La luce del XXI secolo
I LED a luce blu, alla base delle moderne lampadine a bassissimo consumo, hanno valso il Premio Nobel per la fisica a Isamu Akasaki e Hiroshi Amano della Nagoya University e a Shuji Nakamura dell'Università della California Santa Barbara.
L'invenzione dei blu LED risale all'inizio degli anni '90 quando per la prima volta si è riusciti a generare un fascio di luce blu da materiali semiconduttori. Fino ad allora esistevano soltanto LED a luce rossa e verde che da soli non potevano generare una sorgente di luce bianca capace di fornire illuminazione efficiente e dai consumi estremamente ridotti.
Their inventions were revolutionary. Incandescent light bulbs lit the 20th century; the 21st century will be lit by LED lamps.
White LED lamps emit a bright white light, are long-lasting and energy-efficient. They are constantly improved, getting more efficient with higher luminous flux (measured in lumen) per unit electrical input power (measured in watt). The most recent record is just over 300 lm/W, which can be compared to 16 for regular light bulbs and close to 70 for fluorescent lamps. As about one fourth of world electricity consumption is used for lighting purposes, the LEDs contribute to saving the Earth's resources. Materials consumption is also diminished as LEDs last up to 100,000 hours, compared to 1,000 for incandescent bulbs and 10,000 hours for fluorescent lights.
The LED lamp holds great promise for increasing the quality of life for over 1.5 billion people around the world who lack access to electricity grids: due to low power requirements it can be powered by cheap local solar power.
