Development of high luminous efficacy red-emitting phosphor-in-glass for high-power LED lighting systems using our original low Tg and Ts glass

Abstract

Red-emitting phosphor-in-glass (PiG) materials with a high luminescence efficiency were developed by co-firing commercial red-emitting $({\rm Sr},{\rm Ca}){{\rm AlSiN}_3}\text{:}{{\rm Eu}^{2 + }}$ (SCASN) phosphor and our original glass frits with a composition of ${{\rm Li}_2}{\rm O} {-} {{\rm Na}_2}{\rm O} {-} {\rm ZnO} {-} {{\rm Al}_2}{{\rm O}_3} {-} {{\rm B}_2}{{\rm O}_3} {-} {{\rm P}_2}{{\rm O}_5}$, which has a low Tg (271°C) and Ts (380°C) temperatures. By optimizing the sintering temperature and the content of the phosphor, the highest luminous efficacy was obtained for the 3 wt.% SCASN-based PiG sintered at 400°C, which showed a luminous efficacy of 25 lm/W rad by combining the PiG materials with a blue light-emitting diode (LED) chip-on-board (COB, incident power = 100 mA). The internal quantum efficiency of this sample under excitation at 450 nm was 53%. The PiG-based LED maintained a high luminous efficacy when the incident power of the blue COB increased up to 5.5 W (47 lm).