Background Overview of Solid-State Lighting

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light sources

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.

This new white light source would change the way we live:

� 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.