Ce:(Y_1-xLux )₃Al₅O₁₂ single-crystal phosphor plates for high-brightness white LEDs/LDs with high-color rendering (Ra > 90) and temperature stability

Ce:(Y1-xLux)3Al5O12 single-crystals are investigated in detail as phosphors for high-brightness LEDs and LDs. It is demonstrated that single-crystal phosphor plates (SCPPs) present very advantageous characteristics in comparison with standard powder phosphors. On the one side, the very high quantum efficiency of the SCPPs does not decrease with the temperature increase, and on the other side, the SCPPs possess a high thermal conductivity, so that these can be efficiently cooled to avoid device overheating. The optical properties of these SCPPs are investigated from room temperature to 300 °C. Ce:Y₃Al₅O₁₂ SCPPs are adequate for high-brightness cool white light sources. Instead, Ce:(Y_1-xLux)₃ Al5O12 SCPPs, whose emission shifts to the green with the Lu concentration, are very promising for neutral and warm white light sources in conjunction with a red-phosphor. It is shown that these white sources exhibit a color rendering over 90 for a wide range of excitation and SCPP emission wavelengths.