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23 September 2011 YAG:Ce nanoparticle based converter layer for white LEDs
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Our work is devoted to the development of YAG:Ce3+ nanoparticle based films for white LEDs. Very stable suspensions of YAG:Ce nanoparticles are synthesized by a glycothermal method at relatively low temperature (300°C). A protected annealing in a silica matrix allows further treatment of these nanoparticles at high temperature without any aggregation and growth and with a significant improvement of their quantum yield and photostability. The obtained colloidal nanoparticles are finally incorporated into different matrices to be used as converter layer for white LEDs. First, the incorporation in epoxy caps confirms that the annealed particles are much more efficient than the as-made ones and leads to white light generation. YAG:Ce nanoparticles are also dispersed into a sol-gel matrix of TiO2. Thanks to the relative matching of refractive indexes between TiO2 and YAG, and to the sub-wavelength particles size, YAG/TiO2films are not scattering, contrary to the same film containing the commonly used micron size phosphor. Nevertheless, they are not absorbent enough. Thus, YAG:Ce suspensions are then spray-coated to obtain thicker and non diluted films. These films are a bit scattering but this can be solved by filling their porosity with a high refractive index matrix. A yellow component is detected when deposited onto a blue LED, meaning that they absorb much more than the YAG:Ce/TiO2 system. When used as light converters for white LEDs, these spray-coated films could offer the opportunity to diminish the backscattered light absorption losses.
© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Amelie Revaux, Geraldine Dantelle, Stewart Brinkley, Elison Matioli, Claude Weisbuch, Jean-Pierre Boilot, and Thierry Gacoin "YAG:Ce nanoparticle based converter layer for white LEDs", Proc. SPIE 8102, Nanoengineering: Fabrication, Properties, Optics, and Devices VIII, 81020R (23 September 2011);

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