Cooking up new nanoribbons to make better white LEDs
growing in popularity. They use significantly less energy and have far longer lifetimes than do the traditional incandescent bulbs, which are being phased out, and they don't contain mercury, as do compact fluorescents. LEDs do have a drawback, however. The phosphors that convert the single color produced by an LED into white light tend to produce a cool, bluish glow instead of the warmer, yellower color most people prefer.