Blue LED and Phosphor System Yield White Light

By combining a blue organic LED with a down-conversion phosphor system, researchers at General Electric Global Research Center in Niskayuna, N.Y., have created a white-light device that can deliver illumination over the range of color temperatures required for most lighting applications, between 3000 and 6000 K.

The down-conversion system -- which consists of perylene orange, perylene red and inorganic phosphor particles -- is deposited on the opposite side of a glass substrate from the active area of the blue LED. According to results published in the May 13 issue of Applied Physics Letters, at 5.5 V, the device achieved an electrical to optical power conversion efficiency of 1.3 percent at a brightness level of 1080 cd/m².