPerformanceWhiteLED-LightingResearchCenter.pdfVIP

Improved Performance White LED Nadarajah Narendran Lighting Research Center Rensselaer Polytechnic Institute 21 Union St., Troy, NY 12180 Narendran, N. 2005. Improved performance white LED. Fifth International Conference on Solid State Lighting, Proceedings of SPIE 5941, 45-50. Bellingham, WA: International Society of Optical Engineers. Copyright 2005 Society of Photo-Optical Instrumentation Engineers. This paper was published in the Fifth International Conference on Solid State Lighting, Proceedings of SPIE and is made available as an electronic preprint with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. Invited Paper Improved Performance White LED Nadarajah Narendran Lighting Research Center Rensselaer Polytechnic Institute, Troy, NY 12180 ABSTRACT This paper describes work leading to the development of a new packaging method for white LEDs, called scattered photon extraction (SPE). Previous work by our group showed that the traditional placement of the phosphor close to the die negatively affects the overall luminous efficacy and lumen maintenance of phosphor-converted white LEDs. The new SPE method enables higher luminous efficacy by placing the phosphor at a remote location from the die and by shaping the lens surrounding the die to extract a significant portion of the back-transferred light before it is absorbed by packa