Thermally stable multi-color phosphor-in-glass bonded on flip-chip UV-LEDs for chromaticity-tunable WLEDs

Area of Science:

• Materials Science
• Solid-State Lighting
• Photonics

Background:

• White light-emitting diodes (WLEDs) are crucial for energy-efficient lighting.
• Existing WLEDs face challenges with thermal stability and color quality.
• Phosphor-in-glass (PiG) technology offers potential for improved WLED performance.

Purpose of the Study:

• To propose and demonstrate a thermally stable multi-color phosphor-in-glass (PiG) for chromaticity-tunable WLEDs.
• To investigate the fabrication and performance of PiG-based WLEDs.
• To evaluate the thermal stability and color quality of the developed WLEDs.

Main Methods:

• Screen-printing and co-sintering of red, green, and blue (RGB) phosphors on a glass plate at 600°C.
• Fabrication of an ultra-compact WLED by bonding the RGB-PiG onto a flip-chip ultraviolet (UV) LED.
• Tuning chromaticity by controlling RGB phosphor ratios, layer thickness, and phosphor-to-glass ratios.

Main Results:

• Achieved natural white light with a luminous efficacy of 27.8 lm/W, a correlated color temperature of 4245 K, and a color rendering index of 92.6.
• Demonstrated high thermal stability with only 4.7% luminous efficacy loss after 1000 hours of aging at 100°C.
• Showcased significantly better LE retention compared to phosphor-in-silicone WLEDs (14.6% loss).

Conclusions:

• The proposed multi-color PiG is a promising material for UV-excited WLEDs.
• The PiG technology enables high-performance, chromaticity-tunable WLEDs with excellent thermal stability.
• This approach offers a viable alternative to conventional WLED conversion methods.