Monochromatic amber light emitting diode with YAG and CaAlSiN 3 phosphor in glass for automotive applications

Abstract

Monochromatic amber phosphor in glasses (PiGs) for automotive LED applications were fabricated with YAG:Ce 3+ , CaAlSiN 3 :Eu 2+ phosphors and Pb-free silicate glass. After synthesis and thickness-thinning process, PiGs were mounted on high-power blue LED to make monochromatic amber LEDs. PiGs were simple mixtures of 566 nm yellow YAG, 615 nm red CaAlSiN 3 :Eu 2+ phosphor and transparent glass frit. The powders were uniaxially pressed and treated again through CIP (cold isostatic pressing) at 200 MPa for 20 min to increase packing density. After conventional thermal treatment at 550°C for 30 min, PiGs were applied by using GPS (gas pressure sintering) to obtain a fully dense PiG plate. As the phosphor content increased, the density of the sintered body decreased and PiGs containing 30 wt% phosphor had full sintered density. Changes in photolu-minescence spectra and color coordination were investigated by varying the ratio of YAG/CaAlSiN 3 and the thickness of the plates. Considering the optical spectrum and color coordinates, PiG plates with 240 µm thickness showed a color purity of 98% and a wavelength of about 605 nm. Plates exhibit suitable optical characteristics as amber light-converting material for automotive LED applications.