High-Brightness Red-Emitting Phosphor La 3 (Si,Al) 6 (O,N) 11 :Ce 3+ for Next-Generation Solid-State Light Sources.

A novel high-brightness red-emitting phosphor, La3(Si,Al)6(O,N)11:Ce3+ (LSA) which can potentially be used for laser-excited light sources is demonstrated. Laser-excited phosphor system have great potential for use as white-light sources, as they are orders of magnitude brighter than white-LEDs. Although conventional yellow-green phosphors show excellent luminescent properties even under high-power laser-excitation, red-emitting phosphors, which are essential to achieve a high color-rendering-index and low color-temperature, show quantum efficiency quenching. This limits the output power in multi-phosphor excitation systems. Ce3+ should successfully tolerate high-power excitation due to the shortest emission-lifetime seen in rare-earth ions, caused by the 5d1-4f1 spin-allowed transition, however, a red-emitting Ce3+-doped phosphor of practical use has not been realized. LSA is described by the crystal-field modification of a yellow-emitting phosphor, La3Si6N11:Ce3+, with substitution of Al in Si sites. LSA shows 640-nm red-emission together with a tolerance for high-power excitation and thermal quenching, suggesting its significant potential for industrial applications that require ultra-high-brightness.