Color Tunable Composite Phosphor Ceramics Based on SrAlSiN3:Eu2+/Lu3Al5O12:Ce3+ for High-Power and High-Color-Rendering-Index White LEDs/LDs Lighting

Lu3Al5O12:Ce3+ phosphor ceramics were fabricated by vacuum sintering. On this basis, a bi-layer composite phosphor was prepared by low-temperature sintering to cover the phosphor ceramics with a layer of SrAlSiN3:Eu2+-phosphor-in-glass (PiG). The optical, thermal, and colorimetric properties of LuAG:Ce3+ phosphor ceramics, SrAlSiN3:Eu2+ phosphors and SrAlSiN3:Eu2+-PiG were studied individually. Combining the bi-layer composite phosphors with the blue LED chip, it is found that the spectrum can be adjusted by varying the doping concentration of SrAlSiN3:Eu2+-PiG and the thickness of Lu3Al5O12:Ce3+ phosphor ceramics. The maximal color rendering index value of the white LED is 86, and the R9 is 61. Under the excitation of a laser diode, the maximum phosphor conversion efficacy of the bi-layer composite phosphors is 120 lm/W, the R-a is 83, and the correlated color temperature is 4534 K. These results show that the bi-layer composite phosphor ceramic is a candidate material to achieve high color rendering index for high brightness lighting.