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Dramatic changes are unfolding in lighting technology. Semiconductor light-emitting diodes (LEDs), until recently used mainly as simple indicator lamps in electronics and toys, have become as bright and efficient as incandescent bulbs. They have already begun to replace incandescent bulbs in many applications, particularly those requiring durability, compactness, cool operation and/or directionality (e.g., traffic, automotive, display, and architectural directed-area lighting). Moreover, further major improvements are believed achievable. Electrical-to-optical energy conversion efficiencies over 50% have been achieved in infrared light emitting devices. If similar efficiencies were achieved in visible light emitting devices, the result would be a 150-200 lm/W white light source two times more efficient than fluorescent lamps, and ten times more efficient than incandescent lamps.
· Worldwide electricity consumption due to lighting could be decreased by more than 50%, and total consumption of electricity could be decreased by more than 10%.
· Carbon emissions, and new capital infrastructure associated with electricity generation, would decrease proportionately, also by more than 10%.
· The human visual experience would be enhanced through digital and independent control over the color, intensity, and spatial distribution of lights. Along the way, compact visible and UV light sources, useful for water purification and detection of bio-agents will have been developed.
Yet, to realize this future, enormous challenges lie ahead. These challenges include:
· An improved understanding of the physics of AlGaInP and AlGaInN materials and nanostructures
· Improved optoelectronic devices for efficient photon generation and extraction
· Improved wavelength-conversion and color-mixing technologies for generation of white light
· Improved packaging technologies for high power lamps
· New lighting fixtures and systems based on the unique ways in which people can interact with solid-state lighting
· Development of the science and technology foundation for high-volume low-cost manufacturing
These are exciting and rewarding challenges that are engaging scientists, technologists and engineers in universities, national laboratories and industry throughout the world.