It’s Not Easy Being Green

by Michael Mullaney on May 11, 2011

In a recent post, I briefly mentioned the work of physics professor Christian Wetzel to develop high-power green LEDs.

The hunt for the elusive green LED is one of my favorite research endeavors here at Rensselaer. It’s intriguing, intuitive, and the green color is loaded with rich sustainability symbolism. Here’s the gist:

Think of your TV or computer monitor. New and old. The screens produce every color imaginable using three colors: red, blue, and green. In old-school CRT TVs and monitors, a trio of electron guns produced red, blue, and green phosphor dots that were bent, spun, and stretched into moving images on the screen. In modern flatscreen LCD – liquid crystal display– TVs and monitors, white light from subpixels is passed through red, blue, and green filters to create pixels in more than 16 million colors. These pixels make up the larger picture we’re viewing.

That brings us to LEDs. We have high-power blue LEDs and high-power red LEDs. But no green. Once we build green LEDs that are on par with their red and blue cousins, no doubt we’ll start to see a whole new generation of LED TVs and displays. Not LCD displays with a LED backlight, which you’ll find on the market today misleadingly labeled as LED TVs. But true, honest-to-goodness LED displays that are longer lived and much, much cheaper and energy efficient to run than the LED displays we use today.

And that’s only the beginning. Once we have a high power green LED, we can combine it with red and blue to create true white LEDs – the kind of white lights we like to use to illuminate our homes and workplaces. This could spell the quick demise of conventional light bulbs. The white LEDs you may see today on keychains, in supermarket freezers, or headlights are actually blue LEDs with a coating that strips out most – but not all – of the blue. That’s why they always have a bluish tint.

Click here and here to read all about Wetzel’s efforts to “close the green gap” in LEDs.

Also, check out the video below: