| Project Detail |
The white light emitting diode (LED) has transformed the general lighting industry since its invention. Today, the most efficient white LEDs use a blue light emitting diode with a rare earth phosphor coating that down-converts some of the blue light to yellow, green and/or red to enable white lighting. The drawbacks are (1) the down-conversion process is inherently inefficient as the photons must lose some energy in the form of heat to convert to yellow and red photons, (2) rare earth phosphors are chemically unstable and add significant raw material and packaging cost (20%) to the device, and (3) blue LEDs suffer from “efficiency droop,” or decreasing efficiency at high temperatures. Today’s white light LEDs used in solid-state lighting (SSL) generate seven times more heat than light output. To have enough light output for general lighting purposes, multiple LED chips are used to maintain an acceptable efficiency, and the cost and form factor increase accordingly. Project Innovation + Advantages: The University of Illinois at Urbana-Champaign (UIUC) will pursue novel cubic gallium nitride-based green LEDs that, when combined with blue and red LEDs, will enable more efficient white light SSL without the use of down-converting phosphors. This project will close the “green gap” in the visible spectrum through an innovative green LED technology and create new opportunities in mainstream SSL (e.g., general lighting) and advanced SSL (e.g., connected smart lighting, visible light communication, horticulture, and medicine). Potential Impact: UIUC’s proposed technology could double the efficiency and halve the droop in green LEDs. |
