ABSTRACT
Lighting has a great impact on the lifestyle of humans, architectural design, and the quality of building, as well as entertainment environments. Starting with ”re 500,000 years ago, lighting sources have consisted of gas/oil lamps, electric ”lament bulbs, and –uorescent tubes. The ”rst electric ”lament (incandescent) lamp was invented by Edison in 1879, producing only 1.4 lm/W. Although today’s incandescent lamp has the luminous ef”cacy of 15-25 lm/W, it generates more heat than light, with the ef”ciency of converting electricity into visible light being about 5%. The lighting industry was revolutionized by the introduction of the –uorescent lamp by General Electric (GE) in 1937; it now has a much higher luminous ef”cacy (60-100 lm/W) and conversion ef”ciency (~20%), as well as a longer lifetime (7,500-30,000 h), than the incandescent lamp (1,000 h). With increasing concerns about energy savings , environmental protection, and life quality, novel lighting sources that exhibit higher luminous ef”cacy, energy ef”ciency, and longevity are continuously pursued. Solid-state lighting (SSL) is considered the third revolution of the lighting industry, following the introduction of incandescent bulbs and –uorescent lamps. Solid-state lighting is a new lighting source that is based on semiconductor devices, with the light emitted by solid-state electroluminescence, which has great potential to signi”cantly surpass the energy ef”ciencies of incandescent and –uorescent lamps, and thus promises huge energy savings and reduction of greenhouse gas emissions.
