Abstract
We proposed a flexible and mask-less approach to directly fabricate a patterned red phosphor layer on a Y3Al5O12:Ce3+ (YAG:Ce3+) phosphor-in-glass (PiG) for high-power white light-emitting diodes (WLEDs). This approach was realized by ultraviolet (UV) assisted and initiative cooling based water condensing. A low-temperature precursor glass matrix with a high refractive index was synthesized for the YAG:Ce3+ PiG. By controlling the UV pre-curing time, the micro-concaves with adjustable sizes were fabricated on the red phosphor layer embedded with UV-curable polymer. With the pre-curing time of 20 s, 30 s, and 40 s, the average aspect ratio of the micro-concave is 1.03, 0.76, and 0.41, respectively. Consequently, the patterned sample achieves a highest luminous efficacy (LE) of 108.5 lm/W at the current of 350 mA, which is 16.2% higher than the unpatterned sample. The corresponding correlated color temperature (CCT) and color rendering index (CRI) are 4831 K and 80.5, respectively. The results demonstrate that the YAG:Ce3+ PiG coated with the water condensing patterned red phosphor layer is a feasible and effective method to enhance the light extraction and color quality of high-power WLEDs.
Highlights
White light-emitting diodes (WLEDs) have been widely applied in display backlighting, street lamps, headlamps, and indoor illuminations due to their compact size, energy saving, environmental friendly, and long lifetime [1,2,3]
We have innovatively developed YAG:Ce3+ based PiG converter by introducing yellow YAG:Ce3+ phosphor embedded with borosilicate glass through screen-printing and low-temperature sintering, which yields cool white light with a luminous efficacy (LE) of 114 lm/W, a correlated color temperature (CCT) of 5524 K, and a color rendering index (CRI) of 69 [16,17]
The LE of these three patterned samples is increased of 11.7%, 16.2%, and 10.0%, respectively, compared with the unpatterned sample, which is attributed to increase in photon escape cone and reduction in total internal reflection (TIR) loss
Summary
White light-emitting diodes (WLEDs) have been widely applied in display backlighting, street lamps, headlamps, and indoor illuminations due to their compact size, energy saving, environmental friendly, and long lifetime [1,2,3]. “Chromaticity tailorable glass-based phosphor-converted white light-emitting diodes with high color rendering index,” Opt. Express 23(15), A1024–A1029 (2015).
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