The EVATEG Center for Energy Efficient Electronics and Lighting Technology recently demonstrated a new optical extraction technology for RGB and phosphor LEDs that extends light extraction limits by more than 53%.
Conventional LED packages consist of a silicone-phosphorus mixture on top of a chip. This leads to significant optical losses due to refractive index mismatch, local heat transfer, and also due to local heating of the phosphor. EVATEG’s new idea increases light output by using a phosphor with a coating away from the chip under a glass dome, and lowers junction temperature with optothermal liquid cooling technologies.
A comprehensive comparison system of a conventional LED package (base) with an LED under an air-filled dome (1), a cured silicone dome (2) and a dome with an optothermal liquid (3), showed an increase in lumen output power of 23%, 40% and 53% by compared with the base, respectively.
In addition, this new idea brings the following key benefits over traditional approaches:
- Provides effective cooling for LED luminaires, reducing local temperature fluctuations;
- Simplifies complex lighting system designs;
- Significantly reduces the thermal resistance between the chip and the heatsink and results in high light emission;
- Lowers chip and phosphor junction temperature while increasing light output and lifetime;
- Higher conversion efficiency in phosphor with decreasing temperature;
- Eliminates color shifts due to temperature changes;
- Provides better refractive index matching, reducing optical loss.