Efficient Blue-emitting Phosphor SrLu 2 O 4 :Ce 3+ with High Thermal Stability for Near Ultraviolet (~400?nm) LED-Chip based White LEDs

摘要

Blue-emitting phosphors for near ultraviolet (NUV) based tri-color RGB phosphor blend converted white light emitting diodes (LEDs) have been extensively investigated in the past few years. LED chip peaked near 400?nm is the most efficient among the NUV chips currently. However, most of blue phosphors show inefficient excitation around 400?nm. Herein, a novel blue phosphor SrLu2O4:Ce3+ matching well with near 400?nm chip and showing high thermal stability has been developed. The photoluminescence spectrum presents a broad emission band peaking at 460?nm with a bandwidth of nearly 90?nm. By optimizing the Ce3+ concentration, an internal quantum efficiency (IQE) as high as 76% was achieved. Furthermore, 86% of the room-temperature emission intensity is still maintained at 150?°C, indicating a good thermal stability and practicality. A series of white LEDs were fabricated based on 405?nm chips coated with a blend of the new blue phosphor with the commercial yellow and red phosphors. High color rendering indexes (≥90) were achieved while the correlated color temperature was tuneable in the range of 3094 to 8990?K. These results suggest that SrLu2O4:Ce3+ can be utilized as a blue-emitting phosphor in NUV based white LEDs.