Material properties of the Ce³⁺-doped garnet phosphor for a white LED application

Abstract

The 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 Ce 3+ -activated Y 3 Al 5 O 12 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, Y 3 Al 5 O 12 :Ce 3+ phosphor was synthesized through flux-assisted solidstate 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 D 50 was used. ARTICLE HISTORY

Saturation Mechanisms in Common LED Phosphors

“… 6 , 7 , 14 − 16 These materials can be made with a close to 100% internal quantum yield and prolonged LED operating hours without severe degradation. 17 − 20 …”

405-nm pumped Ce3+-doped silica fiber for broadband fluorescence from cyan to red

“…These Ce-doped materials has been used as scintillators and light emitters exploiting the allowed 5d-4f transition in Ce 3+ ions. 1,2 On one hand radiation detection has been the motivation to forward the research on scintillators; 3,4 and on the other hand Ce-doped silica fiber has been studied for non-invasive biomedical technique such as high resolution optical coherence tomography (OCT). 5,6 At the same time, Ce has been used with phosphors to achieve white light from light-emitting diodes.…”

The effect of BaF2 concentration and particle size distribution on the luminescence efficiency of YAG:Ce3+ phosphors

“…The luminescence spectrum of YAG:Ce 3+ phosphors is characterized by a maximum wavelength in the spectral range of 530-560 nm due to emission from the 5d level to the ground state 4f energy level of Ce 3+ [4]. The most common method for the commercial manufacturing of YAG phosphors is the solid-state reaction method (SSR) [5,6]. However, for the phosphors preparation using SSR methods is required a sufficiently long treatment at high temperatures (over 1500°C).…”