Two phosphor converted white LED with improved CRI

Most of the commercial white LED lamps use blue chip coated with yellow emitting phosphor. Use of blue excitable red and green phosphors is expected to improve CRI. Several phosphors such as SrGa2S4:Eu2+, (Sr,Ba)SiO4:Eu2+ have been suggested in the past as green components. However, there are issues of sensitivity and stability of such phosphors. Here, we describe gallium substituted YAG:Ce3+ phosphor as a green emitter. YAG structures are already accepted by the industry for the stability and efficiency. LED’s with improved CRI could be fabricated by choosing Y3Al4GaO12:Ce3+ (green and yellow) and SrS:Eu2+ (red) phosphors along with blue chip.