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Proceedings Paper

Fully phosphor-converted LEDs with Lumiramic phosphor technology
Author(s): Helmut Bechtel; Peter J. Schmidt; Andreas Tücks; Matthias Heidemann; Danielle Chamberlin; Regina Müller-Mach; Gerd O. Müller; Oleg Shchekin
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Paper Abstract

Fully phosphor-converted LEDs (FpcLeds) with saturated emission have been realized in the green and amber spectral region. With the Lumiramic™ phosphor technology it is possible to achieve high package efficiency with minimum transmission of blue light from the primary LED source. This is done by keeping the scattering properties of the phosphor layer low while the phosphor thickness is chosen to fully convert all blue LED emission. It is shown that this can be done not only for optically isotropic Lumiramic materials like garnets, but also for oxonitridosilicate materials like the green emitting Europium doped SrSi2O2N2, crystallizing in a triclinic lattice with three optical axes. The scattering power of the Lumiramic can be decreased to acceptable levels by increasing the size of the crystallites in the densely sintered ceramics. Light propagation is found to be described well with Mie scattering of mono-sized SrSi2O2N2 spheres with refraction index differing by 0.07 to the refractive index of a SrSi2O2N2 matrix material. Using this technology, the green-yellow gap of visible light emitting LEDs can be bridged and color tunable lamps with the efficiency and flux of today's white phosphor-converted LEDs become feasible.

Paper Details

Date Published: 18 August 2010
PDF: 11 pages
Proc. SPIE 7784, Tenth International Conference on Solid State Lighting, 77840W (18 August 2010); doi: 10.1117/12.864240
Show Author Affiliations
Helmut Bechtel, Philips Research Europe (Germany)
Peter J. Schmidt, Philips Research Europe (Germany)
Andreas Tücks, Philips Research Europe (Germany)
Matthias Heidemann, Philips Research Europe (Germany)
Danielle Chamberlin, Philips Lumileds Lighting Co. (United States)
Regina Müller-Mach, Philips Lumileds Lighting Co. (United States)
Gerd O. Müller, Philips Lumileds Lighting Co. (United States)
Oleg Shchekin, Philips Lumileds Lighting Co. (United States)

Published in SPIE Proceedings Vol. 7784:
Tenth International Conference on Solid State Lighting
Ian Ferguson; Matthew H. Kane; Nadarajah Narendran; Tsunemasa Taguchi, Editor(s)

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