White LED wins DISCOVER award for technical innovation

17 Jun 2002

Fred Schubert of Boston University's Photonics Center is among the eight technological visionaries who have been named winners of the Eleventh Annual DISCOVER Magazine Awards for Technological Innovation, presented by the Christopher Columbus Fellowship Foundation.

Called a photon recycling semiconductor light-emitting diode, (PRS-LED), Schubert's invention combines up to three different wavelengths of light to produce a highly efficient, long-lasting white light suitable for many lighting situations. PRS-LED lighting has a very long life expectancy, and is very efficient, running at a fraction of the cost of today's conventional light bulbs. It is likely to someday soon replace the incandescent, fluorescent, and sodium vapor lights now in use and become common sources of artificial light in homes and in public spaces.

LEDs in use today have one active region and produce a single color of light - Schubert's PRS-LED utilizes at least two active regions. The first region, made of gallium indium nitride (GaInN), takes an electrical current, and converts it to photons in the blue range. Some of these photons are then redirected to a second active region, made of aluminum gallium indium phosphide (AlInGaP), that absorbs the light and re-emits it at a different wavelength, producing photons in the yellow/orange/red range.

The two wavelengths are chosen so that when combined they are perceived as white light by the human eye. By changing the active regions to produce different wavelengths, the PRS-LED can be configured to produce hundreds of different colors.

The PRS-LED is 15 to 20 times more efficient than conventional light bulbs, theoretically producing white light with an efficiency exceeding 300 lumens per Watt. Since GaInN is one of the most stable chemical compounds available, nearly as stable as diamond, the PRS-LED is also very reliable. It is predicted that a lighting device based on this technology will be able to last as long as 50 years in normal household use. NA

Further information about Professor Schubert and his work

Story courtesy of Opto and Laser Europe magazine.