Material properties of the Ce ³⁺ -doped garnet phosphor for a white LED application

ABSTRACTThe luminous flux of the phosphor-converted white-light-emitting diode (WLED) is correlated to the optical properties of a phosphor, such as the excitation band, emission spectrum, and decay time. Also, the crystallinity, particle size, and morphology may influence the device performance, such as the luminous flux, as well as the device longevity and efficiency. The device application of the Ce3+-activated Y3Al5O12 garnet phosphor was limited because of its strong patent. Its patent is set to expire in the year 2017, and the high-power operation of the WLED is becoming important. To obtain insights regarding its usability, Y3Al5O12:Ce3+ phosphor was synthesized through flux-assisted solid-state reaction. It was found that this garnet phosphor has a very stable crystal structure and is inert in the processing environment. Its quantum yield reached 95%, and no photosaturation was shown within the measurement limit. It was also found that the synthetic procedures are very straightforward and that the particle size may be easily controlled. The luminous flux of the WLED was maximum when 17.7 µm D50 was used.