"Smart" solid-state light sources now being developed not only have the potential to provide significant energy savings, but also offer new opportunities for applications that go well beyond the lighting provided by conventional incandescent and fluorescent sources, according to Rensselaer professors E. Fred Schubert and Jong Kyu Kim. In an article published May 27 in the journal Science, the authors describe research currently under way to transform lighting into "smart" lighting, with benefits expected in such diverse fields as medicine, transportation, communications, imaging, and agriculture.

The ability to control basic light properties — including spectral power distribution, polarization, and color temperature — will allow "smart" light sources to adjust to specific environments and requirements and to undertake entirely new functions that are not possible with incandescent or fluorescent lighting. For example, "smart" solid-state light sources have the potential to adjust human circadian rhythms to match changing work schedules, to allow an automobile to imperceptibly communicate with the car behind it, or to economically grow out-of-season strawberries in northern climates, according to Professors Schubert and Kim.

Solid-state lighting sources such as light-emitting diodes (LEDs) already offer energy savings and environmental benefits compared to traditional incandescent or fluorescent lamps, say Schubert, the Wellfleet Senior Constellation Professor of the Future Chips Constellation, and Kim, a post-doctoral fellow. Fundamental principles of physics place far greater limits on the efficiency of incandescent and fluorescent lights than on solid-state lights. In theory, solid-state devices with perfect materials and designs would require only 3 watts to generate the light obtained from a 60-watt incandescent bulb.

Solid-state sources potentially could cut in half the 22 percent of electricity now consumed by lighting. Traffic lights using LEDs, for example, use only one-tenth the power of signals using incandescent lamps. Further development of solid-state sources to replace traditional lighting will reduce energy consumption and dependency on oil and decrease emissions of greenhouse gases, acid-rain-causing sulphur dioxide, and mercury.

However, it is the possibility of controlling such basic properties of solid-state lighting as spectral content, emission pattern, polarization, color temperature, and intensity that gives these light sources the ability to provide entirely new functions. To achieve these benefits, according to Schubert and Kim, improvements are needed in materials, device design and fabrication, and packaging of solid-state components into lamps and luminaires.

Press Release

Published June 6, 2005