White light-emitting diodes (LEDs) using (oxy) nitride phosphors

(Oxy) nitride phosphors have attracted great attention recently because they are promising luminescent materials for phosphor-converted white light-emitting diodes (LEDs). This paper reports the luminescent properties of (oxy) nitride phosphors in the system of M-Si-Al-O-N (M = Li, Ca or Sr), and optical properties of white LEDs using a GaN-based blue LED and (oxy) nitride phosphors. The phosphors show high conversion efficiency of blue light, suitable emission colours and small thermal quenching. The bichromatic white LEDs exhibit high luminous efficacy (similar to 55 1m W-1) and the multi-phosphor converted white LEDs show high colour rendering index (Ra = 82-95). The results indicate that (oxy) nitride phosphors demonstrate their superior suitability to use as down-conversion luminescent materials in white LEDs.