Robust thermal performance of Sr2Si5N8:Eu2+: An efficient red emitting phosphor for light emitting diode based white lighting

An important component to the advent of solid state lighting technology is the development of inorganic crystalline phosphors for efficient conversion of photons from blue light emitting diodes (LEDs) to other visible wavelengths for greater color rendering and "warmer" white lighting. We present the results of a recently developed rare earth doped nitride-based red emitting phosphor, Sr2Si5N8:Eu2+, combined with GaN-based blue emitting LEDs and YAG:Ce phosphor for improved white lighting applications. A unique remote phosphor packaging approach was used in all testing to isolate LED performance from phosphor performance. Luminous efficacies were achieved at 94 lm/W with an improved color rendering index (CRI) of 72, mixing red phosphor with YAG: Ce. The Sr2Si5N8:Eu2+ red emitting phosphor was found to have a low temperature sensitivity (only 28% power reduction at 150 degrees C) and greater luminous performance at low concentrations in the encapsulant by weight relative to other typical red emitting phosphors. (C) 2011 American Institute of Physics. [doi:10.1063/1.3666785]