NREL lasers used to analyze light emitting properties gallium indium phospate alloys
One day, LED lights will be common throughout your house. But right now they’re not only far too expensive, the quality of the light they give off basically stinks. NREL (the National Renewable Energy Laboratory) is working to change that. They’ve come up with a way to get LEDs to generate green light. That may not sound like a breakthrough, but in order to get LEDs to give off light that appears white and natural looking, you need at a minimum the colors red, blue, and green. Red and blue LEDs have been around for awhile now, but until now, nobody has been able to come up with a good green LED. (The LED lights that you can buy now fake the green part by aiming the blue light at a phosphor, which then emits green light. Not only does this trickery not look all that great, it also is a very inefficient process).
NREL researchers, led by Angelo Mascarenhas, used their expertise in the making of solar cells that capture light from across the color spectrum to develop the new LEDs. By tuning the layer of gallium indium phosphide in the LED, they were able to produce radiant deep green light on their very first try. Adding the new green LED to blue and red LEDs produces better quality and more efficient white light. For the next step, NREL is now trying to produce a fourth color to make the white light even whiter. They expect to be able to produce in a couple of years an LED that has a color-rendering index of over 90. By comparison, most CFLs have a color rendering index in the mid 80’s, and a normal incandescent light bulb has a color rendering index of about 95.