Five-Surface Phosphor-in-Glass for Enhanced Illumination and Superior Color Uniformity in Large-View Scale LEDs

Area of Science:

• Materials Science
• Optoelectronics
• Solid-State Lighting

Background:

• Traditional phosphor-in-glass (PiG) LEDs often face limitations in illumination and color uniformity, particularly for large-view applications.
• Conventional phosphor-in-organic silicone materials can degrade under high temperatures, leading to lumen loss and chromaticity shifts.
• Developing robust and efficient light sources is crucial for advanced sensor, display, and automotive lighting.

Purpose of the Study:

• To demonstrate a novel five-surface phosphor-in-glass (FS-PiG) structure for enhanced LED performance.
• To evaluate the optical properties and reliability of FS-PiG LEDs compared to single-surface phosphor-in-glass (SS-PiG) LEDs.
• To explore the potential of FS-PiG LEDs as a replacement for conventional materials in high-power LED applications.

Main Methods:

• Fabrication of FS-PiG LEDs using YAG:Ce phosphor mixed with ceramic, sintered, and then laser-engraved to create saddle-shaped structures.
• Characterization of FS-PiG and SS-PiG LED performance, including illumination, correlated color temperature (CCT), and color coordinates (CIE).
• Accelerated aging tests at 350 °C for 1008 hours to assess lumen loss and chromaticity shift under thermal stress.

Main Results:

• FS-PiG LEDs achieved higher illumination (401 lm vs. 380 lm) and better color uniformity (CCT ±110 K, CIE ±0.003) compared to SS-PiG LEDs.
• FS-PiG LEDs demonstrated superior performance metrics, with 1.7x higher illumination, 7x better CCT stability, and 23x improved CIE uniformity over SS-PiG LEDs.
• Under accelerated aging, FS-PiG LEDs exhibited significantly lower lumen loss (2%) and chromaticity shift (5.4 × 10^-3) due to the high ceramic melting temperature.

Conclusions:

• The novel FS-PiG structure significantly enhances illumination and color uniformity in large-view scale LEDs.
• FS-PiG LEDs offer superior reliability and stability under high-temperature conditions compared to conventional SS-PiG LEDs.
• The proposed FS-PiG technology shows promise for next-generation high-power LEDs in sensor, display, and headlight applications.